International Workshop on Semiconductor Pixel Detectors for Particles and Imaging (PIXEL2014)

1 Sept 2014, 08:00 → 5 Sept 2014, 14:30 Canada/Eastern

Niagara Falls, Canada

Harris Kagan (Ohio State University (US)), William Trischuk (University of Toronto (CA))

The workshop will cover various topics related to pixel detector technology. Development and applications will be discussed for charged particle tracking in High Energy Physics, Nuclear Physics, Astrophysics, and X-ray imaging in Astronomy, Biology, Medicine and Material Science. The conference program will also include reports on front and back end electronics, radiation effects, low mass mechanics and construction techniques, and new technologies such as monolithic and 3D integrated detectors. All sessions will be plenary. Talks will be chosen from abstracts submitted.

Conference Dinner Photos Pixel2014-Dinner-Photos.zip

Group Photo Group_photo_final.jpg

More conference photos https://www.flickr.com/photos/101136409@N06/sets/72157647254193076/

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Monday 1 September

08:00 Participant Registration

Hybrid Pixel Experience

Convener: Heinz Pernegger (CERN)

1 Introduction/Participant Orientation

Speaker: William Trischuk (University of Toronto (CA))

2 Physics Performance with the ATLAS Pixel Detector

The ATLAS Pixel Detector is the innermost detector of the ATLAS experi- ment at the Large Hadron Collider at CERN, providing high-resolution mea- surements of charged particle tracks in the high radiation environment close to the collision region. The operation and performance of the Pixel Detector during the first years of LHC running are described. More than 96% of the detector modules were operational during this period, with an average intrinsic hit efficiency larger than 99 %. The evolution of the noise occupancy is discussed, and measurements of the Lorentz angle, delta-ray production and energy loss presented. The alignment of the detector was found to be stable at the few-micron level over long periods of time.

Speaker: Silvia Miglioranzi (Abdus Salam Int. Cent. Theor. Phys. (IT))

Slides Toronto_talk_nobkup_Friday.pdf

3 Physics Performance with the CMS Pixel Detector

This talk presents the results of searches for various physics channels in proton-proton collisions at $\sqrt{s}=7$ and 8 TeV delivered by the LHC and collected with the CMS detector. Many obtained results crucially depend on the performance of the CMS pixel detector. Among others b- and tau-tagging as well as primary and secondary vertex reconstruction algorithms are discussed. Application of these algorithms for searches of the Higgs boson and measurements of branching ratio of $\mathrm{B}\to\mu^+\mu^-$ will be presented.

Speaker: Frank Meier (University of Nebraska (US))

Slides praesPixel2014.pdf

4 Operational Experience with the CMS Pixel Detector

Since the beginning of its operation the CMS Silicon Pixel detector performed very well. The operational challenges included the maximization of data taking efficiency, dealing with beam gas interactions and single event upsets, and the recovery of lost modules. The data acquisition techniques also had to adapt to the rapidly changing LHC beam conditions. In order to maximise the physics potential and the quality of the data, online and offline calibrations were performed on a regular basis. The timing calibration which took place in the commissioning periods ensured maximal hit and charge collection efficiency. The position resolution was improved by pixel charge thresholds, gain and various other online calibrations. By the end of Run I, 3.7% of the modules were not operational of which most have been already recovered during the current shutdown. In this talk the operational challenges of the silicon pixel detector in Run I are presented, and the expectations for the next LHC data taking period in 2015 are discussed.

Speaker: Janos Karancsi (University of Debrecen (HU))

Slides 2014_09_01_PIXEL_2014_JKarancsi_v5.pdf 2014_09_01_PIXEL_2014_JKarancsi_v5.pptx

10:40 Coffee

5 Operational Experience with the ALICE Pixel Detector

The ALICE Silicon Pixel Detector (SPD) constitutes the two innermost layers of the ALICE experiment, which is the LHC experiment dedicated to the investigation of strongly interacting matter in heavy-ion collisions. The SPD consists of ~10 million silicon pixels organized in two layers at radii of 39 mm and 76 mm that cover a pseudorapidity range of |η|<2 and |η|<1.4, respectively. It provides the position of the primary and secondary vertices, and it has the unique feature of generating a trigger signal that contributes to the L0 trigger of the ALICE experiment. Installed in 2007, the SPD started to record data since the first LHC collisions. This contribution presents the main features of the SPD, the detector performance and the operational experience, including calibration and optimization activities, since installation in ALICE. The ongoing consolidation activities carried out to prepare the detector for the data taking during the Run2 of LHC will also be described.

Speaker: Costanza Cavicchioli (Acad. of Sciences of the Czech Rep. (CZ))

Slides 140814_slides_Cavicchioli.pdf

6 Radiation Experience with the ATLAS Pixel Detector

With the increasing radiation dose accumulated by the ATLAS Pixel Detector at the LHC, effects of radiation damage become more and more visible due to the creation of silicon crystal defects. The monitoring of the detector reveals an increase in the leakage current, which is proportional to the rising radiation dose. Measurements of the effective depletion voltage show a general trend of reduction due to the decrease of the effective n-doping concentration. The most recent measurement of the radiation damage is presented along with a comparison to the theoretical model.

Speaker: Igor Gorelov (University of New Mexico (US))

Slides gorelov-pix2014.v2.pdf

7 Radiation Experience with the CMS Pixel Detector

The CMS pixel detector is the innermost component of the CMS tracker occupying the region around the center of CMS, where the LHC beams are crossed, between 4.3 cm and 30 cm in radius and 46.5 cm along the beam axis. They are operated in a high-occupancy and high-radiation environment created by particle collisions in the LHC. Studies of radiation damage effects to the sensors were performed throughout the first running period of the LHC. Leakage current, depletion voltage, pixel read-out thresholds, and hit finding efficiencies were monitored as functions of the increasing particle fluence. The methods and results of these measurements will be described in the presentation together with their implications to detector operation as well as to performance parameters in offline hit reconstruction.

Speaker: Viktor Veszpremi (Wigner RCP, Budapest (HU))

Slides Veszpremi_PIXEL14.pdf

8 Physics Performance with the ALICE Silicon Tracker

The detailed characterization of quark gluon plasma (QGP) produced in heavy-ion collisions is the main goal of the ALICE experiment at CERN LHC. The analysis of heavy quarks via the decays of their short-lived hadrons is among the prominent measure to address the in-medium properties of QGP. To efficiently reconstruct these decays ALICE comprises a precise Inner Tracking System (ITS) made out of six layers of silicon detectors based on three different technologies, namely two layers of pixels, two of drifts and two of double-sided microstrip. The two-layer pixel barrel is the innermost detector of ALICE and therefore it plays a key role in the determination of the position of the primary vertex as well as for the measurement of the impact parameter of secondary tracks originating from the weak decays of strange, charm and beauty particles. In this contribution the main physics measurement, which have been accomplished thanks to the successful operation with proton and lead beam of the ALICE pixel detector will be discussed.

Speaker: Vito Manzari (INFN - Bari)

Slides Pixel2014_manzari.pdf

13:00 Lunch

Monolithic Devices

Convener: Marko Mikuz (Jozef Stefan Institute (SI))

9 Experience from Construction and Operation of the STAR PXL MAPS Based Vertex Detector

A new silicon based vertex detector called the Heavy Flavor Tracker (HFT) was installed at the STAR experiment for the RHIC 2014 heavy ion run to improve the vertex resolution and extend the measurement capabilities of STAR in the heavy flavor domain. The HFT consists of 4 concentric cylinders around the STAR interaction point composed of three different silicon detector technologies based on strips, pads and for the first time in an accelerator experiment CMOS monolithic active pixels (MAPS). The two innermost layers at a radius of 2.7cm and 8 cm from the beam line are constructed with 400 high resolution MAPS sensors arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors giving a total silicon area of 0.16 m2. Each sensor consists of a pixel array of nearly 1 million pixels with a pitch of 20.7 um with column-level discriminators, zero-suppression circuitry and output buffer memory integrated into one silicon die with a sensitive area of ~3.8 cm2. The pixel detector has a low power dissipation of 170 mW/cm2, which allows air cooling. This results in a global material budget of 0.5% radiation length per layer for detector used in this run. A novel mechanical approach to detector insertion allows for the installation and integration of the pixel sub detector within a 12 hour period during an on-going STAR run. The detector specifications, experience from the construction and operation, lessons learned and initial measurements of the PXL performance in the 200 GeV Au-Au run will be presented.

Speaker: Leo greiner (Lawrence Berkeley National Laboratory)

Slides 2014_09_03_PIXEL_2014_LG.ppt

10 MAPS Development for the ALICE Upgrade

The Monolithic Active Pixel Sensor (MAPS) technology offers the possibility to build pixel detectors with very high spatial resolution and low material budget; at the same time they can be produced in commercial CMOS processes. They are therefore very interesting for the innermost tracking layers of particle physics experiments. Significant progress has been made in the field of MAPS in the recent years, such that they are now considered a viable option also for the upgrades of the LHC experiments. This contribution will focus on MAPS detectors developed for the upgrade of the ALICE ITS and manufactured in the TowerJazz 180 nm CMOS imaging sensor process on wafers with a high resistivity epitaxial layer. Within the currently ongoing R&D program, several sensor chip prototypes have been developed and produced to optimise both charge collection and readout circuitry. The chips have been characterised before and after irradiation by means of electrical measurements as well as with lasers, radioactive sources and in test beams. The tests indicate that the sensors satisfy the requirements of the experiment and first prototypes with the final size of 1.5×3cm2 have been produced in the first half of 2014. This contribution summarises the characterisation measurements from the R&D program and presents first results with the full-scale chips.

Speaker: Ping Yang (Central China Normal University CCNU (CN))

Slides PIXEL2014_PingYang.pdf

11 DEPFET Based Ultra-light All-silicon Modules for Vertexing at a Future Linear Collider

The DEPFET Collaboration develops highly granular, ultra-thin active pixel detectors for high-performance vertex reconstruction at future collider experiments. A fully engineered vertex detector design, including all the necessary supports and services and a novel ladder design with excellent thermo-mechanical properties, is being developed for the Belle II experiment. The self-supporting all-silicon ladder combined with the low power density of the DEPFET array and a cooling strategy that relies on forced convection of cold air to cool the active area allow for a very thin detector. I this paper, the technical implementation of the all-silicon concept of Belle II is extended to the extremely material senstive forward region of a vertex detector at the ILC. In addition, a novel cooling concept based on fully integrated micro-mechanical cooling channels in the support silicon will be discussed on the basis of simulations and measurements on realistic thermally active all-silicon samples.

Speaker: Laci Andricek (MPG Semiconductor Lab)

Slides Monday-2-Andricek.pdf

12 The DEPFET Pixel Detector for the Belle II Experiment at SuperKEKB

A pixel detector built with the DEPFET technology will be used for the two innermost layers of the Belle~II experiment at the $e^+e^-$ SuperKEKB collider at KEK. The physics goals of the experiment impose challenging requirements to the design of the pixel detector in terms of performance, material budget and power consumption. The DEPFET technology has proven to be a suitable solution for the Belle II requirements and has been chosen as the baseline for the detector. This paper reviews the DEPFET pixel detector for Belle II and the various system aspects that have driven its final design.

