PSD11: The 11th International Conference on Position Sensitive Detectors

Europe/London
The Open University, Milton Keynes, UK.

The Open University, Milton Keynes, UK.

The Open University, Walton Hall, Milton Keynes. MK7 6AA, UK.
Description

The 11th International Conference on Position Sensitive Detectors featured the latest developments in position sensitive detectors from leading researchers around the world and across a wide range of scientific disciplines. The conference has a strong multidisciplinary bias and encourages cross-fertilisation and transfer of ideas between researchers working in many different fields. Keynote speakers gave overviews of latest developments and challenges for the future.

Further details of the conference can be found on the PSD11 Conference Website at: www.psd11.co.uk.

The conference photo can be found here.

Please see the letter below titled "PSD11 Instructions for Authors".  This gives instructions on how to submit your paper for the Journal of Instrumentation (JINST); submission of papers will be handled through the JINST website: http://jinst.sissa.it.  The deadline for the submission of papers has been extended to 30th September 2017.

Support
• Sunday, 3 September
• 17:00 21:00
Welcome drinks reception 4h Kents Hill Park (first floor foyer) ()

Kents Hill Park (first floor foyer)

Timbold Dr, Kents Hill, Milton Keynes MK7 6BZ

Drinks and nibbles will be available on the first floor of Kents Hill Park (near to the Open University).

A hot meal will be available to purchase at the Kents Hill Park restaurant from 7pm until 9pm.

• Monday, 4 September
• 08:45 09:00
Opening address by Peter Horrocks (VC) 15m Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 09:00 10:30
Detectors for ground and space-based astronomy, planetary and space science (I) Berill Lecture Theatre (OU) ()

Berill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 09:00
Detectors and imagers for planetary exploration missions 30m

In the last 50 years many spacecrafts have explored all major planets and many other small planetary objects within our solar system. Most of the missions are based on remote-sensing instruments to globally explore the physical-, chemical and geological nature of the planetary objects. Many recent and future missions will explore our solar system by landers and rovers with in-situ instrumentation or by sampling mission in order to bring sampling probes back to our Earth for more detailed analysis at our home-laboratories.
In nearly all of the missions electro-optical instruments and particularly imaging instruments play a major role.

The key components of all electro-optical and imaging instruments are the optical subsystem (e.g. the lens or telescope), the detectors and the associated detector electronics.

This talk shall give an overview about past and recent developments of VIS/NIR detectors and imagers for planetary exploration missions with some emphasis to European instrumental contributions. It will also give an outlook about some future missions and their imaging sensors.

Speaker: Harald Michaelis (DLR)
• 09:30
High-Energy 3D Calorimeter for Use in Gamma-ray Astronomy based on position-sensitive virtual Frisch-grid CdZnTe (CZT) detectors 20m

We will present a concept for a calorimeter based on a novel approach of 3D position-sensitive virtual Frisch-grid CZT detectors. This calorimeter aims to measure photons with energies from ~100 keV to 20- 50 MeV. The expected energy resolution at 662 keV is better than 1% FWHM, and the photon interaction position-measurement accuracy is better than 1 mm in all 3 dimensions.
Each CZT bar is a rectangular prism with typical cross-section of 6x6 mm2 and length of 2-4 cm. The bars are arranged in modules of 4 x 4 bars, and the modules themselves can be assembled into a larger array. The 3D virtual voxel approach solves a long-standing problem with CZT detectors associated with material imperfections that limit the performance and usefulness of relatively thick detectors (i.e., > 1 cm). Also, it allows us to relax the requirements on the quality of the crystals, while maintaining the same energy resolution and significantly reducing the instrument cost.
Such a calorimeter can be successfully used in space telescopes that use Compton scattering of gamma rays, such as AMEGO, serving as part of its calorimeter and providing the position and energy measurement for Compton-scattered photons (like a focal plane detector in a Compton camera). Also, it could provide suitable energy resolution to allow for spectroscopic measurements of gamma-ray lines from nuclear decays. Another viable option is to use this calorimeter as a focal plane to conduct spectroscopic measurements of cosmic gamma-ray events. In combination with a coded-aperture mask, it potentially could provide mapping of the 511-keV radiation from Galactic Center.

Speaker: Dr Alexander Moiseev (CRESST/NASA/GSFC and University of Maryland)
• 09:50
The All-sky Medium Energy Gamma-ray Observatory (AMEGO) 20m

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is an Astrophysics Probe mission concept designed to explore the MeV sky. It has a unique capability to cover with high sensitivity both the Compton and pair conversion regimes from ~200 keV to >10 GeV. To date the MeV regime remains a poorly explored window on the Universe, and promises a rich return similar to what Fermi-LAT achieved in the GeV band.

The AMEGO instrument features an anti-coincidence detector, a double-sided Silicon microstrip tracker with analog readout, a segmented CZT calorimeter optimized for the Compton regime, and a segmented CsI calorimeter optimized for the pair regime. This design choice provides substantial performance improvements relative to the predecessors in both energy bands, namely CGRO-COMPTEL and Fermi-LAT. In particular, the detector is tailored to the challenging task of imaging
Compton events with unprecedented resolution.

On behalf of the AMEGO Team (https://asd.gsfc.nasa.gov/amego/team.html).

Speaker: Riccardo Rando (University and INFN Padova)
• 10:10
High frame rate and low noise CMOS WaveFront imager for E-ELT Adaptative Optics 20m

The European Southern observatory’s extremely Large Telescope (E-ELT) will allow the search for exoplanets, drastically advance astrophysical knowledge (super-massive black holes or the nature and distribution of the dark matter for instance) and to study far distant galaxies. This telescope uses sophisticated Adaptive Optics systems and the laser/Natural guide star WaveFront imager is a very critical component of this system. The WaveFront imager is composed of 800x800 pixels of 24μm2. It is to used detect multiple sub-images from the guide star in a way that allows the centroid of each sub-image to be accurately found. Both natural and laser guide stars produce a very low signal on the detector. This requires the detector to be low read noise (<3e-), low lag (<2e- at 100e- charge capacity), highly linear at low signals, to have a very high QE (> 90%) and to operate at -10oC. This detector also needs to operate at high frame rate of 700 frames per second to enable the monitoring of rapid atmospheric fluctuations. All these requirements makes the design of this imager very challenging. To achieve this performance a CMOS back illuminated technology has been selected for this imager.

This presentation will focus of the design details of this CMOS WaveFront imager. The architecture and the column ADC approach to reach low noise at high frame rate will be discussed. The lag and QE performance versus temperature will be presented. Finally, the design of the Peltier package challenges will be discussed.

Speaker: Jerome Pratlong (Teledyne e2v)
• 10:30 11:00
Tea and coffee 30m Berill Foyer (OU) ()

Berill Foyer (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 11:00 12:50
X-ray and gamma-ray detectors Berill Lecture Theatre (OU) ()

Berill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 11:00
Chromatic X-ray imaging with a fine pitch CdTe sensor coupled to a large area photon counting pixel ASIC 30m

An innovative X-ray imaging sensor based on Chromatic Photon Counting technology
with intrinsic digital characteristics is presented. The system counts individually the incident X-ray photons and selects them according to their energy to produce two color images per exposure. The energy selection occurs in real time and at radiographic imaging speed (GHz global counting rate).
Photon counting, color mode and a very fine spatial resolution (more than 10 LP/mm at MTF50) allow to obtain a high ratio between image quality and absorbed dose. The individual building block of the imaging system is a two-side buttable semiconductor radiation detector made of a thin pixellated CdTe crystal coupled to a large area VLSI CMOS pixel ASIC. Modules with 1, 2, 4, and 8 block units have been built. The largest module has 25x2.5 cm2 sensitive area. Results and images obtained from testing different modules are presented.

Speaker: Ronaldo Bellazzini (INFN Pisa)
• 11:30
Performances of depleted Monolithic Active Pixel Sensor in a high-resistivity CMOS process for X-ray detection 20m

We discuss the performances measured in laboratory of a MAPS prototype we developed with a pixel architecture allowing substrate depletion from the front side. The sensor was fabricated in a 180 nm CMOS Image Sensor Technology and features 4 matrices of 16 x 128 pixels with 22 x 22 µm² pitch. For all matrices, the charge sensing diode is AC-coupled to a source follower or amplifier and is biased through a forward diode connected to the high voltage. Analogue pixel values are read out with a rolling-shutter steering.

The chips were produced over two types of high-resistivity substrates: 18 µm epitaxial layer (> 1 $k\Omega \cdot cm$), and 200 µm Czochralski (>600 $\Omega \cdot cm$). Front-side measurements using a monochromatic X-ray $^{55}$Fe source and ß-ray $^{90}$Sr source have been conducted on chilled sensors to evaluate the noise, gain, energy resolution and charge collection for applied bias up to 40 V. Energy resolution (FWHM) of 300 eV for the epitaxial layer and 490 eV for the Czocharlski substrate were obtained for 5.9 keV X-rays.

For the epitaxial layer version, our tests indicate that full depletion is achieved for bias below 20 V, in line with predictions from TCAD simulations. Sensors were irradiated with various neutron fluences up to $5\cdot10^{14}$ neq/cm2. We will report on the mild performance degradation observed under these conditions.

The TCAD simulation of the 200 µm thick Czochralski substrate predicts a depleted depth of a few tens of micrometers, largely depending on the actual value of the resistivity assumed. However sensors thinned to 50 µm (the CMOS process occupying the top 10 µm) were also characterized in backside illumination condition, targeting the efficient detection of soft X-rays. We will present our conclusion considering a model for the charge collection within the depleted substrate.

Speaker: Julian Heymes (IPHC)
• 11:50
Processing of Cadmium Telluride (CdTe) X-ray pixel detectors 20m

We report a fabrication process of pixel detectors made of bulk Cadmium Telluride (CdTe) crystals. Prior the processing the quality and defect density in CdTe material was characterized by infrared (IR) spectroscopy. The semiconductor detector and Flip-Chip (FC) interconnection processing was carried out in clean room premises of Micronova center in Espoo, Finland. The chip scale processes consist of the aluminum oxide (Al2O3) low temperature thermal Atomic Layer Deposition (ALD), titanium tungsten (TiW) metal sputtering depositions and an electroless Nickel growth. The CdTe crystals the size of 10 × 10 × 0.5mm3 were patterned with several photo-lithography techniques. In this study, gold (Au) has been chosen as the material for the wettable Under Bump Metallization (UBM) pads. The application-specific integrated circuits (ASIC) PSI46dig read out chip (ROC) with double 80 pixel columns and 26 rows resulting in 4160 pixels in 1 cm2 area. Indium (In) based metallurgy solder bumps were grown on the CdTe detectors using a low temperature FC bonding technique. The In-Au cold weld bonding connections were successfully connecting both elements.
After the processing the detector packages were wire bonded into associated read-out electronics. The pixel modules were tested at the premises of Finnish Radiation Safety Authority (STUK). During the measurement campaign, the modules were tested by exposure to a Cs137 source of 1.5 TBq for 8 minutes. We detected at the room temperature a photopeak at 662keV with about 7% energy resolution.

Speaker: Ms Akiko Gädda (Helsinki Institute of Physics (HIP), Helsinki, Finland. Advacam Oy, Espoo, Finland)
• 12:10
Detector requirements for single mask edge illumination x-ray phase contrast imaging applications 20m

X-ray phase contrast imaging (XPCI) detects signals arising from the phase shifts suffered by x-rays as they traverse matter. Unlike other approaches, Edge illumination (EI) XPCI can be implemented with large focal spot and polychromatic (i.e. conventional) sources. It normally employs a pre-sample and a detector mask: the first splits the beam into a series of beamlets, and the second partially intercepts them. The detector mask redefines the pixel response, making it maximally sensitive to phase effects. However, multiple frames have to be acquired while displacing the pre-sample mask in two or more positions to retrieve signals relating to different physical properties of a sample, which increases the acquisition time, dose and potential errors in the acquired data, potentially hindering the translation of XPCI methods to “real-world” applications. Recent developments have focused on eliminating the detector mask by exploiting the advantages offered by state-of-the-art direct conversion detectors, i.e. increased efficiency, high-resolution, and sharper point spread functions (PSFs), while extracting multiple signals in a single shot. These “single mask” EI (SM-EI) approaches can be implemented in either the “position-sensing” (PS) or “beam-tracking” (BT) modes. The former uses the edge between neighbouring detector pixels to directly “sense” the beam position, and translates it into separated attenuation and refraction signals. A wave optics model of the PS set-up was developed and benchmarked against experimental data, which enabled studying the refraction sensitivity as a function of detector PSF. In order to retrieve an additional, complementary contrast channel (known as “dark-field”), however, detectors with higher granularity are required to “track” beam variations in more detail (BT setup). This approach has been demonstrated for both synchrotron and conventional sources, in both planar imaging and computed tomography applications. This talk will present an overview of the two SM-EI approaches and some of their key results.

Speaker: Gibril Kallon (University College London)
• 12:30
Detectors for use with high-intensity laser-driven sources of radiation 20m

High intensity lasers, such as the Vulcan and the Gemini Lasers at the Rutherford Appleton Laboratory, can be used to generate high-intensity ultra-short pulses of energetic radiation. The advent of new high-repetition laser technology, such as DIPOLE, make laser driven radiation a potential source for future science facilities and industrial applications. The characterisation and exploitation of the laser driven radiation sources require specific and customised detector technologies to match the short, repeated pulses of high energy X-rays.
We present results from two detector systems being used to separately measure the spectrum of the emitted x-rays and image the laser source from a single laser shot. The first is a 10cm x 10cm position sensitive energy resolving detector based on the HEXITEC ASIC. The detector is comprised of 25 CdTe sensors arranged in a array with a total of 160k energy resolving pixels that can each measure a single X-ray photon per laser shot and can be combined to give an energy spectrum per shot with <2keV FWHM energy resolution in the 10-200keV range. The second detector is made from 2x2 Lassena wafer scale CMOS monolithic active pixel sensors with an active area of 24cm x 28cm and 27 MPixels. A 1mm thick CsI(Tl) scintillator is mounted directly onto the Lassena sensors to maximise detector efficiency for energies of 100 to 150 keV while maintaining adequate spatial resolution. The sensor operates with a full frame rate of up to 30 fps and is operated in a triggered mode to capture images from single laser shots to image the X-ray beam. We also present potential detector designs based on these technologies that would allow the full range of radiation that can be generated from these laser driven sources to be measured.

Speaker: Sion Richards (Science & Technology Facilities Council)
• 12:50 14:10
Lunch 1h 20m Hub Theatre (OU) ()

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Lunch will be served a short walk from the Berrill Theatre in the second of the conference's main venues, the Hub Theatre.

• 14:10 15:40
Detectors for synchrotron and free electron laser radiation (I) Berill Lecture Theatre (OU) ()

Berill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 14:10
Hybrid pixel detector developments for Synchrotrons and Free Electron Lasers at the Paul Scherrer Institut 30m

The X-ray detector group at the Paul Scherrer Institute (PSI), Switzerland, has a long history in hybrid detector developments for use at the Swiss Light Source (SLS) and other synchrotrons worldwide. One of the developments for synchrotrons is the EIGER single photon counting detector, which is characterized by 75$\times$75~$\mu$m$^2$ pixels and a frame rate as high as 23~(6)~kHz for a 4~(12) bit counter. Detector systems ranging from 0.5 to 9~Mpixels are being integrated into beamline operations. Some experimental results and challenges for large area detector operations will be presented. EIGER has also proved to be a competitive detector for electrons with energy ranging from 8$-$20~keV in photo-emission electron microscopes and from 100$-$300~keV in transition electron microscopes. Measurements will be presented.

The construction of the Swiss Free Electron Laser (Swiss-FEL) at PSI and other FELs worldwide has shifted developments towards charge integrating detectors, which are able to sustain a high number of photons in pulses with length of order of tenth of fs. The versatile JUNGFRAU detector has 75$\times$75~$\mu$m$^2$ pixels, like EIGER. It is characterized by single photon resolution and high dynamic range. These characteristics can be simultaneously achieved through a dynamic gain switching mechanism. Details on the detector concept and results on the characterization will be shown. Although JUNGFRAU has been designed for FEL applications at photon energies in the 2$-$20 keV range, a frame rate as high as 2~kHz enables the use of the JUNGFRAU detector also at synchrotron sources like the SLS. The use of charge integrating systems for synchrotron applications will allow to sustain higher incoming photon rates per pixel, which have to be limited when single photon counting systems are used. Pros and cons of the use of both technologies at synchrotrons will be presented.

Finally, the M\"{O}NCH charge integrating detector, characterized by small pixels of $25 \times 25$~$\mu$m$^2$, will be shown. This research project is meant to investigate perspectives for hybrid detectors with high spatial resolution thanks to the small pixel size and low noise, which allows to detect soft X-rays at synchrotrons and FELs. Moreover, by exploiting the charge sharing effect, the sub-pixel spatial resolution is achieved and opens possibilities for high resolution imaging at synchrotrons and with X-ray tubes.

Speaker: Dr Gemma Tinti (Paul Scherrer Institute)
• 14:40
AGIPD detectors - fast cameras for the experimental stations of the European XFEL 20m

AGIPD is an Adaptive Gain Integrating Pixel Detector designed in a collaboration between Deutsches Elektronen-Synchrotron (DESY), Paul-Scherrer-Institut (PSI) and the Universities of Hamburg and Bonn. It is a hybrid pixel X-ray detector developed for the European XFEL, whose key features will be the high brilliance coherent pulses with a specific bunch structure. 2700 pulses in a bunch-train will be separated by 220 ns from each other with a 99.4 ms between the bunch-trains. One of the aims of the detector is to catch as many consecutive pulses out of the bunch-train as possible. The other important requirement is the dynamic range, starting from single photon sensitivity up to 10^4 12.5 keV photons. In order to the fulfill mentioned requirements a radiation tolerant Application Specific Integrated Circuit (ASIC) is designed. Each pixel has a fast charge-sensitive preamplifier, providing the possibility to write the image data into one of 352 random-access analogue memory cells at a 4.5 MHz frequency. The preamplifier uses an adaptive gain technique allowing a reduction of the gain with respect to the input charge and thus extending the dynamic range. Some additional techniques like correlated double-sampling and double-column readout are also used. Over about 10 years of the project more than 5 multi-project wafer and 2 engineering runs were made in order to characterize and improve the ASIC performance and calibration possibilities.

A hybrid module, consisting of a silicon sensor bump bonded to 16 ASICs, has 128x512 pixels 200x200 µm2 each, and is served by back-end electronics. The 1M pixel detector incorporates four quadrants of 4 modules each, operating in vacuum. Two systems will be installed at the SPB and MID experimental stations of the European XFEL. A 4M version for the SFX experimental station is now under development. Assembly, calibration and integration efforts will be presented.

Speaker: Alexander Klyuev (Deutsches Elektronen-Synchrotron)
• 15:00
LAMBDA 2M GaAs – A multi-megapixel hard X-ray detector for synchrotrons 20m

Synchrotrons provide very intense and focused X-ray beams, which can be used to study the structure of matter down to the atomic scale. In many experiments, the quality of the results depends strongly on detector performance; in particular, experiments studying changes in samples over time require fast, sensitive X-ray detectors.

“LAMBDA” is a photon-counting hybrid pixel detector system for synchrotron experiments, based on the Medipix3 readout chip. Its main features are a combination of relatively small pixel size (55µm), high readout speed at 2000 frames per second with no time gap between images, a large tileable module design, and compatibility with high-Z sensors for efficient detection of higher X-ray energies.

A large LAMBDA system for hard X-ray detection has been built using Cr-compensated GaAs as a sensor material. The system is composed of 6 GaAs tiles, each of 768 by 512 pixels, giving a system with approximately 2 megapixels and an area of 8.5 by 8.5 cm$^2$. While the sensor uniformity of GaAs is not as good as that of silicon, its behaviour is stable over time, and it is possible to correct nonuniformities effectively by postprocessing of images. By using multiple 10 Gigabit Ethernet data links, the system can still be read out at the full speed of 2000 frames per second.

The system has been used in hard X-ray experiments studying the atomic-scale structure of samples under extreme pressure in diamond anvil cells. These experiments can provide insight into geological processes. Thanks to the combination of high speed readout, large area and high sensitivity to hard X-rays, it is possible to obtain useful information about atomic-scale structure on a millisecond timescale during rapid changes of pressure or temperature.

Speaker: David Pennicard (DESY)
• 15:20
Using EMCCDs with centroiding to achieve better than 5 µm spatial resolution for soft X-ray RIXS 20m

Advancement in synchrotron and free electron laser facilities means that X-ray beams with higher intensity than ever before are being created. The high brilliance of the X-ray beam, as well as the ability to use a range of X-ray energies, means that they can be used in a wide range of applications. One such application is Resonant Inelastic X-ray Scattering (RIXS).

RIXS uses the intense and tunable X-ray beams in order to investigate the electronic structure of materials. The photons are focused onto a sample material and the scattered X-ray beam is diffracted off a high resolution grating to disperse the X-ray energies onto a position sensitive detector. Whilst several factors affect the total system energy resolution, the performance of RIXS experiments can be limited by the spatial resolution of the detector used. Electron-Multiplying CCDs (EMCCDs) at high gain in combination with centroiding of the photon charge cloud across several detector pixels can lead to sub-pixel spatial resolution of 2-3 µm.

