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The Timepix2-based hybrid-pixel detector with a 500 μm thick silicon sensor was employed for fast-neutrons registration to be applied in neutron radiography of metallic printed circuit heat exchanger (PCHE). Two energies of neutrons were experimentally tested. The detection of 3.55 MeV neutrons from the deuteron–deuteron (DD) reaction was compared to 15.7 MeV neutrons from the deuteron–tritium (DT) neutron generator. In order to distinguish the signal induced by the registered neutrons from the accelerator background, filtration of the recorded particle spectral tracks was applied. The benefit of applying hydrogen-based converter layer for 3.55 MeV neutrons was observable. On the other hand, in the case of 15.7 MeV neutrons, the direct registration by interaction with the sensor Si significantly dominates the conversion.

The calibration process for a hybrid pixel detector designed for the High Energy Photon Source in China, called HEPS-BPIX, is presented in this article. The relationship between the energy and threshold is quantified for the threshold calibration based on a threshold scanning. For threshold trimming, a precise algorithm based on local digital to analog converter (LDAC) characteristics and a fast algorithm based on LDAC scanning are proposed in this article to study the performance of threshold digital to analog converters (DACs) that will be applied to pixels. The threshold dispersion was reduced from 46.28 mV without the algorithm to 6.78 mV with the precise algorithm, whereas it was 7.61 mV with the fast algorithm. For temperatures from 5 °C to 60 °C, the threshold dispersion of the precise algorithm varies in the range of 5.69 mV. In contrast, it is 33.21 mV with the fast algorithm, which can be recorrected to 1.49 mV. The measurement results show that the fast algorithm could obtain the applicable threshold dispersion for a silicon pixel module and took less time. In comparison, the precise algorithm could obtain better threshold dispersion but was time-consuming. The temperature dependence of the silicon pixel module noise was also studied to assess the detector working status. The minimum detectable energy threshold could be reduced to 0.83–4.36 keV at a temperature of 5 °C. [ABSTRACT FROM AUTHOR]

First measurements characterizing dosimetric properties of a dosimetry system designed for the purpose of active personal dosimetry for photons with mean energies from 12.4 to 1250 keV according to Physikalisch-Technische Bundesanstalt (PTB) requirements are presented. The system consists of three Dosepix detectors, which is a hybrid, pixelated, photon-counting X-ray detector. The energy and angular dependence of the normalized response and the coefficients of variation of the personal dose equivalents $H_{\mathrm{p}}{(10)}$ and $H_{\mathrm{p}}{(0.07)}$ are determined on an International Organization for Standardization (ISO) water slab phantom in continuous reference photon radiation fields according to ISO 4037-1 and ISO 4037-3. The energy response is presented for the narrow spectra N-15 to N-300 and the radiation qualities S-Cs and S-Co for angles of incidence of 0°, 30°, and ±60°. The highest deviation of the response from the reference response is found at N-60, −60° with 1.179 ± 0.007 (standard deviation) for $H_{\mathrm{p}}{(10)}$. The energy range of use for $H_{\mathrm{p}}{(10)}$ is expected to extend from 12.4 to 1250 keV. For the personal dose equivalent $H_{\mathrm{p}}{(0.07)}$ , the normalized response at ±60° is below the lower limit for N-15, N-20, and N-25. It results in an energy range of use from 24.6 to 1250 keV. The coefficient of variation increases with increasing photon energy and stays below 1% for all measurements. [ABSTRACT FROM AUTHOR]

Compared with X‐rays, electron diffraction faces a crucial challenge: dynamical electron scattering compromises structure solution and its effects can only be modelled in specific cases. Dynamical scattering can be reduced experimentally by decreasing crystal size but not without a penalty, as it also reduces the overall diffracted intensity. In this article it is shown that nanometre‐sized crystals from organic pharmaceuticals allow positional refinement of the hydrogen atoms, even whilst ignoring the effects of dynamical scattering during refinement. To boost the very weak diffraction data, a highly sensitive hybrid pixel detector was employed. A general likelihood‐based computational approach was also introduced for further reducing the adverse effects of dynamic scattering, which significantly improved model accuracy, even for protein crystal data at substantially lower resolution. Experimental and computational reduction of dynamical electron scattering allows for visualizing of individual hydrogen atoms. [ABSTRACT FROM AUTHOR]

