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22nd International Workshop on Radiation Imaging Detectors

Europe/Brussels
Gather.town (Online)

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Andrea Giammanco (Universite Catholique de Louvain (UCL) (BE)) , Matthieu Boone (Universiteit Gent) , Michael Tytgat (Ghent University (BE))
Description

IMPORTANT MESSAGE CONCERNING THE ORGANIZATION OF IWORID2021

Dear colleagues,

Due to the continuing uncertainty concerning the regulations and measures to reduce the impact of the COVID-19 pandemic, the LOC and SC have decided to organize the iWoRID2021 conference as a fully digital conference. Therefore, registration will be limited to online attendance.

Registration is now open!


If you have any questions or comments, please do not hesitate to contact us at iworid2021@ugent.be (or iworid2020@ugent.be).
 
Kind regards,
 
Matthieu Boone, LOC
Michael Tytgat, LOC

Eduardo Cortina, LOC
Andrea Giammanco, LOC
Christer Fröjdh, SC

The International Workshops on Radiation Imaging Detectors are held yearly and provide an international forum for discussing current research and developments in the area of position sensitive detectors for radiation imaging, including semiconductor, gas and scintillator-based detectors. Topics include processing and characterization of detector materials, hybridization and interconnect technologies, design of counting or integrating electronics, readout and data acquisition systems, and applications in various scientific and industrial fields. The workshop will have plenary sessions with invited and contributed papers presented orally and in poster sessions. The invited talks will be chosen to review recent advances in different areas covered in the workshop.

Due to the COVID-19 pandemic in 2020, the Workshop will be arranged for the 22nd time on June 27- July 1, 2021 in Ghent, Belgium. Welcome!

 

We want to thank our sponsors and exhibitors for their contribution

 

 

Videoconference Rooms
22nd International Workshop on Radiation Imaging Detectors
Zoom Meeting ID
64122392094
Host
Michael Tytgat
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    • 17:00 18:30
      Other: Platform testing Gather.town

      Gather.town

      Online

    • 09:00 09:20
      Other: Opening / welcome speech Gather.town

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      Convener: Matthieu Boone (Universiteit Gent)
    • 09:20 10:10
      Invited lectures: M. Veale Zoom

      Zoom

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    • 10:10 10:50
      Oral presentations: ASICs 1 Zoom

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      Convener: Bernd Schmitt (Paul Scherrer Institut)
      • 10:10
        A new AGIPD detector generation 20m

        The Adaptive Gain Integrating Pixel Detector (AGIPD), a megahertz frame-rate, high-dynamic range integrating pixel detector, was developed for photon science experiments at the European X-Ray Free Electron Laser (European XFEL) and tailored to its unique specifications. Two 1-Megapixel AGIPD detector systems have been installed at the European XFEL and are producing numerous scientific publications. In order to further improve the existing systems, and to provide dedicated systems for two user consortia, we have been developing the next generation of hardware. These developments will also reach out into entirely new areas.

        Two new generation of ASICs have been developed. AGIPD1.2 corrects a problem with the gain encoding in AGIPD1.1, which made it difficult or impossible to distinguish whether a pixel was in medium or low gain, effectively reducing the useful dynamic range of the system. The improved gain bit encoding was tested and verified in a test beam experiment at the HED scientific instrument at the European XFEL in November 2020. The other generation, AGIPD1.3, is an electron collecting version of the ASIC, needed for readout of high-Z sensor materials such as Gallium-Arsenide (GaAs), Cadmium-Telluride (CdTe), or Cadmium-Zinc-Telluride (CdZnTe). Such sensors are needed to provide higher absorption efficiencies for photon energies in the range from 15-30 keV, which are demanded by a number of user communities.

        On the backend, new, more compact, read-out electronics have been developed most notably including a new FPGA, firmware, and all-optical communication with new multifibre Gbit tranceivers.
        A 0.5-Megapixel prototype system, using the new readout electronics, firmware and AGIPD1.2 ASIC has been built, commissioned and operated in user experiments at the HED instrument in 2020 (see figure). This system provided the first Megahertz diffraction capabilities for HED science at the European XFEL.

        This new generation of AGIPD will be used to build two new detector systems. A 4-Megapixel system for the SFX user consortium at the SPB/SFX station, and a 1-Megapixel system with high-Z sensors for the HED instrument at the European XFEL. In addition, also the existing AGIPD detectors at SPB and MID will be equipped with new front-end modules containing AGIPD1.2.

        In this talk we will present and discuss the current status of all AGIPD developments on the front-end and read-out electronics and show results from the data of the Second Generation prototype AGIPD system at HED.

        Speaker: Torsten Laurus (Deutsches Elektronen-Synchrotron DESY)
      • 10:30
        FASTpix - small collection electrode CMOS sensors for precise time-stamping capabilities, high efficiency in thin sensors and high radiation tolerance 20m

        In the framework of the ATTRACT FASTpix project monolithic small collection electrode CMOS technologies for fast signal collection, high radiation tolerance and precise timing in the sub-nanosecond range are investigated.
        Deep sub-micron CMOS technologies give access to very small, sub-femtofarad collection electrodes and large signal-to-noise ratios, essential for very precise timing in monolithic sensors. However, the small collection electrode design results in highly non-uniform electric and weighting fields in the sensor, that introduce variations of the charge collection times in dependence of the particle incident position, a key limitation for precise timing and radiation tolerance.
        Within the FASTpix project sensor design modifications have been developed to mitigate these variations. Special implant structures have been designed that shape the electric field to uniformize the drift path within a pixel cell. In particular, reduced charge collection times in the pixel edges have been achieved, that reduce the charge sharing, increase the efficiency before and after irradiation and improve the time stamping capabilities. Additionally, a hexagonal arrangement of the collection electrodes has been found to mitigate slow charge collection at the pixel edges. Moreover, the hexagonal pixel geometry is also favorable for timing and efficiency measurements due to the reduced number of neighboring pixels, minimizing the charge sharing and therefore increasing the single pixel signal-to-noise ratios.
        The FASTpix chip contains several mini-matrices with digital and analogue pixels and different sensor designs and geometries. Pixel pitches down to about 8.7 micrometer between collection electrodes are implemented in a 180 nm technology by placing only a minimum amount of circuitry inside the pixel matrix. The optimized well structures are implemented on a high resistivity epitaxial layer.
        At present, the FASTpix has been investigated in laboratory measurements, showing the improved performance of the optimized designs even at small pixel pitches below 10 micrometer. This talk presents the concepts and results of 3D TCAD based sensor design optimizations as well as measurement results comparing different sensor designs.

        Speaker: Magdalena Munker (CERN)
    • 10:50 11:20
      Coffee break 30m Gather.town

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    • 11:20 12:20
      Oral presentations: Particles Zoom

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      Convener: Joaquim Marques Ferreira Dos Santos (Universidade de Coimbra (PT))
      • 11:20
        High-angular resolution tracking of energetic charged particles in wide field-of-view with compact tracker telescope MiniPIX Timepix3 1×2 Stack 20m

        We developed a highly integrated particle telescope assembled from two Timepix3 ASIC chip detectors [1] operated and readout in sync with highly integrated MiniPIX readout interfaces. The pixel detectors are used as particle trackers stacked on top of each other (see Fig. 1a) being accommodated in close geometry. The small distance gap (about 10 mm) between the pixel detectors provides a wide field-of-view (FoV) of about 1/3 of the full 2π with high angular resolution (sub-degree). The remaining FoV, about 2/3 of full 2π, which corresponds to particles incident at large angles (>35°) to the plane of the sensors, can be covered by each of the detectors separate. The angular resolution in this remaining region is few degrees [2] and, in a narrow range, also sub-degree (for very large incident directions and grazing angles). This configuration also enables to register all energetic charged particles in full tracking mode i.e. with tracks having elongated morphology which allows performing high-resolution tracking. This enables to derive precise wide-range spectrometric and tracking information of individual particles e.g. precise LET and also provide enhanced particle-type resolving power of up to 8 event classes [3]. The device is controlled, operated and readout via two USB 2.0 connectors (each tracker detector is connected to a separate USB port). Communication and fast clock timing synchronization between both trackers is realized by the SPI ports. The coincidence timing window between both trackers is in the range 50 – 100 ns. Control, operation and data readout is performed on standard PC/laptop and the software package PIXET. Test measurements were performed with energetic i.e., penetrating charged particles, 5–25 MeV electrons (at the Microtron MT-25 electron accelerator) and 8–36 MeV protons – see Fig. 1, (at the cyclotron U–120M proton/light ion accelerator) both at the NPI-CAS in Rez near Prague. Future measurements and novel applications include space radiation studies in outer space, nuclear and cosmic ray physics and particle radiotherapy research.

        [1] T. Poikela et al., Timepix3: a 65k channel hybrid pixel readout chip with simultaneous ToA/ToT and sparse readout, J. of Instrum. JINST 9 (2014) C05013
        [2] C. Granja et al, Directional detection of charged particles and cosmic rays with the miniaturized radiation camera MiniPIX Timepix, Nucl. Instrum. and Meth. A 911 (2018) 142-152
        [3] C. Granja et al., Resolving power of pixel detector Timepix for wide-range electron, proton and ion detection, Nucl. Instrum. Meth. A 908 (2018) 60-71

        Work performed in frame of Contract 40001250020/18/NL/GLC/hh of the European Space Agency. Measurements at the NPI-CAS cyclotron were performed in frame of the CANAM Infrastructure LM 2015056 MSMT. Support in part by JINR-CZ Committee Grant.

        Speaker: Dr Carlos Granja (Advacam)
      • 11:40
        Electron detection with CdTe and GaAs sensors using the charge integrating hybrid pixel detector JUNGFRAU 20m

        JUNGFRAU is a charge integrating hybrid pixel detector developed for use at X-ray free electron lasers. With in pixel gain switching it provides single photon sensitivity down to 2 keV while maintaining a dynamic range of 120 MeV. The pixel size is 75 x 75 $\mu m^2$ and the largest detector currently in use has 16M pixels. The characteristics of Jungfrau makes it an interesting detector for electron detection, capable of both providing information about the energy deposition of single electrons, in the low flux regime as well as measuring very high fluxes, for example in diffraction experiments, due to the charge integrating architecture. Exploiting the possibility to acquire per pixel information on energy deposition and leakage current it also is a useful tool for sensor characterization.

        While Silicon sensors coupled to hybrid pixel detectors show good results up to ~100 keV [1, 2], at higher electron energies multiple scattering in the sensor layer reduces the spatial resolution. One strategy to mitigate this is to use a high Z sensor material which gives a shorter track of the primary electron. In this work we compare Si, GaAs and CdTe sensors bump bonded to JUNGFRAU and present results on energy resolution, cluster size and modular transfer function. The measurements were carried out using a 300 keV FEI Tecnai G2 Polara microscope at 100, 200 and 300 keV. We also compare the results to simulations done in Geant4.

        [1] J. Mir, R. Clough, R. MacInnes, C. Gough, R. Plackett, I. Shipsey, H. Sawada, I. MacLaren, R. Ballabriga, D. Maneuski, V. O’Shea, D. McGrouther, A. Kirkland, Characterisation of the Medipix3 detector for 60 and 80 keV electrons, Ultramicroscopy 182 (2017) 44–53.

        [2] G. Tinti, E. Fröjdh, E. van Genderen, T. Gruene, B. Schmitt, D. A. M. de Winter, B. M. Weckhuysen, J. P. Abrahams, Electron crystallography with the EIGER detector, IUCrJ 5 (2) (2018) 190–199.