X-ray radiation can cause damage to CCDs by displacement of an atom in the crystal lattice, as well as the creation of surface traps due to dangling bonds at the Si-SiO2 interface. Understanding the effect of radiation damage on EMCCDs is important in order to predict lifetime as well as the change in performance over time. Two CCD-97s were taken to PTB at BESSY II and irradiated with large doses of soft X-rays in order to probe the front and back surfaces of the device. The dark current was shown to decay over time with two different exponential components to it.

The paper will discuss the use of EM-CCDs for readout of RIXS spectrometers, and limitations on spatial resolution and pileup-limited count rate, together with any limitations on instrument use which may arise from X-ray-induced radiation damage.

Speaker: Mr David Gopinath (The Open University)
• 15:40 16:30
Industrial exhibit (with tea and coffee) 50m Berrill Foyer, ground and first floor (OU) ()

Berrill Foyer, ground and first floor (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The industrial exhibit will be open on the first floor outside of the lecture theatre.

• 16:30 18:30
Sensor development Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 16:30
3D sensors 30m

3D sensors have a been successfully installed in the innermost pixel layer of the ATLAS Detector at the CERN-LHC in 2014, after 20 years of the proposal of the original idea, and are currently being considered for all the major LHC detector upgrades. In the 3D design electrodes are processed inside the silicon bulk rather than being implanted on the wafer's surface. This results in an improved speed and signal efficiency after irradiation due to the strong and homogeneous electric field throughout the full sensor thickness and allows for the presence of active edges with sensitivity up to the device physical edge. This presentation will highlight the technology state of the art, the future trends and applications of 3D sensors in high energy physics and other fields.

Speaker: Dr Cinzia Da Via (University of Manchester (GB))
• 17:00
High Performance Infrared Imaging Sensors, Basic Principles to the State-of-the-Art 30m

The universe is an amazingly huge place. While humankind has directly explored Earth’s sister planets with space probes, we don’t have the means to venture beyond the solar system, and so almost all information about the universe comes from sensing light that happens our way. Astronomy is constantly striving to find better ways to sense the feeble amount of energy from distant stars and galaxies. This quest has led to a new generation of very large telescopes (10-m diameter) on the ground and the deployment of the 2.4-meter Hubble telescope in space. Ground-based astronomy has commenced construction of an ambitious generation of 30-meter class Extremely Large Telescopes, and the James Webb Space Telescope’s 6.5-meter mirror will launch in 2018.

Possibly more important than the development of bigger telescopes is the rapid advancement in solid state detector technology. The detector revolution was led by silicon CCDs starting in the 1970’s for sensing visible light, but the materials that were developed during the past three decades for sensing infrared light have made the most significant difference in astronomy. Long before the CCD, astronomers could detect visible light with the human eye and photographic plates, but until recently, infrared astronomy was not possible.

This paper presents the basic principles of high performance infrared imaging sensors, including the physics of detector materials, the electronic readout circuitry, and the packaging that is required to keep the detector flat and not self-destruct during cooling to the cryogenic temperature of operation.

In addition to presenting astronomical detectors which are optimized for low light level long exposures, this paper will cover the design of sensors used for Earth Science and laboratory instrumentation, for which the light levels and frame rates are much higher than needed for astronomy.

Speaker: Dr James Beletic (Teledyne Imaging Sensors)
• 17:30
Teledyne-e2v - recent developments in CCD and CMOS sensors and characterisation techniques 30m

This paper will summarise new developments in CCD and CMOS imagers predominantly for astronomy applications.

Also in this paper characterisation techniques used by Teledyne e2v will be described. Often device performance can be optimised for different applications and these techniques can help find the best operating point.

Speaker: Dr Doug Jordan (Teledyne-e2v)
• 18:00
Sensor Development at MPG HLL 30m

Since more than twenty years the semiconductor laboratory of the Max-Planck Society (MPG HLL) is developing high-performing, specialised, scientific Silicon sensors including the integration of amplifying electronics on the sensor chip. This presentation summarises the actual status of these devices like pnCCDs and DePFET Active Pixel Sensors and their applications.

Speaker: Alexander Bahr (MPG HLL)
• 18:30 20:30
Industrial exhibit and drinks reception 2h Berrill Foyer, first and ground floor (OU) ()

Berrill Foyer, first and ground floor (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• Tuesday, 5 September
• 08:30 11:25
Position sensitive detectors for extreme and other environments Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 08:30
The Tynode: a new vacuum electron multiplier for ultra fast pixelised particle detectors 30m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

By placing, in vacuum, a stack of transmission dynodes (tynodes) on top of a CMOS pixel chip, a generic, digital, single free electron detector could be made with potentially a ps time resolution. Its essential element is the tynode: an ultra thin membrane, which emits, at the impact of an energetic electron on one side, a multiple of electrons at the other side. The tynode’s electron yields have been
calculated by means of GEANT-4 Monte Carlo simulations, applying special low-energy extensions. The results are in line with another simulation based on a continuous charge-diffusion model. By means of MEMS technology, tynodes and test samples have been realised. The secondary electron yield of several tynode prototypes have been measured in three different stations. Our best result so far
is a transmission secondary electron yield of 5.5, obtained with an MgO membrane made using Atomic Layer Deposition ALD technology. Several possibilities to improve the yield are presented. A prototype soft photon detector, based on a stack of tynodes placed in a Planacon (Photonis) detector, is now under construction. This new photon detector may outperform SiPMs in terms of time resolution and absence of noise. Its efficiency, however, is limited by the Quantum Efficiency (QE) of the photocathode. The QE of modern photocathodes never exceeds 50%. We propose the development of a MEMS-made active photocathode in which the absorption/conversion layer is biased with an electric field, forcing
migrating electrons towards the emission side.

Speaker: Harry Van Der Graaf (Nikhef National institute for subatomic physics (NL))
• 09:00
The Capacitive Division Image Readout - Development and Experimental Results 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The Capacitive Division Image Readout (C-DIR) is a charge centroiding device for imaging microchannel plate detectors. It comprises a two-dimensional matrix of capacitively coupled electrodes which divide the event charge between four charge measurement nodes. C-DIR’s capacitive nature maintains the bandwidth of the fast MCP signal for event timing applications and places a low capacitive load on the measurement electronics. The combination of these qualities provides an enhanced image resolution/time resolution performance envelope compared with traditional centroiding readout devices such as the resistive anode or wedge and strip anode.
We present experimental performance of the C-DIR in a microchannel plate detector and compare results with theory. We describe developments to the C-DIR design and electronics configuration to optimise spatial resolution, temporal resolution and linearity. We discuss the application of capacitive division centroiding to a 2D discrete pixel array with multichannel electronics to provide sub-pixel spatial resolution with parallel event processing for very high throughput.

Speaker: Jon Lapington (University of Leicester)
• 09:20
A real-time method for particle fall-out detection and monitoring using pixelated silicon sensors 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Dust and particulate contamination monitoring is vital for sensitive equipment being launched into space. Sensitive surfaces such as optical subsystems are particularly vulnerable to the effects of contamination which would lead to performance degradation. Great care is required to monitor the cleanliness levels of the environments in which the subsystem resides during all phases of the launch; before, during and after. Early warning of contamination incidents and failure analysis are key objectives of contamination monitoring methods. Current adopted approaches tend to be retrospective in nature and/or require human intervention for analysis of contaminants to be performed.

Presented here is a novel approach to monitoring surface contamination, originally developed under contract for the European Space Agency (ESA) for use as an on-board particulate contamination monitor within a rocket fairing. The method assumes that particle fall-out (PFO) landing on a sensitive surface will be similar to that landing on the surface of a pixelated position sensitive CMOS sensor placed nearby. A high-resolution silicon CMOS sensor collects and measures particle-fall out and dust which falls on its surface. This is a real-time, automatic approach which notifies the user of contamination incidents early on, and also allows characterisation of contaminants to be performed so that future sources may be identified and eliminated, for example based on the physical characteristics of a specific material. An algorithm has been devised which detects the difference in light intensity of nearby LEDs due to occultation of pixels by particulates across the surface of a silicon sensor. Sub-pixel detection of particles to smaller than the five-micron level has been demonstrated using this method, in addition to distinguishing between particles and fibres. We will describe this novel use of a pixelated imaging CMOS sensor together with results and future perspectives.

Speaker: Ms Abigail Shaylor (XCAM Limited)
• 09:40
SOPHIA: Photon Counting and Time-to-Digital Conversion using Single Photon Avalanche Diodes 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

SOPHIA (Solo PHoton Imaging Array) is a Single Photon Avalanche Diode (SPAD) array with built-in Time-to-Digital Converter (TDC) and photon counting logic, designed at the Rutherford Appleton Laboratory (RAL; Oxford, UK).

SOPHIA was designed to demonstrate the technologies needed for use in applications requiring high sensitivity or precise timing resolution. It achieves this through the use of SPAD pixels with active feedback circuitry for quenching the diode. Present on the device are three main SPAD arrays: pixels with hit counting logic (HITFLAG), pixels with time to digital conversion logic (TDC), and pixels without logic for SAPD measurements. These are arranged into four 16 x 16 arrays of 100 µm pixels, each with a 5 µm radius SPAD. Each area can be operated independently to allow for individual testing.

The HITFLAG variant contains logic to record whether the SPAD was triggered during an experimental window, and the TDC variant expands on this by adding a gated ring oscillator and ripple counter to record the time that the SPAD triggered. Using the gated ring oscillator as a 4-bit fine counter, and the ripple counter as the 4-bit course counter, it was possible to achieve time resolution of sub-1 ns with a total experimental window of 255 ns.

Here we will focus on the arrays with in-pixel logic, and present details of the design of this sensor and data showing the operation of the HITFLAG and TDC pixel variants.

Speaker: Mr Ben Marsh (Rutherford Appleton Laboratory)
• 10:00
Industrial exhibit (with tea and coffee) 45m Berrill Foyer (OU) ()

Berrill Foyer (OU)

• 10:45
Characterisation and comparison of detectors for electrons in the range 10-20 keV 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Interest in direct detectors for low-energy electrons has increased markedly in recent years. Detection of electrons in the energy range up to low tens of keV is important in techniques such as photoelectron emission microscopy (PEEM) and electron backscatter detection (EBSD) on scanning electron microscopes (SEMs). The PEEM technique is used both in the laboratory, with sample excitation by UV light or electron beam, and on synchrotron light sources worldwide, where X-rays provide the sample excitation. The ubiquity of SEMs means that there is a very large market for EBSD detectors for materials studies.
Currently, the most widely used detectors in these applications are based on indirect detection of incident electrons. Examples include scintillators optically coupled to CCDs, or the use of microchannel plates (MCPs) with a phosphor screen and CCD camera. These approaches result in image degradation due to blurring in the phosphor, inefficiencies and distortions in optical systems, and the limited active area of MCPs. In principle, these difficulties can be overcome using direct detection in a semiconductor device. In practice, the limited penetration depth of low-energy electrons into such a device means that any dead layer at the surface affects the performance critically and must be minimised.
As part of a feasibility study into the use of a direct detector for use on an XPEEM, we have built at Rutherford Appleton Laboratory a system to illuminate detectors with an electron beam of energy up to 20keV. We have used this system to measure the performance of a custom back-thinned monolithic active pixel sensor (MAPS), a detector based on the Medipix2 chip, and a commercial detector based on MCPs. We present a selection of the results from these measurements and compare and contrast different detector types.

Speaker: Dr John Matheson (STFC Rutherford Appleton Laboratory)
• 11:05
Initial results from a cryogenic proton irradiation test campaign of P-channel CCD204s 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

This paper details the characterisation of a P-channel and N-channel e2v Teledyne CCD204 before and after simultaneous cryogenic (153 K and 203 K) 6.5 MeV proton irradiation to 7.66 × 108 protons.cm2. Detailed trap location and energy analysis was performed pre- and post-irradiation, at a range of temperatures between 156 K and 203 K, highlighting formation, migration and annealing of traps within the 10-2 – 10-5 s emission time regime (at the above temperatures) during cryogenic (i.e. operational) irradiation. The results detailed here highlight the potential for improvement of performance of devices for critical metrics (especially Charge Transfer Inefficiency) at specified operating conditions in P-channel CCDs when compared to N-channel. Several new effects are found in the initial presentation of the data and discussed, for example, history dependent annealing, and a low-level continuum of trap emission time constants across the measured time base.

Speaker: Ben Dryer (The Open University)
• 11:25 12:25
Applications in life sciences, biology and medicine: X-ray/Gamma Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 11:25
Hybrid gamma camera for medical applications 20m

The development of gamma-ray detectors with low profiles has encouraged a wide range of medical imaging applications including use at the patient bedside and in operating theatres. Early development of SFOV cameras focussed primarily on a single modality - gamma ray imaging. Recently, a hybrid – gamma and optical - imaging system has been developed which combines optical and gamma cameras offering high spatial resolution dual imaging. The new system enables superimposed scintigraphic and optical image offering new possibilities for assisting clinicians and surgeons in localising the site of uptake in a number of surgical procedures. Recent improvements to the hybrid camera have been used to produce dual-modality images in both laboratory simulations and in the clinic.

The hybrid gamma-NIR fluorescence tracer ICG-99mTc-nanocolloid is already being used by some centres for sentinel lymph node biopsy. Once exposed, the NIR fluorescence reporter can be imaged at very high resolution while the radioactive component allows imaging at depths which would not be possible in NIR. Gamma detection may be carried out with a separate portable gamma camera or with a non-imaging probe. Visualisation of NIR fluorescence during surgery requires a dedicated NIR camera, several of which are available commercially.

The hybrid camera concept can be extended to include NIR imaging. We describe a NIR-gamma small field of view camera, capable of displaying co-aligned images from both modalities which can be fused into one image or viewed separately. This study is a preliminary investigation of the performance of the fluorescence component of this camera, including phantom studies and first images from a preclinical pilot study. We also report the first combined gamma and NIR fluorescence images.

Hybrid images taken in the clinic will be also be presented.

Speaker: Prof. John Lees (University of Leicester)
• 11:45
Performance of a Photon Counting CdTe detector for different pixel sizes 20m

Hybrid Photon Counting (HPC) detector technology is envisaged to open a new era on the field of X-ray medical imaging. Numerous applications in medical imaging require the use of high flux and high X-ray tube voltages, exceeding 100kV. This motivates the use of Cadmium Telluride (CdTe) for HPC as a sensor material.

In order to develop a novel HPC detector system with focus on medical imaging, we have bump-bonded CdTe sensors to the new IBEX single photon counting ASIC developed at DECTRIS. The new IBEX ASIC offers compatibility with different pixel sizes, a wide energy range up to 150 keV, and a new multi-threshold feature, which essentially yields four images containing the counts above the corresponding thresholds. Additionally, its instant retrigger functionality allows for a non-paralyzable counting mode and extends a prompt count rate above 10$^{7}$ cts/s/pixel. With this design the new system is especially interesting for the medical imaging field.

The characterization campaign of the new system as a Hybrid Photon Counting detector was carried out both at our in-house laboratories and at the BAMLine at BESSYII Synchrotron in Berlin in collaboration with the Physikalische Technische Bundesanstalt (PTB) group. Its performance has been evaluated with different pixel sizes (150um x 150um, 300um x 300um) in order to assess the impact of the pixel size on the detector performances.

The (prompt) count rate capabilities were measured at 60 keV both in paralyzable and non-paralyzable counting mode. In this last case the maximum allowed incoming rate can be well above 23.5 Mcts/s/pix (1 Gcts/s/mm$^{2}$) and 18.18 Mcts/s/pix (0.21 Gcts/s/mm$_{2}$) for the 150 and 300um pixels, respectively. The energy resolution was measured in the range 10-60 keV for different chip settings and at 40 keV it can be as low as 1.7 and 2.4 keV FWHM for the two pixel sizes. These results will be presented in the talk. Additionally, we have studied how charge sharing effects and the fluorescence arising above the Cd and Te K-edges at 26.73 and 31.82 keV affect the spectral response. This was done by investigating the quantum efficiency (QE) and a newly-introduced and more straight forward quantity called spectral efficiency (SE). The SE dependence on the incoming photon flux was also measured up to several Mcts/s/mm$^{2}$ and it will be discussed.

Speaker: Dr Sonia Fernandez-Perez
• 12:05
Double photon emission coincidence imaging of 111-In using high resolution Ce:GAGG-SiPM pixel detectors 20m

Single photon emission computed tomography(SPECT) is a useful medical imaging modality using single photon detection from radioactive tracers, such as 99Tc and 111In, however further development of increasing the contrast in the image is still under investigation.
A novel method (Double Photon Emission CT / DPECT) using a coincidence detection of two cascade gamma-rays from 111In is proposed and characterized in this study. 111In, which is well-known and commonly used as a SPECT tracer, emits two cascade photons of 171 keV and 245 keV with a short delay of approximately 85 ns. The coincidence detection of two gamma-rays theoretically determines the position in a single point compared with a line in single photon detection and increases the signal to noise ratio drastically. A pixel detector consists of 8 × 8 array of high-resolution type 1.5 mm thickness Ce:GAGG (~3.9 % @ 662 keV, 6.63g/cm3, C&A Co. Ce:Gd3Ga2.7Al2.3O12 2.5×2.5×1.5mm3) crystals coupled a 3 mm pixel SiPM array (Hamamtsu MPPC S13361-2050NS-08). The signal from each pixel is processed and readout using time over threshold (TOT) based parallel processing circuit to extract the energy and timing information. The coincidence was detected by FPGA with the frequency of 400 MHz. Two pixel detectors coupled to multi-hole collimators are located at the degree of 90 to determine the position and coincidence events (time window = ~1µs) are detected and used for making back-projection image. The image quality of SPECT and DPECT are compared and characterized including the detection efficiency and sensitivity.

Speaker: Kenji Shimazoe (The University of Tokyo)
• 12:25 13:45
Buffet lunch 1h 20m Hub Theatre (OU) ()

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 13:45 16:25
Detectors for high energy physics and astrophysics (I) Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 13:45
CHEC: A Compact High Energy Camera for CTA 30m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The Cherenkov Telescope Array will provide unprecedented sensitivity and angular resolution to gamma-rays across orders of magnitude in energy. Above 1 TeV up to around 300 TeV an array of Small-Sized Telescopes (SSTs) will cover several kilometres on the ground. The Compact High-Energy Camera (CHEC) is a proposed option for the camera of the SSTs. CHEC contains 2048 pixels of physical size about 6 mm × 6 mm, leading to a field of view of over 8 degrees. Electronics based on custom Target ASICs and FPGAs sample incoming signals at a gigasample per second and provide a flexible triggering scheme. Waveforms for every pixel in every event are read out without loss at over 600 events per second. A telescope prototype in Meudon, Paris saw first Cherenkov light from air showers in late 2015, using the first CHEC prototype. Research and development for CHEC is currently focussed on taking advantage of the latest generation of silicon photomultipliers (SiPMs). Here I present an introduction to CTA followed by details of the CHEC design and performance with focus on the latest developments in SiPMs and signal digitisation. Results from lab and field tests will be shown and the progress made to a robust camera design for deployment within CTA given.

Speaker: Dr Richard White (Max-Planck-Institut fur Kernphysik)
• 14:15
Operational Experience and Performance with the ATLAS Pixel detector 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The tracking performance of the ATLAS detector relies critically on its 4-layer Pixel Detector, that has undergone significant hardware and software upgrades to meet the challenges imposed by the higher collision energy, pileup and luminosity that are being delivered by the Large Hadron Collider, with record breaking instantaneous luminosities of 1.3 x 10^34 cm-2 s-1 recently surpassed.

The key status and performance metrics of the ATLAS Pixel Detector are summarised, and the operational experience and requirements to ensure optimum data quality and data taking efficiency are described, with special emphasis to radiation damage experience.

Speaker: Juanan Garcia (Institute of High Energy Physics (IHEP))
• 14:35
The construction of the phase 1 upgrade of the CMS pixel detector 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The Compact Muon Solenoid (CMS) is a multi-purpose detector constructed in order to study high-energy particle collisions in the Large Hadron Collider (LHC) at CERN.

The innermost layers of the CMS tracker are built out of pixel detectors arranged in three barrel layers (BPIX) and two forward disks in each endcap (FPIX). The original CMS detector was designed for the nominal instantaneous LHC luminosity of 1 x 10^34 cm^-2 s^-1. Under the conditions expected in the coming years, which will see an increase of a factor two of the instantaneous luminosity, the CMS pixel detector will see a dynamic inefficiency caused by data losses due to buffer overflows. For this reason the CMS Collaboration has installed during the recent extended end of year shutdown a replacement pixel detector.

The Phase I upgrade of the CMS pixel detector will operate at full efficiency at an instantaneous luminosity of 2 x 10^34 cm^-2 s^-1 with increased detector acceptance and additional redundancy for the tracking, while at the same time reducing the material budget. These goals are achieved using a new readout chip and modified powering and readout schemes, one additional tracking layer both in the barrel and in the disks, and new detector supports including a CO2 based evaporative cooling system, that contribute to the reduction of the material in the tracking volume.

This contribution will review the design and technological choices of the Phase I detector with a focus on the challenges and difficulties encountered, as well as the lessons learned for future upgrades. The commissioning steps prior to the availability of colliding beams will also be covered.