Hybrid pixel direct electron detectors are gaining popularity in electron microscopy due to their excellent properties. Some commercial cameras based on this technology are relatively affordable which makes them attractive tools for experimentation especially in combination with an SEM setup. To support this, a detector characterization (Modulation Transfer Function, Detective Quantum Efficiency) of an Advacam Minipix and Advacam Advapix detector in the 15–30 keV range was made. In the current work we present images of Point Spread Function, plots of MTF/DQE curves and values of DQE(0) for these detectors. At low beam currents, the silicon detector layer behaviour should be dominant, which could make these findings transferable to any other available detector based on either Medipix2, Timepix or Timepix3 provided the same detector layer is used. • Timepix DED is excellent at 15–30 keV, PSF-MTF are near ideal, max DQE(0) is 60% • PSF-MTF degrade with e-beam energy increase, PSF-MTF improve with DED threshold rise • DQE values show a significant DQE reduction at increased detector threshold value • At 15keV beam energy both cameras show low DQE due to Al layer on top of sensor [ABSTRACT FROM AUTHOR]

Sensors for environmental radioactivity based on two novel setups using photodiodes, on the one hand, and an advanced tablet-based hybrid pixel detector, on the other hand, are presented. Measurements of four kinds of terrestrial and every-day radiation sources are carried out: Airborne radon, a mineral containing traces of uranium, edible potassium salt, and an old radium watch. These measurements permit comparisons between different types of ambient radioactive sources and enable environmental monitoring. Available data comprise discrimination between α - and β − -particles in an energy range of 33 keV to 8 MeV and under ambient air conditions. The diode-based sensor is particularly useful in portable applications since it is small and sturdy with little power consumption. It can be directly connected to a smartphone via the headset socket. For its development, the low-cost silicon positive-intrinsic-negative (PIN) diodes BPX61 and BPW34 have been characterised with capacitance versus voltage (C-V) curves. Physical detection limits for ionising radiation are discussed based on obtained depletion layer width: ( 50 ± 8 ) μ m at 8 V. The mobile and low-cost character of these sensors, as alternatives to Geiger counters or other advanced equipment, allows for a widespread use by individuals and citizen science groups for environmental and health protection purposes, or in educational settings. Source code and hardware design files are released under open source licenses with this publication.

Hybrid pixel detectors were developed to meet the requirements for tracking in the inner layers at the LHC experiments. With low input capacitance per channel (10–100 fF) it is relatively straightforward to design pulse processing readout electronics with input referred noise of ∼ 100 e-rms and pulse shaping times consistent with tagging of events to a single LHC bunch crossing providing clean ‘images’ of the ionising tracks generated. In the Medipix Collaborations the same concept has been adapted to provide practically noise hit free imaging in a wide range of applications. This paper reports on the development of three generations of readout ASICs. Two distinctive streams of development can be identified: the Medipix ASICs which integrate data from multiple hits on a pixel and provide the images in the form of frames and the Timepix ASICs who aim to send as much information about individual interactions as possible off-chip for further processing. One outstanding circumstance in the use of these devices has been their numerous successful applications, thanks to a large and active community of developers and users. That process has even permitted new developments for detectors for High Energy Physics. This paper reviews the ASICs themselves and details some of the many applications. [ABSTRACT FROM AUTHOR]