        Speaker: Erik Fröjdh (Paul Scherrer Institut)
      • 12:00
        Experimental study of the adaptive gain feature for improved position sensitive ion spectroscopy with Timepix2 20m

        Timepix2 [1] is a hybrid pixel detector developed in the Medipix2 collaboration as the successor of Timepix. It separates the sensor attached to the ASIC into a square matrix of 256 x 256 pixels at a pixel pitch of 55 µm. Similar to Timepix [2], it relies on a frame-based readout scheme. However, it comes with valuable additional features such as an occupancy trigger allowing to force the frame termination if a preset number of columns received entries. Moreover, it prevents the frame shutter from cutting ToT signals at the end of the frames and allows to reduce power consumption by reducing the sensitive area (pixel masking).

        While the aforementioned improvements have already been studied [3,4], in this contribution, we investigate the behaviour of the per-pixel energy measurement with the adaptive gain mode, which was implemented to allow for an extended per pixel energy range.
        A Timepix2 detector with a 300 µm thick silicon sensor was calibrated using x- and gamma-rays in the energy range up to 60 keV. An energy resolution of 1.62 keV (FWHM: 3.8 keV) is achieved for 59.5 keV gamma-rays. To study the high energy response, the device was further irradiated with alpha particles from a 241Am source, whereby the per-pixel energy depositions were varied by changing the applied reverse bias and the distance from the source to the sensor top (utilizing the alphas particle energy loss in air). For completeness, measurements were done in vacuum.
        For each measurement, the energies measured in the alpha tracks are compared with the expected energy calculated by SRIM. While at greater distances (where the maximal per pixel energy is below 650 keV) the expectation and measurement are in good agreement, an underestimation of the alpha energy is found at shorter distances. Assuming correct per-pixel energy measurement up to 650 keV and using the topology of the alpha particle tracks, we can relate the energy measured in the central pixels of the track (Emeas) to the energy required to obtain the predicted alpha particle energy (Eexpected). The scatter plot of Emeas vs Eexp is shown in Figure 1. The observed behaviour is modelled with a bilinear function and used to correct the per-pixel energy calibration curve. Energy spectra at different distances to the alpha-source are shown in Figure 2 after applying the correction function. The energy resolution was determined by fitting Gaussian distributions. We find ~110 keV (FWHM: 260 keV) at 0.9 MeV and ~300 keV (FWHM: 706 keV) at 5.5 MeV. It will be shown that energies up to ~850 ke- (i.e. 3.2 MeV in silicon) can be measured in a single pixel, outperforming the other chip of the Timepix family currently used.
        References:
        [1] W.S. Wong et al., Radiation Measurements, Vol. 131, 106230 (2020).
        [2] X. Llopart et al., NIM A, Vol. 581, Issues 1–2, 485-494 (2007).
        [3] P. Burian et al., JINST 15, C01037 (2020).
        [4] S. George et al., NIM A, Vol. 958, 162725 (2020).

        The work was done within the Medipix collaboration. The authors acknowledge the support of the project “Engineering applications of physics of microworld” with No. CZ.02.1.01/0.0/0.0/16_019/0000766

        Speaker: Benedikt Ludwig Bergmann (Czech Technical University in Prague (CZ))
    • 12:20 13:30
      Lunch break 1h 10m Gather.town

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    • 13:30 14:20
      Invited lectures: M. Endrizzi Zoom

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    • 14:20 15:00
      Oral presentations: Medical Zoom

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      Convener: Renata Longo (Dipartimento di Fisica, Università di Trieste, & INFN, sez. di Trieste, Italy.)
      • 14:20
        Quantum Entangled PET Imaging 20m

        The effect of quantum entanglement was first discussed more than 80 years ago [1,2]. Particles that are quantum entangled are described by a common wavefunction which leads to enhanced correlations between the particle interactions, even when separated over macroscopic distances. The two photons resulting from positron annihilation are predicted to be in such an entangled state. Their entanglement in linear polarisation modifies the double-Compton scattering cross-section as a function of the relative azimuthal scattering angle of the photons (Δɸ), resulting in a cos(2Δɸ) modulation having an amplitude far in excess of that expected for non-entangled photons. Previous experimental measurements have shown enhancement consistent with the entangled predictions, albeit for restricted scattering kinematics and using conventional detectors (e.g. NaI [3]). The recent advances in CZT detector technology allowed us to overcome many of the past difficulties and obtain experimental demonstration of quantum entanglement in MeV range with large acceptance. One of the most exciting applications of quantum entanglement is in Positron Emission Tomography (PET), a technique widely used for medical research and clinical diagnosis. It utilises the back-to-back emission of annihilation photons to image metabolic processes inside of the body. PET images are obtained with significant in-patient scattering and random backgrounds, which reduce image resolution and contrast. Both of those problems are mitigated using scintillator detectors with timing resolution of a few hundreds of nanoseconds, thus making solid state detectors largely impractical for such purpose. Using quantum entanglement principles could open new ways to use CZT detectors in PET.
        To investigate the potential benefits of quantum entanglement, it was incorporated into the GEANT4 code using polarized Klein-Nishina formula [4,5]. The simulation was verified against experimental data from a CZT PET demonstrator developed by Kromek, shown in Figure 1. The detector system is comprised of a pair of 10 mm thick 800 µm pixel pitch CZT detectors connected to the main controlling unit. Events with two interactions in each detector were selected and analysed, Using the excellent energy and 3D position resolution which are among the strongest advantages of CZT detectors allowed reconstruction of photon trajectories along with their scattering angles. In Figure 2 we show the experimental data from the CZT system (black data points) exhibiting the clear modulations predicted by quantum mechanics. The prediction from the QE-GEANT4 simulation including entanglement (blue line) is clearly essential to reproduce the experimental data.
        In addition to the experimental demonstration of quantum entanglement, we present simulated GEANT4 imaging studies of the efficacy of exploiting the implicit quantum entanglement between true PET photon coincidences. PET images of a NEMA_NU4 phantom using a simulated array of CZT detectors were obtained. 2D PET images were reconstructed from the data using simple filtered back projection (FBP) methods. A simple procedure to use the new information from the entanglement enabled spatially resolved determination of the contribution of both scatter and random coincidences to the image. The ability to extract such information purely from the data offers new opportunities for PET imaging methodologies.

        The results indicate that use of CZT detector systems would allow access to previously inaccessible quantum entanglement information in PET. This offers independent, new information to quantify random and scatter backgrounds. In future work, we plan to incorporate this information into more advanced image reconstruction techniques and optimise the design of new imaging systems. The work presented has been accepted for publication at Nature Communications [6].

        [1] D Bohm, Y Aharonov, Phys. Rev. 108, 1070–1076 (1957).
        [2] H S Snyder, S Pasternack, J Hornbostel, J. Phys. Rev. 73, 440 (1948).
        [3] P Caradonna, D Reutens, T Takahashi, S Takeda, V Vegh, J. Phys. Commun. 3 (2019).
        [4] M H L Pryce, J C Ward, Nature 160, 435 (1947).
        [5] M A Stroscio, Phys. Rev. A 29, 1691 (1984).
        [6] arXiv: 2012.04939.

        Speaker: Alexander Cherlin (Kromek Group plc)
      • 14:40
        The timing detectors of the FOOT experiment: the charge changing cross sections measured using 16O beams of 400 MeV/u energy 20m

        In Particle Therapy (PT), nuclear interactions of the beam with the patient’s body causes fragmentation of both the projectile and target nuclei. In treatments with protons, target fragmentation generates short range secondary particles along the beam path, that may deposit a non-negligible dose especially in the entry channel. On the other hand, in treatments with heavy ions, such as C or other potential ions of interest, like He or O, the main concern is long range fragments produced by projectile fragmentation, that release the dose in the healthy tissues downstream of the tumor volume. Fragmentation processes need to be carefully taken into account when planning a treatment, in order to keep the dose accuracy within the recommended 3% of tolerance level. The assessment of the impact that these processes have on the released dose is currently limited from the lack of experimental data, especially for the relevant fragmentation cross sections. For this reason, treatment plans are not yet able to include the fragmentation contribution to the dose map with the required accuracy. The FOOT (FragmentatiOn Of Target) collaboration, funded by INFN (Istituto Nazionale di Fisica Nucleare, Italy) , designed an experiment to fill this gap in experimental data, aiming the measurement of the differential cross sections of interest with an accuracy better than 10%. The apparatus, shown in figure 1, is composed of several detectors that allow fragment identification in terms of charge, mass, energy and direction. Starting from the incident beam direction, the particles cross a plastic scintillator (Start Counter) and a drift chamber to measure the start for the Time Of flight and to monitor the primary beam respectively. Then the beam interacts with the magnetic spectrometer composed by two pixel detectors, a microstrip detector and a permanent magnet system that provides the required magnetic field in order to measure the fragments momentum. The last part of the FOOT electronic setup is composed by a plastic scintillator wall (∆E-TOF detector) and a calorimeter that provide the fragments energy loss (∆E) and the stop of the TOF measurements.The TOF system composed by the SC and after ~ 2 m the ∆E-TOF detector, plays a crucial role as the charge Z of fragments reaching the ∆E-TOF detector can be identified from the energy loss ΔE and the TOF information. The two detectors have been optimized in order to achieve a TOF resolution lower than 100 ps and an energy loss resolution σ(ΔE)/ΔE ~ 5%. For this reason the SC thickness was carefully optimized looking for a good compromise between the out of target fragmentation probability, that called for the smallest possible thickness, and the time resolution, that is directly linked to the light yield requiring a thick detector. The final SC detector layout, that was optimized using MC simulations, foresees a squared EJ – 228 plastic scintillator (5 × 5 cm2 active area) arranged in a set of four different thickness (ranging from 250 μm to 1 mm) used depending on the beam projectile and energy range. According to this geometrical proprieties the expected beam fragmentation inside the SC is about 5% of the incident ions. The plastic scintillator readout is performed by means of 48 3 × 3 mm2 SiPMs, 12 per side, bundled in eight electronic channels, each reading a chain of 6 SiPMs. The ∆E-TOF detector consists of a matrix of EJ-200 bars, 3mm thick, orthogonally arranged in two subsequent layers. The thickness of the bars is chosen as a trade-off between the amount of scintillation light produced in the bar (resulting in a better timing and energy resolution), which increases with the deposited energy and therefore with the bar thickness, and the systematic uncertainty induced on the ∆E- TOF measurement by secondary fragmentation in the bars that would worsen the particle identification and tracking. Each layer is composed of 20 bars that are 2 cm wide and 44 cm long, resulting into a 40 × 40 cm2 active area. The light produced in each bar is collected at both the extremities using to 4 SiPMs per side (3 × 3 mm2 active area) biased and read-out by a single electronic channel. The two detectors share the SiPM read-out system: the 88 output signals of the ΔE- ToF and the SC are digitized and recorded by using the WaveDAQ system, capable of a 0.5–5 GS/s sampling speeds.The FOOT TOF system has been tested with 12C and 16O ion beams with energies ranging from 115 MeV/u to 400 MeV/u in March 2019 at the CNAO (Centro Nazionale di Adroterapia Oncologica) experimental room. The measured TOF resolution has matched the expectations (the average resolution σ(ToF) ranges between 55 ps and 80 ps as a function of the beam kinetic energy) and fulfilled the requirements needed for the fragment atomic mass discrimination level needed by the cross section measurement program of the FOOT experiment. In April 2019 a first data taking was done at GSI Laboratory using a 400 MeV 16O beam impinging on a graphite target with a partial FOOT experiment setup including the SC, the Beam Monitor and the ∆E-TOF detectors. In this contribution the two timing detectors and their performance tested at GSI are explained in detail. In addition, preliminary results of the charge changing cross sections for the production of fragments with Z between 2 and 7 for the case of 400 MeV/u 16O beam integrated in the ∆E-TOF detector acceptance will be presented.