Speaker: Peter Kodys (Charles University (CZ))

Slides Pixel2014_Kodys.pdf

16:00 Coffee

13 Physics Benchmarks for the Belle II Pixel Detector

SuperKEKB, the massive upgrade of the asymmetric electron positron collider KEKB in Tsukuba, Japan, aims at an integrated luminosity in excess of 50 ab$^{-1}$. It will deliver an instantaneous luminosity of $8⋅10^{35}$ cm$^{-2}$s$^{-1}$, which is 40 times higher than the world record set by KEKB. At this high luminosity, a large increase of the background relative to the previous KEKB machine is expected. This and the more demanding physics rate ask for an entirely new tracking system. The expected increase of background would in fact create an unacceptable high occupancy for a silicon strip detector, making an efficient tracks reconstruction and vertexing impossible. The solution for Belle II is a pixel detector which intrinsically provides three dimensional space points. The new two layers silicon pixel vertex detector, based on the DEPFET technology, will be mounted directly on the beam pipe. It will provide an accurate measurement of the tracks position in order to precisely reconstruct the decay vertex of the short living particles. In this talk we will discuss the physics performance of the Belle II pixel vertex detector which will be essential for the precise measurement of the CP parameters in various B and D decay channels.

Speaker: Luigi Li Gioi (Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut) (D)

Slides Pixel2014_LLG.pdf

14 Linear Collider Physics Benchmarks and the CLIC vertex detector

The precision physics needs at TeV-scale linear e+e- colliders (ILC and CLIC) require a vertex-detector system with excellent flavour tagging capabilities through a measurement of displaced vertices. This is essential for example for an explicit measurement of the Higgs decays to pairs of b-quarks, c-quarks and gluons. Efficient identification of top quarks in the decay t—>Wb will give access to the ttH coupling measurement. In addition to those requirements from the physics, the CLIC bunch structure calls for hit timing at the few-ns level. As a result, the CLIC pixel detector system shall have excellent spatial resolution, full geometrical coverage extending to low polar angles, extremely low mass, low occupancy facilitated by time-tagging, and sufficient heat removal from sensors and readout. These considerations push the technological requirements to the limits. A detector concept based on hybrid pixel-detector technology is under development for the CLIC vertex detector. It comprises fast, low-power and small pitch readout ASICs implemented in 65 nm CMOS technology (CLICpix) coupled to ultra-thin planar or active HV-CMOS sensors via low-mass interconnects. The power dissipation of the readout chips is reduced by means of power pulsing, allowing for a cooling system based on forced gas flow. This talk reviews the requirements and design optimisation for the CLIC vertex detector and gives an overview of recent R&D achievements in the domains of cooling, supports, powering, detector integration, sensors and readout.

Speaker: Dominik Dannheim (CERN)

Slides The_CLIC_Vertex_Detector_Pixel2014_1Sep2014.pdf

15 Recent Progress of the SOI Pixel Detector

We are developing monolithic pixel detectors based on 0.2 um fully-depleted Silicon-on-Insulator technology fabricated Lapis Semiconductor Co Ltd. for high energy physics experiments, X-ray applications and so on. To employ SOI devices on such radiation environments, we have to solve effects of total ionization damage for the transistors which are enclosed in the oxide layers. The holes which are generated and trapped in the oxide layers after irradiation affect characteristics of near-by transistors due to its electric field. We have been developing double SOI sensors that have independent electrode in middle of buried oxide layer to adjust the potential for compensation of radiation effect. Performances of double SOI devices are presented. In addition, a new sensor processing scheme "PIXOR (PIXelOR)" which reduces the number of readout channels and avoid degradation of position resolution due to large circuit area has been developing. It is a metric of “superpixel" which consists of 4, 8 or 16 strips in X and Y direction. This feature performs high resolution, low occupancy and signal processing of on-sensor at the same time. Recent progress of other SOI device is also shown in this presentation.

Speaker: Miho Yamada (High Energy Accelerator Research Organization (JP))

Slides PIXEL2014_ver_2.pdf

Welcome Reception/Dinner

Tuesday 2 September

08:00 Participant Registration

New Sensor Technologies

Convener: Robert Orr (University of Toronto (CA))

16 Participant Information

Speaker: Harris Kagan (Ohio State University (US))

17 Overview of HV/HR-CMOS Pixel Sensors

HV-CMOS sensors are presently considered for the use in Mu3e experiment, ATLAS and CLIC. These sensors can be implemented in commercial HV-CMOS processes. HV-CMOS sensors feature fast charge collection by drift and high radiation tolerance. The sensor element is an n-well diode in a p-type substrate. This talk will give the overview of the detector- and readout architectures, such as capacitively coupled pixel detectors, segmented strips or 3D-integrated HV-CMOS sensors. The detector improvements such as the use of substrates with higher resistivity (HV/HR-CMOS sensors) or additional implants will be discussed as well.

Speaker: Ivan Peric (Ruprecht-Karls-Universitaet Heidelberg (DE))

Slides Pixel2014V3.pdf Pixel2014V3.pptx

18 Measurements on HV-CMOS active sensors after irradiation to HL-LHC fluences

Deep-submicron HV-CMOS processes feature moderate bulk resistivity and HV capability and are therefore good candidates for drift-based radiation-hard monolithic active pixel sensors (MAPS). It is possible to apply 60-100V of bias voltage leading to a depletion depth of ~10-20 µm. Thanks to the high electric field, charge collection is fast and nearly insensitive to radiation-induced trapping. Alternatively, CMOS Imaging Processes often feature high-resistive substrates, thinning, stitching and backside processing, which makes them also interesting to study. We explore the concept of using such processes to produce active pixel sensors (APS) that contain simple circuits to amplify and discriminate the signal. A readout chip (ROC) is still needed to receive and organize the data from the active sensor and handle high-level functionality such as trigger management. This chip can follow the pixel chip concept with the readout circuits distributed over the area of the chip, or the strip concept with one or few rows of pads along one (or more) sides of the chip. The connection between APS and ROC can be made in a “traditional” way (wire/bump-bonding) or by capacitive coupling (e.g. gluing) which could lower the production cost significantly. The active sensor approach offers many advantages with respect to standard silicon sensors: fabrication in commercial CMOS processes costs less than traditional diode sensors, aggressive thinning is resulting in much lower mass, bias voltage and operation temperature requirements are favorable. From a practical perspective, maintaining the traditional separation between sensing and processing functions lowers development cost and makes use of existing infrastructure. Test ASICs compatible with ATLAS readout chips were produced in a variety of processes. Pixel-like, strip-like and limited standalone readout could be selected on most devices. Measurements were done on chips either in standalone mode or capacitively coupled by gluing with less than about 10 µm of glue layer thickness. Results of their characterization will be shown, in particular also after irradiation to HL-LHC fluences ($10^{15}$ n_eq/cm² to $10^{16}$ n_eq/cm² and up to 1GRad of dose). In addition, dedicated TCT and edge-TCT measurements have been conducted to study in detail the charge collection homogeneity and extension within the silicon bulk; first results will be shown. Finally, plans for further submissions and improvements (e.g. production on high-resistivity (HR) substrates to increase the signal charge) and perspectives for the use of HV/HR-CMOS active sensors in the Inner Tracker upgrade of the ATLAS detector will be outlined.

Speaker: Branislav Ristic (Universite de Geneve (CH))

Slides PIXEl2014_bristic.pdf

19 Diamond Pixel Detector Systems in High Energy Physics

With the first three years of the LHC running complete, ATLAS and CMS are planning to upgrade their innermost tracking layers with more radiation hard technologies. Chemical Vapor Deposition (CVD) diamond is one such technology. CVD diamond has been used extensively in beam condition monitors as the innermost detectors in the highest radiation areas of BaBar, Belle, CDF and all LHC experiments. More recently the first diamond based hybrid pixel detector system with state-of-art front-end electronics, the ATLAS FE-I4 pixel chip, was built and installed into ATLAS. This talk will describe the lessons learned in constructing diamond-based pixel systems in high energy physics, specifically the ATLAS Diamond Beam Monitor (DBM) and the CMS Precision Luminosity Telescope (PLT).

Speaker: Fabian Huegging (University of Bonn)

Slides RD42_Pixel2014_fh_v3.pdf

10:40 Coffee

20 Results from the Pilot Runs and Beam Tests of Diamond Pixel Detectors

Progress in experimental particle physics in the coming decade depends crucially upon the ability to carry out experiments at high energies and high luminosities. These two conditions imply that future experiments will take place in very high radiation areas. In order to perform these complex and perhaps expensive experiments new radiation hard technologies will have to be developed. Chemical Vapor Deposition (CVD) diamond has been developed as a radiation tolerant material for use very close to the interaction region where detectors must operate in extreme radiation conditions. During the past few years many CVD diamond devices have been manufactured and tested. As a detector for high radiation environments, CVD diamond benefits substantially from its radiation hardness, very low leakage current, low dielectric constant, fast signal collection and ability to operate at room temperature. As a result CVD diamond has now been used extensively in beam condition monitors at every experiment in the LHC. In addition, CVD diamond is now being considered as a sensor material for particle tracking detectors, closest to the interaction region where the most extreme radiation conditions exist. We will present the state of the art results of diamond radiation hardness. We will also present results from the pilot run of the Pixel Luminosity Telescope (PLT), a luminosity monitor for the CMS detector based on single-crystal CVD diamond pixel sensors. During the pilot run the PLT sensors experienced high fluences of incoming particles, at which time the sensors showed a deviation from the results of diamond radiation hardness. In order to understand this deviation, a series of beam tests with pixel and pad detectors have been performed. The results of these beam tests will be presented and will shed the light on the anomalous behavior of the PLT sensors.

Speaker: Rainer Wallny (Eidgenoessische Tech. Hochschule Zuerich (CH))

Slides PIXEL2014-NiagaraFalls_RainerWallny.pdf

21 Experience on 3D Silicon Sensors for ATLAS IBL

To extend the physics reach of the Large Hadron Collider (LHC), upgrades to the accelerator are planned which will increase the peak luminosity by a factor 5-10. To cope with the increased occupancy and radiation damage, the ATLAS experiment plans to introduce an all-silicon inner tracker with the high luminosity upgrade (HL-LHC). The detector proximity to the interaction point will require new radiation hard technologies for both sensors and front end electronics. 3D silicon sensors, where plasma micromachining is used to etch deep narrow apertures in the silicon substrate to form electrodes of PIN junctions, represent possible solutions for inner layers. Based on the gained experience with 3D silicon sensors for the ATLAS IBL project and the on-going developments on light materials, interconnectivity and cooling, we will discuss possible solutions to these requirements as well as key design aspects and device fabrication plans.