Three-dimensional nanometre-sized crystals of macromolecules currently resist structure elucidation by single-crystal X-ray crystallography. Here, a single nanocrystal with a diffracting volume of only 0.14 µm3, i.e. no more than 6 × 105 unit cells, provided sufficient information to determine the structure of a rare dimeric polymorph of hen egg-white lysozyme by electron crystallography. This is at least an order of magnitude smaller than was previously possible. The molecular-replacement solution, based on a monomeric polyalanine model, provided sufficient phasing power to show side-chain density, and automated model building was used to reconstruct the side chains. Diffraction data were acquired using the rotation method with parallel beam diffraction on a Titan Krios transmission electron microscope equipped with a novel in-house-designed 1024 × 1024 pixel Timepix hybrid pixel detector for low-dose diffraction data collection. Favourable detector characteristics include the ability to accurately discriminate single high-energy electrons from X-rays and count them, fast readout to finely sample reciprocal space and a high dynamic range. This work, together with other recent milestones, suggests that electron crystallography can provide an attractive alternative in determining biological structures. [ABSTRACT FROM AUTHOR]

With the remarkable progress of accelerator-based X-ray sources in terms of intensity and brightness, the investigation of structural dynamics from time-resolved X-ray diffraction methods is becoming widespread in chemistry, biochemistry and materials science applications. Diffraction patterns can now be measured down to the femtosecond time-scale using X-ray free electron lasers or table-top laser plasma X-ray sources. On the other hand, the recent developments in photon counting X-ray area detectors offer new opportunities for time-resolved crystallography. Taking advantage of the fast read-out, the internal stacking of recorded images, and the gating possibilities (electronic shutter) of the XPAD hybrid pixel detector, we implemented a laboratory X-ray diffractometer for time-resolved single-crystal X-ray diffraction after pulsed laser excitation, combined with transient optical absorption measurement. The experimental method and instrumental setup are described in detail, and validated using the photoinduced nitrosyl linkage isomerism of sodium nitroprusside, Na2[Fe(CN)5NO]·2H2O, as proof of principle. Light-induced Bragg intensity relative variations Δ I( hkl)/ I( hkl) of the order of 1%, due to the photoswitching of the NO ligand, could be detected with a 6 ms acquisition window. The capabilities of such a laboratory time-resolved experiment are critically evaluated. [ABSTRACT FROM AUTHOR]

The AGIPD (adaptive gain integrating pixel detector) detector is a high frame rate (4.5 MHz) and high dynamic range (up to 10 4 ·12.4 keV photons) detector with single photon resolution (down to 4 keV taking 5 σ as limit and lowest noise settings) developed for the European XFEL (XFEL.EU). This work is focused on the characterization of AGIPD1.0, which is the first full scale version of the chip. The chip is 64×64 pixels and each pixel has a size of 200×200 μm 2 . Each pixel can store up to 352 images at a rate of 4.5 MHz (corresponding to 220 ns). A detailed characterization of the AGIPD1.0 chip has been performed in order to assess the main performance of the ASIC in terms of gain, noise, speed and dynamic range. From the measurements presented in this paper a good uniformity of the gain, a noise around 320 e − (rms) in standard mode and around 240 e − (rms) in high gain mode has been measured. Furthermore a detailed discussion about the non-linear behavior after the gain switching is presented with both experimental results and simulations. [ABSTRACT FROM AUTHOR]

The Dosepix hybrid pixel detector was designed for dosimetry and radiation monitoring applications. It has three programmable modes of operation: photon counting mode, energy integration mode, and dosimetry mode. The dosimetry mode measures the energy of individual X-ray photons and automatically sorts events into pre-defined energy bins. The output is a histogram representing the measured X-ray energy spectrum, permitting a dose reconstruction that accounts for the attenuation of photons at each energy bin. This presents a potential radiation protection and dosimetry instrument in medical radiodiagnostic practices, including high flux systems such as computed tomography (CT). In this paper, we characterise the Dosepix chip by investigating the energy response and count rate capabilities when coupled to a 300 μm silicon sensor under high fluxes of monochromatic synchrotron radiation. Under nominal settings, the Dosepix detector can detect photons down to 3.5 keV, with an energy resolution of 16.5% FWHM for 8.5 keV photons and 8% FWHM for 40 keV photons. The chip can count up to 1.67 Mcps/mm 2 of 40 keV photons whilst maintaining linear counting behaviour. This count rate range can be further increased by changing the programmable operating settings of the detector, making it suitable for a range of photon dosimetry applications. [ABSTRACT FROM AUTHOR]