        Speaker: Gaia Franciosini (INFN - National Institute for Nuclear Physics)
    • 15:00 15:30
      Coffee break 30m Gather.town

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    • 15:30 16:50
      Oral presentations: Systems Zoom

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      • 15:30
        Development of an intensified neutron camera system for high sensitivity white-beam imaging 20m

        Thermal Neutron Imaging is a steadily expanding area of imaging technology and techniques with increasing interest from applications such as cultural heritage, palaeontology, and metallurgy [1,2]. Increased demand for access combined with a limited number of suitable beamlines requires efficient use of available beamtime [3,4]. N-Cam is a new experimental neutron camera system designed with increased sensitivity, thus able to capture detailed images with reduced exposure time as compared to most neutron cameras. N-Cam utilizes a 20µm thick Gadox scintillator applied directly onto the input window of an image intensifier. In experiments performed at the Rutherford Appleton Laboratory ISIS-IMAT facility, N-Cam demonstrated high contrast imaging with 10 lp/mm spatial resolution in 5 second exposures over a 75mm field of view. The Modular Transfer Function was calculated at multiple positions to assess the direction dependence of spatial resolution as seen in Figure 1. The fractional standard deviation of a 24 mm × 24 mm region is given as a function of binned pixel size in Figure 2, where T = 5 seconds and Fn = 2 × 107 n/(s·cm2). The data are well fit with the given equation, resulting in an estimated DQE = 16%. Additional data on contrast-to-noise and tomography will also be presented.

        [1] B. Schillinger et al, J. Imaging, 4(1) (2018), 22
        [2] E. Lehmann et al, Physics Procedia, 88 (2017), 5 – 12
        [3] W. Kockelmann et al, J. Imaging, 4(3) (2018), 47
        [4] E. Lehmann et al, Physics Procedia, 88 (2017), 140 – 147

        Authors acknowledge the support of the UK government and STFC Rutherford Appleton Laboratory

        Speaker: Dr Paul Hink (Photek USA LLC)
      • 15:50
        The new GEM station GE1/1 of the CMS muon detector: status, commissioning and early performance studies 20m

        During Run 3 the LHC will deliver instantaneous luminosities of 510^34 cm^-2 s^-1 or even 710^34 cm^-2 s^-1. To cope with the high background rates and to improve the trigger capabilities in the forward region, the muon system of the CMS experiment has been upgraded with a new station of detectors based on triple-GEM technology, named GE1/1. The station, which has been installed in 2020, consists of 72 ten-degree chambers, each made up of two layers of triple-GEM detectors. GE1/1 provides two additional muon hit measurements which will improve muon tracking and triggering performance. This contribution will describe the status of the ongoing commissioning phase of the detector together with the preliminary results obtained from cosmic-ray events. Detector and readout electronics operation, stability and performance will be discussed, as well as the preparation for Run 3 of the LHC.

        Speaker: Federica Maria Simone (Universita e INFN, Bari (IT))
      • 16:10
        Pixel chamber: a solid-state active-target for 3D imaging of charm and beauty 20m

        Modern vertex detectors are based on cylindrical or planar layers of silicon sensors, generally immersed in a magnetic field. These detectors are used for precision measurements of the particles produced in the interactions and, in particular, of the dacay products of those with a long mean life, such as open charm and beauty. Since the tracking layers are always few to tens of cm from the interaction point, this poses an ultimate limitation in the achievable resolution of the vertex position.

        A silicon-based active target detector capable to image particles produced inside the detector volume in 3D, similarly to a bubble chamber, does not exist. Ideas for a silicon active target providing continuous tracking were put forward already 40 years ago but the required technology just did not exist until recently (1).

        In this talk, I will describe the idea for the first silicon active target based on silicon pixel sensors, called Pixel Chamber (2), capable to perform continuous, high resolution (O($\mu m$)) 3D tracking, including open charm and beauty particles.
        The aim is to create a bubble chamber-like high-granularity stack of hundreds of very thin monolithic active pixel sensors (MAPS) glued together. To do this, the ALPIDE sensor chip, designed for the ALICE experiment at the CERN LHC, will be used (3). This sensor is a matrix of 1024x512 monolithic active pixels (size $\sim$ 29x27 $\mu m^2$) with an area of $\sim$1.5x3 $cm^2$ and thickness $\sim$ 50 $\mu m$. Pixel Chamber is conceived as a stack of 216 ALPIDE chips, having a volume of $\sim$1x1.5x3 $cm^3$ and forming a 3D matrix of almost $10^8$ pixels.

        Figure 1 shows a comparison between a bubble chamber image for the strange barion $\Omega^{-}$ (4) and a Geant4 simulation of a $D^{+}$ meson decaying to $K \pi \pi$ in a proton-silicon interaction with Pixel Chamber.

        A tracking and vertexing algorithm developed specifically for reconstructing the interactions inside Pixel Chamber will be discussed. Monte Carlo simulations of proton-silicon interactions at 400 GeV, based on Geant4, were used to test tracking and vertexing performances. According to those simulations, it is possible to obtain a high efficiency for the reconstruction of hadronic tracks, and for the primary interaction vertex and secondary decay vertices inside the detector. The vertex resolution can be up to one order of magnitude better than state-of-the-art detectors like those of LHC experiments.

        (1) G. Bellini et al., Miniaturization of High-Energy Physics Detectors, pp41-55, Springer, 1983
        (2) G.Usai et. al, “Pixel Chamber: A universal silicon heavy-avor imager for fixed-target measurements of charm and beauty with unprecedented precision”, R&D project funded by the Regional Government of Sardinia - Italy
        (3) Gianluca Aglieri Rinella, on behalf of the ALICE Collaboration, Nucl. Instrum. Meth. A, volume 845 (2017)
        (4) V. E. Barnes et al., Observation of a Hyperon with Strangeness Minus Three, Phys. Rev. Lett. 12, 204, 24 February 1964

        Left: the discovery of $\Omega^{-}$ in the Brookhaven National Laboratory 80 inch hydrogen bubble chamber in 1964 (4). Right: PixelChamber imaging a 400 GeV p-Si interaction with the production of a $D^{+}$ meson.

        Speaker: Alice Mulliri (Universita e INFN, Cagliari (IT))
      • 16:30
        Development, construction and tests of the Mu2e electromagnetic calorimeter mechanical structures 20m

        The “muon-to-electron conversion” (Mu2e) experiment at Fermilab will search for the Charged Lepton Flavour Violating neutrino-less coherent conversion -N(A,Z)  e-N(A,Z) of a negative muon into an electron in the field of an aluminum nucleus. The observation of this process would be the unambiguous evidence of physics beyond the Standard Model. Mu2e detectors comprise a straw-tracker, an electromagnetic calorimeter and an external veto for cosmic rays. The electromagnetic calorimeter provides excellent electron identification, complementary information to aid pattern recognition and track reconstruction, and a fast online trigger. The detector has been designed as a state-of-the-art crystal calorimeter and employs 1340 pure Cesium Iodide (CsI) crystals readout by UV-extended silicon photosensors and fast front-end and digitisation electronics. A design consisting of two annular disks positioned at the relative distance of 70 cm downstream of the aluminum target along the muon beamline satisfies Mu2e physics requirements.
        The hostile Mu2e operational conditions, in terms of radiation levels, 1 tesla magnetic field and 10^-4 Torr vacuum have posed tight constraints on the design of the detector mechanical structures and materials choice. The support structure of the two 670 crystals matrices employs two aluminum hollow rings and parts made of open-cell vacuum-compatible carbon fibre. The photosensors and front-end electronics associated to each crystal are assembled in a unique mechanical unit inserted in a machined copper holder. The 670 units are supported by a machined plate made of vacuum-compatible plastic material. The plate also integrates the cooling system made of a network of copper lines flowing a low temperature radiation-hard fluid and placed in thermal contact with the copper holders to constitute a low resistance thermal bridge. The digitisation electronics is hosted in aluminum crates positioned on the external surfaces of the two disks. The crates also integrate the digitisation electronics cooling system as lines running in parallel to the front-end system.
        In this talk we will review the constraints on the calorimeter mechanical structures, the mechanical and thermal simulations that have determined the design technological choices, and the status of mechanical components production, tests and assembly.

        Speaker: Dr Daniele Pasciuto (INFN Pisa)
    • 17:30 20:00
      Other: Student social programme Gather.town

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    • 09:00 09:50
      Invited lectures: C. Carloganu Zoom

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    • 09:50 10:30
      Oral presentations: Muons Zoom

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      Convener: Michael Tytgat (Ghent University (BE))
      • 09:50
        From muography to muon tomography of large structures 20m

        Muography is a penetrating imaging technique making use of the natural cosmic muons to probe the inside density distributions of objects. Since the pioneering work from Luis Alvarez in the 1960s, different imaging modes have been implemented depending on the size of these objects. The most common and only usable one for very large structures is the so-called transmission muography, where the image is obtained from muons which passed through the structure. This image is by nature a 2D density distribution, the density along the direction of observation being integrated. This situation is very similar to medical imaging, and a 3D picture can be accessed by combining different projections. In this case, however, the size of the objects as well as the modest number of available projections impose several challenges to this inverse problem. Following a previous work on absorption muography, a SART algorithm was successfully applied on simulated transmission data. This talk will review the various challenges of this inversion and how they were addressed. By the time of the conference, new results should be released from the ScanPyramids collaboration, and the application of the SART algorithm to the CEA data will then be shown.

        Speaker: Sebastien Procureur (Université Paris-Saclay (FR))
      • 10:10
        Three years of muography at Mount Etna: results and future perspectives 20m

        Mount Etna Volcano is characterized by the Summit Craters system which represents the crucial point of its persistent tectonic activity. The Muography of Etna Volcano project started in 2016 and the first muon-tracking telescope prototype has been installed on the slope of North-East Crater from August 2017 to October 2019 (Figure 1). The aim of the project was to find anomalies in the density of volcanic edifice and monitor their time evolution. In this work, the major results achieved by the project are presented, including the detection of an expanding underground cavity months before the collapse of the crater floor, but we also want to focus on our strategy and plans to realize a muography application at Mount Etna.
        In designing the first telescope prototype of the MEV project, built at the Department of Physics and Astronomy (DFA) "E. Majorana" of the University of Catania, all common characteristics among detectors for an out-of-laboratory muography application were included: ruggedness and water-tightness to face every climatic condition at high altitude, power network independence (by means of solar panels and a battery pack) and low consumption, connection to the internet in order to remotely access and operate the telescope. The telescope is designed to work horizontally oriented with three X-Y position-sensitive tracking planes (TP) vertically placed and spaced in the horizontal direction. The distance D between the two external planes is 97 cm . The third TP is located in the middle between the two external planes. Particle detection and tracking are based on scintillating plastic bars technology, with two wavelength-shifting optical fibers (WLS) embedded in to transport the scintillation light to the sensor.
        At the base of this design choice, there is the intention to measure at the same time the muon flux coming from the front and back sides of the detector. In this way, it is possible to measure the flux through the object of interest and the flux directly coming from the sky (not attenuated), or “open sky” flux. By comparing these two quantities, we have direct access to the spatial distribution of the absorption coefficient through the target object, which is a quantity related to its opacity, i.e. density integrated over the particle path along the direction of sight of the telescope.
        Each TP is completed by a 64 channels Multi-Anode Photomultiplier (MAPMT, mod. Hamamatsu H8500) that allows us to read-out the scintillation light signal. Counting both WLS for each scintillating bars, there are 4 ⨯ N = 396 optical channels for each TP, but only 64 channels on the sensor. The coupling is made possible by a proper routing of the WLS that allows us to minimize the number of corresponding front-end channels by a factor 1/sqrt(N). The choice to develop custom electronic boards allowed to remove all the redundant components that can be found in an evaluation board and to keep only the ones required for the specific purpose. At the end of summer 2018, before the interruption of the second year of the data acquisition campaign, a module to measure particle time-of-flight (TOF) between the external tracking planes was installed. The purpose of this measurement is the correct discrimination of near-horizontal tracks.
        The MEV telescope was installed and remained at the measurement site at the base of NE crater from 1st August 2017 till the end of September 2019, thus for more than two years. However, in 2017 and 2018, the whole detector, including solar panels, was buried under a huge snow coverage with the incoming winter. With solar panels covered, the detector went off after a short time and remained quiet during both winters. Only at the beginning of the summer, when the snow melted down, and the measurement site was again reachable by a car, it was possible to restore the power supply and start a new acquisition. However, the detector's design has demonstrated to be able to overcome exceptional weather conditions during winters at high altitudes without detriments to electronics and tracking modules. Only the components outside of the box were partially damaged, i.e., solar panels and antennas for data transmission over the LTE network, and required to be repaired or substituted.