Speaker: Nanni Darbo (Universita e INFN (IT))

Slides Pixel2014_GD.pdf

22 3D Pixel Detectors for the AFP Experiment

Pixel detectors with cylindrical electrodes that penetrate the silicon substrate (so called 3D detectors) offer advantages over standard planar sensors in terms of radiation hardness, since the electrode distance is decoupled from the bulk thickness. In the framework of the ATLAS Forward Physics (AFP) program, work has been carried out to study the suitability of 3D pixel devices for forward proton tracking. The AFP tracker unit will consist of an array of six pixel sensors placed at 2-3~mm from the Large Hadron Collider (LHC) proton beam. The proximity to the beam is essential for the AFP physics program as it directly increases the sensitivity of the experiment. Thus, there are two critical requirements for the AFP pixel detector. First, the dead region of the sensor has to be minimized. Second, the device has to be able to cope with a very inhomogeneous radiation distribution. Results of the characterization and beam test studies of inhomogeneously irradiated and slim-edged 3D pixel sensors produced at CNM-Barcelona will be presented.

Speaker: Joern Lange (IFAE Barcelona)

Slides Lange_AFP_PIXEL2014.pdf

12:30 Lunch

HL-LHC/LC Sensor Developments

Convener: Richard Kass (Ohio State University (US))

23 Development of KEK/HPK Planar p-type Pixel Sensor and Lead-free Bumpbonding for HL-LHC

We have been developing a planar-process pixel sensor in p-type 6-in. silicon wafer for an application in ATLAS detector for the luminosity upgrade of the large hadron collider (HL-LHC). Our motivation is to develop highly radiation-tolerant and cost-effective sensors for covering large area of the pixel detector. After irradiations and beamtests, inefficient regions in detecting passing-through charged particles in pixel structures were identified in the 1st prototype pixel sensors. The 2nd prototype sensors with new pixel structures were fabricated and are shown to improve the inefficiency associated with the bias rail greatly. The pixel sensor are readout with an ATLAS pixel readout ASIC FE-I4 being bumpbonded. The bumpbonding has been successful for a thick sensor and a thick ASIC with a Lead-free (SnAg) solder bumps. In reducing the material, usage of thin sensors and thin ASIC’s are envisaged. The difficulty associated with the thin sensor and ASIC’s was experienced and the sources of difficulty have been identified. The latest bumpbonding has been successful by improving the flatness of the thin ASIC’s and the vacuum chucking area of both the thin sensor and the ASIC’s.

Speaker: Yoshinobu Unno (High Energy Accelerator Research Organization (JP))

Slides UnnoPixelJapan140902R2.pdf

24 Large area pixel modules for HL-LHC Tracker Upgrades

To meet the challenges of tracking at the luminosities delivered by the HL-LHC requires replacing and upgrading the tracking systems. To be able to perform pattern recognition and vertexing in events with pile-up of up to 200 requires a larger area pixel system within the tracker. The increase in area requires the development of large area planar detectors for pixel layers at large radii and the pixel endcaps. The paper reports on the development of large area sensors of area 2x2cm2 have been fabricated and mounted onto 4 FE-I4 readout ASICs, so called quad-modules, and their performance evaluated in the laboratory and testbeam. The current-voltage characteristics of the sensors have been studied and this has been used to improve the design of the biasing, guard rings and doping of the dicing streets. The assembled modules have been characterised in the laboratory to evaluate noise, threshold and bump-bond yield. A particular challenge in producing thinned large area modules is the bump-bonding, where low yield can be observed due to bowing of the sensor and readout chip during the bonding process. A new bump-bonding process using backside compensation to address the issue of low yield will be discussed. The performance of the modules in testbeams will also be presented.

Speaker: Craig Buttar (University of Glasgow (GB))

Slides Pixel2014_CMB_final.pdf

25 Measurements and 3D simulation of novel ATLAS planar pixel detector structures including edgeless and alternative bias grid geometries for the HL-LHC upgrade

In 2022, the LHC accelerator complex will be upgraded to the High-Luminosity-LHC to substantially increase statistics for the various physics analyses. These modifications will result in an increase in occupancy and of radiation damage to the ATLAS Inner Detector (ID). In order to operate under these challenging new conditions, and maintain excellent performance in track reconstruction and vertex location, the ATLAS pixel detector must be substantially upgraded and a full replacement is expected. A vital selection parameter for the innermost layers of the ATLAS pixel detector will be radiation hardness, which can be achieved through the thinning of sensors. Through new pixel designs, such as active edges and alternative bias rail geometries, minimisation of inactive regions and reductions in efficiency loss can be obtained, allowing sensors to be placed adjacent to each other. This layout is preferable to shingling as it reduces the material budget of the ID as well as cooling requirements and power consumption. Characterisation of novel pixel designs in a laboratory environment will be presented, including IV and CV measurements, and charge collection measurements with a laser, radioactive sources and cosmic muons. Non-perpendicular particle tracks, forming clusters of charge within the pixel devices, have been analysed. Pixel designs studied include novel layouts for coupling to the ATLAS FE-I4 readout chip and also reduced pixel pitch designs (50 x 50 ${\mu}$m) for the new 3D OmegaPIX front-end chip. Processing techniques for novel pixel designs are optimised through 3D simulations with Technology Computer Aided Design (TCAD). Comparison of simulation with Secondary Ion Mass Spectrometry (SIMS) measurements to study the doping profile of structures will also be included.

Speaker: Clara Nellist (LAL-Orsay (FR))

Slides 2014-09-02_PIXEL2014.pdf

15:30 Coffee

26 Calibration, Simulation and test-beam characterization for hybrid-pixel readout assemblies with ultra-thin sensors

A vertex-detector concept based on the hybrid planar pixel-detector technology is currently under development for the proposed Compact Linear Collider (CLIC). The low material budget of only 0.2% X0 per layer corresponds to an equivalent thickness of 200 um of silicon and includes the infrastructure for powering and mechanical support. To reach this material budget, sensors and readout ASICs will each have to be thinned down to approximately 50 um. In a first phase of R&D, assemblies were produced using thin planar pixel sensors (50-300 um) hybridised to Timepix readout ASICs. Both standard thickness ASICs and ASICs thinned to 100 um are used. Sensors include active-edge sensors from Advacam with 50 um thickness and Micron semiconductor sensors with 100 um thickness hybridised by IZM. The assemblies have been calibrated with sources and X-ray fluorescence measurements and characterised in beam telescope tests at DESY with a 5.5 GeV electron beam. In this talk we present the current status of sensor calibration, test-beam analysis and comparison with GEANT4 simulation using a sensor and electronics digitization model. We also show first measurement results for the recently produced CCPDV3 active HV-CMOS sensors matching the 25 um pitch of the 65 nm CLICpix readout ASIC prototypes.

Speaker: Mathieu Benoit (CERN LCD)

Slides

• MB_Pixel2014.pdf
• MB_Pixel2014.pptx
• Surrogate_Fit_1Column.gif

27 Irradiation and Testbeam of KEK/HPK Planar p-type Pixel Modules for HL-LHC

In the ATLAS detector upgrade for the high luminosity LHC (HL-LHC), a n-in-p planar pixel sensor-module is being developed with HPK. The modules were irradiated at the cyclotron radioisotope center (CYRIC) using 70 MeV protons. For the irradiation, we have designed a novel irradiation box that carries 16 movable slots to irradiate the samples slot-by-slot independently, to reduce the time for replacing the samples by hand, thus reducing the irradiation to human body. The box can be moved horizontally and vertically to scan the samples for an area of 11 cm x 11 cm at the maximum. We have then carried out tests with beam at CERN by using 120 GeV pions, at DESY 4 GeV electrons, and at SLAC 13 GeV electrons. We describe the analyses of the testbeam data of the KEK/HPK sensor-modules, focussing on the comparison of the performance of old and novel designs of pixel structures, together with a reference of the simplest design (no biasing structure). The novel design has shown as good performance as the no-structure design in detecting passing-through charged particles.

Speaker: Koji Nakamura (High Energy Accelerator Research Organization (JP))

Slides 20140902_PIXEL2014_Nakamura.pdf

28 Laboratory and testbeam results for thin and epitaxial planar sensors for HL-LHC

The High-Luminosity LHC (HL-LHC) upgrade of CMS pixel detector will require the development of novel pixel sensors which can withstand the increase in instantaneous luminosity to $5\times 10^{34}cm^{-2}s^{-1}$ and collect ~3000 fb$^{-1}$ of data. The innermost layer of the pixel detector will be exposed to doses of about $1 \times 10^{16}neq/cm^{2}$. Hence, new pixel sensors with improved radiation hardness needs to be investigated. A variety of silicon materials (Float-zone, Magnetic Czochralski and Epitaxially grown silicon), with thicknesses from 50 $\mu m$ to 320 $\mu m$ in p- and n-type substrates have been fabricated at one company (Hamamatsu Photonics K.K.) using single-sided processing. The effect of reducing the sensor active thickness to improve radiation hardness by using various techniques (deep diffusion, wafer thinning, or growing epitaxial silicon on a handle wafer) have been studied. The results for electrical characterization, charge collection efficiency, and position resolution of various n-in-p and n-in-n pixel sensors with different substrates and different pixel geometries (different bias dot gaps and pixel implant sizes) will be presented.

Speaker: Mayur Bubna (Purdue University (US))

Slides PIXEL_Mayur_Epitaxial.pdf

Poster Session

29 Firmware development and testing of the ATLAS IBL Back-Of-Crate card

ATLAS is one of the four big LHC experiments and currently its Pixel-Detector is being upgraded with a new innermost 4th layer, the Insertable B-Layer (IBL). The upgrade will result in better tracking efficiency and compensate radiation damages of the Pixel-Detector. Newly developed front-end electronics and the higher than originally planned LHC luminosity will require a complete re-design of the Off-Detector-Electronics consisting of the Back-Of-Crate card (BOC) and the Read-Out-Driver (ROD). The main purpose of the BOC card is the distribution of the LHC clock to all Pixel-Detector components as well as interfacing the detector and the higher-level-readout optically. It is equipped with three Xilinx Spartan-6 FPGAs, one BOC Control FPGA (BCF) and two BOC Main FPGAs (BMF). The BMF are responsible for the signal processing of all incoming and outgoing data. The data-path to the detector is running a 40 MHz bi-phase-mark encoded stream. This stream is delayed by a fine delay block using Spartan-6 IODELAY primitives. The primitives are reconfigured using partial reconfiguration inside the FPGA. The 160 MHz 8b10b-encoded data-path from the detector is phase and word-aligned in the firmware and then forwarded to the ROD after decoding. The ROD will send out the processed data which is then forwarded to the higher-level readout by the BOC card. An overview of the firmware, which has been developed, will be presented together with the results from production tests and the system test at CERN. One focus will be the partial reconfiguration and results of the fine delay measurements.

Speaker: Maria Elena Stramaglia (Universitaet Bern (CH))

Slides Stramaglia_PIXEL2014.pptx

30 Diamond pixel detector for beam profile monitoring in the COMET experiment at J-PARC

We present the design and initial prototype results of a pixellized proton beam profile monitor for the COMET experiment at J-PARC. The active element of the detector is single crystal diamond grown by chemical vapor deposition (sc-cvd). The goal of the COMET experiment is to look for charged lepton flavor violation by direct $\mu$ to e conversion at a sensitivity of $10^{-18}$. In the first phase, an 8 GeV proton beam pulsed at 100 ns with current corresponding to $10^{10}$ protons/second will be be used to create muons through pion production and decay. In the final experiment, the proton flux will be raised to $10^{14}$ protons/sec to increase the sensitivity with an intense muon beam. These requirements of harsh radiation tolerance and fast readout have led us into developing a sc-cvd diamond based pixel detector to profile the proton beam. The design details and first prototype readout results of the detector will be presented.