The new generation of X-ray detectors, the hybrid pixel area detectors or `pixel detectors', is based on direct detection and single-photon counting processes. A large linearity range, high dynamic and extremely low noise leading to an unprecedented high signal-to-noise ratio, fast readout time (high frame rates) and an electronic shutter are among their intrinsic characteristics which render them very attractive. First used on synchrotron beamlines, these detectors are also promising in the laboratory, in particular for pump-probe or quasi-static experiments and accurate electron density measurements, as explained in this paper. An original laboratory diffractometer made from a Nonius Mach3 goniometer equipped with an Incoatec Mo microsource and an XPAD pixel area detector has been developed at the CRM2 laboratory. Mo Kα accurate charge density quality data up to 1.21 Å−1 resolution have been collected on a sodium nitroprusside crystal using this home-made diffractometer. Data quality for charge density analysis based on multipolar modelling are discussed in this paper. Deformation electron densities are compared to those already published (based on data collected with CCD APEXII and CAD4 diffractometers). [ABSTRACT FROM AUTHOR]

A dedicated in-vacuum X-ray detector based on the hybrid pixel PILATUS 1M detector has been installed at the four-crystal monochromator beamline of the PTB at the electron storage ring BESSY II in Berlin, Germany. Owing to its windowless operation, the detector can be used in the entire photon energy range of the beamline from 10 keV down to 1.75 keV for small-angle X-ray scattering (SAXS) experiments and anomalous SAXS at absorption edges of light elements. The radiometric and geometric properties of the detector such as quantum efficiency, pixel pitch and module alignment have been determined with low uncertainties. The first grazing-incidence SAXS results demonstrate the superior resolution in momentum transfer achievable at low photon energies. [ABSTRACT FROM AUTHOR]

Abstract: The CSPAD-140k is a 140 kilopixel detector based on the Cornell-SLAC hybrid Pixel Array Detector (CSPAD) platform, developed around the CSPAD ASIC. Room temperature operation, 14bit on chip digitization with a purely digital data interface, and scaling modularity are some important characteristics that make this platform an effective choice for designing detector variants optimized for a range of experiments and applications. The CSPAD-140k has an active area of approximately 4×4cm2 and four ASICs, bundled in a small, inexpensive and easy-to-deploy package. Due to its versatility it has already been used successfully in several experiments at the CXI, XPP and XCS instruments at LCLS. This work also describes problems faced by scaling from a prototype system to a full size X-ray camera and presents the current status on the improvements achieved. [Copyright &y& Elsevier]

Abstract: The experiment will make use of cooled antiproton beams of unprecedented quality that will become available at the Facility for Antiproton and Ion Research in Darmstadt, featuring a 1.5–15GeV/c momentum range. The physics program includes measurements of hyperons produced at low energies, spectroscopy of charmonium and open-charm mesons. To handle the forward peaked particle distribution due to the Lorentz boost, the apparatus is arranged in an asymmetric layout around the interaction point. In particular the Micro Vertex Detector based on silicon devices will have a rather unusual geometry. The MVD features fast data readout, since the experiment is triggerless, particle identification over the full range of energies, limited material budget and good spatial and time resolution. The status of the MVD design is shown and the present prototypes are described. [Copyright &y& Elsevier]

The performance of a single-photon-counting hybrid pixel detector has been investigated at the Australian Synchrotron. Results are compared with the body of accepted analytical models previously validated with other detectors. Detector functionals are valuable for empirical calibration. It is shown that the matching of the detector dead-time with the temporal synchrotron source structure leads to substantial improvements in count rate and linearity of response. Standard implementations are linear up to ∼0.36 MHz pixel−1; the optimized linearity in this configuration has an extended range up to ∼0.71 MHz pixel−1; these are further correctable with a transfer function to ∼1.77 MHz pixel−1. This new approach has wide application both in high-accuracy fundamental experiments and in standard crystallographic X-ray fluorescence and other X-ray measurements. The explicit use of data variance (rather than N1/2 noise) and direct measures of goodness-of-fit (χ r2) are introduced, raising issues not encountered in previous literature for any detector, and suggesting that these inadequacies of models may apply to most detector types. Specifically, parametrization of models with non-physical values can lead to remarkable agreement for a range of count-rate, pulse-frequency and temporal structure. However, especially when the dead-time is near resonant with the temporal structure, limitations of these classical models become apparent. Further, a lack of agreement at extreme count rates was evident. [ABSTRACT FROM AUTHOR]