        Speaker: Dr Giuseppe Gallo (University of Catania)
    • 10:30 11:00
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    • 11:00 12:00
      Oral presentations: Readout Zoom

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      Convener: Roelof de Vries (Malvern-PANalytical)
      • 11:00
        WiggleCam: a method to cope with inter-sensor gaps for high-framerate tiled sensor arrays 20m

        In order to keep down costs and control yields, large area hybrid detectors are commonly implemented using multiple sensor tiles in various geometries. Due to the presence of guard rings, readout connections and other design considerations it is practically impossible to make tiled sensor arrays where the tiles meet up exactly. Even in the case of four side buttable sensors, arrays will still have some measure of dead space between the tiles. A variety of hardware and software techniques currently exist to fill in the inactive space, such as roof tile arrangements of sensor tiles, software interpolation to fill in gaps, and stitching together multiple overlapping but shifted exposures. All of these techniques present their own drawbacks, from greatly increasing hardware complexity, introducing undesirable artefacts in certain applications, or increasing measurement times and experimental overhead.

        The authors propose a novel technique, called WiggleCam, for mitigating inactive regions and malfunctioning pixels in X-ray cameras which use very high frame rates (often exceeding 1 kHz). This is commonly the case in hyperspectral imagers, which provide raw ADC output frames at very high time resolution for energy dispersive single photon detection. In this work we present the results of a proof-of-concept implementation of the method using a HEXITEC 2x2 camera[1] mounted on an XY-stage, with all data processing done using SpeXIDAQ, the in-house developed framework for hyperspectral imagers[2]. A practical implementation requires access to the raw high-framerate camera output before it is integrated into the final exposure. By moving the detector such that every section of the region of interest is imaged at least part of the desired exposure time, and shifting the individual photon events using the coincident detector position in the lab frame before integration, any inactive areas are fully covered. By then compensating for the non-uniform exposure time no deterministic motion path is required, and a final image output is obtained free from gaps, without temporal overhead, and with no further post-processing required by the end-user.

        The method is shown to accurately compensate for the inter-tile gaps without compromising the spatial and spectral resolution. It also provides a way to increase the effective spatial resolution without physically reducing the pixel pitch. This presentation will conclude by demonstrating a new camera device under development using multiple HEXITEC sensors, designed to include the Wigglecam method in the camera construction itself for a more compact and useful implementation.

        [1] Wilson, Matthew D., et al. “Multiple module pixelated CdTe spectroscopic X-ray detector” IEEE Transactions on nuclear science 60.2 (2013): 1197-1200
        [2] Van Assche, Frederic, et al. “The Spectral X-ray Imaging Data Acquisition (SpeXIDAQ) Framework” Sensors 21(2) (2021): 563

        The authors acknowledge funding from the Research Foundation Flanders (FWO) under grant G0A0417N, the Industrial Research Fund under grant F2020/IOF-StarTT/135, and thank STFC for providing the HEXITEC system used in the development of this work.

        Speaker: Mr Frederic Van Assche (Ghent University)
      • 11:20
        Development of Data Correction Techniques for the 1M Large Pixel Detector at FXE 20m

        STFC’s developed 1M Large Pixel Detector (LPD) [1] is now in operation on the femtosecond experiment (FXE) instrument [2] at the EuXFEL. LPD consists of more than 1 million pixels split across 2048 ASICs, with each ASIC having dimensions 32 × 16 pixels and a pixel pitch of 500m. LPD’s three parallel gain stages provide a large dynamic range, capable of detecting 105 photon/pixel/12keV x-ray pulse. When adding in the fact that each image is captured using 1 of the 512 available memory cells, more than 1.5 billion sets of individual pixel gain correction coefficients are required. This paper reviews recent progress in finalising these values. One method for calculating these coefficients is through comparison of LPD signals to an independent reference signal. In these measurements a combination of Si photodiodes and Si Avalanche Photodiodes (APD) were used. Through utilising these correlations the entire 1M of individual pixel outputs can be aligned on a common axis and their relative gains extracted, with correction to a common axis the first step towards a unified energy calibration per pixel. This technique is expanded across a range of memory cells as well as the detector gain stages. Finally a validation of the correction will be presented, including examples applied to liquid scatter data acquired at FXE.

        [1] M. Hart et al., "Development of the LPD, a high dynamic range pixel detector for the European XFEL," 2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC), pp. 534-537, doi: https://doi.org/10.1109/NSSMIC.2012.6551165
        [2] D. Khakhulin et al., “Ultrafast X-ray Photochemistry at European XFEL: Capabilities of the Femtosecond X-ray Experiments (FXE) Instrument”, 2020, Applied Sciences, 10(3), 995. https://doi.org/10.3390/app10030995

        Speaker: Rhian Mair Wheater (UKRI Science & Technology Facilities Council)
      • 11:40
        A Low-Noise Pixelated ASIC for the Readout of Micro-Channel Plates 20m

        In the field of astronomy, photon counting detectors based on micro-channel plates (MCP) are commonly used for UV detection and their characteristics often limit the overall instrument performance. In particular, UV spectroscopy is adopted in solar physics and for the investigation of planetary exospheres. The PLUS (PLanet extreme Ultraviolet Spectrometer) Project aims at developing a spectrometer in the 55-200 nm range leveraging a dual channel (VUV/EUV) architecture and high-efficiency optical components individually optimized for each channel. Within this context, we present the first version of a new ASIC custom-designed for MCP readout. The ASIC will be able to detect the electrons cloud generated by each photon interacting with the MCP, sustaining high local and global count rates to fully exploit the MCP intrinsic dynamic range with low dead time The main rationale that guided the electronics design is the reduction of the input equivalent noise charge (ENC) in order to reduce the gain of the MCP, thus, enlarging its lifetime, crucial for long missions.
        The readout chain (Fig. 1) is composed of the low-noise charge sensitive amplifier (CSA), a filtering stage with selectable analog processing time (125 or 250 ns, Fig. 2), a discriminator with a 5-bit selectable threshold, a charge-sharing compensation logic (CSCL) offering two arbitration modes and, finally, two 17-bit counters alternating in parallel and, thus, granting zero dead time in the serial digital readout. The frame rate is 1 Hz and the maximum count rate per pixel is 100 kcps. The maximum collectable charge at the anode is 6000 e- with an ENC of only 25 e-. This value can be compared with 72 e- of MEDIPIX 3 (55 µm pixel [1]) and 84 e- of CHASE Jr. (100 µm pixel [2]).
        The charge cloud on the array of collecting anodes is expected to spread at maximum among 4 adjacent pixels. In the basic arbitration mode, the event is assigned to the pixel with the highest detected charge. Instead, to address conditions of equally partitioned charge, in the advanced mode (an evolution of the MEDIPIX 3 approach), the cluster that received the highest charge is identified by the summing nodes between pixels and then the winning pixel is identified by vertical and horizontal comparisons.
        A scaled 65-nm CMOS technology has been selected in order to achieve a compact pixel size (35 ×35 µm2 with an anode size of 20 ×20 µm2 for a 32% fill factor), providing high spatial resolution which is a key characteristic for the spectrometer under study, but which also makes the device suitable for different photon-counting (spectroscopic or imaging) applications. The first prototype of the ASIC contains an array of 32 × 32 pixels for a total chip area of 2 ×2 mm2, including several pads for diagnostics and characterization. Analog and digital block are carefully separated in a super-pixel configuration (Fig. 4).

        Speaker: Mr Edoardo Fabbrica (Politecnico di Milano and INFN)
    • 12:00 12:30
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    • 12:30 13:30
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    • 12:30 13:30
      Poster session 1: Part 1 Gather.town

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    • 13:30 14:50
      Oral presentations: X-rays Zoom

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      Convener: Matthieu Boone (Universiteit Gent)
      • 13:30
        On the possibility to utilize a PCO Edge 4.2 bi scientific CMOS imager for extended ultra violet and soft X-ray photon detection 20m

        Photon science with extended ultra violet (EUV) to soft X-ray photons generated by state of the art synchrotrons and FEL sources imposes an urgent need for suitable photon imaging detectors. Besides a high quantum efficiency, requirements on such EUV detectors include high frame rates, very large dynamic range, single-photon sensitivity with low probability of false positives, small pixel pitch and (multi)- megapixels. Owing to their unique features back illuminated scientific CMOS (sCMOS) imagers can be tailored to these particular needs [1]. In general application driven detector development is a sensible, albeit time consuming approach allowing to take full advantage of the luminosity improvements that FELs and diffraction-limited synchrotron rings (SRs) can provide. Conversely such characteristics can be found in few state of the art commercial detectors based on sCMOS, which have been recently developed for other applications mainly in the visible light regime. In particular back thinned sCMOS are suited for experiments exploiting the water window (between 282 eV and 533 eV) and transition metal L-edges, a target photon energy range which implies vacuum operations. Applying some modifications, in particular UHV compatibleness, these commercial devices can be disposed for EUV and soft X-ray applications as demonstrated by [2].
        In this contribution we describe the adaption of the PCO edge 4.2 bi for soft X-ray imaging in the energy range from 35 eV – 2000 eV. The PCO edge is build around the GSENSE2020BSI-APM-NUN PulSar back thinned sCMOS sensor, which has been designed by Gpixel (https://www.gpixel.com) and has been processed by Tower Semiconductor (https://towersemi.com). The sensor comprises 2048 x 2048 pixels with a pixel size of 6.5 µm x 6.5 µm, which translates into an active area of 13.3 mm x 13.3 mm. The sensor exhibits a full well capacity of 48 000 e- and a readout noise of 1.9 e- (rms) with a typical dynamic range of 88 dB. The integration time can be adjusted between 10 µs – 2 seconds. Using its USB 3.1 data interface the maximum frame rate is given by 40 fps for the full frame while it can reach for instance 520 fps for a region of interest of 2048 x 128 pixels. In addition, a total of 4 trigger signals are provided to synchronize image acquisitions. Vacuum compatibility has been obtained by sealing the carrier board of the sensor, which constitutes the barrier between vacuum and normal atmosphere. In this fashion it is possible to keep the entire readout and trigger electronics in air. At the moment a KF flange based interface plate is utilized to attach the camera and subsequently sensor to the experimental vacuum chamber (Figure 1). Here we present the first measurements carried out at the CiPo beamline at Elettra Sincrotrone Trieste with a modified soft X-ray PCO Edge 4.2 bi showing a very high quantum efficiency greater than 60% in the energy range between 30 eV and 100 eV and greater than 80% for energies between 100 eV and 1000 eV. Soft X-ray imaging capabilities have been assessed by means of slanted edges and generation of Airy patterns through a pin hole (Figure 1). Moreover, spectral X-ray imaging with this single photon processing detector can be accomplished.
        [1] A. Marras, J. Correa, S. Lange, et al., J. Synchrotron Radiat. 2021, 28, 131.
        [2] Desjardins, K., Medjoubi, K., Sacchi, M., Popescu, H., Gaudemer, R., Belkhou, R., et al. (2020). research papers. J. Synchrotron Rad (2020). 27, 1–13.