Speaker: Pradeep Sarin (Bhabha Atomic Research Centre (IN))

Slides PSarin_PIXEL2014_SuperFinal_20141115.pdf

31 Characterization of thin irradiated epitaxial silicon sensors for the CMS phase II pixel upgrade

The high luminosity upgrade of the Large Hadron Collider (HL-LHC) foreseen for 2022 will allow the experiments at the collider to collect data at a luminosity of $5~\times~10^{34}$ cm$^{-2}$s$^{-1}$, enhancing the discovery potential for new physics. The precise determination of vertices in the high radiation environment close to the HL-LHC interaction points demands the development of solid state detectors that can withstand unprecedented fluences. The CMS experiment strategy to overcome this challenge consists in the replacement of the whole tracking system, the so-called phase II tracker upgrade. The innermost layers of the upgraded pixel detector will experience fluences in the order of $\phi_{eq} \approx 10^{16}$ cm$^{-2}$ after an integrated luminosity of 3000 fb$^{-1}$. Several options are under investigation to provide a material and a design still operational after such fluences. Thin planar silicon sensors are candidates to achieve this goal since they show a less severe degradation of the charge collection efficiency with irradiation than thicker devices. The University of Hamburg and DESY are carrying on the characterization of highly irradiated epitaxial silicon sensors with an active thickness of 100 $\mu$m. The investigation includes diodes and strip detectors irradiated up to a fluence of $\phi_{eq} = 1.3 \times 10^{16}$ cm$^{-2}$. The properties of the diodes are determined through their current- and capacitance-voltage characteristics, while their charge collection efficiency is measured using laser and radioactive sources. A test beam campaign has been carried out at the DESY II test beam facility to characterize the strip detectors. A beam telescope has been used to determine precisely the impact position of beam particles on the sensor. This allows an unbiased measurement of the charge deposit in the strip sensor and reduces the effects of the noise. In this talk the results of the diode characterization and of the strip sensor test beam are presented.

Speaker: Matteo Centis Vignali (Hamburg University (DE))

Slides posterPixel2014.pdf

32 Characterization of Low Gain Avalanche Detectors (LGAD) irradiated with protons and neutrons

This work presents new avalanche pad detectors with low gain (LGAD) fabricated with a technology based on APD but with a modified doping profile, in order to have detectors suitable to be used for tracking in high energy physics experiments (such as colliders) and resistant to the high radiation fluencies expected in the future LHC upgrade at CERN. If a significant improvement of the collected charge is found after heavy irradiation, this geometry can be directly applied to microstrip and pixels sensors. A Sentaurus TCAD simulation was performed to predict the electrical behavior of the proposed structures since some of the new technological solutions might compromise the voltage breakdown properties. The capacitance behavior of these new devices is to be studied too, since an increase of the capacitance value will increase the noise, worsening the signal to noise ratio, even for the highest gain values. In this work we show the electrical measurements and charge collection studies obtained with MIP and alpha radiations before and after irradiations with neutrons and protons at fluences up to 1015 cm-2 1 Mev equivalent.

Speaker: Giulio Pellegrini (Centro Nacional de Microelectrónica (IMB-CNM-CSIC) (ES))

Slides Poster_Pixel2014.pdf

33 IBL modules construction experience and developments for future upgrade

The first upgrade of the ATLAS Pixel Detector is the Insertable B-Layer (IBL), just installed in May 2014 in the core of ATLAS. Two different silicon sensor technologies, planara n-in-n and 3D, were used, connected with the new generation 13o0nm IBM CMOS FE-I4 readout chip via solder bump-bonds. Production quality control tests were set up to verify and rate the performance of the modules before integration into staves. An overview of module design and construction, the quality control results and production yield will be discussed, as well as future developments foreseen for future detector upgrades.

Speaker: Kazuki Motohashi (Tokyo Institute of Technology (JP))

Slides PIXEL2014_kazuki_v1_4.pdf

34 Firmware development and testing of the ATLAS Pixel Detector / IBL ROD card

The ATLAS Experiment is reworking and upgrading systems during the current LHC shut down. In particular, the Pixel detector is inserting an additional inner layer called Insertable B-Layer (IBL). The Readout-Driver card (ROD), the Back-of-Crate card (BOC), and the S-Link together form the essential frontend data path of the IBL’s off-detector DAQ system. The strategy for IBLROD firmware development focused on migrating and tailoring HDL code blocks from PixelROD to ensure modular compatibility in future ROD upgrades, in which a unified code version will interface with IBL and Pixel layers. Essential features such as data formatting, frontend-specific error handling, and calibration are added to the ROD data path. An IBLDAQ testbench using realistic frontend chip model was created to serve as an initial framework for full offline electronic system simulation. In this document, major firmware achievements concerning the IBLROD data path implementation, tested in testbench and on ROD prototypes, will be reported. Recent Pixel collaboration efforts focus on finalizing hardware and firmware tests for IBL. Time plan is to approach a final IBL DAQ phase by the end of 2014.

Speaker: Alessandro Gabrielli (Universita e INFN (IT))

Poster Poster-gabrielli.pdf

35 A high rate test beam of the CMS Phase 1 Upgrade pixel chip

The CMS collaboration will upgrade the CMS pixel detector in 2016/2017. For this upgrade the readout chip (ROC) had to be modified. An improved readout logic, larger data buffers and the digital readout scheme promise a significant increase in hit detection efficiency at the high particle flux expected in the LHC environment of a luminosity of $2\times 10^{34}$ cm$^{-2}$s$^{-1}$. To test the chip’s high rate capabilities a test beam was performed at the Fermilab Test Beam Facility (FTBF). The chip was tested in a telescope with rates of up to 500 MHz/cm$^2$. This talk will describe the new ROC, the telescope electronics and show results from the test beam.

Speaker: Andreas Kornmayer (KIT - Karlsruhe Institute of Technology (DE))

Slides 02092014_PIXEL@NIAGRAFALLS_POSTER_PSI.pdf

36 Silicon avalanche-photodiode linear array detector with multichannel scaling system for pulsed synchrotron X-ray experiments

We have been developing an X-ray detector system using a 64-pixel silicon avalanche- photodiode (Si-APD) linear array (pixel size: 100 μm × 200 μm) and pulse counting electronics for multichannel scaling (MCS).　 The Si-APD linear array consists of 64 pixels 100 × 200 μm^2, with a pixel pitch of 150 μm and a depletion depth of 10 μm. The fast response of Si-APD and the MCS system are used for time-resolved X-ray diffraction and nuclear resonant scattering experiments using pulsed synchrotron X-rays. The detector system can resolve successive X-ray pulses at 2 ns intervals and record the pulse counts with a rate of >10^7 cps per channel and position of X-rays coming to each pixel of the linear array. The time resolution of 1.4 ns (FWHM) was obtained. The electronics consisting of an ultrafast application-specific integrated circuit, field-programmable gate arrays and a network processor was developed for the linear array system. The detector successfully recorded nuclear resonant small-angle scattering on Fe-57 by scanning the detector position.

Speaker: Shunji Kishimoto (KEK)

Poster Pos_S_Kishimoto_14Sep02.pdf

37 Qualification of a new supplier for silicon particle detectors

Silicon based sensors have become the dominant technology for the tracking systems of most modern particle physics experiments. The demand for these sensors is increasing and the existing production capabilities might not be sufficient to fulfill the demands of the future upgrades of the LHC experiments. To establish a new supplier for the production of silicon strip and pixel sensors a process for p-on-n strip sensors has been developed in a cooperation between the Institute of High Energy Physics of the Austrian Academy of Sciences (HEPHY) and the European semiconductor manufacturer Infineon Technologies Austria AG.

Speaker: Wolfgang Treberer-Treberspurg (Austrian Academy of Sciences (AT))

Poster wtreb_pixel2014_a0.pdf

38 Operation and testbeam results of HV/HR-CMOS active sensors with pixel readout

In the Phase-II Upgrade of the Large Hadron Collider, the instantaneous luminosity will be increased up to about 5*10³⁴ cm^-2s^-1, which creates many challenges for future detectors. This necessitates a fundamental redesign of the ATLAS Inner Tracker (ITk) to cope with increased radiation damage and increased occupancy in the sub-detectors.
Several industrial CMOS foundries offer a High Voltage (HV) and High Resistivity (HR) design option, allowing the creation of a deep depletion zone, suitable for particle detection with active pixel detectors. These so-called HV/HR-CMOS detectors offer new in-pixel signal processing solutions, reduced clustersizes and are potentially more cost eective than current hybrid detectors.
An ATLAS R&D project has been started to qualify commercial HV/HR-CMOS technologies suitable for Pixel Detectors for the ATLAS ITk. To optimize the performance of the active sensors together with the readout chips, intricate tuning procedures are implemented in a easy-to-use test system for the collaboration to use. The latest results from characterization measurements in the lab, using the newly developed tuning procedures, and in beam tests of prototypes from several vendors will be presented.

Speaker: Jens Weingarten (Georg-August-Universitaet Goettingen (DE))

Slides Pixel2014_Poster.pdf

39 Simulation of the Dynamic Inefficiency of the CMS Pixel Detector

The Pixel Detector is the innermost part of the CMS Tracker. Therefore it has to prevail in the hardest environment in terms of particle fluence and radiation. Also it is one of the most important detectors of CMS: it gives essential information for vertex reconstruction which is crucial for every analysis. The efficiency of the Pixel Detector can decrease throughout a run by several reasons. It is mainly caused by DAQ problems and/or SEUs (Single Event Upset). Besides that there is still a smaller but significant efficiency loss called the dynamic inefficiency. It is caused by various data loss mechanisms inside the ROC (Read Out Chip) and depends strongly on the data occupancy. In the 2012 data, at high values of instantaneous luminosity the efficiency reaches 98% (for the first layer) which is not negligible. In the 2015 run higher instantaneous luminosity is expected, which will result in lower efficiencies, therefore the simulation of this effect is necessary. A data-driven method has been developed to simulate dynamic inefficiency in which the efficiency is parametrised as a function of instantaneous luminosity and detector geometry using past data. This way the dynamic inefficiency is independent of the quality of the physics simulation, but has to be calibrated for different run conditions. With this method the dynamic inefficiency is successfully simulated resulting in a much improved description of the Pixel Detector.