Speaker: Hannsjorg Weber (Fermi National Accelerator Lab. (US))
• 14:55
Monolithic Pixel Development in TowerJazz 180~nm CMOS for the outer pixel layers in the ATLAS experiment 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The upgrade of the ATLAS [1] tracking detector for the High-Luminosity Large Hadron Collider at CERN requires the development of novel radiation hard silicon sensor technologies. Latest developments in CMOS sensor processing offer the possibility of combining high-resitivity substrates with on-chip high-voltage biasing to achieve large depleted active sensor volume. We characterized depleted monolithic active pixel sensors (DMAPS), which were produced in a novel modified imaging process implemented in the TowerJazz 180nm CMOS process\footnote{manufactured by Tower Semiconductor Ltd, Israel} in the framework of the monolithic sensor development for the ALICE experiment [2]. The novel process modification [3] implemented in this technology allows full depletion of the epi layer even after substantial irradiation as expected for the ATLAS High-Luminosity LHC upgrade tracker ITk". The required tolerance to non-ionizing energy loss (NIEL) in the outer ATLAS ITk pixel layers is 1.5$\times 10^{15}$1 MeV $n_{eq}/cm{^2}$, two orders of magnitude higher than the ALICE ITS.

The designed sensor aims to minimise the capacitive load on the amplifier and enable fast signal collection, in time for the LHC 25ns bunch spacing. Separating the collection well from digital area allows to decouple analog and digital electronics to further minimize capacitance and prevent cross-talk. The radiation hardness of the charge collection to Non Ionizing Energy Loss (NIEL) has been characterized for the different pixel sensor cell designs. The talk focuses on the charge collection properties measured in the laboratory using radioactive sources, focused X-ray beam tests and in test beams. The talk summarises results on charge collection efficiency and charge collection time measured in the lab and beam tests, local efficiency distribution in the pixel as determined in beam tests with comparisons before and after irradiation.

These results showed the significantly improved radiation hardness obtained for sensors manufactured through the modified process. Achieving these results opened the way to the design of two large scale demonstrators for the ATLAS ITk outermost pixel layers, where the expected hit rate is 0.4 to 2 MHz/$mm^2$. The "MALTA" chip contains a 512$\times$512 pixel matrix of 36.4 $\mu$m pitch featuring a 1 $\mu$W frontend with in-pixel discrimination based on ALPIDE [5] with a time response $<$ 20ns. The full asynchronous readout without clock distribution over the matrix reduces digital power. The "TJ-Monopix" chip implements the same front-end as MALTA combining it with the well-established column drain architecture [6].

[1] The ATLAS Collaboration, JINST 3 (2008) S08003.

[2] G. Aglieri et al., JINST 8 (2013) C12041.

[3] W. Snoeys et al., submitted to NIMA.

[4] J. Willem van Hoorne et al., IEEE NSS/MIC 2016.

[5] D. Kim et al., JINST 12 (2016) C02042.

[6] I.Peric et al. NIMA 565 (2006) 178.

Speaker: Ivan Berdalovic (CERN)
• 15:15
A new strips tracker for the upgraded ATLAS ITk detector 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The inner detector of the present ATLAS detector has been designed and developed to function in the environment of the present Large Hadron Collider (LHC). At the next-generation tracking detector proposed for the High Luminosity LHC (HL-LHC), the so-called ATLAS Phase-II Upgrade, the particle densities and radiation levels will be higher by as much as a factor of ten. The new detectors must be faster, they need to be more highly segmented, and covering more area. They also need to be more resistant to radiation, and they require much greater power delivery to the front-end systems. At the same time, they cannot introduce excess material which could undermine performance. For those reasons, the inner tracker of the ATLAS detector must be redesigned and rebuilt completely.

The design of the ATLAS Upgrade inner tracker (ITk) has already been defined. It consists of several layers of silicon particle detectors. The innermost layers will be composed of silicon pixel sensors, and the outer layers will consist of silicon microstrip sensors. This contribution focuses on the strip region of the ITk. The central part of the strips tracker (the "barrel") will be composed of rectangular "short" (~ 2.5 cm) and "long" (~5 cm) strip sensors. The forwards regions of the strips tracker (the "endcaps") consist of 6 disks per side, with trapezoidal shaped microstrip sensors of various lengths and strip pitches. In response to the needs of the strip region for the ITk, highly modular structures are being studied and developed, called "staves" for the central region (barrel) and "petals" for the forward regions (end-caps). These structures integrate large numbers of sensors and readout electronics, with precision light weight mechanical elements and cooling structures. The silicon sensors are
fabricated in n-in-p float zone (FZ) technology. Low mass kapton-based circuit boards (the "hybrids") are directly glued on top of the sensors, hosting the so-called ABCN130 binary readout ASICs. Those ASICs are fabricated in a 130 nm CMOS process. The ASICs are connected to the microstrips via wirebonds. There are 256 channels per ABCN130. Those silicon "modules" are then directly glued onto low-mass, carbon fiber-based stave and petal core structures, with embedded titanium cooling pipes and data and power rails. A data concentrator board on each stave and petal side (the "end of structure" board, EoS) sends all the multiplexed data to the outside world via optical links, and host most of the components of the Detector Control System (DCS). The staves and petals are then
arranged into cylinders and disks, respectively, by means of the integration and global structures. The service module elements, part of the global structure, provide data, power, and cooling to groups of petals and staves. In the baseline design, each of the service modules provides services to 8 staves/petals.

A strong prototyping effort has been put in place over the course of the last years in order to optimize the stave and petal structures. This contribution summarizes the R&D activities performed by the numerous institutes within the Strips ITk collaboration that culminated recently in the release of the ATLAS Strips ITk Technical Design Report (TDR).

Speaker: Claire David (Deutsches Elektronen-Synchrotron (DE))
• 15:35
Tea and coffee 30m Berrill Foyer (OU) ()

Berrill Foyer (OU)

• 16:05
Limits in point to point resolution of MOS based pixels detector arrays 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Point to point resolution is a key prerequisite for particle detector pixel arrays. In high energy physics current and future experiments require the development of inner-detectors able to resolve the tracks of particles down to the micron range. Present-day technologies, although not fully implemented in actual detectors can reach a 5 µm limit, based on statistical measurements, with a pixel-pitch in the 10 µm range [1]. We present a design based on CMOS compatible technology that may reduce the pixel size to the submicron range, enabling a reduction of the resolution down to the submicron range. It physics principle relies on a buried carrier-localizing collecting gate. Although not yet practically implemented the process needed to fabricate this pixel is based on existing process steps used in Deep-Submicron silicon and SiGe microelectronics [2].The present paper is devoted to the evaluation of the building blocks with regard to the use of such pixel arrays for the accurate tracking of the charged particles in the silicon material.The bottlenecks and how to overcome them will be described. The role of the dimensions in the three directions of the pixel on the detection sequence will be studied. The pixel speed and the possibility of in-pixel circuit integration will be discussed. We’ll conclude by introducing similar pixels based on the FDSOI technology.

[1] N. Fourches, Y. Degerli, M. Besançon, A. Besson, G. Claus, G. Deptuch, W. Dulinski, M. Goffe, A. Himmi, Y. Li, P. Lutz, F. Orsini, and M. Szelezniak, “Performance of a Fast Programmable Active Pixel Sensor Chip Designed for Charged Particle Detection”, Contributed Talk (Nicolas Fourches), to the Nuclear Science Symposium, October 23-29, 2005, Porto Rico, 2005 IEEE Nuclear Science Symposium Record,N4-7, https://doi.org/10.1109/NSSMIC.2005.1596214

Y. Degerli,,M Besançon,A. Besson, G. Claus, G.; Deptuch, W. Dulinski, N Fourches, M. Goffe,A Himmi Y Li, P. Lutz, F. Orsini, M. Szelezniak, “Performance of a Fast Binary Readout CMOS Active Pixel Sensor Chip Designed for Charged Particle Detection”, IEEE Transactions on Nuclear Science, Volume 53,Issue 6,Part 2, Dec. 2006 Page(s): 3949 – 3955, https://doi.org/10.1109/TNS.2006.886151

[2] Nicolas T. Fourches, “Ultimate Pixel Based on a Single Transistor With Deep Trapping Gate”, IEEE Transactions On Electron Devices, Volume 64, Issue 4, (2017) 1619-1623
https://doi.org/10.1109/TED.2017.2670681

Speaker: Dr Nicolas Fourches (CEA/IRFU, Université Paris –Saclay, 91191 Gif/Yvette, France,)
• 16:25 18:05
Detectors for ground and space-based astronomy, planetary and space science (II) Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 16:25
The SMILE Soft X-ray Imager (SXI) CCD design and development 20m

SMILE, the Solar wind Magnetosphere Ionosphere Link Explorer, is a joint science mission between the European Space Agency and the Chinese Academy of Sciences. The spacecraft will be uniquely equipped to study the interaction between the Earth’s magnetosphere-ionosphere system and the solar wind on a global scale. SMILE’s instruments will explore this science through imaging of the solar wind charge exchange soft X-ray emission from the dayside magnetosheath, simultaneous imaging of the UV northern aurora and in situ monitoring of the solar wind and magnetosheath plasma and magnetic field conditions.

The Soft X-ray Imager (SXI) is the instrument being designed to observe X-ray photons emitted by the solar wind charge exchange process at photon energies between 200 eV and 2000 eV, using a lobster-eye micropore optic to observe over an ultra-wide field of view around 16° x 25°. X-rays will be collected using a focal plane array of two custom-designed CCDs, each consisting of 18 µm square pixels in a 4510 by 4510 array. The pixel array is asymmetrically split into image and store regions with a ratio of approximately 6:1 such that areas of 6 x 6 native pixels are binned on-chip before readout, thus creating super-pixels of 108 µm square in the image area.

SMILE will be placed in a highly elliptical polar orbit, passing in and out of the Earth’s radiation belts every 48 hours. Proton damage accumulated in the CCDs during the mission’s nominal 3-year lifetime will degrade their performance (such as through decreases in Charge Transfer Efficiency), negatively impacting the instrument’s ability to detect low energy X-rays incident on the regions of the CCD image area furthest from the detector outputs. The design for the SMILE-SXI CCDs will be presented here, including discussion of proposed operating schemes, event detection algorithms, expected end of life CCD performance and results obtained from representative devices.

Speaker: Matthew Soman (Open University)
• 16:45
On-Ground and In-Orbit Characterisation Plan for the PLATO CCD Normal Cameras 20m

PLAnetary Transits and Ocillations (PLATO) is the third European Space Agency (ESA) medium class mission in ESA’s cosmic vision programme due for launch in 2025. PLATO will carry out high precision un-interrupted photometric monitoring (months to years) in the visible band of large samples of bright solar-type stars. The primary mission goal is to detect and characterise terrestrial exoplanets with emphasis on planets orbiting in the habitable zone, this will be achieved using light curves to detect planetary transients. PLATO uses a novel multi-telescope instrument concept consisting of 26 small wide field telescopes. The 26 telescopes are made up of a telescope optical unit, four Teledyne e2v CCD270s, a custom Charge Coupled Device (CCD) designed for use in PLATO, mounted on a focal plane array and a set of Front End Electronics (FEE). There are 2 fast cameras with high read-out cadence (2.5 s) for magnitude ~4-8 stars, being produced by the German Aerospace Centre (DLR) and 24 normal (N) cameras with a cadence of 25 s to monitor stars with a magnitude greater than 8. The N-FEEs are being developed at the Mullard Space Science Laboratory (MSSL) and will be characterised along with the associated CCDs. The CCD and N-FEE will undergo rigorous on-ground characterisation and the performance of the CCDs will continue to be monitored in-orbit. This paper discusses the initial development of the experimental arrangement, test procedures, N-FEE and initial results from the CCD. The parameters explored will include gain, quantum efficiency, pixel response non-uniformity, dark current and Charge Transfer Efficiency (CTE). The current in-orbit characterisation plan is also discussed which will enable the performance of the CCDs and their associated N-FEE to be monitored during the mission, this will include measurements of CTE giving an indication of the impact of radiation damage in the CCDs.

Speaker: Jason Gow (University College London)
• 17:05
Initial trap pumping results from the Euclid CCD273 radiation campaign 20m

The Visible imager instrument (VIS) on board the Euclid mission will deliver high resolution shape measurements of galaxies down to very faint limits (R~25 at 10$\sigma$) in a large part of the sky, in order to infer the distribution of Dark Matter in the Universe. To mitigate radiation damage effects that will accumulate in the detectors over the mission lifetime, the properties of the radiation induced traps needs to be known with as high precision as possible. For this purpose the trap pumping method will be employed as part of the in-orbit calibration routines.
Using trap pumping it is possible to identify and characterise single traps in a charge-coupled device (CCD), thus providing information such as the density, emission time constants and sub-pixel positions etc. of the traps in the detectors.

This paper presents the trap pumping algorithms used for the radiation testing campaign of the CCD273 detectors, performed by the Centre for Electronic Imaging at the Open University, that will be used for the VIS instrument. The CCD273 is a 4-phase device with uneven phases, which complicates the trap pumping analysis. However, we find that by optimising the trap pumping algorithms and analysis routines it is possible to obtain sub-pixel and even sub-phase positional information about the traps. Further, by performing the trap pumping at various temperatures it is possible to infer energy levels and emission cross sections of the trap species in question.

Speaker: Jesper Skottfelt (The Open University)
• 17:25
Radiation testing of Solid State Detectors flying on the JUICE mission 20m

ESA are planning an L-class mission to Jupiter called JUICE (JUpiter Icy Moons Explorer) in June 2022. Its objective is to explore in detail Jupiter and the Jovian magnetosphere as it currently represents an archetype of gas giant planetary systems. 11 scientific instruments have been selected to fly on JUICE, of which PEP (Particle Environment Package) is one. PEP will deliver a 3D view of the Jovian plasma system by measuring ions, electrons, energetic neutral atoms and neutral gas simultaneously over nine decades of energy with full angular coverage. To achieve this PEP incorporates six different types of sensor, two of which are JoEE (Jovian Energetic Electrons instrument) and JENI (Jupiter Energetic Neutrals and Ions instrument). At their core, both JoEE and JENI employ position sensitive Solid State Detectors (SSD) to sense the electrons, ions and energetic neutral atoms. The Jupiter radiation environment is very severe; it has the strongest radiation belts in the solar system. This necessitates a robust radiation mitigation strategy and also requires that the SSDs are tested for their tolerance to the expected Jovian radiation environment. This paper will address the radiation testing of the SSDs used in JoEE and JENI.

Speaker: Dr Richard Gillham Darnley (University College London)
• 17:45
Calibration Techniques for CCDs in the Presence of the Brighter Fatter Effect 20m

It has become increasingly clear in recent years that dynamic charge
collection effects (notably the "brighter-fatter" effect) are evident and of
interest in thick CCDs. Apart from the implications of these effects on
shape measurement of point sources, and the unclear sensitivity of their
dependence on factors such as incident wavelength and device operating
voltage, it is also somewhat troublesome to perform standard calibration of
parameters such as gain and electrical crosstalk on devices with significant
brighter-fatter contributions. For example: correlations introduced due to
the brighter fatter effect are hard to distinguish from those due to
electrical crosstalk, or even serial charge transfer inefficiency.

After a brief review of existing and previous work about how the brighter-
fatter effect is coupled to measurements of other, more familiar parameters,
a discussion will be presented about the currently known extent of the
inter- dependence between the brighter-fatter effect and the parameters of
gain, crosstalk, noise and charge transfer inefficiency and how these can be
mitigated in post-hoc data analysis. Finally, some new measurement
techniques involving more specialist operation of the CCD during data
acquisition will be discussed, which aim to extract performance parameters
whilst exclusing the brighter-fatter effect.

Speaker: Dr Daniel Weatherill (University of Oxford)
• 18:30 20:30
Conference BBQ 2h Mulberry Lawn, outside the Hub Theatre (OU) ()

Mulberry Lawn, outside the Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The conference BBQ will take place on the Mulberry Lawn outside of the Hub Theatre (weather permitting; alternative arrangements in place inside the university restaurant if the weather is bad).

• 20:30 22:30
Film: The Imitation Game 2h Hub Theatre (OU) ()

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

We will be showing the award winning 2014 film "The Imitation Game" (starring Benedict Cumberbatch and Keira Knightley). With the film being set at Bletchley Park, this is the perfect evening's entertainment before the visit to the museum, situated a few miles from the Open University, on the Wednesday afternoon.

• Wednesday, 6 September
• 09:00 10:30
Detectors for ground and space-based astronomy, planetary and space science (III) Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 09:00
X-ray Polarimetry Techniques 30m

Polarimetry promises to be an important tool for discriminating between competing models in many areas of high-energy astrophysics including black holes, pulsars, and gamma-ray bursts. However, limitations in instrumental sensitivity have hindered progress since the first measurement of the Crab in the 1970’s.  In recent years there have been numerous efforts to develop instruments with the sensitivity required for astronomical polarimetry. We describe the historical measurements in the 2-10 keV band, the available techniques, and the missions proposed that will make these measurements a reality.

Speaker: Dr Hill Joanne (NASA)
• 09:30
A Flight Photon Counting Camera for the WFIRST Coronagraph 20m

A photon counting camera based on the Teledyne-e2v CCD201-20 electron multiplying CCD (EMCCD) is being developed for the NASA WFIRST coronagraph, an exoplanet imaging technology development of the Jet Propulsion Laboratory (Pasadena, CA) that is scheduled to launch in 2026. The coronagraph is designed to directly image planets around nearby stars, and to characterize their spectra. The planets are exceedingly faint, providing signals similar to the detector dark current, and require the use of photon counting detectors. Red sensitivity (600-980nm) is preferred to capture spectral features of interest. Since radiation in space affects the ability of the EMCCD to transfer the required single electron signals, care has been taken to develop appropriate shielding that will protect the cameras during a five year mission. In this paper, consideration of the effects of space radiation on photon counting observations will be described with the mitigating features of the camera design. An overview of the current camera flight system electronics requirements and design will also be described.

Speaker: Patrick Morrissey (Jet Propulsion Laboratory)
• 09:50
Mitigating Radiation Damage in Photon Counting EMCCDs for the WFIRST Coronagraph: survival in an L2 orbit 20m

The Wide-Field Infrared Survey Telescope (WFIRST) is a NASA flagship space observatory due to launch in the mid-2020s. In addition to probing dark energy and carrying out broad infrared surveys with the Wide-Field Instrument, WFIRST will also image and spectrally characterize extrasolar planets with a coronagraph at an unprecedented level of sensitivity. The faint planet targets require photon counting detectors to meet the stringent signal-to-noise requirements, with a CCD201-20 EMCCD sensor baselined for flight. However, the challenging WFIRST L2 radiation environment must first be considered. Radiation effects in the form of displacement damage from protons can hinder the charge transfer efficiency (CTE) of EMCCDs, as well as affecting dark current and other performance. In order to investigate these effects, we established a photon-counting laboratory at JPL, where we designed and completed a pre- and post-irradiation study of these sensors. Beyond characterization, which also included studies of read out noise, clock induced charge and electron multiplication gain, we discuss techniques we developed to identify damaged regions of the devices and mitigate their effects. Finally, we outline an on-going EMCCD technology development program currently underway between JPL and Teledyne e2v to modify the CCD201-20 for radiation hardness in space.

Speaker: Leon Harding (Jet Propulsion Laboratory)
• 10:10
Proton Induced Traps within EM-CCDs 20m

Electron multiplying (EM)-CCD technology has been successfully implemented for many ground-based applications (from astronomical telescopes to synchrotrons and life sciences), but has yet to be utilized within the space environment. The technology has the potential to offer superior photon-counting performance compared to competing technologies, however the effects of radiation damage must be understood and mitigated. The primary concern is damage from solar protons that manifests as signal trapping sites within the device. These traps can act to capture and defer signal charge to later pixels, degrading Charge Transfer Efficiency (CTE). They are of particular concern for photon-counting applications where the loss of a single photoelectron represents the loss of the entire signal packet, leaving nothing to detect or correct.

Here we present results from in-situ defect characterisation within irradiated Teledyne e2v CCD201 20 EM-CCDs using the “trap pumping” technique. At least 4 silicon defects have been identified that have the potential to degrade charge transfer performance of EM-CCD based instruments within a radiation environment. The key physical properties for each defect are presented, including population densities following exposure to proton fluences consistent with long duration space missions. The final population of silicon defects within a device is thought to be dependent upon the temperature at which the device is irradiated, and so differences between irradiation at room temperature (298 K) and cryogenic temperatures (165 K) are also discussed. We conclude with mitigation strategies to improve CTE in the presence of these traps, supported by results from TCAD simulation of charge transfer in the CCD201-20 image and register pixels.

Speaker: Mr Nathan Bush (The Open University)
• 10:30 11:00
Tea and coffee 30m Berrill Foyer (OU) ()

Berrill Foyer (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 11:00 12:20
Applications in life sciences, biology and medicine: Protons Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 11:00
Development of a range telescope for proton CT 20m

The use of Proton Therapy for cancer treatment demands new and more accurate imaging modalities for treatment planning, based on direct measurements of tissue stopping power instead of tissue density (as in conventional X-ray Computed Tomography) to reduce the errors in converting the latter quantity into the former [1]. The expected benefits of proton CT (pCT) for treatment planning in Proton Radiotherapy are producing great interest worldwide to develop instruments for clinical-quality pCT.

In 2012 a new UK-based collaboration, named PRaVDA (Proton Radiotherapy Verifications and Dosimetry Applications), was formed to develop a fully solid state instrument for pCT [2]. The PRaVDA pCT system, based on Silicon Strip Detectors (SSDs), comprises two sets of trackers to track protons through the patient [3] and a solid-state Range Telescope (RT) to measure the individual proton’s residual energy.
Design, assembly, track reconstruction techniques, range calibration and resolution will be shown for the PRaVDA RT. Experimental results obtained at the iThemba LABS clinical proton facility will also be reported together with preliminary results on pCT reconstruction of a test object with tissue substitute inserts.