        Speaker: Ralf Hendrik Menk (Elettra Sincrotrone Trieste)
      • 13:50
        X-ray imaging of moving objects using on-chip TDI and MDX methods with single photon counting CdTe hybrid pixel detector 20m

        X-ray imaging of moving objects by using line detectors stays the most popular method of object content and structure examination with a typical resolution limited to 0.4 -1 mm. Higher resolutions are difficult to obtain as for the detector in the form of a single pixel row, the narrower the detector is, the lower the image Signal to Noise Ratio (SNR). This is because, for smaller pixel sizes, fewer photons hit the pixel in each time unit for given radiation intensity.
        To overcome the trade-off between SNR and position resolution, a two-dimensional sensor, i.e., pixel matrix can be used. Imaging of moving objects with pixel matrix requires time-domain integration (TDI). Straight forward TDI implementation is based on the proper accumulation of images acquired during consecutive phases of object movement. Unfortunately, this method is much more demanding concerning data transfer and processing. Data from the whole pixel matrix instead of a single pixel row must be transferred out of the chip and then processed.
        The alternative approach is on-chip TDI implementation. It takes advantage of photons acquired by multiple rows (higher SNR) but generates the same data amount as a single pixel row and does not require data processing out of the chip.
        In this paper on-chip TDI is described and verified by using single photon counting two-dimensional (matrix of 128 x 192 pixels) CdTe hybrid X-ray detector with 100 um x 100 um pixel size with up to four energy thresholds per pixel. The spatial resolution verification is combined with Material Discrimination X-ray (MDX) imaging method.

        The authors acknowledge funding from the National Science Center, Poland, contract No. UMO-2016/21/B/ST7/02228.

        Speaker: Miroslaw Zoladz
      • 14:10
        Multi-bin energy-sensitive Micro-CT using large area photon-counting detectors Timepix 20m

        Jan Dudak1,*, Jan Zemlicka1

        1 Institute of Experimental and Applied Physics, Czech Technical University in Prague, Husova 240/5,
        110 00 Prague, Czech Republic

        *Corresponding author: jan.dudak@cvut.cz

        X-ray micro-CT has become a popular widely used tool for purposes of scientific research. Although the current state-of-the-art micro-CT technology is on a high technology level it still has some known limitations. One of relevant issues is an inability to clearly identify and quantify certain materials [1].
        The mentioned drawback can be solved by energy-sensitive CT approaches. The dual-energy CT (DECT), which is already frequently used in human medicine, offers identification of two different materials – i. e. to differentiate an intravenous contrast agent from bones or to analyze composition of urinary stones [2].
        Resolving of a higher number of constituents within a single object requires also a higher number of energy measurements and, therefore, DECT is not applicable for such measurement. A possible solution for multi-bin – or so-called spectral-CT – is the application of technology of photon-counting detectors (PCD). PCD technology is equipped with an integrated circuitry capable of resolving the energy of incoming photons in each pixel. Therefore, it is possible to collect data in user-defined energy widows [3].
        This contribution evaluates the applicability of large-area photon-counting detectors Timepix for multi-bin energy-sensitive micro-CT [4]. It presents a phantom-study focused on simultaneous K-edge-based identification and quantification of multiple contrast agents within a single object. It is based on a set of simulations searching for optimal settings of the energy bins considering their mean energy, width and achievable signal-to-noise ratio. The experimental part of the contribution presents a series of multi-bin energy-sensitive micro-CT scans of a phantom object and results of its material decomposition carried-out using an in-house implemented decomposition algorithm.

        [1] M. Willemink et al: "Photon-counting CT: Technical Principles and Clinical Prospects", Radiology, vol. 289, no. 2, pp. 293-312, 2018.
        [2] A. C. Silva et al: "Dual-Energy (Spectral)" CT: Applications in Abdominal-Imaging", Radiographics, vol 31, pp. 1031-1046, 2011.
        [3] C. McCollough et al: "Dual- and Multi-Energy CT: Principles, Technical Approaches, and Clinical Applications", Radiology, vol. 276, no. 3, pp. 637-653, 2015.
        [4] J. Jakubek et al: "Large area pixel detector WIDEPIX with full area sensitivity composed of 100 Timepix assemblies with edgeless sensors", Journal of Instrumentation, vol. 9, no. 04, pp. C04018, 2014.

        The work was done in the frame of Medipix Collaboration and was financially supported from
        European Regional Development Fund-Project "Engineering applications of microworld physics"
        (No. CZ.02.1.01/0.0/0.0/16_019/0000766).

        Speaker: Mr Jan Dudak (Institute of Experimental and Applied Physics, Czech Technical University in Prague )
      • 14:30
        First user experiments of the PERCIVAL soft X-ray imager 20m

        The PERCIVAL detector is a CMOS imager specifically designed for the soft X-ray regime. In 2020, although still in a development phase, it served its two first user experiments, at a Storage Ring (SR) and also at a Free Electron Laser (FEL). We will report some preliminary results and sketch future plans.
        With its 2 Megapixels, 27 µm pixel size, and 4 x 4 cm2 active area (extendable to 8 x 8 cm2 in clover-leaf like configurations), PERCIVAL can provide images with high spatial resolution. Moreover, its fast readout was designed to reach speeds up to 300 frames per second. In fully optimised mode, the sensor’s dynamic range is expected to cover a range from 16e- to 3.5 Me-. The development, jointly carried by 5 light sources (Deutsches Elektronen Synchrotron (DESY), Pohang Accelerator Laboratory (PAL), Elettra Synchrotron, Diamond Light Source (DLS) and SOLEIL Synchrotron), and the Rutherford Appleton Lab (RAL/STFC), will enable increased science yielded from today’s FEL and SR sources in the soft X-ray regime.
        In collaboration with groups at the Helmhotz Zentrum Berlin (HZB) and Max-Born Institute (MBI), we used the P04 XUV beamline at PETRA-III to perform holographic imaging of topological materials (in particular skyrmions) at an energy of 780eV. Together with colleagues from FLASH, we used the beamline FL24 at the FLASH2 FEL to perform ptychographic imaging of plasma treated surfaces in an energy range between 92 and 462eV. Both experiments benefited from the very large dynamic range provided by the PERCIVAL detector.
        The development will go on in order to reach the nominal specification parameters. In the meantime, new user experiments with a high impact factor will be scheduled and will help us to speed up the process.

        Speaker: Jonathan Correa Magdalena (Deutsches Elektronen-Synchrotron DESY)
    • 14:50 15:20
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    • 15:20 16:20
      Oral presentations: ASICs 2 Zoom

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      Convener: Cinzia Da Via (University of Manchester (GB))
      • 15:20
        SparkPix-ED: a readout ASIC with 1 MHz frame-rate for rare event experiments at LCLS-II 20m

        The LCLS-II accelerator will provide pulses with a repetition rate of up to 1 MHz. To cope with the increase in repetition rate, a new family of detectors named SparkPix is being developed at SLAC.
        SparkPix-ED is the first detector based on the Event-Driven information extraction engine, which combines high-frame rates and a triggering capability. Coarse X-ray images are streamed out at 1 MHz in a “Continuous Wave” (CW) mode. These images will be processed by an external computing layer to detect rare events and generate a “trigger” signal when one is found. While the low-resolution images are streamed out, the ASIC records high-resolution images on a pulse-by-pulse basis at 1 MHz repetition rate. The high-resolution images are stored in a local memory implemented as a circular buffer with depth N (in the first prototype, N=4). In this manner, when a rare event is detected, N high-resolution images taken around the event can be read-out.
        The ASIC can also be operated as stand-alone in high-resolution mode, trading off frame-rate for spatial resolution and noise performance. In this case, the frame-rate scales down to 100 kHz with continuous readout.
        The first prototype has been designed with a CMOS 130 nm technology. Due to the high level of parallelism required to achieve 1 MHz operation, analog-to-digital converters and control logic has been distributed in the pixel matrix. The first prototype has been received and characterized with a dedicated carrier board, as shown in Figure 1. At the time of writing, the functionality of all blocks has been demonstrated, as shown in Figure 2. Detailed results about the performance will be presented at the conference.

        Speaker: lorenzo rota (Stanford University)
      • 15:40
        Characterization of the ePixM monolithic CMOS sensor for soft X-rays 20m

        ePixM is a charge-integrating pixel detector which is being developed for soft X-rays experiments at LCLS-II. To enable single-photon detection with photon energies down to 250 eV, a monolithic active pixel sensor has been designed on a CMOS 150 nm process with a high-resistivity substrate [1]. The sensor is fully depleted, so charges are collected by drift. The back-side of the wafers has been post-processed at SLAC to form a thin entrance window [2]. Small-scale devices, consisting of 48x48 pixels, have been mounted on a dedicated carrier board, as shown in Figure 1. The response of the pixel circuitry has been measured with a calibration signal injected at the pixel input, as shown in Figure 2, as well as with an Fe55 source. Both the automatic gain-switching capability and the correlated pre-charging technique are functional. A readout noise of 16 electrons has been measured with the devices operated at room temperature. The performance of the sensor and of the readout electronics will be presented.

        Speaker: lorenzo rota (Stanford University)
      • 16:00
        18k Pixel Readout IC for CdTe Detectors Operating in Single Photon Counting Mode with Interpixel Communication 20m

        This paper presents a readout integrated circuit (IC) of pixel architecture called MPIX (Multithreshold Pixels), designed for CdTe pixel detectors used in X-ray imaging applications. The MPIX IC of the area of 9.6 mm x 20.3 mm is designed in a CMOS 130 nm process. The IC core is a matrix of 96 x 192 square-shaped pixels of 100 µm pitch. Each pixel contains a fast analog front-end followed by four independently working discriminators and four 12-bit ripple counters. Such pixel architecture allows photon processing one by one and selecting the X-ray photons according to their energy (X-ray color imaging). To fit the different range of applications the MPIX IC has 8 possible different gain settings, and the IC can process the X-ray photons of energy up to 154 keV. The MPIX chip is bump-bonded to the CdTe 1.5mm-thick pixel sensor with a pixel pitch of 100 um (see Fig.1) To deal with charge sharing effect coming from a thick semiconductor pixel sensor, Multithreshold Pattern Recognition Algorithm is implemented in the readout IC [1]. The implemented algorithm operates both in the analog domain (to recover the total charge spread between neighboring pixels, when a single X-ray photon hits the pixels border) and in the digital domain (to allocate a hit position to a single pixel). The example of the measured integral spectra with three different X-ray energies is shown in Fig. 2.