Speaker: Marton Bartok (University of Debrecen (HU))

Slides poster_pixel2014_dyn_ineff_final.pdf

40 Pixel module production and qualification for the Phase 1 Upgrade of CMS

The instantaneous luminosity of the Large Hadron Collider (LHC) is being increased in several steps over the next 10 years to maximize its discovery potential for new physics. However, at a luminosity of twice the design luminosity of the LHC of $1 \times 10^{34}$ cm$^{−2}$s$^{−1}$, the performance of the current CMS pixel detector is degraded by substantial deadtime incured by the readout chip (ROC). To make full use of the proton-proton collisions being provided by the LHC, CMS will replace its pixel detector during the extended winter shutdown in 2016-17 by a new detector with four barrel layers and three disks in each endcap. Module production includes bump bonding, wire bonding, and gluing processes, as well as a series of functionality tests, calibrations and thermal cycling. One of the calibration steps is the x-ray calibration, which provides an absolute energy calibration of an internal calibration circuit. This circuit injects charge into the preamplifier to simulate a signal, and is used to define several parameters of the readout chip, including the threshold. Therefore, an absolute calibration is required in order to know the threshold in units of electrons. In this talk the barrel module assembly is explained, with a special focus on the x-ray calibration of the pixel detector.

Speaker: Mercedes Minano Moya (National Taiwan University (TW))

Slides PIXEL_2014_ToPrint.pdf

Wednesday 3 September

Pixel Front End Electronics Development

Convener: Rainer Wallny (Eidgenoessische Tech. Hochschule Zuerich (CH))

41 Participant Information

Speaker: Wendy Taylor (York University (CA))

42 RD-53 Progress on High Rate Pixel Readout chip

This talk will introduce the RD-53 collaboration and focus on on-going work in defining the next generation pixel readout chi for the ATLAS and CMS experiments. Will focus on particular on the issue on high data hit rate with MHz trigger rate readout. Will cover issues and possible solutions for internal data flow within the chip, which impacts layout, and options for data compression.

Speaker: Maurice Garcia-Sciveres (Lawrence Berkeley National Lab. (US))

Slides pixe2014-mgs.pdf

43 The CMS Pixel Readout Chip for the Phase 1 Upgrade

The present CMS pixel Read Out Chip (ROC) has been designed for operation at 25 ns and to be efficient up to the nominal instantaneous luminosity of $10^{34}$ cm$^{-2}$s$^{-1}$. Based on the excellent LHC performance to date, and the upgrade plans for the accelerators, it is anticipated that the instantaneous luminosity could reach $2\times 10^{34}$ cm$^{-2}$s$^{-1}$ before Long Shutdown (LS) 2 in 2018, and well above this by LS3 in 2022. That’s why a new ROC has been designed and a completely new pixel detector will be built with a scope of its installation in CSM during an extended winter shutdown in 2016/17. The ROC for the upgraded pixel detector is an evolution of the present architecture. It will be manufactured in the same 250 nm CMOS process. The core of the architecture is maintained, with enhancement in the performance in three main areas: readout protocol, reduced data loss and enhanced analog performance. The main features of the new CMS pixel ROC are presented together with measured performance of the chip.

Speaker: Dmitry Hits (Eidgenoessische Tech. Hochschule Zuerich (CH))

Slides CMS-ROC_v1.pdf

44 VeloPix: The Pixel ASIC for the LHCb VELO Upgrade

The LHCb Vertex Detector (VELO) will be upgraded in 2018 along with the other subsystems of LHCb in order to enable full readout at 40 MHz, with the data fed directly to the software triggering algorithms. The upgraded VELO is a lightweight hybrid pixel detector operating in vacuum in close proximity to the LHC beams. The readout will be provided by a dedicated front end ASIC, dubbed VeloPix, matched to the LHCb readout requirements and the 55 x 55 um VELO pixel dimensions. The chip is closely related to the Timepix3, from the Medipix family of ASICs. The principal challenge that the chip has to meet is a hit rate of up to 900 Mhits/s, resulting in a required effective bandwidth of more than 16 Gbit/s. The occupancy is also very non uniform, and the radiation levels reach an integrated 400 MRad over the lifetime of the detector. VeloPix is a binary pixel chip with a data driven readout, designed in 130 nm technology. The pixels are combined into groups of 2x4 super-pixels, enabling a shared logic and a reduction of bandwidth due to combined address and timestamp information. The pixel hits are combined with other simultaneous hits in the same super-pixel, timestamped, and immediately driven off-chip. The analog front end must be sufficiently fast to accurately timestamp the data, with a small enough dead time to minimize data loss in the most occupied regions of the chip. The data is driven off chip with a custom designed high speed serialiser. The current status of the ASIC design, performance simulations and prototyping will be described, along with recent lab and testbeam results.

Speaker: Tuomas Poikela (University of Turku (FI))

Slides Pixel2014_VeloPix_ASIC_TuomasPoikela.pdf

10:40 Coffee

45 TDCpix - Pixel Read-out ASIC with 100 ps Time-tagging Capability for the NA62 Gigatracker Experiment

Abstract The TDCpix is a pixel readout ASIC designed for the NA62 Gigatracker detector at the CERN Super Proton Synchrotron. Each of the three hybrid pixel Gigatracker detector stations provides tracking and time stamping of individual particles with a time resolution of 200 ps rms. The TDCpix features 45 × 40 square pixels of 300 × 300 µm$^2$ and a peripheral region including an array of 720 TDC channels providing a time binning of 100 ps. This contribution will describe the complete design, test results and integration of the TDCpix ASIC.

Speaker: Matthew Noy (CERN)

Slides mnoy.03.09.2014.pdf

46 Low power, high resolution MAPS for particle tracking and imaging

This contribution describes a Monolithic Active Pixel Sensor (MAPS) specifically designed to improve current MAPS state of the art for particle tracking when very high speed, low power consumption and/or small pixels (down to micron size) are required. The low power target is especially important as one of the design goal is to provide a cheaper and easier to implement alternative to present state of the art strip sensors in large volume tracking detectors. The key innovation implemented to improve performance is the OrthoPix architecture, a compressing readout scheme specially developed for tracking high rate particles over large area pixel detectors. Such architecture has been specifically designed to read out with efficiency the large area (10 cm^2 or bigger) MAPS which stitching technique now allow to produce. Being the compression passive, with no active elements embedded into the pixel cell, the pixel size can shrink down to the micron level (if necessary) and power dissipation over the matrix area is minimal. Depending on pixel pitch, a particle rate of many tens of MHz / cm^2 can be sustained at full efficiency. To demonstrate the validity of this novel design a 255 × 255 pixel array (10 µm pitch) prototype has been realized in the Tower-Jazz 0.18 µm quadruple-well CMOS process on a 18 µm thick high resistivity (1 kΩ cm) epitaxial layer. The epitaxial layer can therefore be reverse biased at low bias voltages (<10 V) and used as the sensitive volume. Measurements which highlights the device actual performances will be shown, discussed, and compared with simulations to assess the potentiality of future developments. An overview of how the proposed technology could find applications in High Energy Physics, Medical Imaging, and Electronic Microscopy will be also discussed.

Speaker: Piero Giubilato (Universita e INFN (IT))

Slides Pixel2014_Giubilato_03.pdf

47 Evaluation of SOI Pixel Detector with Charge Sensitive Amplifier Circuit for Event-Driven X-ray Readout

We have been developing monolithic active pixel detectors, "XRPIX", with the silicon-on-insulator (SOI) technology for future X-ray astronomical satellite missions. XRPIX is wide-band (0.3 – 40 keV) fine imaging spectrometer and the advantage is low background. Our objective performance are high coincidence time resolution (∼ 1 ${\rm \mu}$s), superior hit-position readout time (∼ 10 ${\rm \mu}$s) in order to reduce the non-X-ray background by cosmic rays. XRPIX contains comparator circuit in each pixel to detect an X-ray photon injection; it offers intra-pixel hit trigger (timing) and two-dimensional hit-pattern (position) outputs. Therefore, it is capable of direct access to selected pixels to read out the signal amplitude. X-ray readout by this function is called ''Event-Driven readout''. By introducing an anti-coincidence method between the hit signal and the external active shield detector, the back ground can be greatly reduced. It realizes about 1 % of low background of CCD at 20 keV. In our previous study, we developed prototype of XRPIX and demonstrated the acquisition of X-ray spectra in Event-Driven readout. The energy resolution are 900 eV (FWHM) for Frame mode and 1.2 keV (FWHM) for Event-Driven mode at 22.2 keV. And the readout noise is 68 e- (rms) for Frame mode. Recently, we designed a new prototype which has charge sensitive amplifier (CSA) in each pixel in order to increase the gain and improve energy resolution. Then, the readout noise reached 33 e- (rms) and the energy resolution is about 300 eV (FWHM) at 5.9 keV. The Event-Driven X-ray readout by CSA circuit is under evaluation now. In this presentation, we report the present status of development focusing on spectrum performance.

Speaker: Ayaki Takeda (Kyoto University)

Slides 20140903_pixel2014_takeda_v1.pdf

48 Novel Active Signal Compression in Low-noise Analog Readout at Future XFEL Facilities

This work presents the design of a low-noise front-end implementing a novel active signal compression technique. This feature can be exploited in the design of analog readout channels for application to the next generation free electron laser (FEL) experiments. The readout architecture includes the low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time variant shaper used to process the signal at the preamplifier output and a 10 bit successive approximation register (SAR) analog-to-digital converter (ADC). The channel will be operated in such a way to cope with the high frame rate (exceeding 1 MHz) foreseen for future XFEL machines. The choice of a 65 nm CMOS technology has been made in order to include all the building blocks in the target pixel pitch of 100 um. This work has been carried out in the frame of the PixFEL project funded by Istituto Nazionale di Fisica Nucleare (INFN), Italy. The members of the PixFEL Collaboration are affiliated with Università di Bergamo, Università di Pavia, Università di Pisa, Università di Trento and INFN, Italy.

Speaker: Massimo Manghisoni (Università di Bergamo - Italy)

Slides pixel2014_manghisoni.pdf

13:00 Lunch

X-Ray Imaging Applications

Convener: Yoshinobu Unno (High Energy Accelerator Research Organization (JP))

49 Similarities and Differences of Recent Pixel Detectors for X-ray and High Energy Physics

Hybrid pixel detectors are being developed for both photon science and high energy physics. In the talk we will cover similarities and differences in pixel detectors for both applications using as examples two of the pixel detectors developed at Paul Scherrer Institute (Switzerland): the EIGER photon counting detector and the psi46dig chip, which has been developed for the Compact Muon Solenoid (CMS) tracking pixel detector upgrade. EIGER is a single photon counting hybrid pixel detector for applications at synchrotron light sources in an energy range from a few to 25 k$e$V. It is characterized by a small pixel size, high count rate capability (10$^6$ counts/pixel/s) and very high data rate, which reaches 6 Gb/s for a 256$\times$256 pixel chip. The CMS pixel detector has been designed to provide charge information from the pixels in the harsh Large Hadron Collider environment. The short time between bunches of 25 ns and the high event rate at peak luminosities up to $10^{34}\textrm{cm}^{-2}\textrm{s}^{-1}$ require a fast detector, which retain timestamp information for the hits. The readout architecture is based on the transfer of hits from the pixels to the periphery, where the trigger verification is performed before the data transfer. The data rates of the digitized output reach 160 Mb/s for a 52$\times$80 pixel chip. In addition to address the specific timing and rate requirements for the detectors, the talk will cover the analog performances (minimum threshold, threshold dispersion and noise), power consumption and radiation hardness requirements. To conclude, an overview on the future developments based on mutual learning and common solutions will be discussed.