[1] M.Yang et al. 2012,“Comprehensive analysis of proton range uncertainties related to patient stopping-power-ratio estimation using the stoichiometric calibration,” Physics in Medicine and Biology, vol. 57, no. 13, p. 4095.

[2] G. Poludniowski et al 2015, “Proton radiography and tomography with application to proton therapy”, The British Journal of Radiology 88:1053

[3] J. T. Taylor et al 2016, “An experimental demonstration of a new type of proton computed tomography using a novel silicon tracking detector” Med Phys. 2016, Nov;43(11):6129

Speaker: Michela Esposito (University of Lincoln)
• 11:20
Innovative thin silicon detectors for monitoring of therapeutic proton beams: preliminary beam tests. 20m

Purpose. A multidisciplinary project (Move-IT) of the Italian National Institute for Nuclear Physics (INFN) aims at translating research in charged particle therapy into clinical outcome. To this scope, new models in the treatment planning system will be developed and validated, using dedicated devices for beam characterization and monitoring in radiobiological and clinical irradiations. Innovative silicon detectors with internal gain layer (LGAD) represent a promising option, overcoming the limits of ionization chambers for on-line monitoring of the dose delivered with active beam scanning. Two devices are being developed: one to directly count individual protons at high rates, exploiting the large signal-to-noise ratio and fast collection time in small thicknesses (1 ns in 50 $\mu$m) of LGADs, the second to measure the beam energy with time-of-flight techniques, using LGADs optimized for excellent time resolutions (Ultra Fast Silicon Detectors, UFSDs). The preliminary tests of UFSD sensors with a therapeutic beam will be presented.
Methods. Counting and timing properties of UFSDs are evaluated using two pads (1 mm$^{2}$ x 50 $\mu$m) aligned to the proton beam (10$^{9}$ p/s, FWHM 1 cm). Several algorithms to determine the number of particles and crossing time difference between the sensors are tested via offline analysis of collected waveforms.
Results. The sensors signals show well separated contributions from single particles, with low pile-up probability up to almost 10$^{9}$ p/(cm$^{2}$s), and time resolution of ~50ps for single crossing. The measured numbers of counts from two aligned detectors are well correlated, and the beam structure is resolved at the nanosecond level. Studies of time resolution, pile-up probability, count linearity vs beam flux, and degradation with dose will be presented.
Conclusion. UFSDs are found to be a viable option for monitoring of therapeutic beams. Based on these results, the design and expected performance of the two devices will be presented and discussed.

Speaker: Anna Vignati (INFN - National Institute for Nuclear Physics - Torino (IT))
• 11:40
Development of a silicon tracker for imaging with protons 20m

Tomography has found extensive applications in medicine, industry and security due to its ability to produce detailed 3D images of objects and their internal structure. In medicine, computed tomography (CT) using x-rays is routinely used for the treatment planning of radiotherapy which most often uses x-rays for treating patients with various types of cancer. Radiotherapy using beams of charged particles such as protons is known as proton or hadron therapy and is rapidly becoming a more popular way of treating cancers that are deep inside the body or close to critical structures. The advantage of using charged particles for radiotherapy lies in its potential to target more dose into the cancerous tissue than with x-rays, reducing the dose to healthy tissue in the process.

The Proton Radiotherapy, Verification and Dosimetry Applications (PRaVDA) consortium have developed a new silicon micro-strip detector and readout ASIC based upon technology from high-energy physics for performing proton computed tomography (pCT). This technique utilizes measurements of the deflection and residual energy of many individual protons as they pass through a rotating object. The ultimate aim of pCT is to enable patients undergoing proton therapy to have their treatment planning and therapy carried out with the same particle beam, which in turn allows the margins of error associated with proton therapy to be reduced and the advantages of this treatment increased even further.

Details will be shown of the tracker assembly, readout and track reconstruction techniques using results from measurements made with therapy beams of ~100-200 MeV at the iThemba LABS, South Africa. Results that demonstrate the possibility to reconstruct new varieties of pCT images based upon tracking information alone will be discussed using images of a test object (phantom) containing tissue equivalent inserts.

Speaker: Jon Taylor (University of Liverpool (GB))
• 12:00
Imaging of prompt gamma emissions during proton cancer therapy for geometric and dosimetric verification 20m

The demand for proton therapy as a form of cancer treatment has been growing rapidly over the past decade. This is due to the sharp Bragg peak of the protons, which potentially enables radiation dose to be closely conformed to tumour dimensions, hence sparing normal tissues.

However, uncertainties in the proton range in tissue, beam delivery and resulting dose deposition in the patient, could lead to serious adverse effects [1]. Therefore, it is necessary for in vivo proton range verification during therapy. Prompt gamma-ray emissions whose energies are above 2 MeV can offer a check of in vivo proton range [2]. These emissions result from the interaction of protons with the tissue nuclei within the body. Currently, different techniques are being explored for imaging these emissions.

One of the techniques being used is Compton Camera Imaging. The University of Liverpool is working in collaboration with University College London and Clatterbridge Cancer Centre to develop a detector for prompt gamma-ray imaging. This system known as GRI+ is a three layer detector system, comprising of one Si(Li) scatter detector and two High Purity Germanium absorber detectors. Pulse Shape Analysis (PSA) is used to determine the interaction position and energy in each detector. Using code written at the University of Liverpool, it is possible to determine the gamma-ray emission position and hence proton range in 3D space.

In this presentation, the characterisation of the GRI+ system using laboratory isotopes such as Y-88 for high photon energies will be discussed. It will be compared with system simulations performed using GAMOS (Geant4-based Architecture for Medicine-Oriented Simulations)[3][4]. We will discuss about measurements on radiation and neutron background we performed at the Clatterbridge Cancer Cancer. We will use Compton Camera in realistic conditions during proton therapy. The first preliminary results will be presented.

[1] H. Paganetti, Phys. Med. Biol. 57, R99-R117 (2012).

[2] C.H. Min et al., Appl. Phys. Lett. 89, 183517 (2006).

[3] P. Arce et al. NIM A 735, 304-313 (2014).

[4] L.J. Harkness et al. NIM A 671,29-39 (2012).

Speaker: Dr Benjamin Le Crom (University of Liverpool)
• 12:20 13:40
Lunch 1h 20m Hub Theatre (OU) ()

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 14:00 20:00
Visit to Bletchley Park Museum and the National Museum of Computing (including buffet dinner and drinks reception) 6h Coaches will depart from outside of the OU library ()

Coaches will depart from outside of the OU library

Departing together in coaches at 2pm, we will first visit the Bletchley Park Museum, a few miles from the Open University campus. After some free time to visit the open-air museum and to see the huts, we will move across the road to the National Museum of Computing for a private tour and buffet supper, before returning by coach to the Open University.

• Thursday, 7 September
• 08:30 11:20
Detectors for synchrotron and free electron laser radiation (II) Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 08:30
The Development of the LPD Pixel Detector at RAL 30m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The UK Science and Technology Facilities Council (STFC) delivers detector systems to large scale scientific facilities both in the UK and world-wide. It achieves this through a combination of central laboratory and university led projects and wider generic research and development programmes.

As part of this programme RAL recently delivered the Large Pixel Detector[1] (LPD) to the European XFEL project in Hamburg. The LPD is one of several large area megapixel scale x-ray detectors that have been designed for the first XFEL beamlines. The LPD has been developed in close collaboration with scientific instrument FXE [2] to meet their demanding pump–probe experiments on ultrafast timescales. The complete system has been assembled from custom silicon sensors and ASICs as well as programmable data acquisition cards, other supporting electronics, mechanics and cooling. The required large detector area was then achieved by tiling multiple units that operate in parallel. The LPD system features a large in pixel memory depth of 512 multiple gain images that can be stored and accessed with a flexible readout system. Data is then transferred off the detector head in between x-ray pulses with an accompanying high rate data acquisition system >10 GB/s.

The delivered detector has been demonstrated to be capable of operating with a frame rate of 4.5MHz and record images with a dynamic range of 1:100,000 photons whilst maintaining low noise. The performance of the complete system will be presented along with first images from LPD at the FXE beamline. The presentation will include lessons learned in the development process as well as upgrade ideas for the future.

References:

[1] A. Koch et al. “Performance of an LPD prototype detector at MHz frame rates under Synchrotron and FEL radiation”, JINST , vol. 8, pp. C11001-10, (2013).

[2] http://www.xfel.eu/research/instruments/fxe

Speaker: Marcus Julian French (STFC - Rutherford Appleton Lab. (GB))
• 09:00
Multi-port CCD detector family at SACLA: six-year operation status and future outlook 30m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

We review our six-year operation from 2011 to 2017 of the multi-port charge-coupled device (MPCCD) detector family at the X-ray Free-Electron Laser (XFEL) facility SACLA. We first summarize the architecture and performance with three types of sensors with 50 [1] and 300 micrometer thick MPCCDs, in combination with the first generation camera system [1] and upgraded compact camera system. The major performance figures are at the modest level compared with the recent detector developments [2], but yielded a variety of scientific results [3]. In this presentation, we take two examples, namely, non-linear X-ray optics [4,5], and time-resolved protein crystallography [6,7] to show the link of these results to the detector performance figure.
Through the experiences of the MPCCD detector deployment, we determine that the robust operation with low calibration cost have been one of the critical feature for the rapid science development. In this paper, we discuss with particular emphasis on the sensor behavior upon X-ray radiation degradation and its link to the calibration cost. Calibration cost is more tangible for high-speed imaging detectors for XFELs and diffraction limited storage ring (DLSR) sources because high-speed framing demands large number of amplifiers in the X-ray illumination area. We present our target performance figures of our detector development plan for DLSR (SPring-8-II) with a route to mitigate the calibration cost.

[1] T. Kameshima et.al., Review of Scientific Instruments 85, 033110 (2014).

[2] References in the review, T. Hatsui and H. Graafsma IUCrJ, Vol. 2, p. 371 (2015).

[3] Publications can be found at http://xfel.riken.jp/eng/research/indexnne.html.

[4] K. Tamasaku, et.al., Phy. Rev. Lett., 111 (2013) Art.No. 043001.

[4] H. Yoneda, et.al, Nature 524 (2015) 446.

[5] M. Suga, et.al., Nature 543 (2017) 131.

[6] E. Nango, et.al. Science 354 (2016) 1552.

Speaker: Takaki Hatsui (RIKEN)
• 09:30
Development of Gotthard-II Detector for the European X-ray Free-Electron Laser 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Gotthard-II is a silicon microstrip detector developed for the European X-ray Free-Electron Laser (XFEL.EU). Its potential scientific applications include X-ray absorption/emission spectroscopy, hard X-ray high resolution single-shot spectrometry (HiREX), energy dispersive experiments at 4.5 MHz frame rate, beam diagnostics, as well as veto signal generation for pixel detectors at the XFEL.EU. Gotthard-II uses a silicon microstrip sensor with a pitch of 50 µm or 25 µm and with 1280 or 2560 channels wire-bonded to readout chips (ROCs). In the ROC, an adaptive gain switching preamplifier (PRE), a fully differential Correlated-Double-Sampling (CDS) stage, an Analog-to-Digital Converter (ADC) as well as a Static Random-Access Memory (SRAM) capable of storing all the 2700 images in an XFEL bunch train will be implemented. Several prototypes with different designs of analogue front-end (PRE and CDS) and ADC test structure have been fabricated in UMC-110nm technology and their performance has been evaluated according to the XFEL.EU specifications. In addition, a prototype with complete circuit chain of 8 channels including analogue front-end, ADC and SRAM has been designed and fabricated. The performance of the prototype in terms of noise, linearity, dynamic range, coupling between channels and speed have been investigated and will be discussed.

• 09:50
First results of the MYTHEN-III strip detector prototype 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

After more than ten years of operation, the MYTHEN-II detector at the Swiss Light Source (SLS) at the Paul Scherrer Institutut, Switzerland, is being upgraded. MYTHEN-II is a 60k-channel single-photon-counting 50µm pitch silicon microstrip detector optimized for powder diffraction experiments.
A new readout chip called MYTHEN-III is being developed by the SLS detector group in 110nm UMC technology. It is expected to improve the performance of the previous version in terms of noise, count rate capability, threshold dispersion and frame rate.
Every readout channel features a preamplifier and a shaper with variable gain and shaping time. The shaper output is fed to three independent discriminators, each one having a dedicated threshold, trim bit set and enable signal. The outputs of the three discriminators are processed by the counting logic section which, according to the mode of operation selected, generates the hits for the three following 24-bit counters. Several operation modes are foreseen: dual polarity, energy-windowing, count rate improvement, charge sharing suppression and pump with multiple probe time slots.
The first 64-channel prototype has been tested in the lab, with fluorescence X-rays and with a synchrotron beam to characterize its noise and count rate capability. The architecture of the chip and the first experimental results will be presented.

Speaker: Roberto Dinapoli (Paul Scherrer Institut)
• 10:10
Tea and coffee 30m Berrill Foyer (OU) ()

Berrill Foyer (OU)

• 10:40
Characterisation of GaAs:Cr Detector Systems for High Flux X-Ray Imaging 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The STFC Rutherford Appleton Laboratory (UK), Tomsk State University (Russia), the Diamond Light Source (UK) and SLAC LCLS (USA) have been working together to develop, characterise and commission detector systems based on chromium-compensated gallium arsenide (GaAs:Cr) semiconductor material for high flux X-ray imaging at next generation light sources.

In this talk an overview of the STFC’s work characterising this material will be presented using measurements made with a variety of different ASIC technologies. The STFC HEXITEC and PIXIE ASICs have been used to study the charge transport and spectroscopic performance of the material [1] while, working with the Diamond Light Source, detectors produced using the Medipix 3RX ASIC have been used to characterise the imaging performance at fine pixel pitches.

Most recently GaAs:Cr sensors have been bonded to the STFC LPD ASIC [2] and have been tested at the SLAC LCLS FEL (USA) to explore their suitability for use in high flux and high frame rate imaging systems at Free Electron Lasers (FEL). Results from these measurements have demonstrated that at lower fluxes (~ 1 MeV mm-2 per pulse) the GaAs:Cr performs well but under direct irradiation (> 500 MeV mm-2 per pulse) polarisation leads to non-uniformity in the detector response.

References

[1] Veale et al, “Chromium compensated gallium arsenide detectors for X-ray and g-ray spectroscopic imaging”, Nuclear Instruments and Methods A, 752, pg. 6-14, 2014. [https://doi.org/10.1016/j.nima.2014.03.033]

[2] Veale et al, “MHz rate X-ray Imaging with GaAs:Cr sensors using the LPD detector system”, Journal of Instrumentation, 12, P02015, 2017. [https://doi.org/10.1088/1748-0221/12/02/P02015]

Speaker: Dr Matthew Veale (STFC Rutherford Appleton Laboratory)
• 11:00
Performance of the Lancelot Beam Position Monitor at the Diamond Light Source 20m Berrill Lecture Theatre (OU)

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The Lancelot beam position and profile monitor records the scattered radiation off a thin, low-density foil, which passes through a pinhole perpendicular to the path of the beam and is detected by a Medipix-RX sensor. This arrangement does not expose the detector to the direct beam at synchrotrons and results in a negligible drop in flux downstream of the module. It allows for magnified images of the beam to be acquired in real time with high signal-to-noise ratios, enabling measurements of tiny displacements in the position of the centroid of approximately 2 $\mu$m. A constant frame rate of up to 90 Hz is achieved. The results of measurements with two Lancelot detectors installed in different environments at the Diamond Light Source are presented and their performance is discussed.

Speaker: Hassan Chagani (Diamond Light Source Ltd.)
• 11:20 12:40
Detectors for high energy physics and astrophysics (II) Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 11:20
FBK-INFN-LPNHE thin n-on-p pixel detectors: beamtest results 20m

To cope with High luminosity conditions of HL-LHC, the ATLAS pixel
detectors has to be upgraded to be fully efficient in harsh radiation
environment with a good granularity, a maximised geometrical
acceptance and an high read out rate.
LPNHE, FBK and INFN are involved in the development of thin and edgeless
planar pixel sensors in which the insensitive area at the border of
the sensor is minimized thanks to a special technology: the active
edge.
We have studied two productions, a first one featured 200 um thick n-on-p edgeless sensors, a second one composed of
100 um thick n-on-p sensors.
Those sensors were tested on beam, both at CERN-SPS and at DESY
and their performances before and after irradiation will be presented.

Speaker: Audrey Ducourthial (Centre National de la Recherche Scientifique (FR))
• 11:40
Diamond Detector Technology: Status and Perspectives 20m

At present most experiments at the CERN Large Hadron Collider (LHC)
are planning upgrades in the next 5-10 years for their innermost
tracking layers as well as luminosity monitors to be able to take data
as the luminosity increases and CERN moves toward the High Luminosity-LHC
(HL-LHC). These upgrades will most likely require more radiation
tolerant technologies than exist today. As a result this is one area of
intense research. Chemical Vapor Deposition (CVD) diamond has been
used extensively and successfully in beam conditions/beam loss monitors
as the innermost detectors in the highest radiation areas of essentially
all LHC experiments. The startup of the LHC in 2015 brought a new
milestone where the first diamond pixel modules were installed in an LHC
experiment (ATLAS) and successfully began taking data. As a result,
this material is now being discussed as a possible sensor material
for tracking very close to the interaction region and for pixelated
beam conditions/beam loss monitors of the LHC/HL-LHC upgrades where
the most extreme radiation conditions will exist.

The RD42 collaboration at CERN is leading the effort to use CVD diamond
as a material for tracking detectors operating in extreme radiation
environments. During the last three years the RD42 group has succeeded
in producing and measuring a number of devices to address specfic issues
related to use at the HL-LHC. We will present status of the RD42 project with
emphasis on recent beam test results. In particular we present the latest
results on material development, the most recent results on the independence
of signal size on incident particle rate in poly-crystalline CVD
diamond pad and pixel detectors over a range of particle fluxes up to
20 MHz/cm^2 measured, and results from first 3D diamond detectors which
produce an extremely radiation tolerant device and collect nearly all of
the charge deposited in the material. In addition we will present the plans
for future use of the most recent devices

Speaker: Lukas Baeni ( Department of Physics, ETH Zurich)
• 12:00
Development of Ultra-Fast Silicon Detectors for 4D Tracking 20m

In this contribution I will review the progress towards the development of a novel type of silicon detectors suited for tracking with a picosecond timing resolution, the so called Ultra-Fast Silicon Detectors.

The goal is to create a new family of particle detectors merging excellent position and timing resolution with GHz counting capabilities, very low material budget, radiation resistance, fine granularity, low power, insensitivity to magnetic field, and affordability. We aim to achieve concurrent precisions of ~ 10 ps and ~ 10 um with a 50 um thick sensor.

Ultra-Fast Silicon Detectors are based on the concept of Low-Gain Avalanche Detectors, which are silicon detectors with an internal multiplication mechanism so that they generate a signal which is factor ~ 10 larger than standard silicon detectors.
The basic design of UFSD consists of a thin silicon sensor with moderate internal gain and pixelated electrodes coupled to full custom VLSI chip.

First UFSD have been installed in the CMS-TOTEM Precision Protons Spectrometer for the forward physics tracking, and first results from LHC collisions at √s = 14 TeV will be presented.
In the proposal for the HL-LHC upgrade, the ATLAS and CMS detectors foresee the insertion of a forward timing detector for MIPs using UFSD.

Speaker: Amedeo Staiano (Universita e INFN Torino (IT))
• 12:20
Overview of the latest developments in HV-CMOS detectors for particle physics 20m

Due to their capability to cope with very high rates in very harsh radiation environments, hybrid silicon detectors have been the preferred option to track particles in high energy physics experiments. However, their large material thickness, together with their laborious and expensive assembly process, have motivated the pursuit of a new generation of thin and cost-efficient position sensitive detectors. The industry standard High Voltage-CMOS (HV-CMOS) technology has emerged as a very attractive solution. Tracker detectors in HV-CMOS technologies merge on the same substrate the sensing diode, biased at a high voltage to create a large depleted volume for fast charge collection by drift and high radiation tolerance, and a high integration density of low-voltage CMOS readout electronics which can be embedded inside the collecting electrode. Novel developments have shown the feasibility of fully monolithic HV-CMOS detectors, which integrate analogue and digital front-end electronics on the same sensor chip, removing the need for bump bonded or glued readout ASICs.

In this talk, I will give an overview of the latest activities in HV-CMOS detectors developed by an international collaboration, in which the Liverpool group contributes to both the design and evaluation of the prototype sensors. I will review the design details of recent submissions, which include demonstrator size and small size prototypes in ams and LFoundry aimed at the ATLAS ITk upgrade and the Mu3e experiment. I will also report on recent electrical tests and measurements from monolithic matrices and test structures on these prototypes with radioactive sources and lasers. Finally, I will provide details of a planned R&D submission within the CERN/RD50 collaboration (an international project to develop radiation hard semiconductor devices for very high luminosity colliders), which aims at improving the timing resolution of HV-CMOS sensors with different solutions implemented at the readout circuit level.