        [1] P. Otfinowski, et al., 2019 JINST 14 C01017

        The authors acknowledge funding from the National Science Center, Poland, contract No. UMO-2016/21/B/ST7/02228.

        Speaker: Pawel Grybos (AGH University of Science and Technology)
    • 16:20 16:40
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    • 16:40 17:30
      Invited lectures: Z. Wang Zoom

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    • 17:30 19:00
      Poster session 1: Part 2 Gather.town

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    • 09:00 09:50
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    • 09:50 10:30
      Oral presentations: LHC Zoom

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      Convener: Eduardo Cortina Gil (Universite Catholique de Louvain (UCL) (BE))
      • 09:50
        The LHCb Vertex Locator Upgrade 20m

        The Large Hadron Collider Beauty detector is a flavour physics detector, designed to detect decays of b- and c-hadrons for the study of CP violation and rare decays. At the end of Run-II, many of the LHCb measurements will remain statistically dominated. In order to increase the trigger yield for purely hadronic channels, the hardware trigger will be removed and the detector will be read out at 40 MHz. This, in combination with the five-fold increase in luminosity requires radical changes to LHCb’s electronics, and, in some cases, the replacement of entire sub-detectors with state-of-the-art detector technologies.

        The Vertex Locator (VELO ) surrounding the interaction region is used to reconstruct the collision points (primary vertices) and decay vertices of long-lived particles (secondary vertices). The upgraded VELO will be composed of 52 modules placed along the beam axis divided into two retractable halves. The modules will each be equipped with 4 silicon hybrid pixel tiles, each read out with by 3 VeloPix ASICs. The silicon sensors must withstand an integrated fluence of up to 8$\times 10^{15}$ 1 MeV n$_{eq}$/cm$^{2}$, a roughly equivalent dose of 400 MRad. The highest occupancy ASICs will have pixel hit rates of 900 Mhit/s and produce an output data rate of over 15 Gbit/s, with a total rate of 1.6 Tbit/s anticipated for the whole detector.

        The VELO upgrade modules are composed of the detector assemblies and electronics hybrid circuits mounted onto a cooling substrate, which is composed of thin silicon plates with embedded micro-channels that allow the circulation of liquid CO$_2$. This technique was selected due to the excellent thermal efficiency, the absence of thermal expansion mismatch with silicon ASICs and sensors, radiation hardness of CO2, and very low contribution to the material budget. The front-end hybrid hosts the VeloPix ASICs and a GBTx ASIC for control and communication. The hybrid is linked to the opto-and-power board (OPB) by 60 cm electrical data tapes running at 5 Gb/s. The tapes must be vacuum compatible and radiation hard and are required to have enough flexibility to allow the VELO to retract during LHC beam injection. The OPB is situated immediately outside the VELO vacuum tank and performs the opto-electrical conversion of control signals going to the front-end and of serial data going off-detector. The board is designed around the Versatile Link components developed for high-luminosity LHC applications.

        The design of the complete VELO upgrade system will be presented with the results from the latest R\&D. The LHCb upgrade detector will be the first detector to read out at the full LHC rate of 40 MHz. The VELO upgrade will utilise the latest detector technologies to read out at this rate while maintaining the required radiation hard profile and minimising the detector material.

        Speaker: Pawel Kopciewicz (AGH University of Science and Technology (PL))
      • 10:10
        System Tests for the ATLAS ITk Pixel Detector 20m

        The ATLAS tracking system will be replaced by an all-silicon detector for the HL-LHC upgrade around 2025. The innermost five layers of the detector system will be pixel detector layers which will be most challenging in terms of radiation hardness, data rate and readout speed. A serial power scheme will be used for to reduce the radiation length and power consumption in cables. To handle the expected data output of about 11 Tb/s, a high-speed transmission chain with many parallel lines running at 1.28 Gb/s will transmit data from the detector to an opto-electrical conversion system. This Optosystem features custom-designed radiation-hard electronics devoted to signal equalisation, aggregation (to 10.24 Gb/s) and optical-electrical conversion.
        Operation of the optical system together with FELIX readout hardware, which is also used to trasmit DCS data, is currently being tested using RD53 prototype ASICs and will soon be included in the larger scale Demonstrator setups. In this talk we will present the current status of the system tests exercising these systems.

        Speakers: Jens Weingarten (Technische Universitaet Dortmund (DE)) , Paul Dervan (University of Liverpool (GB))
    • 10:30 11:00
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    • 11:00 12:00
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      Convener: Dr Seppo Nenonen
      • 11:00
        Study of charge carrier transport properties and lifetimes in HR GaAs:Cr with Timepix3 20m

        The response of a Timepix3 [1] (256 x 256 pixels, pixel pitch 55 $\mu$m) detector with a 500 $\mu$m thick HR GaAs:Cr [2] sensor was studied with proton beams at the Danish Centre for Particle Therapy in Aarhus, Denmark. The detector was irradiated at different angles with protons of 125, 171 and 219 MeV. The readout chip was configured to operate in electron or hole collection modes.

        Measurements at grazing angles allow to see elongated tracks with well-defined impact and exit points, so that charge carrier production depths can be determined in each pixel. We extracted the charge collection efficiencies (Figure 1) and the charge carrier drift times (Figure 2) as a function of the distance to the pixel matrix plane.
        It was found that measured proton tracks are shorter in hole collection than in the case of electron collection, which is explained by the shorter lifetime of holes. At the angle of 60 degrees with respect to the sensor normal, the average track length in hole collection is ~600 $\mu$m, while it is 880 $\mu$m in electron collection mode.

        To understand the experimental findings, models describing the properties of HR GaAs:Cr were implemented into the Allpix$^2$ simulation framework [3]. We added previously presented experimental results describing the dependence of the electron drift velocity on the electric field [4] and validated the response by comparing measurement and simulation or various X- and gamma-ray sources in the energy range from 5 – 60 keV.

        Results presented in Figure 1 and Figure 2 were reproduced in the simulation using the hole mobility $\mu_h$ = (300 ± 45) cm$^{2}$/V/s and the lifetime of holes as $\tau_h$ = (6 ± 2) ns. Further studies will include results seen for measurements at different proton energies and bias voltages.

        [1] T. Poikela et al., 2014 JINST 9 C05013
        [2] A.V. Tyazhev et al., 2003 NIM A 509 34.
        [3] S. Spannagel et al., 2018 NIM A 901 164
        [4] B. Bergmann et al., 2020 JINST 15 C03013

        The authors acknowledge the support of the project “Engineering applications of physics of microworld” (No. CZ.02.1.01/0.0/0.0/16_019/0000766). The work was carried out in the Medipix collaboration. This work has been done using the INSPIRE Research Infrastructures and is part of a project that has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No 730983.

        Speaker: Dr Petr Smolyanskiy (Institute of Experimental and Applied Physics, Czech Technical University in Prague)
      • 11:20
        High-spatial resolution measurements with GaAs sensor with the charge integrating MÖNCH detector 20m

        In contrast to silicon-based sensors, high-Z sensors materials like GaAs or Cd(Zn)Te provide a good quantum efficiency for the detection of hard X-rays above 15 keV. However, high-Z sensors require a careful characterization to better understand their performance since they typically suffer from crystal inhomogeneities, charge-trapping (leading to the so-called polarization effect) and high energetic fluorescence photons which are not present in silicon. Extensive studies performed with GaAs:Cr sensors bump-bonded to the charge integrating detector JUNGFRAU have proved that JUNGFRAU with GaAs:Cr is a promising X-ray detector for imaging applications at synchrotron facilities for high energies [1][2].
        In this work we present a GaAs:Cr sensor bump-bonded to a MÖNCH readout chip. The MÖNCH0.3 detector [3] is a low-noise charge-integrating hybrid pixel detector which has 160k, 25 μm pitch pixels covering an active area of 1 x 1 cm2 with a noise of 35 electrons ENC (rms) with Si sensors.

        Recently we have characterized a GaAs:Cr sensor bump-bonded to MÖNCH03 and we measured a low noise of ~80 e- ENC in high gain mode and at 6 µs exposure time.Recent imaging measurements acquired with a GaAs:Cr sensor mounted to a MÖNCH readout chip have shown that it is possible to use subpixel interpolation algorithms and thus enhance the spatial resolution beyond the actual pixel size. In this contribution, first imaging results of a Siemens Star with GaAs and Silicon based sensors acquired at the TOMCAT beamline of the Swiss Light Source at energies from 10 keV to 30 keV will be presented. We will show the preliminary results on the quantum efficiency as a function of the energy for both sensor materials, the energy dependent spatial resolution (affected by fluorescence / charge sharing), including energy-binned imaging achievements as well as a quantitative evaluation of the spatial resolution by means of determining the MTF.

        These preliminary results are very promising since they open new possibilities to apply interpolation algorithms for micrometre resolution for colour imaging with MÖNCH at high energies. Further measurements with an X-ray microfocus tube are under way to exploit the energy-resolving power of colour imaging.

        [1] D. Greiffenberg et al. JINST (2019) 14 P05020
        [2] D. Greiffenberg, et al. Sensors (2021),21, 1550
        [3] R. Dinapoli et al, J. Instrum. 9 (2014) p. C050115.

        Speaker: Sabina Chiriotti Alvarez (PSI - Paul Scherrer Institut)
      • 11:40
        Intercalibration and comparative tests of 3D diamond and diamond on iridium detectors for medical dosimetry 20m

        Thanks to a new emerging technology, diamond devices with 3-dimensional structures are produced using laser pulses to create graphitic paths in the diamond bulk. The fabrication of very narrow and close by columnar electrodes perpendicular to the detector surface allows the employment of a lower bias voltage at which the saturation charge velocity is reached and faster detector response, due to the decreased distance between the polarizing electrodes, compared to a planar geometry detector. Also due to the much shorter electrodes distance, the 3D diamond detector charge collection efficiency is less deteriorated by the radiation damage of the diamond material.
        On the other hand, diamond tissue-equivalence, high radiation sensitivity and high resistance to radiation damage make it a good candidate for high precision measurement of the doses released during medical radiation therapy.
        In medical radiation dosimetry, the use of small photon fields is almost a prerequisite for high precision localized dose delivery to delineated target volume. However, such fields have inherent characteristics of charge particle disequilibrium and high-dose gradient, making dosimetric measurements challenging. The accurate measurement of standard dosimetric quantities in such situations strongly depends on the size of the detector with respect to the field dimensions.
        3D diamond detectors with small dimensions compared to the field size, have been tested under photon irradiation and evaluated for medical radiation dosimetry referring particularly to the problem of small fields dosimetry and/or of high spatial gradient fields dosimetry.
        We will present results obtained with two new 3D finely segmented detectors made of a 500 um polycrystalline diamond substrate and a 500 um diamond on iridium substrate where multiple 3D cells are read in parallel when irradiated by a medical linear accelerator with the aim of understanding which substrate is the best solution for a more linear, stable and repeatable dose rate response in order to measure small field profiles in one measurement session, reducing the uncertainty of the delivered dose.