Speaker: Gemma Tinti (p)

Slides tinti_PIXEL2014.pdf

50 Cornell Integrating Pixel Array Detector Development for Synchrotron X-ray Light Sources

Synchrotron light sources are capable of producing x-ray synchrotron radiation of extreme brilliance and coherence. These sources create opportunities to exploit experimental techniques in both time-resolved and coherent x-ray imaging experiments, assuming the availability of area detectors designed to capture and record the relevant and desired x-ray information. Capturing this information presents challenges for both the speed and dynamic range of the imaging detectors. The on-going integrating detector development efforts at Cornell addressing these needs will be presented. These will include high-speed and high-dynamic range detectors that have been developed by the group and recently used in scientific collaborations at synchrotron sources; and less mature development efforts aimed at increasing detector capabilities with an eye on future light source and experimental capabilities.

Speaker: Hugh Philipp (Cornell University)

Slides PIXEL_2014_Philipp_final.pptx

51 Pixel Detectors for the LCLS

Fourth generation light sources such as the LCLS represent a unique and challenging environment in which to operate x-ray detectors. Their pulsed time structure, in which a large number of x-rays impinge on a sample essentially simultaneously, demands detectors capable of handling large signals while maintaining sensitivity to single photons. Both energy and absorption depth in silicon of the delivered x-rays vary by orders of magnitude. Under certain conditions during a single 50 femtosecond long burst, parts of a detector can absorb a radiation dose similar to that seen by the inner pixel layers at the LHC over a ten year period. These detectors enable a diverse range of science from fusion energy and biology to material science and chemistry. To meet all these needs a suite of detectors is being designed and manufactured.

Speaker: Chris Kenney (SLAC)

Slides Kenney-v5.pptx

52 Development of High Performance X-ray Cameras at DESY: from prototypes to complete systems

With the continual drive towards bigger, better and brighter light sources, whole new areas of scientific research are possible that would have been unimaginable or even believed impossible before. However, even the best experiment or the best light source is worthless if the employed detection system is not up to the task at hand. This is especially true for light sources like the current and upcoming generation of Hard X-ray FELs, which introduce special challenges that are distinctly different from the challenges posed at current 3rd generation synchrotrons. Cutting edge area-detector developments nowadays mostly, but not exclusively, provide a separate readout channel for each pixel, allowing sophisticated parallel signal processing. The hybrid pixel approach further makes it possible to optimize the sensor and the readout chip independently from each other, and profit from technological advances very quickly. Improvements in microchip production (Moore’s law) make it possible to achieve faster readout, smarter signal processing and smaller pixels, while new sensor materials and designs can have a range of benefits such as better quantum efficiency. In this talk, two hybrid pixel systems and one CMOS imaging system developed by the photon science detector group at DESY (FS-DS) are presented: The AGIPD system, a high dynamic range 4.5 MHz burst mode camera for use at the European XFEL, the LAMBDA system, a Medipix3 based large area detector with 55 um pixel size and the ability to support either silicon or high-Z sensors and is currently being commissioned at PETRA-III synchrotron beamlines, and the PERCIVAL system with 27 um pixels and large dynamic range, optimized for operation at soft x-ray energies between 250 eV and 1 keV at 120 Hz repetition rate.

Speaker: Julian Becker (DESY)

Slides 20140903_JBecker_Pixel2014_V2.pptx

16:00 Coffee

53 The PixFEL Project: development of advanced X-ray pixel detectors for application at future X-FEL facilities

The PixFEL project aims to develop an advanced X-ray camera for imaging suited for the demanding requirements of next generation free electron laser (FEL) facilities. The deployment of new technologies and innovative solutions, already under study for future pixel detectors for tracking, can also boost the performance of imaging instrumentations. In the first phase of the PixFEL project, recently approved by the INFN, the focus will be on the development of the microelectronics building blocks, carried out with a 65 nm CMOS technology, implementing a low noise analog front-end channel with high dynamic range and compression features, a low power ADC and high density memory. At the same time the collaboration will investigate and implement some of the enabling technologies to assembly, in a second phase of the project, a seamless large area X-ray camera composed by a matrix of multilayer four-side buttable tiles. In order to minimize the dead area on the sensor tiles, a pixel matrix with active edge will be developed. Vertical interconnection of two CMOS layers, with low density and high density through silicon vias, will be explored to build a four-side buttable readout chip with small pixel pitch and all the on-board required functionality. The ambitious target requirements of the pixel device under development are: single photon resolution, $1$ to $10^4$ photons @ 1 keV to 10 keV input dynamic range, 10-bit analog to digital conversion up to 5 MHz, 1 kevent in-pixel memory and 100 um pixel pitch. The final goal of a longer term research program will be the construction of a versatile X-ray camera for application to high frame rate X-FEL operated either in burst mode, up to 5 MHz, like at the European X-FEL, or in continuous mode with the high repetition rates foreseen for the upgrade phase of the LCLS-II at SLAC.

Speaker: Giuliana Rizzo (INFN & University - Pisa)

Slides pixel2014_rizzo.pdf

54 First characterization results of the MÖNCH hybrid pixel detector

MÖNCH is a novel hybrid silicon pixel detector based on charge integration and analog readout, featuring a challengingly small pixel size of 25x25 μm2. It is a research project which aims to push the development of hybrid pixel detectors to its limits in terms of photon flux, position resolution, energy information and low energy detection. MOENCH02 is a fully functional, small scale prototype of 4x4mm2, containing an array of 160x160 pixels, designed in UMC 110nm technology [1]. This array is subdivided in five sub blocks, each featuring a different pixel architecture. The first block targets high resolution, low flux synchrotron applications, as RIXS (resonant inelastic X-ray scattering) or X-ray tomography with X-ray tubes. In this case the charge sharing effect between pixels, together with the signal analog readout, can be exploited to interpolate the hit position with a precision that could reach the sub-μm resolution. The first characterization results of this sub block of MÖNCH02 in terms of bump-bonding yield, linearity, dynamic range and energy resolution will be shown. The noise performance will be presented in more detail, showing a total noise as low as <40 e-, as well as an overview of the noise contribution of the different blocks, from the amplifier to the off-chip buffer. The latest version of the interpolation algorithm and tests showing its effectiveness in obtaining sub-pixel resolution will also be shown. The encouraging results obtained lead to the design of a bigger size prototype, MÖNCH03. MÖNCH03 has an active area of 5x10mm2 and it contains an array of 200x400 identical pixels, based on the first block of MÖNCH02. Several improvements are implemented in the chip periphery and in the readout system, which should result in a final frame rate of ~8 kHz.

Speaker: Roberto Dinapoli (Paul Scherrer Institut)

Slides Dinapoli_PIXEL14.ppt

Winery Dinner

55 Buses leave Sheraton

56 Hors d'oeuvres

57 Dinner

58 First bus returns to Sheraton

59 Last bus returns to Sheraton

Thursday 4 September

LHC Upgrade Detector Designs

Convener: Fabian Huegging (Universitaet Bonn (DE))

60 The Pixel Detector of the ATLAS Experiment for Run2 at the Large Hadron Collider

The Pixel Detector of the ATLAS experiment has shown excellent performance during the whole Run-1 of LHC. Taking advantage of the long showdown, the detector was extracted from the experiment and brought to surface, to equip it with new service quarter panels, to repair modules and to ease installation of the Insertable B-Layer (IBL). IBL is a fourth layer of pixel detectors, and has been installed in May 2014 between the existing Pixel Detector and a new smaller radius beam-pipe at a radius of 3.3 cm. To cope with the high radiation and pixel occupancy due to the proximity to the interaction point, a new read-out chip and two different silicon sensor technologies (planar and 3D) have been developed. Furthermore, the physics performance will be improved through the reduction of pixel size while, targeting for a low material budget, a new mechanical support using lightweight staves and a CO2 based cooling system have been adopted. An overview of the refurbishing of the Pixel Detector and of the IBL project as well as the experience in its construction will be presented, focusing on adopted technologies, module and staves production,qualification of assembly procedure, integration of staves around the beam pipe and commissioning of the detector.

Speaker: Heinz Pernegger (CERN)

DinnerPhotos Pixel2014-Dinner-Photos.zip Pixel2014-Dinner-Photos.zip

Slides Pixel2014-PerneggerV5.pdf

61 Near Future Upgrades for the CMS Pixel Detector

The silicon pixel detector is the innermost component of the CMS tracking system, providing high precision space point measurements of charged particle trajectories. The performance of the current pixel detector has been excellent during Run 1 of the LHC. However, the foreseen significant increases of the instantaneous and integrated luminosities at the LHC necessitate an upgrade of the pixel detector in order to maintain the excellent tracking and physics performance of the CMS detector. The new pixel detector is planned to be installed during an extended LHC winter shutdown in 2016-17. The main new features of the upgraded pixel detector would be ultra-light mechanical design, an additional 4th layer in the barrel and two additional endcap disks, and a new digital readout chip with increased buffers to minimize data-loss. The other important features are a new two-phase CO2 cooling system and a new powering scheme via DC-DC converters. Each of these aspects will be summarized and the resulting improvements in physics performance will be discussed. Current status on module assembly and testing will also be reported.

Speaker: Ashish Kumar (State University of New York (US))

Slides Pixel2014_v3.pdf

62 Upgrades for the ALICE Inner Tracking System

ALICE (A Large Ion Collider Experiment) is studying the physics of strongly interacting matter, and in particular the properties of the Quark-Gluon Plasma (QGP), using proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN LHC (Large Hadron Collider). The ALICE Collaboration is preparing a major upgrade of the experimental apparatus, planned for installation in the second long LHC shutdown in the years 2018-2019. A key element of the ALICE upgrade is the construction of a new, ultra-light, high-resolution Inner Tracking System (ITS). The primary focus of the new ITS is on improving the performance for detection of heavy-flavour hadrons, and of thermal photons and low-mass di-electrons emitted by the QGP. With respect to the current detector, the new ITS will significantly enhance the determination of the distance of closest approach to the primary vertex, the tracking efficiency at low transverse momenta, and the read-out rate capabilities. This will be obtained by seven concentric detector layers based on a 50$\mu$m thick CMOS pixel sensor with a pixel pitch of about 30$\times$30$\mu$m$^2$. A key feature of the new ITS, which is optimized for high tracking accuracy at low transverse momenta, is the very low mass of the three innermost layers, which feature a material thickness of 0.3% X0 per layer. This contribution presents the design goals and layout of the new ALICE ITS, a summary of the R&D activities, with focus on the technical implementation of the main detector components, and the projected detector and physics performance.