Abstract: We have performed measurements of an integrated circuit named PXD18k designed for hybrid pixel semiconductor detectors used in X-ray imaging applications. The PXD18k integrated circuit, fabricated in CMOS 180nm technology, has dimensions of 9.64mm×20mm and contains approximately 26 million transistors. The core of the IC is a matrix of 96×192 pixels with 100μm×100μm pixel size. Each pixel works in a single photon counting mode. A single pixel contains two charge sensitive amplifiers with Krummenacher feedback scheme, two shapers, two discriminators (with independent thresholds A and B) and two 16-bit ripple counters. The data are read out via eight low voltage differential signaling (LVDS) outputs with 100Mbps rate. The power consumption is dominated by analog blocks and it is about 23μW/pixel. The effective peaking time at the discriminator input is 30ns and is mainly determined by the time constants of the charge sensitive amplifier (CSA). The gain is equal to 42.5μV/e− and the equivalent noise charge is 168e− rms (with bump-bonded silicon pixel detector). Thanks to the use of trim DACs in each pixel, the effective threshold spread at the discriminator input is only 1.79mV. The dead time of the front end electronics for a standard setting is 172ns (paralyzable model). In the standard readout mode (when the data collection time is separated from the time necessary to readout data from the chip) the PXD18k IC works with two energy thresholds per pixel. The PXD18k can also be operated in the continuous readout mode (with a zero dead time) where one can select the number of bits readout from each pixel to optimize the PXD18k frame rate. For example, for reading out 16 bits/pixel the frame rate is 2.7kHz and for 4 bits/pixel it rises to 7.1kHz. [Copyright &y& Elsevier]

The article presents the analog integrating pixel array detector with in-pixel storage and temporal resolution for synchrotron time-resolved imaging. It confirms that analog integration minimizes count-rate limitations and in-pixel storage captures successive pulses. The fundamental tests of noise and linearity as well as high-speed laser measurements are also discussed.

Abstract: The new DSSC (DEPFET sensor with signal compression) detector system is being developed in order to fulfil the requirements of the future XFEL in Hamburg. The instrument will be able to record X-ray images with a maximum frame rate of 5MHz and to achieve a high dynamic range. The system is based on a silicon pixel sensor with a new designed non-linear-DEPFET as a central amplifier structure. The detector chip is bump-bonded to mixed signal readout ASICs that provide full parallel readout and temporary data storage. The signals coming from the detector are processed by an analog filter, immediately digitized by 8-ENOB ADCs and locally stored in a custom designed memory. The ASICs are designed in 130nm CMOS technology. During the time gap of 99ms of the XFEL machine, the digital data are sent off the focal plane to a DAQ electronics that acts as an interface to the back-end of the whole instrument. The pixel sensor has been designed so as to combine high energy resolution at low signal charge with high dynamic range. This has been motivated by the desire to be able to be sensitive to single low energy photons and, at the same time, to measure at other positions of the detector signals corresponding to up to 104 photons of 1keV. In order to fit this dynamic range into a reasonable output signal swing, achieving at the same time single photon resolution, a strongly non-linear characteristic is required. The new proposed DEPFET provides the required dynamic range compression at the sensor level, considerably facilitating the task of the electronics. At the same time the DEPFET charge handling capacitance is enormously increased with respect to standard DEPFETs. The sensor matrix will comprise pixels of hexagonal shape with a side-length of . The simultaneous implementation of the 5MHz frame rate, of the single low-energy photon resolution and of the high dynamic range goes beyond all the existing instruments and requires the development of new concepts and technologies. [Copyright &y& Elsevier]