        Speaker: Dr Keida Kanxheri (INFN - National Institute for Nuclear Physics)
    • 12:00 12:30
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    • 12:30 13:30
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    • 12:30 13:30
      Poster session 2: Part 1 Gather.town

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    • 13:30 14:20
      Invited lectures: D. Batey & S. Cipiccia Zoom

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    • 14:20 15:00
      Oral presentations: Applications Zoom

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      Convener: valeria rosso (INFN and University of Pisa)
      • 14:20
        Imaging of Biomacromolecules in Mass Spectrometry Using Timepix Detectors 20m

        The Timepix (TPX) is a micropixelated imaging detector capable of recording both the arrival time and position of individual ions. In this study, we have integrated TPX detectors to three different mass spectrometers (MS) for the spatially resolved detection and structural analysis of macromolecular assemblies (MMAs). First, a dual microchannel plate (MCP) stack-TPX quad detection assembly has been coupled to a nano-electrospray ionization(nanoESI)-orthogonal time-of-flight(TOF)-MS for the analysis of multiply charged non-covalent protein complexes of molecular weight in excess of 800 kDa. Using this experimental setup, we demonstrate the ability of the TPX to unambiguously detect and image individual macromolecular ion events, providing the first report of single-ion imaging of protein complexes. The single ion imaging capability has been further exploited to gain a better understanding on the effect of ion and voltage parameters on the MCP response for the detection of a broad mass range of 192 to 800,000 Da. Moreover, we have used both the impact position and arrival time information of the ions at the detector to visualize the effects of various ion optical parameters on the flight path of ions. This led to the identification of the origin of an unexpected TOF signal that could easily be mistaken as a fragment of the protein complex as the secondary electron signal arising from ion-surface collisions inside the TOF housing. The TPX detector used for this work is limited by a moderate time resolution (20 ns here, at best 10 ns) and single-stop detection for each pixel that can bias the detection of ions with a low TOF at high count rates. Our second work has been benefited from the implementation of the next generation Timepix3 (TPX3) detector that offers 1.56 ns time resolution, per-pixel multi-hit functionality and kHz readout rates. In this experimental set up, a TPX3CAM (optically coupled to MCP via a fast scintillator) has been added to a MALDI (matrix-assisted laser desorption/ionization)-linear TOF MS, which allowed the detection and ion imaging of singly and doubly charged intact protein ions of mass to charge (m/z) ratio up to 1,150,000 Da. We also demonstrate the spatial and temporal separation of metastable neutrals produced in MALDI MS, and the effect of the matrix structure and laser power on the metastable decay rate for various proteins. Additionally, TPX and TPX3 assemblies used in the first two experimental studies have been added to an in-house developed nanoESI-Orbitrap-linear/orthogonal-TOF MS platform. This innovative imaging approach targets the structural determination of MMAs by analyzing the relative positions of the fragment ions produced from the precursor MMA ion via ultraviolet photo dissociation (UVPD).

        Speaker: Ms Anjusha Mathew (Maastricht MultiModal Molecular Imaging (M4I) Institute)
      • 14:40
        Studies of high-field QED with the LUXE experiment at the European XFEL 20m

        The LUXE experiment aims at studying high-field QED in electron-laser and photonlaser interactions, with the 16.5 GeV electron beam of the European XFEL and a laser beam with power of up to 350 TW. The experiment will measure the spectra of electrons and photons in non-linear Compton scattering where production rates in excess of 10^9 are expected per 1 Hz bunch crossing. At the same time positrons from pair creation in either the two-step trident process or the Breit-Wheeler process will be measured, where the expected rates range from 10^-3 to 10^3 per bunch crossing, depending on the laser power and focus. These measurements have to be performed in the presence of low-energy high radiation-background. To meet these challenges, for high-rate electron and photon fluxes, the experiment will use Cherenkov radiation detectors, scintillator screens, sapphire sensors as well as lead-glass monitors for back-scattering off the beam-dump. A four-layer silicon-pixel tracker and a compact electromagnetic tungsten calorimeter with GaAs sensors will be used to measure the positron spectra. The layout of the experiment and the expected performance under the harsh radiation conditions will be presented.

        Speaker: Maryna Borysova (National Academy of Sciences of Ukraine (UA))
    • 15:00 15:30
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    • 15:30 16:50
      Oral presentations: ASICs 3 Zoom

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      Convener: heinz graafsma (DESY)
      • 15:30
        8b 10MS/s Differential SAR ADC in 28 nm CMOS for Precise Energy Measurement 20m

        In this article we present an 8-bit differential Successive Approximation Register (SAR) Analog-to-Digital Converter (ADC), designed and manufactured in 28 nm CMOS process.

        Radiation imaging is an essential part of medical diagnostics. Although integrating detectors are still widely used, more and more medical institutes have already switched to single photon counting (SPC) devices. The next step is colorful imaging, where each color represents the energy of the acquired photon, and the intensity – the number of hits in the pixel in the given time [1]. This could break new ground in medical imaging, reducing the number of exposures and thus the total irradiation dose. In the literature, there are examples of well-characterized detectors with two levels of energy discrimination [2]. However, in older technologies it was difficult to combine high spatial and energy resolution, maintaining a high count rate and low power consumption. Our aim is to enable fast imaging with the resolution of 256 energy levels, placing an ADC in each of the thousands of 100 μm × 100 μm pixels.

        The SAR ADC presented in this article allows to distinguish 256 levels of energy and is capable of converting 10 MS/s. The Integrated Circuit (IC) (Fig. 1.) is currently under measurement and preliminary results show the INL and DNL of about ±0.5 LSB and ±0.6 LSB, respectively. Importantly, the proposed ADC’s comparator input offset voltage correction in the time domain allows to effectively compensate mismatches without affecting the conversion rate as reported in [3-4]. Here, by changing the delay buffer voltage, the transfer characteristic can be shifted within the range of about 45 mV (Fig. 2.).

        The whole IC area is 400 μm × 450 μm, while the core of the ADC occupies only 30 μm × 60 μm, and this can still be decreased by reducing the unit capacitance (here 0.5 fF), or by applying another switching scheme and changing the capacitor array. Nevertheless, such an ADC is able to fit into a considered pixel and to enable fast imaging with high energy resolution, while maintaining the spatial one at a fine level.

        [1] K. Taguchi and J. S. Iwanczyk, Med. Phys. 40 (2013), 100901
        [2] P. Gryboś et al., IEEE Trans. Nucl. Sci. 63 (2016), 1155–1161
        [3] X. Yang et al., ESSCIRC 2019, 305-308
        [4] P. Kaczmarczyk and P. Kmon, Przegląd Elektrotechniczny 96 (2020), 119-122

        The authors acknowledge funding from the Ministry of Education and Science of Poland for the research project under the ‘Diamond Grant’ program (0071/DIA/2018/47).

        Speaker: Piotr Kaczmarczyk (AGH University of Science and Technology)
      • 15:50
        Timepix4, a large area pixel detector readout chip which can be tiled on 4 sides providing sub-200ps timestamp binning 20m

        The Timepix4 chip is designed to read out a large area pixel detector comprised of 448 x 512 pixels of 55 micron square. The chip is the first large area pixel detector which can be tiled on all 4 sides when Through Silicon Vias are used to access the chip IO. There are two operating modes: data driven and photon counting. In data driven mode each pixel which is hit will produce a 64-bit word containing the hit pixel address, the Time over Threshold (with a precision of ~ 120 e- rms) and the arrival time stamped to within a 200ps bin over a total time of up to ~80 days. The maximum flux which can be read out correctly is ~ 7Mhits/mm2/s when all 16 serial links running at 10 Gbps are used. In photon counting mode the chip can operate at up to 44kfps in 16-bit mode and 89 kfps in 8-bit mode. This paper will describe the requirements, the chip architecture and show first measurements

        Speaker: Xavi Llopart Cudie (CERN)
      • 16:10
        The MYTHEN III single photon counting detector for powder diffraction 20m

        After more than 12 years of users operation, the MYTHEN II single photon counting microstrip detector has been upgraded in order to cope with progresses in the detector and data acquisition technology. MYTHEN III presents the same geometry as its predecessor (50 μm pitch 8 mm long strips, 6.4 mm wide modules), but it provides an enhanced performance.
        In particular, a new readout chip has been developed by the SLS detector group in 110nm UMC technology.
        Every readout channel features a double polarity preamplifier and 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 a counting logic that, according to the selected mode of operation, generates the increment signals for the three following 24-bit counters. The new readout chip features an improved noise of 115 e- ENC and a threshold dispersion of about 20 eV RMS [1]. The maximum frame rate is up to 300 kHz with no dead time between frames, and the count rate capability can reach up to 3.5 MHz per strip with 90% counting efficiency. Moreover, it is possible to exploit the three counters per strip with independent thresholds and gates not only for energy binning and time resolved pump-probe applications, but also to push the count rate capability to above 20 MHz per strip with 90% efficiency, thanks to the possibility of counting piled-up photons [2]. Finally, we implemented an innovative digital communication logic between channels, which allows charge sharing suppression and improves the spatial resolution beyond the strip pitch, as a first demonstration of on-chip interpolation in a single photon counter detector.
        A 48 modules MYTHEN III detector is under commissioning and the first 14 modules recently started users operation at the powder diffraction end station of the Swiss Light Source.
        We will present the architecture of the new detector, starting from the readout chip, as well as the first results of its performance characterization.
        [1] Andrä M, The MYTHEN III Detector System - A single photon-counting microstrip detector for powder diffraction experiments, DISS. ETH NO. 27290, doi: 10.3929/ethz-b-000462676.
        [2] Andrä M, et al. Journal of Instrumentation. 2019, 14(11): C11028. doi: 10.1088/1748-0221/14/11/C11028

        Speaker: Roberto Dinapoli (Paul Scherrer Institut)
    • 16:50 18:20
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    • 09:00 09:50
      Invited lectures: J. Garrevoet Zoom

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    • 09:50 10:30
      Oral presentations: Applications 2 Zoom

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      Convener: Ralf Hendrik Menk (Elettra Sincrotrone Trieste)
      • 09:50
        A Miniaturized Radiation Monitor for Continuous Dosimetry and Particle Identification in Space 20m

        Space radiation poses a threat not only to human space flight missions, but also to the electronic equipment of any space mission. Some dramatic space system failures and disturbances in recent years have been assumed to be radiation-induced malfunction of critical electronics parts. The space radiation environment consist of a variety of particle species, including electrons, protons and heavy ions, which may pose threats at different levels to different electronic devices. Therefore, the presence of a radiation monitor on-board of any mission is highly desirable to provide the capability to take protective measures in-flight and to contribute with flight-data to the improvement of existing radiation environment models. This contribution describes the development of a novel Miniaturized Radiation Monitor (MIRAM) for this purpose. Compared to the currently used devices, it is cheaper, has lower weight and power consumption. It is capable of providing a continuous measurement of dose as well as an estimation of the particle species composition of the radiation environment.

        MIRAM has the dimensions 80 x 60 x 30 mm. It's nominal power consumption is 1.2 W with a peak consumption of 1.8 W. The device features four single pad diodes and a Timepix3 pixel detector with 256 x 256 pixels in a 55 $\mu$m pixel pitch. The diodes and the Timepix3 are separated by a 4 mm thick copper shield to separate electrons. Sensor material of diodes and the Timepix3 are made of Si and each is 300 $\mu$m thick. The electronic parts are low-power consuming and radiation tolerant commercial off-the-shelf components. The device further features a high-voltage power supply, 4 MB data storage M-RAM with an optional 16 MB DRAM and a CAN interface. MIRAM is capable of on-board real-time self-diagnostic. The device can be seen in Figure 1 with the box opened.