Speaker: Markus Keil (CERN)

Slides PixelKeil.pdf

10:30 Coffee

63 The VELO Pixel Upgrade

The LHCb Vertex Detector (VELO) will be upgraded in 2018 to a lightweight hybrid pixel detector capable of 40 MHz readout at a luminosity of 2x1033 cm-2 s-1 and operation in very close proximity to the LHC beams. The pattern recognition and track reconstruction precision is enhanced relative to the current VELO detector even at the high occupancy conditions of the upgrade, due to the pixel geometry and a closest approach to the LHC beams of just 5 mm. The pixel modules must withstand non-uniform irradiation levels reaching 8 x 1015 neq/cm2 at the regions closest to the beam, over the lifetime of the upgraded VELO. In order to achieve this, radiation hard technologies are employed for the sensors and electronics, and the sensors must be efficiently cooled. The pixel modules are mounted onto silicon plates which provide cooling via bi-phase CO2 circulating in microchannels etched within the silicon. The entire detector is split into two retractable halves, with the modules occupying a secondary vacuum volume separated from the primary vacuum by a thin, corrugated foil. The detector contains 41 million 55 x 55 um square pixels, read out by the custom developed VeloPix front end ASIC. This ASIC, which is a development in common with the Medipix family of ASICs, most tolerate rates of over 900 Mhits/s and be capable of reading out every bunch crossing, leading to data rates of above 16 Gbits/s. The ASIC operates with a data driven readout and on-chip data packing into super pixels. The high speed signals are transmitted via electrical and optical links to the off detector electronics which incorporate FPGAs to time order and process the data for delivery into the software farm where the trigger is implemented. The current status of R&D for the VELO upgrade, together with the prototyping results will be reviewed.

Speaker: Eddy Jans (NIKHEF (NL))

Slides Pixel2014.EJ.140904.final.pdf

64 LHC Phase 2 upgrade of the ATLAS Pixel Detector

From 2024, the HL-LHC will provide unprecedented pp luminosities to ATLAS, resulting in an additional integrated luminosity of around 2500 fb-1 over ten years. This will present a unique opportunity to substantially extend the mass reach in searches for many signatures of new physics, in several cases well into the multi-TeV region, and to significantly extend the study of the properties of the Higgs boson. The increased luminosity and the accumulated radiation damage will render the current Inner Tracker no longer suitable for long term operations. It will need to be replaced with a new all silicon tracker to maintain tracking performance in the high occupancy environment and to cope with the increase of approximately a factor of ten in the total radiation fluence. New technologies are used to ensure that the system can survive this harsh radiation environment and to optimise the material distribution. Present ideas and solutions for the pixel detector will be discussed in this talk.

Speaker: Paolo Morettini (INFN Genova)

Slides ATLAS Pixel HL-LHC

65 Pixel sensors for the CMS phase-II upgrade

The high luminosity phase of the Large Hadron Collider (HL-LHC) requires a major pixel detector R&D effort to develop both readout chip and sensor that are capable to withstand unprecedented extremely high radiation damage. The target integrated luminosity of 3000 fb-1, that the HL-LHC is expected to deliver over about 10 years of operation, translates into a hadron fluence of 2x10^16 1MeV eq. n / cm2 at about 3 cm from the interaction region where the first layer of the pixel detector could be located, and to a radiation dose of 10 MGy for the readout chip. The CMS collaboration has undertaken two baseline sensor R&D programs on thin n-in-p planar and 3D Silicon sensor technologies. Alternative technologies are also being investigated such as polycrystalline Diamond and HV-CMOS. Status, progresses, and prospects of this effort will be discussed.

Speaker: Mauro Dinardo (Universita & INFN, Milano-Bicocca (IT))

Slides Dinardo_Pixel2014.pdf

66 Performance Tests During the IBL Stave Integration

In preparation of the ATLAS Pixel Insertable B-Layer integration, two detector components, so called staves, were mounted around the Beryllium ATLAS beam pipe and tested using production quality assurance measurements as well as dedicated data taking runs to validate a correct grounding and shielding schema. Each stave consists of 32 FE-I4 readout chips of ~ 2x2cm size which sums up to over 860k pixels per stave. The integration tests include verification that neither the silicon n-in-n nor the silicon 3D sensors were damaged by mechanical stress, and that their readout chips, including their bump bond and wire bond connections, did not suffered from the integration process. Evolution of the IBL performance during its integration will be discussed as well as its final performance before installation

Speaker: Jennifer Jentzsch (Technische Universitaet Dortmund (DE))

Slides Pixel2014_JJentzsch.pdf

12:50 Lunch

Cooling, Interconnections, Radiation Tolerance

Convener: Markus Keil (CERN)

67 Evaporative CO2 Microchannel Cooling for the LHCb VELO Pixel Upgrade

The LHCb Vertex Detector (VELO) will be upgraded in 2018 to a lightweight, pixel detector capable of 40 MHz readout and operation in very close proximity to the LHC beams. The thermal management of the system will be provided by evaporative CO2 circulating in micro channels embedded within thin silicon plates. This solution has been selected due to the excellent thermal efficiency, the absence of thermal expansion mismatch with silicon ASIC’s and sensors, the radiation hardness of CO2, and very low contribution to the material budget. Although micro channel cooling is gaining considerable attention for applications related to microelectronics, it is still a novel technology for particle physics experiments, in particular when combined with evaporative CO2 cooling. The R&D effort for LHCb is focusing on the design and layout of the channels together with a fluidic connector and its attachment which must withstand pressures in excess of 200 bars. This talk will describe the design and optimization of the cooling system for LHCb together with latest prototyping results. Even distribution of the coolant is ensured by means of the use of restrictions implemented before the entrance to a race-track layout of the main cooling channels. The coolant flow and pressure drop has been simulated together with the thermal performance of the device. The design of a suitable low mass connector, together with the vacuum soldering technique to the cooling plate will be described. Long term reliability as well as resistance to extremes of pressure and temperature is of prime importance. The setup and operation of a cyclic stress test of the prototype cooling channel designs will be described.

Speaker: Oscar Augusto De Aguiar Francisco (Univ. Federal do Rio de Janeiro (BR))

Slides PIXEL2014_Oscar_v1r0.pdf

68 RD53 investigation of CMOS radiation hardness up to 1Grad

This talk will review progress and status of testing of deep submicron CMOS technology for tolerance to radiation with total ionizing dose up to 1Grad, and also for tolerance to single event effects. Multiple prototypes have been fabricated and tested with x-rays, gamma rays, and protons. Devices tested range from single transistors to full circuits. A summary of results obtained so far will be presented.

Speaker: Mohsine Menouni (Centre National de la Recherche Scientifique (FR))

Slides pixel2014_MM_TID65nm.pdf

69 Silicon as Pixel Sensor Material at Extreme Fluences up to 10^17 n/cm^2

Raising the electric field so as to provoke charge multiplication of electrons has enabled silicon to provide measurable signals from sensors irradiated to unprecedented radiation levels up to 1.6x10^17 n_eq/cm^2, making it a contender also for HL-LHC very forward tracking and calorimneters. A simple scaling of collected charge vs. applied bias has been established experimentally for fluences above 10^15 n_eq/cm^2 for planar strip sensors. Field investigations by edge-TCT have been carried out to 10^16, 10^17 is in the planning. Distinct features as a SCR and ENB with a sizable electric field were observed. Leakage current generation seems confined to the SCR, therefore the observed departure from linear scaling of leakage current vs. fluence at fixed voltage is not surprising. While experimental results are obtained with strip detectors, their scaling to pixel geometry will be discussed, and expected differences pointed out.

Speaker: Marko Mikuz (Jozef Stefan Institute (SI))

Slides Pixel2014-mm.pdf

70 The RD50 Activity in the Context of Future Pixel Detector Systems

The CERN/RD50 collaboration is dedicated to the radiation hardening of semiconductor sensors for future super-collider needs. It is therefore natural that the findings of our collaboration in this field are relevant to the pixel devices for the LHC experiment upgrades. A summary of the consistent amount of results on radiation tolerance enhancement of silicon sensors from RD50 will be presented. Moreover, the research towards radiation hardening has highlighted, and increased knowledge on properties of sensors that are relevant to other applications. For example radiation hardening relies on the speed of signal collection in irradiated devices. As a consequence, the methods envisaged for increasing this collection speed turn out to be promising for significantly enhancing the performance of time resolved, high spatial resolution systems. Another technology strongly emerging for future pixel sensor systems is HV-CMOS. RD50 results provide relevant information for this technology regarding the behaviour of the deep collecting electrode (deep n-well) for this type of devices after irradiation. Moreover, the methodology we have developed for the radiation tolerance studies could be a very good framework for comparing the new devices with the current state of the art.

Speaker: Gianluigi Casse (University of Liverpool (GB))

Slides Gcasse-Pixel2014.pptx

16:00 Coffee

71 3D Integration Technology for Pixel Detector and Image Sensor using 3-μmφ Au Cone Bump Junctions

Abstract A 3D IC is an effective solution for reducing the manufacturing costs of advanced 2D LSI while ensuring equivalent device performance and functionalities. This technology allows a new device architecture of stacked detectors/sensor devices with a small dead sensor area and facilitates hyper-parallel data processing. In pixel detectors or image sensor devices, many transistors are required to be accommodated per pixel area without increasing the pixel size. Consequently, many methods to realize 3D-LSI devices have been developed to meet this requirement by focusing on the unit processes of 3D-IC technology: (1) through-silicon via (TSV) formation and (2) bonding electrically and mechanically between tiers of the stack. The bonding process consists of several unit processes such as bump or metal contact formation, chip/wafer alignment, chip/wafer bonding, and underfill formation, and many combinations of the processes have been reported. Our research focuses on the bonding technology with the objective of realizing a versatile bonding technology for silicon LSI devices, compound semiconductor devices, and MEMS devices at temperatures less than 200 C for heterogeneous integration. The gold cone bump formed by the NpD (nanoparticle deposition) method is one of the promising candidates for this purpose. This paper presents the experimental results of the prototype pixel detector with 3-μmφ gold cone bump connections with adhesive injection. The as-deposited cone bump consists of gold nanoparticles and is easier to deform compared to plating gold. Consequently, the collapsibility of the gold cone bump allows for low-stress bonding, resulting in a compliant and reliable junction. The bump size is determined by photoresist patterning, and the bump connection does not protrude largely during junction formation, in contrast with the melting type bump connections. In addition, the shrink ratio of the volume is larger than that of the surface area. So the bump resistance of an easily oxidized metal with a diameter of few microns is affected by the bonding atmosphere. On the other hand, gold is an oxidation-resistive material; therefore, bonding with a micro gold cone bump does not adversely affect the electrical characteristics. Figure 1 shows a 3-μmφ gold cone bump array, while Figure 2 shows the bump resistance of the daisy chain TEG. The resistance per bump is approximately 6 Ω.