Speaker: Eva Vilella Figueras (University of Liverpool (GB))
• 12:40 14:30
Poster session: Poster session (including buffet lunch) Hub Theatre (OU) ()

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 12:40
A Novel gain stage for Microchannel Plate Imaging Photomultipliers 1h 30m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

We describe a technique to improve microchannel plate (MCP) detector dynamic range and lifetime by means of a novel technology, an “active anode” employing atomic layer deposition (ALD) to provide an additional gain stage after the MCP.
The ALD technique allows complex surfaces to be conformally coated with ultra thin films in a wide variety of materials. ALD has already been shown to benefit MCP detectors, allowing increased detector gain and reducing outgassing with dramatic benefit to detector lifetime.
We describe an additional gain stage behind the MCP stack comprising a mesh anode and reflection dynode and incorporating a two-dimensional image readout via the Image Charge technique. ALD is used to provide a dynode coating with high secondary electron emission and the resistive properties required for Image Charge. The additional gain stage allows MCP gain to be lowered increasing both the local and global count rate limits and enhancing detector lifetime.
We present measurements of secondary electron emission from ALD coatings and imaging performance of an MCP detector employing the active anode device.

Speaker: Jon Lapington (University of Leicester)
• 12:40
A Novel Multi-SiPM Position Sensitive Detector for Neutron-Gamma Discrimination 1h 30m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The separation of neutron and gamma signals through exploitation of the pulse shape discrimination (PSD) phenomena is a trusted technique, but with the advent of PSD sensitive plastic scintillators the prospect for mass deployment in homeland security or environmental radiation scenarios is increased. In an equally progressive technological advance the silicon photomultiplier (SiPM) is rapidly becoming a replacement for the traditional PMT. The combination of plastic scintillator with multiple SiPMs has enabled the development of a compact neutron-sensitive detector for deployment in, say, an environmental radioactivity situation where position sensitivity is required.

A monolithic piece of scintillator is optically coupled to four SensL J-series SiPM arrays at each corner of the scintillator and secured by a 3D-printed housing. We use triangulation methods from the four readout channels to measure the position of the radiation interaction within the scintillator tile, and assess the performance of this method as a low cost position-sensitive neutron/gamma detector. By design, the nature of the detector is such that swift replacement of components is possible allowing exploitation of the PSD capable plastic EJ299-33 or the fast timing properties of the alternative EJ200 plastic scintillator.

We report the testing of this device with standard radioisotopes (22-Na, 60-Co, 137-Cs), the response when exposed to the mixed radiation field of an AmBe neutron source, and its suitability for locating “unknown” sources under laboratory conditions.

Speaker: Dr Matt Taggart (University of Surrey)
• 12:40
A Segmented Anode Vacuum Phototriode with Position Sensitivity 1h 30m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Vacuum phototriodes (VPT) have been used for many years in particle physics experiments. For example, they were used in the OPAL experiment at LEP and are currently used in the endcap Electromagnetic Calorimeter of the CMS experiment, at CERN’s Large Hadron Collider. Since the VPT is a fast, proximity focused device, the anode or dynode can be subdivided into several independent channels within the same overall vacuum envelope. Such a device could be useful for reading out scintillating or wavelength shifting fibres from a “SPACAL” type of calorimeter.

A prototype VPT made for us by Hamamatsu is configured with a segmented anode, followed by a fine mesh dynode. This is one of the first of its kind and the novelty of the tube allows four independent channels within a single tube sharing a common photocathode and gain stage. This is beneficial for applications with limited space, as the dead region due to the electrode structure and diameter of active photocathode is considerably minimised compared to four smaller devices; significant cost savings would also accrue. The length of the prototype VPT is 40 mm with a 23 mm diameter vacuum envelope; the anode is split into four equal quadrants with a 1mm gap between each quadrant.

This paper presents the experimental characterisation of the new segmented anode VPT as well as the predictions from a COMSOL multi-physics simulation. Measurements of the induced signal as a function of time are presented, with the effects of electrical and optical cross-talk in adjacent quadrants.

Initial experiments with a DC optical source indicate the quadrants have almost identical performance on the outputs. Results include a detailed area scan, illustrating the position sensitivity, using a blue LED focussed to a 0.5 mm spot on the photocathode. Measurements are taken of the gain using magnetic fields up-to 4T. Fast pulse characterisation is carried out using an 80 ps diode laser operating at 435 nm.

Speaker: Sema Zahid (Brunel University (GB))
• 12:40
Ageing and Proton Irradiation Effects on an EMCCD Manufactured in a CMOS Process 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Electron Multiplying Charge Coupled Devices (EMCCDs) have revolutionised low light level imaging, providing highly sensitive detection capabilities. Implementing Electron Multiplication (EM) in Charge Coupled Devices (CCD) can increase the Signal to Noise Ratio (SNR) and lead to an improvement in low light level application. With the increase in demand for CMOS sensors with comparable or superior performance to CCDs, this paper describes the implementation of a low voltage EMCCD in a CMOS process. EMCCDs are known to experience an ageing effect, such that the gain achieved gradually decreases over the period of operation. This ageing process has been observed at high avalanche potentials, with a decrease in gain that is comparable to traditional EMCCDs. This paper presents results detailing the effect of EM ageing in EMCMOS (Electron Multiplying Complementary Metal-Oxide-Semiconductor) on factors such as CTI and thermal dark signal. When aged at room temperature an average decrease of 10% over a period of 175 hours was noted before plateauing, however there was a distinct variation across the pixels. The two new pixels experienced considerably higher reduction in the gain, surpassing a 20% loss in the gain. The sensor was developed for operation in space and as such its radiation hardness when exposed to proton damage, was tested. This paper presents the results of a proton irradiation completed at the Paul Scherrer Institut (PSI) at a fluence of 109 protons/cm2, 10MeV equivalent. The pre-irradiation characterisation, irradiation methodology and post irradiation results are detailed, including an increase in CTI, averaging at over 20%. Finally this paper presents a comparison of the damage caused by EM gain ageing and proton irradiation.

Speaker: Ms Alice Dunford (The Open University)
• 12:40
Characterisation of a CdTe detector for medical imaging applications 1h 30m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

A number of portable gamma cameras for medical imaging use CdTe based detectors. These can offer much better spectral resolution than scintillator based devices.

A CdTe pixelated detector has been coupled to a single photon counting, spectroscopic, readout ASIC (Application Specific Integrated Circuit) that has been developed at theRutherford Appleton Laboratory for use with small pixel CdTe and CdZnTe detectors in the energy range 10–600 keV. The CdTe detectors was 1mm thick with an array of 80 80 pixels on a250 microns pitch with a wide 200 micron guard ring running around the outside of the array.

Characterisation of the device was carried out follow a new protocol developed for accessing small field of view (SFOV) gamma cameras for medical applications. These protocols are based on the NEMA standards but tailored to test the higher spatial and spectral resolution found in current SFOV systems and includes measurement of the spatial resolution, uniformity, sensitivity and energy resolution for a number of radioisotopes used in medical imaging e.g. 99mTc.

The energy resolution at 140.5keV was measured to be 1.25keV using a 2MBq of a 99m Tc solution. Details of the detectors performance and images of phantoms will be presented.

Overall the characterisation of the CdTe system indicates that it could be used in a number of medical imaging applications.

Speaker: Prof. John Lees (University of Leicester)
• 12:40
Characterisation of the Charge Transport Properties of High-Flux Capable CdZnTe 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The STFC‘s Rutherford Appleton Laboratory (RAL) has been characterising high-flux capable CdZnTe [1]. This detector material has potential use in a number of high-flux industrial applications such as medical and security imaging. The next generation of free electron laser light sources, like the European XFEL or SLAC LCS, also require detectors able to image at high x-ray fluxes and high energies ( > 10 keV).

Small CZT detectors were fabricated by Redlen Technologies and flip-chip bonded by STFC to PIXIE ASICs. [2] This ASIC consists of four arrays of 3x3 pixels on pitches of 250um and 500um. Each pixel consists of a charge sensitive pre-amplifier, whose analog output is buffered straight off the chip. An XIA DGF PIXIE-16 system was used to digitise each of the nine analog signals at a rate of 100 MHz, giving a timing resolution of 10ns. The results of digitial pulse shape processing have been used to carry out characterisation of the performance of this CZT material, including the charge transport properties of electrons and holes.

In this paper, the results of rise time and charge collection efficiency measurements as a function of applied bias voltage will be reported. Early measurements suggest that in this material the hole mobility-lifetime is of the order ~ 10-4 cm2 V-1 and has a hole mobility of ~ 100 cm2 V-1 s-1; giving a lifetime value that is approximately an order of magntiude greater than previously reported values for spectroscopic grade CdZnTe. The improved charge transport properties of holes suggests that this material will be less suseptable to polarisation effects that have previously been reported to occur at high-fluxes due to hole trapping.

References

[1] K. Iniewski et al., “CZT sensors for Computed Tomography: from crystal growth to image quality” JINST 11 C12034 (2016) https://doi.org/10.1088/1748-0221/11/12/C12034

[2] M. C. Veale et al., "An ASIC for the Study of Charge Sharing Effects in Small Pixel CdZnTe X-Ray Detectors," IEEE Transactions on Nuclear Science, vol. 58, no. 5, pp. 2357-2362, Oct. 2011 https://doi.org/10.1109/TNS.2011.2162746

Speaker: Brett Thomas (Science and Technology Facilities Council)
• 12:40
Characterization of a new HV/HR CMOS sensor in LF150nm technology for the ATLAS Inner Tracker Upgrade 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The Large Hadron Collider (LHC) upgrade planned for 2026, will allow to develop new type of sensor to replace the ATLAS Inner Tracker. For this upgrade, the HV/HR CMOS technology has been studied because of his low price, the limitation of the scattering (reduction of the material budget), the good tracking precision (pixels sizes) and the charge collection by drift allow a high radiation tolerance and a high time resolution. A HV/HR CMOS detector prototype called LFCPIX, has been developed with LFoundry 150nm technology and has been tested. In this sensor we have implemented, in the diode, with a pitch of 250µm x 50µm, the front-end (using NMOS and PMOS transistors. This demonstrator is an implementation of a matrix of smart pixels which the diode composed by a DNWell and Psubstrate is used as a depleted sensor. Three types of pixels has been developed: passive pixels, analog-digital pixels, analog pixels (connected to the FE-I4). The FE-I4 is the present readout IC of the innermost ATLAS pixel layer and the demonstrator is able to be connected to the demonstrator. In addition to present the different versions of the LFCPIX demonstrators, laboratory tests results like the characterization of the different pre-amplifiers with external injection signal first and source 55Fe calibration then of the analog-digital pixels, results of the pixels connected to the FE-I4 and radiation hardness results will be presented.

Speaker: Mohamed Lachkar (CEA/IRFU,Centre d'etude de Saclay Gif-sur-Yvette (FR))
• 12:40
Characterization of Detector Modules for the CMS Pixel Phase 1 Upgrade 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

In high energy particle physics, accelerator- and detector-upgrades always go hand in hand. Along with an anticipated improvement of the Large Hadron Collider (LHC) to reach and exceed the luminosity of L = 2 x10^34 cm^-2s ^-1 during Run 2 until 2023, a new pixel detector has been installed in the Compact Muon Solenoid (CMS) detector early 2017 to cope with the new conditions. This so-called Phase 1 Upgrade of the CMS pixel detector was built to operate at higher rates with increased tracking efficiency and vertex resolution. It features amongst others an additional detector layer, a new bi-phase CO2 cooling and new readout chips with on-chip digitization of the data stream.
The barrel detector consists of 1184 modules, each with a silicon sensor bump-bonded to sixteen readout chips, supported and coordinated by a high-density-interconnect. The innermost layer, exposed to the highest particle flux compared to all other parts in CMS, has a different design dedicated to cope with extreme data rates and radiation damage.
An intense performance investigation and optimization program has been performed in addition to the extended qualification and calibration procedure under controlled environments to ensure the module functionality after being installed into CMS.
This presentation summarizes the characterization results of module performance with focus on the new on-chip digitization of analog hit information that is mandatory for good position resolution and the module qualification results with focus on methods using module-internal calibration signals. This method allows extended characterizations on pixel level such as electronic noise and bump bond connectivity, optimization of operational parameters, calibrations, thermal stress resistances and sensor quality. “Lessons-learned” are shared regarding optimizations in detector manufacturing technologies based on feedbacks from characterization activities.

Speaker: De Hua Zhu (Eidgenoessische Technische Hochschule Zuerich (CH))
• 12:40
Clock Induced Charge in EM-CCD Image Sensors 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Clock-Induced Charge (CIC) is a noise source commonly ignored in standard CCD technology since the net generation per frame is typically negligible compared to the noise introduced by the output circuit. For Electron Multiplication based technologies such as EM-CCDs, the sensitivity of the image section is reduced to the single electron level and so any spuriously generated signal can significantly degrade photon counting performance.

This paper describes an investigation into Clock Induced Charge generation within e2v EM-CCDs. Techniques are discussed that are able to provide sub-pixel resolution of CIC generation characteristics. The impact of operating mode, temperature, clocking frequency and radiation damage are also discussed. Advanced TCAD simulations of EM-CCD pixel structures are used to highlight the primary CIC generation sites within a pixel to further explain some of the trends observed in laboratory data. Additional mitigation techniques are discussed in terms of operating modes that may reduce CIC for applications where it remains a dominant noise source.

Speaker: Nathan Bush (The Open University)
• 12:40
Deep Diffused Avalanche Photo Diodes for Timing at the High Luminosity LHC 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The high luminosity upgrade of the CERN Large Hadron Collider (HL-LHC) foreseen for 2026 will provide an instantaneous luminosity of $5 \cdot 10^{34}$ cm$^{-2}$s$^{-1}$ and an average pile-up of 200 collisions per bunch crossing.
To reduce the effects of pile-up on the physics analyses, both the ATLAS and CMS experiments are planning to implement dedicated systems to measure the time of arrival of minimum ionizing particles with an accuracy of about 30 ps.
These systems include both scintillators coupled to photo-detectors and silicon detectors.
These timing detectors will be subjected to a radiation damage corresponding to a 1-MeV neutrons fluence ($\Phi_{eq}$) of $10^{15}$ cm$^{-2}$ for the goal integrated luminosity of HL-LHC of 3000 fb$^{-1}$.

In this talk deep-diffused Avalanche Photo Diodes (APDs) produced by Radiation Monitoring Devices are examined as candidate timing detectors for HL-LHC applications.
These APDs are operated at 1.8 kV, resulting in a gain up to 500.
A detailed characterization of the devices before irradiation is presented.
The timing performance of the detectors as well as their response uniformity is evaluated using a pulsed laser.
The response to charged particles is investigated using beta particles from a $^{90}$Sr source.
The effects of radiation damage on gain, noise, and timing of the APDs are evaluated using detectors irradiated with neutrons up to $\Phi_{eq} = 10^{15}$ cm$^{-2}$.
The measurements are compared to TCAD simulations of the devices.

Speaker: Matteo Centis Vignali (CERN)
• 12:40
Design and characterization of pixelated needle probe for molecular neuroimaging on awake and freely moving rats 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

IMIC is a Monolithic Active Pixels Sensor prototype designed for the MAPSSIC project, which aims at developing wireless intracerebral probes dedicated to the local counting of low energy positrons in situ in the brain of awake and freely moving rats. Former experiments using a passive PIXSIC circuit validated the proof of concept, but have also clearly demonstrated the need to improve signal-to-noise ratio and robustness. The IMIC circuit features a matrix of 16 x 128 pixels of 30 x 50 µm2 size. The sensor has a needle-like aspect ratio of 610 µm x 12 000 µm. The sensitive layer consists in a thin 18 µm thick high-resistivity epitaxial layer preceded by a 10 µm thick integrated electronic layer.

The foreseen application requires high sensitivity to ß+ rays while being immune to gamma-ray background. Another important constraint is the limited power dissipation to avoid thermal-induced damages in the brain of the rat, hence requiring low electrical power consumption. The sensor is a fully-programmable digital output sensor. The pixel design is based on the front-end architecture of the ALPIDE chip developed at CERN. However, modifications have been made to mark fired pixels between two readouts.

Laboratory tests confirm the designed low power consumption, which reaches 161 µW for the whole sensor. Characterizations using a $^{55}$Fe X-ray source, and a $^{90}$Sr ß– source with various metallic shielding thicknesses show a constant measured activity for short, and long integration times if the activity is sufficiently low not to saturate the sensor. Various measurements with a $^{18}$F source indicate an excellent response to ß+ rays with a low sensitivity to the background 511 keV annihilation gamma rays.

In this paper, we will present the probe design in detail together with the principal features of the needle shaped sensor. We will also discuss complete characterization results.

Speaker: Julian Heymes (IPHC)
• 12:40
Design of image quality phantoms to evaluate positron emission mammography systems 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The lack of international protocols for the evaluation of positron emission mammography (PEM) systems has led us to design image quality phantoms based on the average compressed breast dimensions and the most common lesion sizes. The main body phantom consists of a polymethyl-methacrylate (PMMA) cylinder (63 mm diameter, 50 mm height) which can be filled with a small amount of activity to mimic a uniform background and placed inside a rectangular PMMA container (100×100×56 mm3). Two interchangeable inserts have been designed: a) a microDerenzo hot-rod phantom with diameters in the 1 to 5 mm range arranged in a pie-like distribution, and b) a micro-hollow sphere lesion detection phantom that simulates hot and cold spherical lesions with internal diameters between 4.93 and 10 mm. The phantoms were filled with F-18 or Ga-68, with maximum positron energy of 634 keV and 1899 keV, respectively, to include positron range effects in the studies. The phantoms have been used to evaluate the Naviscan Solo II, a commercial PEM system currently used in the clinic. The experimental results are compared to Monte Carlo simulations using GATE v7.2. We thank the support from PAPIIT-UNAM IN110616 and IN108615, Conacyt Problemas Nacionales 2015-612, PAEP-UNAM and Conacyt MSc scholarship (LF Torres-Urzúa).

Speaker: Mr Luis Fernando Torres-Urzúa (Instituto de Física, UNAM)
• 12:40
Development of a bump cathode element for two-dimensional neutron detection 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

A neutron detection element consisting of circular cathode bumps was developed for two-dimensional neutron measurement, and an irradiation experiment was performed using a Cf-252 neutron source. The element has triangularly arranged small-sized circular cathode bumps, and the bumps are linked together in x- and y-directions for the detection of incident neutrons. The sensitive area was 128 × 128 mm2 with a pitch of 1 mm in both directions. The bump cathodes act as a collector of the charged signal arisen from a nuclear reaction between neutron and He-3. Preliminary irradiation experiments for the developed element were performed using a neutron detection system consisting of a pressure vessel, amplifier-shaper-discriminator boards, optical signal transmission devices, position encoders with field-programmable gate arrays, and a data acquisition device. The 256 signal lines (x: 128 lines, y: 128 lines) are individually readout by signal-processing electronics. The element was arranged in the pressure vessel with a fill gas of composition He/(15%)CF4 at 0.7 MPa. Neutron irradiation was performed by embedding a Cf-252 neutron source with an intensity of 100 MBq in a graphite cube with dimensions of 80 cm. The detector system exhibited a one-dimensional uniformity of response of 2.5% and 5.3% in the x- and y-directions, respectively. The uniformity of all pixels in the two-dimensional image was 10.1%. The average intrinsic spatial resolution was 1.9 mm full width at half maximum in the sensitive region calculated by taking into account the track lengths of secondary particles.

Speaker: Kentaro Toh (Japan Atomic Energy Agency)
• 12:40
Development of position-sensitive scintillation neutron detector for a new protein crystal diffractometer at J-PARC MLF 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

A high spatial resolution, a large-area position-sensitive scintillation neutron detector module has been developed for a new time-of-flight Laue single crystal diffractometer to be constructed in the J-PARC MLF. We have developed a prototype detector that has a spatial resolution of 2.5 mm with a neutron-sensitive area of 320 x 320 mm2 based on a scintillator / wavelength shifting fiber technology.
The new neutron diffractometer, tentatively called jBIX, aims at collecting diffraction data from biomolecular samples that have large unit cell lengths more than 200 Å. The instrument requires a large number of detector modules that surround the sample, where each detector module should have a spatial resolution of 1-3 mm, a large detection area of 50 x 50 cm2, and high detection efficiency more than 50% for thermal neutrons. We have successfully produced a first prototype detector for this purpose and its detector performances are evaluated. In this paper we present recent experimental results obtained with these prototype detectors.

Speaker: Dr Tatsuya Nakamura (Japan Atomic Energy Agency, J-PARC, MLF)
• 12:40
Development of slew rate limited time-over-threshold (ToT) ASIC for multi-channel silicon based ion detector 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

High-resolution Elastic Recoil Detection Analysis (HERDA) is one of the promising methods of quantitative analysis of hydrogen. The depth distribution of hydrogen can be obtained from the energy of recoiled hydrogen ions by irradiation of ion beams. HERDA consists of a magnet and a position sensitive detector for detecting the recoiled ions. Micro channel plates (MCP) are mainly used as the position sensitive detector, however, it takes long time to acquire one hydrogen distribution spectrum because of the limitation of count rate (~1000 cps). Also the system based on MCPs suffers from noises of dark current and stray ions in a chamber. For solving these problems to achieve higher sensitivity, the detection system using multi-channel Si based position sensitive detector has been developed. In this study, a slew rate limited time over threshold (ToT) ASIC was designed and characterized for low noise, parallel and fast readout from multi-channel silicon based ion detectors. The designed ASIC has 48 sets of a preamplifier with adjustable gain (high/low gain) and a slew rate limited shaping amplifier and a comparator and was fabricated using 0.25 $\mu$m TSMC's 2.5/3.3 V CMOS process. The size of the chip die is 2.2$\times$4.3 mm. This circuit measured the energy by ToT, which is the method that the information corresponding to pulse height is digitally obtained with time width. Moreover, in the resistive part of the shaping circuit, the voltage is reduced with a constant current, and the output of ToT is linearized. The measured equivalent noise charge (ENC) of preamplifier is approximately $3\times10^2$ electrons. The dynamic range of ToT is confirmed over 60 fC in high-gain mode although that of pulse height saturates at approximately 30 fC. Besides, the other characteristics and results combined with multi-channel silicon strip detector will be reported.