        The MIRAM device supports on-board analysis of the measured data to be able to work autonomously. The dose rate is calculated continuously based on the energy deposition in the Timepix3 detector. For the estimation of the particle species composition of the radiation environment, two methods are applied depending on the current flux. At lower fluxes ($< 10^4$ particles per cm$^2$ per s), a more thorough analysis will be utilized. Particles are selected and determined based on the pixels temporal coincidence. The pixels are then sorted into three categories: low, medium and high energy, and the deposited energy is summed up. This data set is then compared with a data base, where typical values for electrons and protons are stored. The particle is classified according the closest similarity or, if there is no similarity, as heavier ion. At higher fluxes, the deposited energy is measured over a fixed time window. Then the average energy per pixel is calculated. The average energy per pixel varies very little around a constant value for a certain composition of different particle species. Towards lower fluxes, the variation around that value increases, so that different compositions cannot be resolved anymore. At this point, a track-by-track analyses is utilized.

        Both methods have been developed with the help of reference measurements of monoenergetic electrons, protons and heavier ions of different energies on the ground in conjunction with measurement of the Space Application of Timepix Radiation Monitor (SATRAM), which measures the space radiation environment in a Low Earth Orbit (LEO) on-board the Proba-V satellite since 2013, in space. The measurements were supported by a Monte Carlo simulation of the MIRAM device.

        Speaker: Mr Milan Malich (Institute of Experimental and Applied Physics, Czech Technical University in Prague)
      • 10:10
        Pioneering use of Monolithic Active Pixel Sensors in space: the HEPD tracker on the CSES-02 satellite 20m

        The most advanced particle trackers for space experiments all rely on micro-strip silicon sensors, readout with custom ASICs including amplification and shaping stages. This technology proved to be efficient, robust and fully compliant with space requirements. Both in its single- and the double-sided versions, microstrips allowed for important experiments like Pamela, AGILE, Fermi, AMS-02 and Dampe. They are still the baseline option for near future enterprises like HERD. Nonetheless, microstrips have become a niche application for silicon foundries, with profound consequences on the pace of their development, the cost of their fabrication and the complexity of their implementation.
        This work reports on what the authors consider to be a breakthrough in the field, i.e. the first space application ever of Monolithic Active Pixel Sensors. The CMOS-fabricated ALPIDE sensor [1], designed and constructed for the ALICE experiment at the Large Hadron Collider, has been used as the building block of a particle tracker to be operated within the HEPD payload, onboard the CSES-02 satellite. The process of spatialisation had mostly to cope with those characteristics that mark the difference between ground-based laboratory applications and space devices, i.e. reduction of the power consumption, implementation of redundant control and readout solutions, design of mechanics suitable to withstand launch stresses and guarantee heat dissipation.
        The project resulted in a three-layer particle tracker, as large as 250 cm2, made of 150 ALPIDE sensors, controlled and readout with a Hybrid Integrated Circuit and supported by Carbon Fiber Reinforced Plastics staves, housed in an aluminium case. The system is going to be in operation in space by mid-2022 and it will possibly change the paradigm of tracking particles in space.
        We describe in detail the HEPD-02 tracker project, demonstrating the advantages of using MAPS in space and manifesting the pioneering nature of the project for next-future larger size space missions.
        Figure 1. A “turret” of the HEPD tracker, made of three layers of ALPIDE sensors.

        [1] NIMA, Volume 824, 11 July 2016, Pages 434-438

        The authors acknowledge funding from the Italian Space Agency (Project n.2019-22-HH.0 Limadou-2 fase B2/C/D/E1, CUP F14E19000100005).

        Speaker: Roberto Iuppa (Universita degli Studi di Trento and INFN (IT))
    • 10:30 11:00
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    • 11:00 12:00
      Oral presentations: Lifetime Zoom

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      • 11:00
        Radiation Damage Study of the ePix100 Detector at the European XFEL 20m

        Operation of detectors at free-electron laser (FEL) facilities with sources providing high brilliance, high repetition rate and ultra-short X-ray pulses poses high risk of radiation damage to detector components exposed to X-ray radiation, e.g. the sensor and the readout Application Specific Integrated Circuit (ASIC). Knowledge about radiation-induced damage is important for understanding its influence on the quality of scientific data and the detector's lifetime.

        The ePix100 detector [1] is a hybrid pixel detector designed for low noise spectroscopy applications and is a member of the ePix detector family providing hybrid pixel detectors to support a wide range of applications at FEL facilities. At the European XFEL (EuXFEL) the ePix100 is used at two scientific instruments, namely High Energy Density Matter (HED) [2] and Material Imaging and Dynamics (MID) [3].

        The aim of our study was to evaluate influence of radiation induced damage by the EuXFEL beam on the performance and lifetime of the ePix100 detector. The detector was irradiated under controlled conditions by a direct attenuated beam with a photon energy of 9$\,$keV and a beam energy of 1$\,\mu$J. An area of $\mathrm{20}\,\mathrm{pixels} \times \mathrm{20}\,\mathrm{pixels}$ was irradiated to a dose of approximately 760$\,$kGy at the location of the $\mathrm{Si}/\mathrm{SiO}_2$ interface in the sensor. The performance changes of the ePix100 detector induced by radiation damage were evaluated in terms of offset, noise, energy resolution and gain. We have observed a dose dependent increase in both offset and noise and the results suggest the main cause being the increase of the sensor leakage current. Energy resolution given as Full Width at Half Maximum (FWHM) was increasing by $\approx$ 115$\,$eV/kGy and can also be attributed to an increase of the noise. Changes in gain were evaluated one and a half hours and 240 days post irradiation. The observed gain changes suggest damage to occur also in the ASIC. Based on the obtained results, we have assessed limits for the long term operation of the ePix100a at EuXFEL and other light sources in terms of its scientific performance. The detector can be used without significant degradation of its operation performance for several years if the incident photon beam intensities do not outperform the detector’s dynamic range by several orders of magnitude.

        [1] G. Blaj, P. Caragiulo, G. Carini, S: Carron, A. Dragone, D. Freytag, G. Haller, P. Hart, J. Hasi, R. Herbst, S. Herrmann, C. Kenney, B. Markovic, K. Nishimura, S. Osier, J. Pines, B: Reese, J. Segal, A. Tomada, and M. Weaver. X-ray detectors at the Linac Coherent Light Source. Journal of Synchrotron Radiation, 22(3):577–583, May 2015.
        [2] HED. Scientific Instrument HED. EuXFEL Webpage, 2021. Status March 2021.
        [3] A. Madsen, J. Hallmann, G. Ansaldi, T. Roth, W. Lu, C. Kim, U. Boesenberg, A. Zozulya, J. M ̈oller, R. Shayduk, M. Scholz, A. Bartmann, A. Schmidt, I. Lobato, K. Sukharnikov, M. Reiser, K. Kazarian, and I. Petrov. Materials Imaging and Dy- namics (MID) instrument at the European X-ray Free-Electron Laser Facility. Journal of Synchrotron Radiation, 28(2):637–649, Mar 2021.

        Speaker: Ivana Klackova (European XFEL, Slovak University of Technology in Bratislava)
      • 11:20
        Impact of X-ray induced radiation damage on FD-MAPS of the ARCADIA project 20m

        The ARCADIA collaboration is developing Fully-Depleted Monolithic Active Pixel Sensors (FD-MAPS) with an innovative sensor design in a 110nm CMOS process. This technology provides efficient charge collection and fast timing over a wide range of operational and environmental conditions [1]. The design targets very low power consumption, of the order of 20mWcm at 100MHzcm hit flux, to enable air-cooled operation.
        In November 2020, the collaboration finalized the first design of a prototype with 1.31.3cm active area, consisting of 512512 pixels with 25m pitch. This prototype is currently being produced in a first engineering run together with additional test structures of pixel and strip arrays with different pitches and sensor geometries and will be available for testing in May 2021.
        In this contribution, we will present the current status of the project and discuss the methodology, based on TCAD simulations, that has been used for the selection of the different pixel geometries included in the first engineering run. An emphasis will be set on the modelling of X-ray induced radiation damage at the Si-SiO interface and the impact on the in-pixel sensor capacitance. The so-called new Perugia model [2] has been used in the simulations to predict the sensor performance after total ionising doses of up to 10Mrad. Figure 1 shows the cross-section of the ARCADIA pixel with 25m pitch and 50m thickness in TCAD simulations at a backside bias voltage of -10V and a sensor bias voltage of 0.8V, with (b) and without (a) introduced surface damage. As visible in Figure 1; the effect of radiation damage at the Si-SiO interface changes the depletion region around the collection electrode, and gives rise to an accumulation of electrons in the gap between the p-, and n-wells. This accumulation originates from the introduced positive oxide charges in the SiO and effectively enlarges the collection nwell. The increase of the pixels’ capacitance, in the given example from 1.9fF to 3.3fF at the depletion voltage of -7V, requires an optimisation of the gap and well sizes to minimise the capacitance after irradiation.
        The simulated sensor characteristics will be related to characterisation results of active (MATISSE chip [3]) and passive pixel matrices produced in ARCADIA sensor technology.

        [1] L. Pancheri et al.: FD-MAPS in 110-nm CMOS process with 100–300-μm active substrate, doi:10.1109/TED.2020.2985639
        [2] A. Morozzi et al., TCAD advanced radiation damage modeling in silicon detectors, PoS(Vertex2019)050
        [3] E. J. Olave et al., MATISSE: A Low power front-end electronics for MAPS characterization, PoS(TWEPP-17)016

        The research activity presented in this article has been carried out in the framework of the ARCADIA experiment funded by the Istituto Nazionale di Fisica Nucleare (INFN), CSN5.

        Speaker: Coralie Neubuser (Universita degli Studi di Trento and INFN (IT))
      • 11:40
        TCAD numerical simulation of irradiated thin Low-Gain Avalanche Diodes 20m

        In this work the results of Technology-CAD (TCAD) device-level simulations of non-irradiated and irradiated Low-Gain Avalanche Diode (LGAD) detectors will be presented, aiming at evaluating the effects of layout and technological parameters on the device performance. LGADs are becoming one of the most promising devices for high performance in harsh operating environment thanks to the compensation of the radiation damage effects by exploiting the controlled charge multiplication in silicon after heavy irradiation. State-of-the-art Synopsys Sentaurus TCAD tools have been adopted to have a predictive insight into the electrical behavior and the charge collection properties of the LGAD detectors up to the highest particle fluences expected in the future HEP experiments. To this purpose, the updated “University of Perugia TCAD radiation damage model” has been adopted [1]. By coupling this numerical model, which allows to consider the comprehensive bulk and surface damage effects, with an analytical model that describes the mechanism of acceptor removal in the multiplication layer [2], it has been possible to reproduce experimental data [3] with high accuracy, demonstrating the reliability of the simulation framework. The good agreement obtained between simulation results and measurement data allows us to apply the new developed model not only for the prediction of the behavior, but also for the optimization of the new thin LGAD detectors fabrication run at the Fondazione Bruno Kessler (FBK) facility.

        [1] D. Passeri, A. Morozzi, “TCAD radiation damage model”, AIDA-2020-D7.4 report (2019)
        [2] M. Ferrero et al., “Radiation resistant LGAD design”, Nucl. Inst. and Meth. in Phys. Res. A (2019)
        [3] V. Sola et al., “First FBK production of 50 µm ultra-fast silicon detectors”, Nucl. Inst. and Meth. In Phys. Res. A (2019)

        The authors acknowledge funding from the Italian PRIN MIUR 2017 (Research Project “4DInSiDe” - Innovative Silicon Detectors for particle tracking in 4Dimensions).

        Speaker: Tommaso Croci (INFN - National Institute for Nuclear Physics)
    • 12:00 12:20
      Other: Closing remarks Gather.town

      Gather.town

      Online

      Convener: Matthieu Boone (Universiteit Gent)