Speaker: Makoto Motoyoshi (Tohoku-MincroTec Co., Ltd (T-Micro))

Slides Sept.04_M.Motoyoshi_.pdf

72 2.5D and 3D Integrated Circuit Technology Capablilities and Industry Readiness

The term 3D integrated circuit covers a wide swath of technologies today. It can mean anything from chip stacking to interposers or “2.5D integration”, to TSV’d wafer stacking or even the latest bleeding edge technology push into monolithic 3D devices. No matter which type, with scaling’s advantages rapidly eroding, 3D integrated circuits appear to be gaining traction in the market. Most designers are cognizant of the numerous possible benefits that can be obtained from advanced 3D integration, including higher density, lower power, and better performance. Perhaps the biggest benefit that separates 3D integration from world of simply More Moore, comes from 3D heterogeneous integration. The fundamental ability offered by 3D integration to separate circuits for implementation in the best suited technology while maintaining thousands or even millions of sub-circuit to sub-circuit interconnects changes fundamental semiconductor capabilities. The market winners need not be only those who can afford new multi-billion dollar investments in next generation lithography and deeper sub-micron technologies. 3D has the potential for reshaping markets. Those who pick the right version or versions of 3D and figure out how to use this new technology can become tomorrow’s market leaders. There is no doubt 3D technology has shown promise, but it has also plagued early adopters with numerous issues including processing inconsistencies, lack of adequate design tools and most importantly the lack reasonable of a supply chain. The question to be addressed is 3D integration really ready or is it like the infamous EUV lithography technology which has been 2 years away from production for almost 30 years. The presentation will cover the available 2.5/3D processes and their capabilities, commercially available design tools and the current supply chain situation. The discussion will also review technical successes and failures and why, which, and how 2.5/3D is now ready industry adoption.

Speaker: Robert Patti (Tezzaron Semiconductor Corp.)

Slides Tezzaron_Presentation_Pixel_090414.pdf

73 New Concept For Forward Tracking In LHC Experiments

Extensive discussions are underway to refine the physics goals and scope of detector upgrades for the future LHC runs, following the Higgs boson discovery. New opportunities for improving performance of the ATLAS and CMS tracking detectors in the very forward region are of particular interest to future Higgs and other measurements, which are central to the ATLAS and CMS physics programs. We propose a new concept for Pixel detectors for very forward tracking in LHC experiments, which consists of two (or more) closely spaced Pixel layers placed very close to the beam line. This design relies on the fact that a length of the pixel cluster depends on the particle's incidence angle and can be used to determine particle's origin and angle respect to the beam-line. We will discuss how availability of this information from the very first pixel layer can be used to improve tracking performance.

Speaker: Aliaksandr Pranko (Lawrence Berkeley National Lab. (US))

Slides Pixel2014_Pranko_090414.pdf

Friday 5 September

Astrophysics and other Pixel Applications

Convener: Hans-Gunther Moser (Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut) (D)

74 Participant Information

Speaker: William Trischuk (University of Toronto (CA))

75 Sensors and Front-end Electronics for the LSST Camera

Over the next 5 years, the Large Synoptic Survey Telescope collaboration will construct a new 8m-class ground-based telescope and 3 Gpixel camera to perform an all-sky survey in the optical and near IR. Science themes of LSST include fundamental cosmology (testing the lambda-CDM paradigm and search for new physics), galactic astronomy (assembly history of the Milky Way), Solar System astronomy (asteroids and Kuiper belt objects), and optical transients. To accomplish these goals, focal plane components (sensors and front-end electronics) must satisfy stringent optical, mechanical, and electronic requirements. LSST's science focal plane incorporates 189 high resistivity, fully-depleted CCDs in a modular arrangement of 21 "raft towers". Each tower is an autonomous, fully-functional camera with complete control, signal processing, diagnostic, and housekeeping functions for 9 CCDs (144 video channels). The sensors, electronics, mechanical, and thermal management elements of the tower are housed in a rectangular enclosure roughly 13 x 13 x 23cm inside the vacuum cryostat. Thanks to the high degree of parallelism, frame readout time is 2s at a pixel rate of 550kpix/s. Video data has a noise floor of about 9 e-, a dynamic range of 86dB and channel-to-channel crosstalk below -62dB. Locating the FE electronics in vacuum necessitates a low power budget; during readout the tower electronics dissipates less than 50W (350mW/channel). We will review performance results from pre-production towers and describe the ongoing characterization and scale-up studies.

Speaker: Paul O'Connor (Department of Physics)

Slides OConnor_Detector_Development_for_LSST_PIXEL2014b.pptx

76 Performance and Qualification of CdTe Pixel Detectors for the Spectrometer/Telescope Imaging X-rays

The Spectrometer/Telescope Imaging X-rays (STIX) is a remote sensing instrument developed to perform X-ray imaging and spectroscopy of solar flares. The imaging is realized by a Fourier-imaging technique using tungsten grid collimators in front of CdTe pixel detectors. The detectors are used for an X-ray spectrometer unit based on the IDeF-X HD ASIC front-end to perform high resolution spectroscopy in the 4-150 keV energy range (< 1 keV @ 6 keV). 32 of such detector modules are mounted inside the Detector Electronics Module of the instrument. STIX will fly on-board the Solar Orbiter satellite to be launched in 2017. 1 mm thick Acrorad CdTe detectors with a plane Aluminum Schottky contact are used as basis for a subsequent patterning process into eight big (9.8 mm2) and four small (1 mm2) pixels. A guard ring is surrounding all twelve pixels. The anode patterning is done by means of microfabrication technologies. The cathode, a thin Platinum plane electrode operates as radiation entrance window. The size of the STIX CdTe pixel detectors is 10 x 10 x 1 mm3. Test equipment has been developed in collaboration with ETH for selecting the best detectors in terms of performance prior shipment to CEA and for qualification purposes. The vacuum setup allows serial dark current measurements pixel by pixel at low temperature. The knowledge of the pixel dark current is the most important parameter since currents higher 60 pA create excess noise in the ASIC. Best pixels show dark currents below 10 pA at -300V bias and -20°C. Spectroscopic measurements with Ba-133 sources confirm the detector operation. For the qualification model more than 60 CdTe pixel detectors have been processed, characterized, and partially delivered to CEA. We show in this paper the CdTe pixel detector performance meeting flight model requirements. Qualification measures including some results will be presented.

Speaker: Oliver Grimm (Eidgenoessische Tech. Hochschule Zuerich (CH))

Slides Talk-Pixel2014-Grimm.pdf

77 DAMIC: A Search for Dark Matter with CCDs

The DAMIC experiment uses high resistivity, fully depleted CCD's as detectors to search for dark matter particles. The low electronic readout noise (RMS ~2 electrons) of the CCD's make possible to reach a detection threshold below 50 eV of deposited energy by nuclear recoils in the silicon target. Owing to these characteristics, DAMIC has an unrivaled sensitivity to WIMPs with masses below 10 GeV. Early DAMIC runs demonstrated the high energy resolution, low energy threshold, and power for background characterizaction of CCDs, and also achieved the world's best cross-section limits on WIMPs with masses below 4 GeV. These results motivated the construction of DAMIC100, which will have a target mass of 100 grams of silicon and will be installed in SNOLAB during the Summer of 2014. This new detector will directly test the parameter space corresponding to the recent results obtained by CoGeNT and by CDMS-Si, which may be hinting at the presence of a low mass WIMP signal. In this talk we will discuss the challenges associated with the scale-up of the experiment, its current status, and the prospects for the first physics results after a one year run.

Speaker: Javier Tiffenberg (Fermi National Accelerator Lab. (US))

Slides pixel2014.pdf

10:40 Coffee

78 Astronomical Instrumentation for Dark Energy Using Superconductor Detectors (MKIDs)

Dark Energy, the driving force for the accelerated expansion of the Universe, has become one of the largest mysteries in our current understanding of Nature. There are several ongoing, and planned astronomical projects to map large scale structure and geometry of the Universe to investigate this. During this talk we will present the newly developed Microwave Kinetic Inductance Detectors, and discuss how they could play an important role in this scientific quest.

Speaker: Emily Macuk (Fermilab)

Slides Pixel_Conference_Presentation.pdf Pixel_Conference_Presentation.pptx

79 X-CSIT: a toolkit for simulating 2D pixel detectors

A new, modular toolkit for creating simulations of 2D X-ray pixel detectors, X-CSIT (X-ray Camera SImulation Toolkit), is being developed. The toolkit uses three sequential simulations of detector processes including photon interactions, electron charge cloud spreading with a high charge density plasma model and many electronic components used in detector readout. In addition, because of the wide variety in pixel detector design, X-CSIT has been designed as a modular platform so that existing functions can be modified or additional functionality added easily if the specific design of a detector demands it. X-CSIT is under development at UCL for European XFEL, and will be used to create simulations of the three bespoke 2D detectors at European XFEL, AGIPD, LPD and DSSC. These simulations and X-CSIT will be integrated into the European XFEL software framework, Karabo, and through that be available to users to aid with planning of experiments and analysis of data. In addition X-CSIT will be released standalone publicly for other users, collaborations and groups to create simulations of their own detectors.

Speaker: Ashley Joy (UCL)

Slides PIXEL_2014_XCSIT_Ashley_Joy.pdf

80 High Resolution Digital Flat-Panel X-ray Detector Based on Large Area CMOS Image Sensor for Mammography and Fluoroscopy

With the help of steady efforts to overcome the size limitations of CMOS image sensors, the development of high resolution flat-panel x-ray detectors based on CMOS technology have been greatly valued. Especially, CMOS active pixel sensors (APSs)-based detectors, which have low-noise, high-speed characteristics, are considered to be appropriate for mammography and fluoroscopy applications. This paper introduces a high resolution X-ray detector to acquire high quality images for real-time display. The high resolution x-ray detector consists of three components: the 12 x 12 (cm2) three-side-tileable CMOS images sensor integrating ADC, a control component, and a host program. The sensor comprises 1200 x 1200 pixels and column-parallel 14 bit digital output. The control component includes on FPGA-based controller to generate control signals for integrating ADC and to acquire and transmit high-resolution image data. This controller is designed to be optimized for a special structure of sensor, which has physically repeated pattern caused by stitching process. Also, it is able to deal with simple image data processing in real time. Lastly, the acquisition data transmit to the host program via Hi-speed USB 2.0 port. In the full-resolution mode, 1 frame data (2.5MB) can be deal within 33.3ms (30fps). In 2 x 2 binning mode, sensor provided, 1 frame data become a quarter of full-resolution data and transmit to end program within 16.7ms (60 fps). The experiment to evaluate the detector was conducted in two stages: the optical response and performances under the visible light conditions and then x-ray imaging analysis using scintillator. At first, with a visible light source at a wavelength of 550nm, we measured optical characteristics of the CMOS image sensor. Using Photon Transfer Curve (PTC), the performance parameters of the sensor including read noise, full well capacity, and dynamic range were evaluated under specific operating conditions. Also, temporal image characteristics such as Image lags were measured using a visible light source at the maximum frame rate. The parameters from this experiment should be highly regarded for the fluoroscopy and high-frame-rate applications. For the next step, we obtained the x-ray images by attaching on the active pixel area, which converts x-ray to visible light of wavelength 550nm. The x-ray source operating condition was operated at 75 kVp, 64 mA. Additionally, the spatial resolution of our x-ray detector system was evaluated by calculating MTF performances from images of the line pair set In this paper, we provide details on the architecture of the high resolution flat-panel x-ray detector and present the results of evaluation for characteristics.

Speaker: Chorong Kim (KERI)

Slides Pixel2014_crkim.pdf Pixel2014_crkim.pptx

81 Farewell

Speaker: Harris Kagan (O)

Slides Pixel2016.pdf Pixel2016.pptx

12:40 Pickup Boxed Lunches