Speaker: Ms Mizuki Uenomachi (The University of Tokyo)
• 12:40
Four-quadrant Silicon and Silicon Carbide Photodiodes for Beam Position Monitor Application: Electrical Characterization and Electron Irradiation Effects 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Silicon photodiodes are very useful devices as X-ray beam monitors in synchrotron radiation beamlines. In order to be used in transmissive mode and given the absorption properties of silicon, the devices must be thinner than 10 um to achieve X-ray transmission higher than 90% for photon energies above 10 keV. On the other hand, bulk silicon segmented devices are also of interest for astronomy and space applications, such as solar tracking systems. Owing to their lower susceptibility to variable temperature and illumination conditions, there is also a special interest on silicon carbide devices for some of these applications. Moreover, radiation hardness of the involved technologies is a major concern for high-energy physics and space applications.
This work presents four-quadrant photodiodes produced on ultrathin (10 um) and bulk silicon, as well as on thick epilayer silicon carbide substrates with different design parameters along with auxiliary technology test structures (single diodes and MOS capacitors). The impact of different temperature (from -50ºC to 175ºC) and visible light conditions on the electrical characteristics of the various devices has been evaluated. An extensive electrical characterization, using current-voltage (I-V) and capacitance-voltage (C-V) techniques, has been carried out on non-irradiated and 2 MeV electron irradiated devices up to 1x1014, 1x1015 and 1x1016 e/cm2 fluences. Special attention has been devoted to the study of charge build-up in diode interquadrant isolation, as well as its impact on interquadrant resistance. The study of these electrical properties and its radiation-induced degradation should be taken into account for device applications.

Speaker: Dr Joan Marc Rafí (Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC))
• 12:40
Fully Depleted, Monolithic Pinned Photodiode CMOS Image Sensor Using Reverse Substrate Bias 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

A new pinned photodiode (PPD) CMOS image sensor (CIS) has been developed and characterised. The sensor can be fully depleted by means of reverse bias applied to the substrate, and the principle of operation is applicable to very thick sensitive volumes. Additional n-type implants under the in-pixel p-wells, called Deep Depletion Extension (DDE), have been added to the manufacturing process in order to eliminate the large parasitic substrate current that would otherwise be present in a normal device.
The first device has been manufactured on a 18 µm thick, 1000 Ω.cm epitaxial silicon wafers using the well-established 180 nm PPD image sensor process from TowerJazz Semiconductor. The chip contains arrays of 10 µm and 5.4 µm pixels, with variations of the shape, size and the depth of the DDE implant. Back-side illuminated (BSI) devices were manufactured in collaboration with Teledyne e2v, and characterised together with the front-side illuminated (FSI) variants. The presented results show that the devices could be reverse-biased without parasitic leakage currents, as predicted by TCAD simulations. The new pixels in both BSI and FSI variants exhibit nearly identical photon transfer curve, image lag and linearity to the reference, non-modified pixels. Special attention was paid to the verification that full depletion of the epitaxial layer can be achieved, using different complementing methods.
This development has the potential to greatly increase the quantum efficiency of scientific PPD CIS at near-infrared and soft X-ray wavelengths, due to the ability to realise sensors with sensitive thickness in excess of 100 µm. Likely applications are in sensors for astronomy, Earth observation, hyperspectral imaging, high speed imaging, spectroscopy, microscopy and surveillance, as well as for soft X-ray (<10 keV) imaging at synchrotron light sources and free electron lasers.

Speaker: Konstantin Stefanov (The Open University)
• 12:40
Gas gain and secondary processes in Ne – N2 mixtures – concentration and pressure scaling. 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

In the present work, the gas gain curves have been measured in the range from the ionization chamber regime to the breakdown limit in Ne – N2 gas compositions (2 – 20% N2, also in pure Ne) at various mixtures pressures (50 – 1800 hPa).
The measured gas gain curves have been fitted to the Diethorn, Williams & Sara and of Aoyama gain models to determine the characteristic mixture constants like effective ionization potential or mean ionization free path. The possible relation between these parameters and the mixture pressure and N2 – concentration will also be discussed. The secondary processes related to electron avalanche development have been also investigated.

Speaker: Dr Tadeusz Z. Kowalski (Faculty of Physics and Applied Computer Science, AGH University of Science and Technology,)
• 12:40
ICP etched position sensitive silicon sensors on silicon and SOI substrates 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Position sensitive detectors have many applications in measurement technology. In this paper we investigate the influence of a trench in the vicinity of the p-n junction of the silicon detector. The trenches were fabricated by inductive coupled plasma (ICP) etching technology. Both, the detectors with and without trenches were processed at the same wafer for comparable results. Further, we discuss the influence of the trench in view of electrical parameters and cross-talk behaviour in a 4-quadrants silicon photodiode.
For high temperature applications a position dependent line array based on SOI (silicon on insulator) material was fabricated. The electrical and optical properties of the SOI detector are presented and discussed.

Speaker: Mr Ralf Röder (CiS Forschungsinstitut für Mirkosensorik GmbH)
• 12:40
Improving radiation hardness in space-based Charge Coupled Devices through the narrowing of the charge transfer channel 1h 50m

Charge-Coupled Devices (CCDs) have been the detector of choice for imaging and spectroscopy in space missions for several decades, such as those being used for the Euclid VIS instrument and baselined for the SMILE SXI. Despite the many positive properties of CCDs, such as the high quantum efficiency and low noise, when used in a space environment the detectors suffer damage from the often-harsh radiation environment. High energy particles can create defects in the silicon lattice which act to trap the signal electrons being transferred through the device, reducing the signal measured and effectively increasing the noise.

We can reduce the impact of radiation on the devices through four key methods: increased radiation shielding, device design considerations, optimisation of operating conditions and image correction. Here, we concentrate on device design operations, investigating the impact of narrowing the charge-transfer channel in the device with the aim of minimising the impact of traps during readout.

Previous studies for the Euclid VIS instrument considered two devices, the e2v CCD204 and CCD273, the serial register of the former having a 50um channel and the latter having a 20um channel. The reduction in channel width was previously modelled to give an approximate 1.6x reduction in charge storage volume, verified experimentally to have a reduction in charge transfer inefficiency of 1.7x. The methods used to simulate the reduction approximated the charge cloud to a sharp-edged volume within which the probability of capture by traps was 100%. For high signals and slow readout speeds, this is a reasonable approximation. However, for low signals and higher readout speeds, the approximation falls short.

Here we discuss a new method of simulating and calculating charge storage variations with device design changes, considering the absolute probability of capture across the pixel, bringing validity to all signal sizes and readout speeds. Using this method, we can optimise the device design to suffer minimum impact from radiation damage effects, here using detector development for the SMILE mission to demonstrate the process.

Speaker: David Hall (The Open University)
• 12:40
Integrated readout electronics for Belle II pixel detector 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Belle II experiment will use a novel type of vertex detector. The detector is based on DEPFET sensor technology which allows construction of 70 micrometer thin sensor modules. A module consists only of silicon components. No mechanical support or cooling structures are needed in the sensor part exposed to particles. DEPFET sensor is operated in rolling shutter mode, with frame period of 20 microseconds and the possibility to electronically enable and disable all pixels within less than one microsecond. Readout components have been designed as integrated circuits. The ICs are connected to DEPFET sensor by bump bonding. Three types of ICs have been developed: SWITCHER for pixel matrix control, DCD for readout and digitizing of sensor signals and DHP for digital data processing. The ICs are radiation tolerant and use several novel features, such as the multiple-input differential amplifiers or the fast and radiation hard high-voltage drivers. SWITCHER and DCD have been developed at University of Heidelberg/KIT and DHP at Bonn University. The IC-development started in 2009 and was accomplished in 2016 with the submission of final designs.
The final ICs for Belle II pixel detector and the related measurement results will be presented in this contribution.

Speaker: Mr Roberto Blanco (KIT)
• 12:40
Measurements and calculations of gas gain in Xe – 5% TMA mixture – pressure scaling. 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

In this contribution we present a systematic study of single anode cylindrical detectors in gaseous Xenon using trimethylamine (TMA) as quencher gas. The choice of quench gas can have a significant effect on the gas gain and energy resolution. Gas gains (55Fe has been used as the radiation source) and energy resolutions for 109Cd radiation source (Ag Kα line of 22.1 keV X-rays) were measured for pressures between 250 and 1800 hPa and concentration of TMA of 5%. We observed stable operation at all pressures, and a strongly enhanced gas gain, by Penning-like energy-transfer processes. The experimental data have been fitted with Magboltz to investigate the Penning energy transfer rates and the secondary processes playing a role in avalanche formations. The probability of the Penning transfer rate and the second ionization Townsend coefficients were determined for all pressures. The gas gain fits with Penning and feedback corrections are all in excellence agreement with the experimental data. The maximum gas gain reached values as high as ~103 (~104) at 250 (1800) hPa. The Diethorn, Williams & Sara and of Aoyama models of the first Townsend coefficient have also been used to determine the basic gas properties. The obtained and presented results can be nice for micromegas-TPC operating in Xe-TMA mixture.

Speaker: Dr Tadeusz Z. Kowalski (Faculty of Physics and Applied Computer Science, AGH University of Science and Technology,)
• 12:40
Measurements of a Multi-anode Microchannel Plate Detector System with 100 picosecond event timing 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

We describe a multi-anode microchannel plate (MCP) detector with a 16 x 16 discrete pixel array designed for 100 picosecond single photon timing at count rates in the MHz range. The pixel array is instrumented using a 256 channel PETsys TOF ASIC evaluation kit, capable of single photon timing to better than 100 picoseconds and maximum count rate of 640 kHz/channel.
The timing performance of the TOFPET multichannel timing ASIC was measured using electronic stim signals, a Photek PMT210 high speed single anode MCP photomultiplier detector and the multi-anode MCP detector. Both MCP detectors were tested using a pulsed laser operated in single photon counting mode.
The PETsys electronics performance was measured at 43 ps rms using the on-board generated stim pulse synchronous with the TDC clock. MCP detector measurements were made using Illuminated using a pulsed laser with a pulse width of ~40 ps. The time over threshold (ToT) feature of the PETsys ASIC was used to correct the amplitude walk of the due to the MCP pulse height distribution and a single photon timing resolution of better than 100 ps rms was measured.

Speaker: Jon Lapington (University of Leicester)
• 12:40
Mitigation Strategies against Radiation-Induced Background for the Athena Wide Field Imager (WFI) 1h 30m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The Advanced Telescope for High ENergy Astrophysics (ATHENA) mission is a major upcoming ESA space-based X-ray observatory due to be launched in 2028, aiming to map the early universe and observe distant black holes. Instrument background from primary solar particles, cosmic rays and the secondaries produced in the shielding are expected to constitute a large fraction of the total noise in images and spectra from the Wide Field Imager (WFI) instrument on ATHENA. Designing an effective system to reduce the background radiation impacting the WFI will be crucial for maximising the instrument’s sensitivity. Due to the variety of different background sources, multiple shielding methods may be required to achieve maximum sensitivity in the WFI and in future space-based x-ray experiments. Here we discuss the latest results and strategies for effective instrument background mitigation for the Athena WFI.

Speaker: Chris Davis (The Open University)
• 12:40
Modeling Radiation Damage to Pixel Sensors in the ATLAS Detector 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Silicon pixel detectors are at the core of the current and planned upgrade of the ATLAS detector at the Large Hadron Collider (LHC). As the closest detector component to the interaction point, these detectors will be subjected to a significant amount of radiation over their lifetime: prior to the High-Luminosity LHC (HL-LHC), the innermost layers will receive a fluence in excess of 1015 neq/cm2 and the HL-HLC detector upgrades must cope with an order of magnitude higher fluence integrated over their lifetimes. Simulating radiation damage is critical in order to make accurate predictions for current future detector performance that will enable searches for new particles and forces as well as precision measurements of Standard Model particles such as the Higgs boson. We present a digitization model that includes radiation damage effects to the ATLAS pixel sensors for the first time and considers both planar and 3D sensor designs. In addition to thoroughly describing the setup, we present first predictions for basic pixel cluster properties, alongside early studies with LHC proton-proton collision data.

Speaker: Clara Troncon (Milano Universita e INFN (IT))
• 12:40
Module production tests and integration of the Belle II pixel detector 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The construction of the new Japanese super flavour factory has been finalized and the machine is ready for commissioning by the end of 2017. This new e$^+$e$^−$ machine (SuperKEKB) will deliver an instantaneous luminosity of 8×10$^{35}$ cm$^{-2}$ s$^{−1}$, which is 40 times higher than the world record set by KEKB. In order to be able to fully exploit the increased number of events and provide high precision measurements of the decay vertex of the B meson systems in such a harsh environment, the Belle detector will be upgraded (Belle II) and a new pixel detector (PXD), based on the DEPFET technology, is being constructed. This contribution will give an overview on the status of the Belle II PXD and its components, including the results of the characterization of the first production detector modules and detector integration.

Speaker: Botho Paschen (University of Bonn)
• 12:40
Monte Carlo based System Matrix calculation for iterative reconstruction in X-ray Luminescence Optical Tomography 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

X-ray luminescence optical tomography (XLOT) has been proposed to study problems related to deep-tissue small-animal imaging. In this technique, luminescent nanoparticles emit optical photons when irradiated with a collimated x-ray beam. The use of this modality for small-animal imaging requires an accurate knowledge of the energy deposition map inside the subject for optimization of the optical imaging model used in the tomographic reconstruction. It is of interest to determine the contribution of scattered radiation to the luminescent signal, since this might limit the spatial and contrast resolution of the system. In this work, we report the use of Monte Carlo simulation for the calculation of a system response matrix including attenuation and scatter effects in mouse size phantoms with embedded Gd2O2S inserts using a W target x-ray tube in the range of 30-90 kVp with an added 1.0 mm Al filtration.
The results show that the scatter contribution is of the order of 25% of the total dose to the insert and that it scales linearly with kVp for a fixed concentration (1 mg/ml) of luminescent nanoparticles at a fixed air-kerma rate. The imaging performance of the system was evaluated by means of simulations of the NEMA NU4 image quality and micro-Derenzo phantoms. The results show that quantification of the luminescent particle concentration deteriorates with object size, up to 80% when going from 5 to 1 mm diameter objects at 1 mg/ml concentration. The optical spatial resolution with 0.5 mm step size and 5 degrees’ angular sampling is of the order of 0.8 mm using the MLEM reconstruction algorithm.
We gratefully acknowledge the economic support of PAPIIT-UNAM IN108615 and IN110616, Conacyt Problemas Nacionales 2015-612, PAEP-UNAM and CONACYT.

Speakers: Mr Raúl Osorio Durán (Instituto de Física, UNAM), Dr Arnulfo Martínez-Dávalos (Instituto de Física, UNAM)
• 12:40
MTF and QE Characterisation of a CMOS Imager for the JUICE JANUS Instrument 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The ESA JUpiter ICy moon Explorer (JUICE) mission hosts the JANUS instrument, a planetary imager for the observation of Jupiter and Jovian moons Ganymede, Europa and Callisto, operating from the year 2030. The JANUS focal plane comprises a 4T 3Mpixel backside-illuminated CMOS Image Sensor (CIS) from Teledyne e2v, which is currently subject to high-energy proton, gamma, electron and heavy-ion radiation damage testing at the Centre for Electronic Imaging.

JANUS is a monochrome imager with 13 optical filters and a spatial resolution varying between 2.4m on Ganymede and 2.4km on Jupiter. The spatial and wavelength characterisation of the imager in the visible spectrum is essential information for determining the available resolution and colour response of the instrument in flight. The design, development and characterisation of an optical test bench for measuring the Quantum Efficiency (QE) and Modulation Transfer Function (MTF) of the CIS115 detector is presented. In addition, a comparison of the beginning of life and end of life performance of the CIS115 is discussed in relation to the projected mission performance.

Speaker: Mr Edgar Allanwood (The Open University)
• 12:40
Performance verification of the CMS Phase 1 Upgrade pixel detector with collision data 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The Compact Muon Solenoid (CMS) is a multi-purpose detector constructed in order to study high-energy particle collisions in the Large Hadron Collider (LHC) at CERN. The pixel detector is the inner part of the all-silicon charged particle tracking system in CMS. It plays a vital role in the seeding of the track reconstruction algorithms used at CMS, and in the reconstruction of primary interaction and secondary decay vertices. This year, the Phase 1 upgrade detector is replacing its older counterpart that has been used in Run 1 and in the first half of Run 2 with the expectation that the instantaneous luminosity of the LHC would reach 2x10E34cm−2s−1, well surpassing the rate capabilities of the old detector. The Phase 1 upgrade of the CMS pixel detector was built to operate at such high rate with its new digital readout scheme. Beyond the upgrade of the readout electronics, the detector's new layout will allow for more efficient tracking with smaller fake rate at higher event pile-up by providing more measurement points, first of which is taken at a smaller radius, and reduced material budget due to a light support mechanics and reorganized arrangement of the services. The presentation will describe the design choices which determine the detector's performance parameters, and it will compare the expectations with measurements taken with the first collision data.

Speaker: Viktor Veszpremi (Wigner RCP, Budapest (HU))
• 12:40
Prototypes of planar n-in-n quad modules for the ATLAS ITk upgrade at HL-LHC 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

In order to meet the requirements of the High Luminosity LHC (HL-LHC), it will be necessary to replace the current tracker of the ATLAS experiment. Therefore, a new full-silicon tracking detector is planned, the so-called Inner Tracker (ITk). The use of quad chip modules is intended in its pixel region. These modules consist of a silicon sensor that forms a unit together with four readout chips.

The current ATLAS pixel detector consists of planar n-in-n silicon pixel sensors. Similar sensors and four FE-I4 read-out chips have been assembled to first prototypes of planar n-in-n quad modules. Main focus of the investigation of these modules was the region between the read-out chips, especially the central area between all four read-out chips. There are special pixel cells placed on the sensor which take the gap between the read-out chips into account.

This contribution focus on the characterization of a non-irradiated device, including important sensor characteristics, charge collection determined with radioactive sources and hit efficiency measurements, performed in laboratory and test beam.
Also presented are the first laboratory results of an irradiated device.

Speaker: Andreas Gisen (Technische Universitaet Dortmund (DE))
• 12:40
Pulsed-Neutron Imaging by a High-Speed Camera and Center-of-Gravity Processing 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Pulsed neutron transmission spectroscopic radiography is attractive technique in the research fields of energy-resolved neutron radiography. The imaging technique is based on the energy-analysis of neutrons by time-of-flight (TOF) method. RIKEN RANS (RIKEN Accelerator-driven compact Neutron Source) produces 7 MeV proton beam and Be target pulsed neutron source. The beam current is about 5 μA, the pulse width is 80 μs and the pulse repetition rate is 100 Hz. Our imaging system consists of a neutron image intensifier, a photo image intensifier and a CMOS high-speed camera. The time-resolved neutron imaging is realized by taking continuous images from the accelerator trigger signal and integrating those images with the same sequence. This conventional imaging system has two problems. The first one is small number of pixels as the priority is given to frame speed. The second one is the degradation of spatial resolution caused by the photo image intensifier.
To overcome these problems the center-of-gravity processing was introduced. Picked up images taken by the high-speed camera have many bright spots caused by neutron reaction at the scintillator. Each center-of-gravity of these bright spots was calculate and accumulated on an image map on a memory. By processing center-of gravity of neutron signal the problem of the degradation of spatial resolution has been solved. In the binary dividing calculation to derive the center-of-gravity if the address is derived to two decimal places, the address map can be increased to four times. This means the spatial resolution can be improved and the second problem has been solved.
The accuracy of these processing was measured using simulated pulsed LED bright spot signals and effectiveness of this technique has been showed and applied to the pulsed neutron imaging at RIKEN RANS.

Speaker: Prof. Koh-ichi Mochiki (Tokyo City University)
• 12:40
Radiation induced damage analysis of CCD47-20 at room temperature 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Space based detectors such as Charge Coupled Devices (CCDs) are subject to a damaging radiation environment. High energy particles, such as protons, can displace atoms in the CCDs regular silicon lattice and create defects that trap signal charge and degrade the image. This document describes the radiation induced damage on three e2v CCD47-20 after room temperature proton irradiation to 5x10^9 and 1x10^10 at 10 MeV p cm-2. The initial results are correlated to the number of traps obtained via the trap pumping technique developed at the Open University. By comparing results from previous irradiations of protons, electrons, and gamma rays results, the study will be used to inform the planning of a future cryogenic irradiation of radiation hardened e2v CCD347s. The initial results demonstrate a clear change for pre to post-irradiation properties in terms of Dark current, X-ray Charge Transfer Efficiency (CTE), End Pixel Edge Response (EPER CTE), Defects in darkness, and Dark Signal Non Uniformity (DSNU) at different fluences.

Speaker: Mr Anton Lindley-DeCaire
• 12:40
Simulated spectrum of the OGRE X-ray camera system 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The X-ray astronomical telescopes in use today, such as Chandra and XMM Newton, use X-ray grating spectrometers to probe the high energy physics of the Universe. These instruments typically use reflective optics for focussing onto gratings that disperse incident X-rays across a detector, often a Charge-Coupled Device (CCD). The X-ray energy is determined from the position that it was detected on the CCD. Improved technology for the next generation of X-ray grating spectrometers has been developed and will be tested on a sounding rocket experiment known as the Off-plane Grating Rocket Experiment (OGRE).
OGRE aims to capture the most accurate soft X-ray spectrum of Capella, a well-known astronomical X-ray source, during an observation period of approximately 5 minutes whilst proving the performance and suitability of three key components. These three components consist of a telescope made from Iridium coated silicon mirrors, gold coated silicon X-ray diffraction gratings and a camera that comprises of four Electron-Multiplying (EM)-CCDs that will be arranged to observe the soft X-rays dispersed by the gratings.

EM-CCDs have an architecture similar to standard CCDs, with the addition of an EM gain register where the electron signal is amplified so that the effective signal-to-noise ratio of the imager is improved. On OGRE, this improved detector performance allows for easier identification of low energy X-rays and fast readouts due to the amplified signal charge making readout noise almost negligible.

A simulation that applies the OGRE instrument performance to the Capella soft X-ray spectrum has been developed that allows the distribution of X-rays onto the EM-CCDs to be predicted. The pixelated X-ray events will be simulated according to the detector architecture to demonstrate the order separation capabilities of the instrument and produce sample images expected from in-flight operation on which X-ray event identification algorithms can be developed.

Speaker: Matthew Lewis (The Open University)
• 12:40
Simulation and characterisation of low gain avalanche detector for particle physics and synchrotron applications 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Low Gain Avalanche detectors (LGAD) are a type of Avalanche Photodiode with gain of approximately ten. LGADs have a very fast
response time, order of picoseconds, and excellent position resolution. This makes them useful in many applications, including tracking for particle physics and synchrotron applications. Coupling of LGAD devices to single photon counting pixel electronics enables detection of incident X-rays of energy below the electronics’ noise threshold, making them of interest to the Synchrotron community.

This work presents results of TCAD detector simulations, device fabrication and characterisation.
Synopsis TCAD software was employed to simulated the device from fabrication process to final detector response and calculation of gain. Modelling started with the detailed simulation of the fabrication process, followed by the modelling of the detector’s electrical properties, the detector’s response to incident radiation and finally its gain.
The dependency of the gain on the device’s doping profiles was determined. The simulations demonstrated the influence of the fabrication process on the doping profiles and therefore gain.

Devices with optimised parameters obtained from simulation, and standard no-gain sensors, were fabricated at Micron Semiconductor Ltd. These were
characterised using laser and alpha particle Transient Current Technique (TCT) for charge
collection, gain variation and sensitivity.
The results presented here concentrate on those obtained from devices fabricated in Run 2.
The first devices (Run 1) saw a small amount of gain. The simulation was modified to match these
results and new simulations performed to optimize the devices (Run 2). These devices have
shown to match, within error, the simulated results for both current-voltage and gain measurements.
Preliminary results show a gain between 3 and 6 is obtained for voltages in the range of 200-800V.
Further device optimization in simulation is presented, which produces higher gain and allows
operation with higher bias voltages.

Speaker: Dr Richard Bates (University of Glasgow (GB))
• 12:40
The LUVMI Imaging System 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

LUVMI (LUnar Volatiles Mobile Instrumentation) is a lunar rover mission concept funded by H2020. The payload is a volatiles sampler and analyser which will accurately measure lunar volatile distribution over a wide area, including in Permanently Shadowed Regions (PSR). The 24 month project will develop to TRL6 instruments that together form a smart modular mobile payload that could be flight ready in 2020.

The imaging system on LUVMI will consist of two light-field cameras. The navigational camera will provide 3D images of the rover’s environment for teleoperation or autonomous navigation. A surface camera will provide close-up images of the lunar regolith and allow depth measurement of the rover tracks. The cameras will also acquire high quality imagery of mission equipment and of Earth.

Each camera will low power and low mass in line with LUVMI’s compact nature. The power requirement will be 4W peak for up to two sensors, not including illumination, the volume is expected to be below 50 mm x 50 mm x 200 mm per sensor, and the mass below 400 g per sensor. Calibrated depth information will be available from single images without an active focusing mechanism.

In this work, we present design details and results from the prototype cameras.

Speaker: Mr Joseph Rushton (Dynamic Imaging Analytics Limited)
• 12:40
The Point Spread Function in CIS113 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Authors: James Ivory, Konstantin Stefanov, Andrew Holland

The Open University, Walton Hall, Milton Keynes, UK

GravityCam is a proposed ground based telescope capable of increasing the angular precision of measurements 3-5 fold from existing telescopes. This is achieved through the use of Lucky Imaging, whereby a large number of short exposure images are taken at a high frame rate and used to create one image, with greatly reduced atmospheric aberrations and defocus effects. This precision is necessary for measuring gravitational microlensing accurately, which GravityCam hopes to accomplish. Traditionally, a CCD would be used as the imaging sensor in such a telescope, but due to the high frame rate needed, interest has turned instead to CMOS sensors. One of the CMOS sensors under consideration is CIS113.

CIS113 was designed and manufactured by Teledyne e2v. It is back illuminated with an image area consisting of 1920x4608 16µm pixels. Each pixel contains 5 transistors, allowing global reset and correlated double sampling. The device is capable of close butting on three sides so can be used to form large arrays. It is also able to read out a large number of small regions of interest (ROIs) with a higher frame rate if needed.

In order to get an accurate measure of the gravitational microlensing, the point spread function (PSF) of the sensor must be well known. In backside illuminated (BSI) CCDs PSF uniformity is quite good. In CMOS sensors however, each pixel varies slightly due to manufacturing inconsistencies. A map of these non-uniformities must be generated. To do this, a spot of light is shone onto the sensor, with spot sizes ranging from sub-pixel to larger than a pixel. The sensor is mounted on translation stages capable of moving the spot from pixel to pixel. PSF measurements are presented at varying wavelengths, with particular interest in the near infrared.

Speaker: Mr James Ivory (The Open University)
• 12:40
Thermal Annealing Response following Total Ionizing Dose of a CMOS Imager for the JUICE JANUS Instrument 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

ESA’s JUICE (JUpiter ICy moon Explorer) spacecraft is an L-class mission destined for the Jovian system in 2030. Its primary goals are to ‘investigate the conditions for planet formation and the emergence of life’ and ‘how does the solar system work’. The JANUS camera, an instrument on JUICE, is using a 4T Back Illuminated CMOS image sensor, the CIS115 constructed by Teledyne e2v.

JANUS imager test campaigns are studying the CIS115 following exposure to gammas, protons, electrons and heavy ions, simulating the harsh radiation environment present in the Jovian system The degradation in 4T CMOS device performance following Total Ionizing Dose (TID) is being studied, as well as the effectiveness of thermal annealing to reverse radiation damage. One key parameter for the JANUS mission is the Dark Current (DC) of the CIS115, which has been shown to degrade in previous radiation campaigns. A thermal anneal of the CIS115 has been used to accelerate any ageing or annealing following the irradiation as well as to study the recovery of any performance characteristics.

CIS115s have been irradiated to double expected End of Life levels of both displacement damage radiation (2x1010 protons, 10 MeV equivalent) and TID levels (up to 200 krad(Si)). Following this, some devices have undergone a thermal anneal cycle at 100°C for 168 hours to reveal the extent to which the CIS115 recovers the pre irradiation performance. DC activation energy analysis following TID gives information of trap species present in the device that contribute to the DC and how effective anneal is at removing these trap species. Extensive recovery of this parameter could prove important in improving the device performance toward the end of the lifetime of the CIS115 on JUICE and other future missions.

Speaker: Daniel-Dee Lofthouse-Smith (Open University)
• 12:40
Time resolved crystallography at ELI Beamlines facility 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The novel X-ray sources that are based on plasma generated from femtosecond lasers will allow for time resolved X-ray diffraction structural studies on a femtosecond time scale. The principle of the laser driven plasma sources shares similarity with the well known laboratory Metal jet sources. Instead of electron beam, the liquid metal is exposed to an intense laser beam. The ELI beamlines facility is planned to start user operation by the end of 2018 in Dolni Brezany, Czech Republic. It will give a unique advantage for time resolved crystallography and wide angle scattering for a crystalline samples, including proteins. The generated pulses will span approx. 100 fs with a repetition rate of 1 kHz. The scattered and diffracted by the crystal X-rays will be counted using a DECTRIS Eiger 1M area detector which operates at the same frame rate as the source, i.e. 1 kHz. Such setup can be combined with several pump probe lasers to study the fast kinetics for example in proteins with photo properties.

Speaker: Borislav Angelov (Institute of Physics, AVCR)
• 12:40
X-ray metrology of a close packed array of 'edgeless' Medipix3 detectors. 1h 50m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

This poster contribution reports on the production of an array of active edge silicon sensors as a prototype of a large array. Four Medipix3RX.1 chips were bump bonded to four single chip sized Advacam active edge n-on-n sensors. These detectors were then mounted into a 2 by 2 array and tested on B16 at Diamond Light Source with an x-ray beam spot of 2um. The results from these tests, compared with optical metrology give confidence that these sensors are sensitive to the physical edge of the sensor, with only a modest loss of efficiency in the final two rows of pixels. We present the efficiency maps recorded with the microfocus beam and a sample powder diffraction measurement. These results give confidence that this sensor technology can be used in much larger arrays of detectors at synchrotron light sources, leading to significantly simplified fabrication processes.

Speaker: Dr Richard Plackett (University of Oxford (GB))
• 13:00
Multi-leaf Collimator (MLC) Edge Reconstruction for Radiotherapy Using Large Area CMOS Image Sensor 1h 30m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

In this paper we present a novel approach which employs a thin large area CMOS image sensor to implement an upstream in-vivo dosimeter for intensity-modulated radiotherapy (IMRT).
Cancer treatments such as IMRT or volumetric modulated arc therapy (VMAT) require increasingly complex methods to verify the accuracy and precision of the treatment delivery. In vivo dosimetry based on measurements made in an electronic portal imaging device (EPID) are affected by the distorting effect of the patient anatomy on the beam intensity. Alternatively, upstream detectors scatter and attenuate the beam. In the proposed solution the signal attenuation due to the CMOS sensor is minimal. The device combines low attenuation with high resolution, high stability and is fully suitable for VMAT. It can also be left in position while the patient is treated, eliminating the need for pre-treatment verification.
The paper presents the challenges of designing a large image sensor (61mm by 63mm). Particular attention has been paid to yield, signal distribution, radiation hardness and readout speed.
Multi-leaf collimator (MLC) edge reconstructions using a commercially available EPID and the designed large area CMOS sensor have been compared. The results show that the proposed CMOS-based solution achieves a precision 3.5 times better compared to EPID. The natural next step is to perform real time tests with a IMRT plan before moving towards larger sensors.
To fully exploit the potential of the proposed solution, in fact, larger, faster and buttable sensors will be needed in the future.

Speaker: Mr Nicola Carlo Guerrini (STFC-RAL)
• 13:00
Quantum and charge collection efficiency measurements back illuminated CCDs in the soft X-ray regime 1h 30m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Soft X-ray CCD detectors are a valuable resource in a variety of fields including spectroscopy, astronomy and nuclear science. For astronomy in particular, the CCD sensitivity can have a dramatic effect on observation time and the attainable signal to noise ratio. Quantum efficiency (QE) is the standard metric used for CCD sensitivity, but it can be defined in multiple ways. The photon counting QE is a measure of photons in to photons detected, and can be measured in the soft X-ray regime using event detection algorithmns. The diode QE is the ratio of charge collected to charge expected, and is Charge Collection Efficiency (CCE) multiplied by the photon counting QE.

Here we present quantum and charge collection efficiency measurements of the Teledyne e2v CCD97 in the soft x-ray regime. We measure two types of devices: a standard process device, and an enhanced process device. The enhanced process device features improved back surface passivation, and extra doping intended to increase the QE in the soft X-ray regime. We show the success of this enhanced process, and present accurate QE models for both basic and enhanced process devices for use in simulations.

Speaker: Dr Jonathan Keelan (The Open University)
• 13:00
The Radiation Gas Detectors with Novel Nano Porous Converter For Medical Imaging Applications 1h 30m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

Since the scintillation detectors have inherent limitation in spatial resolution, recently, researchers tried to improve the quantum efficiency (QE) of position sensitive gas detectors. This imaging system usually consist of a bulk converter and amplification layer. But a bulk converter has its own limitation. For gamma rays, the converter thickness should be increased to achieve a greater detection efficiency, but in this case, the chance of escaping the photoelectrons is reduced. To overcome this problem, a new type of converter, called a nano porous converter such as Anodizing Aluminum Oxides (AAOs) membrane with higher surface to volume ratio is proposed.

But in this novel converter, even if the pores are filled by a suitable gas, the probability of ionization inside the nano channels is low. To overcome this problem, the walls of the pores are coated with nanometer layer of high density material like gold. In this way, the probability of secondary electrons generation inside the gold nano layer is increased and its energy is enough high to enter the pores. Since, these electrons have lower energy and they have higher chance for multiple scattering from the walls (because of gold layer), so the probability of ionization of the gas inside the pores is increased. In this case, by applying a reasonable electric field, the secondary electrons generated in the pores can be easily collected.

According to simulation results with vGATE_v2.1_1, for the 1mm thickness and inter pore distance of 460 nm, for the gamma ray in the energy range of 20–200 keV, in reasonable range of the gas pressure and for different pore diameters, the QE of this nano porous converter can be one to two order of magnitude greater than the bulk ones, which can be a revolutionary approach for proposing high QE position sensitive gas detectors for medical imaging application.

Speaker: Hajar zarei (Energy Engineering and Physics Department, Amirkabir University of Technology, Hafez Ave., Tehran, Iran)
• 14:10
Position sensitive radiation detectors for high temperature environments using single crystal diamond 20m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

A number of harsh industrial environments require radiation detectors which can operate at temperatures in excess of 200 degrees Celsius and may, in addition, require significant tolerance of the sensor to ionising radiation. Two application areas of current importance are the monitoring of radiation near high-pressure steam pipes in nuclear reactors used for electricity generation, and deep-level oil and gas exploration. With its wide band-gap of 5.5 eV and proven resistance to high levels of ionising radiation, single crystal CVD diamond is becoming well known as a particle detector at normal ambient temperatures. Recently we have been studying the performance of such sensors at elevated temperatures up to 250 degrees Celsius and in this paper we present results from a segmented, 4-pixel, radiation sensor utilising a 4×4×0.5 mm^3 CVD single crystal diamond. We present leakage current, noise and the spectroscopic resolution for alpha particles in the few MeV energy range as a function of temperature. We also determine the efficiency and the cross-talk between pixels. We compare our results with data collected previously from smaller, 2×2×0.5 mm^3 CVD single crystal diamond sensors, which have no position sensitive capability.

Speaker: Dr David Smith (Brunel University London)
• 14:10
The ZnO Nanowires in AAO Membrane as a Novel High Spatial Resolution Position Sensitive X-ray Detector 20m Hub Theatre (OU)

Hub Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA

The spatial resolution of an indirect x-ray imaging detector is degraded by the light spreading phenomenon in a scintillation layer. In a position sensitive detector with a thicker x-ray converter, for improving the spatial resolution, microstructured scintillator with optically isolated structures is used. In this case the optical crosstalk between neighboring pixels is prevented, which is suitable for mammography, dental imaging, and micro-CT (computed tomography).

By using a new architecture based on the ZnO nanostructures in a suitable membrane, proposed by our group, a better spatial resolution in comparison to traditional imagers can be achieved. In the proposed imager, each nanowire inside the membrane acts as a light guide (optical ﬁber) that prevents the generated optical photons to spread inside the imager. If this nano scintillator is coupled to a photocathode and the generated electrons enter to nano channels of an Anodic Aluminum Oxide (AAO) for electron multiplication, a new generation of extremely high spatial resolution position sensitive detectors can be achieved.

One of the advantages of ZnO nanowire scintillator is the simplicity of synthesized by template-assisted one-step electrodeposition technique. The results for ordered ZnO nanowire arrays in porous AAO template show that for 10 keV X-ray photons, by suitable selection of detector thickness and pore diameter, the spatial resolution less than one micrometer and detection efficiency of 66% are accessible.

The better spatial resolution of this nano scintillator in comparison to bulk and microstructured ones and the possibility of optimization the detection efficiency by increasing the porosity of the membrane and also its thickness at higher energies, are the advantages which candidate this nano scintillator for medical imaging or even particle tracking in the future.

Speaker: Prof. Shahyar Saramad (Amirkabir University of Technology)
• 14:30 16:20
Applications in nuclear physics Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 14:30
Silicon Photomultipliers: introducing the digital age in low light detection 30m

Single photon sensitivity and photon number resolving capability are enabling features in research and technology development. Quantum information & computing as well as metrology, meteorology, biology, medical physics and security against cyber attacks and nuclear threats are expected to undergo a revolution once low light detection is made easy, reliable and low cost. Single photon detection so far has been mainly as- sociated to photo-multiplier tubes (PMT), the reference instrument since 1934. PMT are certainly a reliable, solid rock technology with decades of improvements and refinements. Their architecture is certainly beautiful but irreducibly complex. Biasing electronics can be sophisticated but the operational voltage necessarily exceeds 1000V. Operation in magnetic fields may be possible but it does not come for free. Last but not least, miniaturisation below a matchbox size is hard to imagine. These figures certainly constrain their integration in apparatus and instruments, with an impact on design and cost. Silicon PhotoMultipliers (SiPM) stand to PMT like transistors stand to thermoionic valves. In essence, SiPM are an array of p-n junctions operated beyond the breakdown voltage, with every cell in the array ready to trigger an avalanche with 10^6 gain as long as the absorption of a photon generates a charge carrier. With the simplicity and cost of a Silicon sensor, operational voltage not exceeding 100V, magnetic field immunity and miniaturization down to 1 mm2, SiPM are state-of-the-art sensors, featuring an unprecedented photon number resolving capability and introducing the digital revolution in low light detection. In my talk, I will address the fundamentals of SiPM, identifying the key figures of merit, their measurements and presenting the state of the art and future directions. Moreover, I will consider exemplary applications in nuclear particle detection and dosimetry, homeland security, medical imaging and environmental science.

Speaker: Prof. Massimo Caccia (University' dell'Insubria)
• 15:00
Development of a pin-hole collimated camera: The CoNG (Compact Neutron-Gamma) Imager 20m

Detectors in the field of Nuclear Security are generally of the larger static format, however, complementary measurements provided by more portable and compact systems are often essential. Similarly, in environmental radiation situations it is necessary to quickly determine the location of an unknown source, and of particular interest is the ability to discriminate between neutron and gamma ray interactions. To provide a solution to these issues the mature technique of pin-hole collimation is combined with recent developments in scintillation, photomultiplier, and digital data acquisition technologies.

The imager itself comprises a position sensitive Hamamatsu PMT coupled to the new EJ299-33 plastic scintillator. EJ299-33 has been specifically developed to take advantage of the pulse shape discrimination (PSD) phenomena for neutron-gamma separation. The multi-anode readout of the PMT allows for a coarse degree of position resolution in an X-Y plane with 6 anodes in each direction, whereas the plastic scintillator exhibits the PSD phenomena allowing for detection, and separation, of both neutron and gamma-ray signals. The detector readout is provided by a fast CAEN digitiser system with analysis performed offline to take advantage of our parallel investigations into a variety of PSD algorithms.

We report the gamma spectroscopic performance as a function of PMT anode, and basic imaging functionality for known locations of standard laboratory sources (241-Am, 22-Na, 57-Co, 60-Co, 137-Cs) along with the preliminary results of a mixed radiation (fast neutron – gamma ray) field survey.

Speaker: Dr Matt Taggart (University of Surrey)
• 15:20
Development of the Glass Micro-Well Detector (g-MWD) 20m

We describe the fabrication and performance of large area glass micro-well detectors (g-MWD) fabricated using APEX® Glass. These microstructure, two-dimensional proportional counters are 85x85 mm^2 square with an array of 100 um diameter wells, 100 um deep, on 200 um centers with crossed anode and cathode electrodes. Their performance in P-10 at 1 atm shows excellent gas gain and stability. Future work will refine the g-MWD fabrication process, demonstrate tiling these detectors to make larger area detectors, and lifetime testing in a closed gas environment.
The g-MWDs are being developed for the Advanced Energetic Pair Telescope (AdEPT), a discovery mission for medium-energy (5-200 MeV) gamma-ray polarimetry, but applications are envisioned in a wide range of medical, military, and homeland security applications.

Speaker: Dr Stanley Hunter (NASA/GSFC)
• 15:40
Characterisation of small electrode HPGe detectors 20m

Canberra BEGe and SAGe Well are high-purity germanium detectors designed for gamma-ray spectroscopy featuring small p+ readout electrodes which provide reduced electronic noise and allow for unrivalled energy resolution, particularly at low gamma-ray energy. A series of characterisation studies has been carried out on a number of detectors at the University of Liverpool to investigate the use of pulse shape analysis (PSA) techniques. This has allowed gamma-ray interactions near to the detector surface to be identified. This information can then be used for improved sensitivity at low gamma-ray energy.

A coincidence scanning method with a highly collimated $^{137}$Cs source has been used to identify single-site interactions at a range of known positions in the detectors. The small readout electrode results in extremely long charge collection times of up to 1.6µs typically leading to poor time resolution. In this work the interaction time has been precisely determined by coincidence with an array of BGO scintillation detectors allowing accurate measurement of charge drift times through the detector.

The results have been used to inform the development of algorithms for the suppression of Compton scatter events based on their interaction location in the detector. A number of source tests have examined the background rejection performance for low energy gamma rays in the presence Compton scatter background from $^{137}$Cs and $^{60}$Co.

Due to the extremely long charge collection times, comparisons between measured charge drift velocity and that predicted by electric field simulations have provided a sensitive test of mobility parameters for holes in germanium.

Speaker: Dr Carl Unsworth (University of Liverpool)
• 16:00
Automatic Detection of Recoil Proton Track and Separation from Radiation Induced Background 20m

High resolution imaging of fast neutrons (>0.5 MeV) combined with energy spectroscopy is employed in variety of applications.

We have previously reported‎ on the development and construction of a detector based on a micro-capillary bundle filled with organic liquid scintillator. The scintillation is observed by a CCD camera that will permit high resolution imaging and spectrometry by secondary ion track reconstruction, without the requirement for techniques such as Time of Flight.

At such energies, the dominant fast neutron reactions in the organic liquid scintillator are elastic scattering with hydrogen (recoil-proton) and carbon, as both elements have similar atomic density within the scintillator. The recoil-proton will travel inside the bundle and create scintillation light track within the multiple capillaries it traverses (as function of its energy), while heavier ions will deposit their energy within a radius of one or two capillaries (ca. 40 µm). A fraction of the scintillation light will travel to the end of these capillaries via total internal reflection and be registered in the optical readout system, thereby creating a projection of the proton track in the plane perpendicular to the optical axis. These proton tracks exhibit bright continuous trajectories with a Bragg peak at their end. Gamma-ray-induced electrons generate small, fainter blobs of light that appear as a multitude of blobs.

Initially, identification of proton tracks has been accomplished by visual inspection of the numerous CCD images. As this is an inefficient, labor and time-consuming task, a computerized rapid automatic track recognition procedure was developed, based on ellipsoid shape parameters analysis.

This work provides description of the capillary detector, analysis of principal features characterizing recoil proton track projections as well as background induced signal which provided basis for excellent background rejection, distinguishing a single proton track over several thousands of background blobs found in each CCD frame.

Speaker: Dr Ilan Mor (Soreq NRC)
• 16:20 16:50
Tea and coffee 30m Berrill Foyer (OU) ()

Berrill Foyer (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 16:50 18:20
Detectors for high energy physics and astrophysics (III) Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 16:50
Silicon microstrip detector for space-borne astroparticle experiments 30m

Since the end of last century it has been proven the possibility to use the technology of silicon microstrip detectors developed for accelerator based experiment in space-borne astroparticle experiments. Detector requirements and additional constraints imposed by the launch process in space flight, as well as by the hostile running environment in orbit, are analysed.
Examples are given of running missions and instruments in orbit, under construction or in the planning phase.

Speaker: Dr Giovanni Ambrosi (Universita e INFN, Perugia (IT))
• 17:20
A High-Granularity Timing Detector for the Phase-II upgrade of the ATLAS Calorimeter system 20m

The expected increase of the particle flux at the high luminosity phase of the LHC with instantaneous luminosities up to L ≃ 7.5 × 10^{34} cm^{−2} s^{−1} will have a severe impact on pile-up. The pile-up is expected to increase on average to 200 interactions per bunch crossing. The reconstruction and trigger performance for especially jets and transverse missing energy will be severely degraded in the end-cap and forward region. A High Granularity Timing Detector (HGTD) is proposed in front of the liquid Argon end-cap calorimeters for pile-up mitigation at Level-0 (L0) trigger level and in the offline reconstruction. This device cover the pseudo-rapidity range of 2.4 to about 4.2. Four layers of Silicon sensors, possibly interleaved with Tungsten, are foreseen to provide precision timing information for charged and neutral particles with a time resolution of the order of 30 pico-seconds per readout cell in order to assign the energy deposits in the calorimeter to different proton-proton collision vertices. Each readout cell has a transverse size of only a few mm, leading to a highly granular detector with several hundred thousand readout cells. The expected improvements in performance are relevant for physics processes, i.e, vector-boson fusion and vector-boson scattering processes, and for physics signatures with large missing transverse energy. Silicon sensor technologies under investigation are Low Gain Avalanche Detectors (LGAD), pin diodes, and HV-CMOS sensors. In this presentation, starting from the physics motivations and expected performance of the High Granular Timing Detector, the proposed detector layout and Front End readout, laboratory and beam test characterization of sensors and the results of radiation tests will be discussed.

Abstract submitted on behalf of the ATLAS Liquid Argon Speaker's Committee
Speaker to be nominated later

Speaker: Sebastian Grinstein (IFAE - Barcelona (ES))
• 17:40
CMOS pixel development for the ATLAS experiment at HL-LHC 20m

To cope with the rate and radiation environment expected at the HL-LHC new approaches are being
developed on CMOS pixel detectors, providing charge collection in a depleted layer. They are based on: HV enabling technologies that allow to use high depletion voltages, high resistivity wafers for large depletion depths; radiation hard processed with multiple nested wells to allow CMOS electronics embedded with sufficient shielding into the sensor substrate and backside processing and thinning for material minimization and backside voltage application.
Since 2014, members of more than 20 groups in the ATLAS experiment are actively pursuing CMOS pixel R&D in an ATLAS Demonstrator program pursuing sensor design and characterizations. The goal of this program is to demonstrate that depleted CMOS pixels are suited for high rate, fast timing and high radiation operation at
LHC. For this a number of technologies have been explored and characterized. In this presentation the challenges for the usage of CMOS pixel detectors at HL-LHC are discussed such as charge collection after irradiation to HL-LHC doses, fast read-out and low power consumption designs as well as fine pitch and large pixel matrices. Different designs of CMOS prototypes are presented with emphasis on performance and radiation hardness results, and perspectives of application in the upgrade of the ATLAS tracker will be discussed.

Speaker: Marco Rimoldi (Universitaet Bern (CH))
• 18:00
Study of prototypes of LFoundry active and monolithic CMOS pixels sensors for the ATLAS detector 20m

High Energy Particle Physics experiments at the LHC use hybrid silicon detectors, in both pixel and strip geometry, for their inner trackers. These detectors have proven to be very reliable and performant. Nevertheless, there is great interest in the development of depleted CMOS silicon detectors, which could achieve similar performances at lower cost of production and complexity. We present recent developments of this technology in the framework of the ATLAS CMOS demonstrator project. In particular, studies of two active sensors from LFoundry, CCPD_LF and LFCPIX, and the first fully monolithic prototype MONOPIX will be shown

Speaker: Luigi Vigani (University of Oxford (GB))
• 19:00 23:00
Conference dinner 4h Hilton Milton Keynes (OU) ()

Hilton Milton Keynes (OU)

Timbold Dr, Kents Hill, Milton Keynes MK7 6HL

The conference dinner and pre-dinner drinks will take place at the Hilton Milton Keynes, situated across the road from the Open University campus.

• Friday, 8 September
• 09:20 11:00
Detectors for high energy physics and astrophysics (IV) Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 09:20
Characterisation of capacitively coupled HV/HR-CMOS sensor chips for the CLIC vertex detector 20m

The capacitive coupling between an active sensor and a readout ASIC has been considered in the framework of the CLIC vertex detector study. The CLICpix Capacitively Coupled Pixel Detector (C3PD) is a High-Voltage CMOS sensor chip produced in a commercial $180$ nm HV-CMOS process for this purpose. The sensor was designed to be connected to the CLICpix2 readout chip. It therefore matches the dimensions of the readout chip, featuring a matrix of $128\times128$ square pixels with $25$ $\mu$m pitch. The sensor chip has been produced with the standard value for the substrate resistivity (of $\sim20$ $\Omega$cm) and characterised in standalone testing mode, before receiving and testing capacitively coupled assemblies. The standalone measurement results show a rise time of $\sim20$ ns for a power consumption of $2.7$ $\mu$A/pixel.

Following the successful characterisation of the C3PD ASICs produced with the standard substrate resistivity a second submission took place, with higher substrate resistivity wafers ($\sim20$, $80$, $200$, and $1000$ $\Omega$cm). The higher resistivity, along with a layout modification done in order to achieve a higher breakdown voltage, are expected to have beneficial results on the sensor performance. A comparison of the performance of the sensor with different substrate resistivities will be presented.

Speaker: Iraklis Kremastiotis (KIT - Karlsruhe Institute of Technology (DE))
• 09:40
Test-beam activities and results for the ATLAS ITk pixel detector 20m

The Phase-II upgrade of the LHC will result in an increase of the instantaneous
luminosity up to about $5\times 10^{34}$ cm$^{-2}$s$^{-1}$. To cope with the
challenges the current Inner Detector will be replaced by an all-silicon Inner Tracker (ITk)
system. The Pixel Detector will have to deal with occupancies of about 300~hits/FE/s
as well as a fluence of $2\times 10^{16}\,\mathrm{n_{eq}cm^{-2}}$.
Various sensor layouts are under development, aiming at providing a high performance, cost effective
pixel instrumentation to cover an active area of about 10~m$^2$. These range from thin
planar silicon, over 3D silicon, to active CMOS sensors.
After extensive characterization of the sensors in the lab, their charge collection
properties and hit efficiency are measured in common testbeam campaigns, which provide
valuable feedback for improvements of the layout. Testbeam measurements of the final prototypes
will be used for the decision of which sensor types will be installed in ITk.
The setups used in the ITk Pixel testbeam campaigns will be presented, including the common
track reconstruction and analysis software. Results from the latest measurements will be shown,
highlighting some of the developments and challenges for the ITk Pixel sensors.

Speaker: Tobias Bisanz (Georg-August-Universitaet Goettingen (DE))
• 10:00
Layout and prototyping of the new ATLAS Inner Tracker for the High Luminosity LHC 20m

The current inner tracker of the ATLAS experiment is foreseen to be replaced at the High Luminosity era of the LHC to cope with the occuring increase in occupancy, bandwidth and radiation damage. It will be replaced by an all-silicon system, the Inner Tracker (ITk). This new tracker will have both silicon pixel and silicon strip sub-systems aiming to provide tracking coverage up to |η|<4.
For a high tracking performance are radiation hard and high-rate capable silicon sensors and readout electronics important. Moreover, services and stable, low mass mechanical structures are essential and give challenges to the system design. In this talk first the tracker layout and challenges, second possible solutions to these challenges will be discussed. The layouts under considerations and their technical realizations in terms of mechanics of local supports will be presented.

Speaker: Dr Ankush Mitra (University of Warwick (GB))
• 10:20
Characterization of Novel Thin N-in-P Planar Pixel Modules for the ATLAS Inner Tracker Upgrade 20m

Facing the high luminosity phase of the LHC (HL-LHC) to start operation around 2026, a major upgrade of the tracker system for the ATLAS experiment is in preparation. The expected neutron equivalent fluence of up to $3 \times 10^{16}\; \text{n}_\text{eq}/\text{cm}^2$ at the innermost layer of the pixel detector poses the most severe challenge. Thanks to their low material budget and high charge collection efficiency after irradiation, modules made from thin planar pixel sensors are promising candidates to instrument these layers.
To optimize the sensor layout for the decreased pixel cell size of $50\times 50\; \mu \text{m}^2$, TCAD device simulations are being performed to investigate the electronic noise as well as the charge collection efficiency before and after irradiation.
In addition, sensors of $100-150\;\mu \text{m}$ thickness, interconnected to FE-I4 read-out chips featuring the previous generation pixel cell size of $50\times 250\; \mu \text{m}^2$, are characterized with radioactive sources as well as test beams at the CERN-SPS and DESY. The performance of sensors with various designs, irradiated up to a fluence of $1 \times 10^{16}\; \text{n}_\text{eq}/\text{cm}^2$, is compared in terms of charge collection and hit efficiency.
It is foreseen to exchange once the two innermost pixel layers during the lifetime of HL-LHC. The exchange will require several months of intervention, during which the remaining detector modules cannot be cooled. They are kept at room temperature, thus inducing an annealing. The expected performance of these modules will be investigated using modules irradiated to the respective fluences, and the method of accelerated annealing at higher temperatures.

Speaker: Julien-Christopher Beyer (Max-Planck-Institut fur Physik (DE))
• 10:40
Development of a serially powered, prototype pixel stave for the upgrade of the ATLAS Inner Tracker 20m

The ATLAS collaboration is planning a major upgrade of the current detector systems in order to operate at the increased luminosity provided by the High Luminosity LHC (HL-LHC) scheduled for operation from 2025.

In order to operate at these increased luminosities, the inner most detector system known as the Inner Tracker (ITk) must be lower mass, higher granularity and more radiation hard than the existing detector system, particularly the pixel layers that are closest to the interaction point. To help achieve this, pixel detectors are ganged together into groups of four known as ‘quads’ reducing the dead regions that are present at the edge of chips and minimising the overlaps needed to provide coverage of the required area. Additionally, thin, flexible PCBs and strong lightweight structures for support and delivery of services and serial powering will be employed to reduce the material budget of the ITk further.

We will present the development and testing of a carbon fibre, serially powered, double-sided stave containing 12 pixel quad modules readout by a total of 48 FEI4-B ASICs. Such a system is designed to allow the testing of multiple quad modules in a realistic environment and facilitate the development of quality assurance and control procedures needed during the production and assembly phases of the ITk pixel end-cap (one of which is to be built in the UK). The pixel quads are mounted on thin, flexible Kapton PCBs and read out with the High Speed Input Output DAQ (HSIO-II) developed by SLAC. For the first time, multiple quad modules have been calibrated and read out together and system tests including threshold and cross-talk scans have been made to assess the performance of the detectors in this configuration. Radiation tests with cosmic rays and a Sr-90 source will also be presented.

Speaker: Jon Taylor (University of Liverpool (GB))
• 11:00 11:30
Tea and coffee 30m Berrill Foyer (OU) ()

Berrill Foyer (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 11:30 13:20
Applications in life sciences, biology and medicine: Electrons and positrons Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
• 11:30
The direct electron detector driven revolution in structural biology 30m

Electron cryo-microscopy, cryoEM, is rapidly replacing X-ray crystallography as the preferred method in structural biology for determining the structures of biological molecules. The rise of cryoEM can be traced to the introduction of higher detective quantum efficiency, DQE, CMOS based direct electron detectors. The resulting improved signal to noise in images of radiation sensitive samples allows near atomic resolution structures to be obtained routinely, with less sample and without the need to first have well diffracting crystals.

CMOS detectors developed for cryoEM differ from the now ubiquitous CMOS optical sensors. The most obvious difference being the need to use enclosed geometries to limit the radiation damage associated with detecting electrons. Optimisation for DQE in electron detection also requires sensors to be backthinned and operated in a counting mode. In the counting mode a final image is assembled from processed images of the individual incident electrons. To be practical this requires both fast frame rate and image processing.

Speaker: Greg McMullan (MRC-LMB)
• 12:00
Performance studies towards a TOF-PET sensor using Compton scattering at plastic scintillators 20m

Positron emission tomography is a powerful tool in nuclear medicine for diagnosing cancers and Alzheimer’s disease in early stages. We develop a sensor head for a Time-of-flight PET scanner using plastic scintillators which have a very fast timing property. Since the cross section of the photoelectric absorption in plastic scintillators is extremely small at 511 keV, we use Compton scattering in order to compensate the detection efficiency. The detector consists of two layers of scatterers and absorbers which are made of plastic and inorganic scintillators such as GAGG:Ce, respectively. Signals are read by monolithic Multi Pixel Photon Counters (MPPCs), a.k.a. SiPMs, and recorded by sampling Analog-to-digital converters and Time-to-digital converters with a timing resolution of 27 ps/bit. The scintillators are built to be capable of resolving interaction position in 3-dimentions, so that our system has also a function as Depth-of-Interaction PET scanners. We roughly estimated and confirmed using Geant4 that the total detection efficiency should be comparable to conventional PET sensors, and then proceeded to experimental demonstrations.
We report the capability of our system which is under active development. We successfully demonstrated the better timing performance of the plastic scintillators than that of LYSO:Ce and GAGG:Ce. We will present the timing resolution of the plastic scintillators for coincidence events, position-resolved spectra, and reconstruction of Compton scattering events.

Speaker: Takeshi Nakamori (Yamagata University)
• 12:20
A thin time-of-flight PET scanner based on novel pixel silicon detectors 20m

The TT-PET project aims at developing a compact Time-of-flight PET scanner with 30ps time resolution, capable of withstanding high magnetic fields and allowing for integration in a traditional MRI scanner, providing complimentary real-time PET images. The very high timing resolution of the TT-PET scanner is achieved thanks to a new generation of Silicon-Germanium (Si-Ge) amplifiers, which are embedded in monolithic pixel sensors. The scanner is composed of 16 detection towers as well as cooling blocks, arranged in a ring structure. The towers are composed of multiple ultra-thin pixel modules stacked on top of each other. Making it possible to perform depth of interaction measurements and maximize the spatial resolution along the line of flight of the two photons emitted within a patient. This will result in improved image quality, contrast, and uniformity while drastically reducing backgrounds within the scanner. Allowing for a reduction in the amount of radioactivity delivered to the patient. Due to an expected data rate of about 250 MB/s a custom readout system for high data throughput has been developed, which includes noise filtering and reduced data pressure. The realization of a first scanner prototype for small animals is foreseen by 2019. A general overview of the scanner will be given including, technical details concerning the detection elements, mechanics, DAQ readout, simulation and results.

Speaker: Yves Bandi (Universitaet Bern (CH))
• 12:40
Regularized Richardson-Lucy deconvolution of positron range effects in micro-PET studies 20m

Positron range effects in positron emission tomography (PET) studies have a negative impact in both spatial resolution and activity concentration quantification, particularly when high energy positron emitters travel in low density tissues. Several methods have been proposed to recover spatial resolution in PET with the aim of improving image quality. In this work, we propose a regularized Richardson-Lucy deconvolution algorithm using synthetic and experimental data. The method was initially optimized using synthetic-blurred transaxial images of the NEMA NU 4-2008 phantom (with and without noise) using the reported Point Spread Functions of the small-animal microPET Focus 120 scanner for F-18 and Ga-68. Experimental studies of the NEMA NU 4-2008 image quality phantom and a new conical-helix phantom filled with F-18 and Ga-68 were also carried out. Finally, a brain scan of a rat injected with C-11-Raclopride was performed. All images were reconstructed using OSEM-2D. A regularized Richardson-Lucy (RRL) algorithm using bilateral filtering (BLF) was implemented to obtain deblurred images, recovering the spatial resolution while maintaining the noise at reasonable levels. The NEMA NU 4-2008 protocol was followed to quantify recovery coefficients (RC) and spill-over-ratios (SOR) of the image quality phantom. The results indicate that the RCs for F-18 increased when using the RRL algorithm from 0.26, 0.47, 0.56, 0.66, 0.81 to 0.64, 0.85, 0.86, 0.88, 1.0 for the 1, 2, 3, 4 and 5 mm hot rods, respectively. SOR values decreased from 0.04 (water) and 0.19 (air) to 0.03 and 0.018. These values changed more drastically for Ga-68, as expected. The proposed method based on a regularized Richardson-Lucy deconvolution also provided a drastic improvement in the image quality for the conical-helix phantom and the rat cerebral PET scan. We acknowledge the support from PAPIIT-UNAM IN110616 and IN108615, Conacyt Problemas Nacionales 2015-612, PAEP-UNAM and Conacyt MSc scholarship.

Speaker: Mercedes Rodriguez-Villafuerte (Instituto de Fisica, UNAM)
• 13:00
A large-area detector module based on SiPM and pixelated LYSO crystal arrays 20m

The optimization and characterization of a large area detector module, aimed at constructing a positron emission mammogram prototype, is presented. The device features a SensL ArrayC-60035-64P-PCB solid state detector (8x8 array of tileable SiPM by SensL, 7.2 mm pitch) covering a total area of 57.4×57.4 mm2. The array was tested using 10 mm thick, LYSO pixelated crystal arrays of different pitches (1.075, 1.683, 2.080, 2.280 mm) to determine the optimum, resolvable crystal size. With these results a detector module was developed using a 40x40 LYSO pixelated array, 1.43 mm pitch. A coupling light guide was used to allow light sharing between adjacent SiPM; 7 mm thickness was found to be the optimum for all crystal pitches. A 16-channel symmetric charge division readout board was designed to multiplex the number of signals from 64 to 16 (8 columns+8 rows) and a center-of-gravity algorithm to identify the position. Data acquisition and digitization was accomplished using a custom-made system based on FPGAs boards. Crystal maps were obtained using a Cs-137 source and Voronoi diagrams were used to correct for geometric distortions and to generate a non-uniformity correction matrix. All measurements were taken at a controlled room temperature of 22°C.The crystal maps showed minor distortion, 90% of the 1600 total crystal elements could be identified, a mean 3.1 peak-to-valley ratio was obtained and a 9.6% mean energy resolution for 662 keV photons was determined. The performance of the detector using our own readout board was compared to that using two different commercially readout boards using the same detector module arrangement. We show that these large area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, excellent energy resolution and detector uniformity. We thank the support from PAPIIT-UNAM IN110616 and IN108615, Conacyt Problemas Nacionales 2015-612, PAEP-UNAM and Conacyt MSc scholarship.

Speaker: Dr Héctor Alva-Sánchez (Instituto de Física, UNAM)
• 13:20 13:30
Closing remarks 10m Berrill Lecture Theatre (OU) ()

Berrill Lecture Theatre (OU)

The Open University, Walton Hall, Milton Keynes, MK7 6AA
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