Abstract: Adaptive Gain Integrating Pixel Detector (AGIPD) is currently under development for the European X-ray Free Electron Laser (XFEL). It is a hybrid pixel detector with a specifically developed readout chip bump bonded to a silicon sensor. The chip is being designed in IBM CMOS technology. This paper is focused on the readout chip design. The main challenges for this chip are: the high dynamic range with single photon sensitivity, the long storage chain with a long hold time (99ms), and the high radiation dose (up to 100MGy). A charge integrating amplifier with a gain adaptive to the number of incoming photons is combined with a correlated double sampling (CDS) buffer to achieve the required dynamic range and single photon sensitivity. Several techniques are implemented in the storage cell design in order to reduce leakage current and signal-dependent charge injection. Four prototype chips have been designed for testing the performance of the implemented switches, capacitors, amplifiers, storage cells and periphery circuitry. The recently submitted test chip has a 16×16 pixel matrix, 100 storage cells in each pixel and a periphery circuitry for accessing and controlling the pixels and storage cells. [ABSTRACT FROM AUTHOR]

Abstract: Single particle counting hybrid pixel detectors simultaneously provide low noise, high granularity and high readout speed and make it possible to build detector systems offering high spatial resolution paired with good energy resolution. A limiting factor for the spectroscopic performance of such detector systems is charge sharing between neighbouring pixels in the sensor part of the detector. The signal spectrum at the collection electrodes of the readout electronics deviates significantly from the photonic spectrum when planar segmented sensor geometries are used. The Medipix3 implements a novel, distributed signal processing architecture linking neighbouring pixels and aims at eliminating the spectral distortion produced in the sensor by charge sharing and at reducing the impact of fluorescence photons generated in the sensor itself. Preliminary results from the very first Medipix3 readouts bump bonded to Si sensor are presented. Material reconstruction is a possible future application of spectroscopic imaging detectors and an example of material reconstruction in small animal imaging is given. [ABSTRACT FROM AUTHOR]

We report on the design of a prototype IC called PX90 dedicated for readout of hybrid semiconductor detectors used for X-ray imaging applications. The PX90 has dimensions of 4 mm x 4 mm and was designed in CMOS 90 nm technology with 9 metal layers. The core of the IC is a matrix of 40 x 32 pixels with 100 µm x 100 µm pixel size. A 60 µm x 60 µm square passivation opening in each pixel allows connecting PX90 to a semiconductor detector using stud bump bonding technique. Each pixel contains two charge sensitive amplifiers with Krummenacher feedback scheme, two second stage amplifiers, two discriminators and two 16-bit ripple counters. The stages are DC-coupled and the front-end electronics uses a fully differential readout scheme. To minimize the effective threshold spread at the discriminators inputs, one 8-bit and one 7-bit trim DACs are used. The PX90 can operate in continuous readout mode and in readout mode separate from exposure. The readout of each pixel has some additional functionality, like compression mode or readout of only given number of bits from each pixel. The data are read out via a single LVDS output with 200 Mbps rate. The effective pulse shaping at the discriminator input is 27 ns and it is mainly determined by the time constants of the CSA. The measurements show an ENC of 204 e- rms without detector and 240 e- rms with stud bump bonded detector. The average gain is 28 µV/e- and the effective threshold variation (using trim DAC) is 1.8 mV rms on one sigma level. Each pixel contains about 1800 transistors and has a static power consumption of 47 µW for nominal bias condition. [ABSTRACT FROM AUTHOR]

A synchrotron beam has been used to investigate the radiation tolerance of a PILATUS II module. It has been demonstrated that radiation-induced threshold shifts become significant above 30 Mrad. Individual adjustment of pixel thresholds after irradiation enabled retention of standard behaviour in excess of 40 Mrad. This implies that a module can be continuously irradiated for in excess of 40 days at an individual pixel count rate of 106 counts s-1. [ABSTRACT FROM AUTHOR]

Pilatus is a silicon hybrid pixel detector system for detecting X-rays in single photon counting mode. The PILATUS II chip, fabricated in a radiation tolerant design with a standard 0.25 μm CMOS process, was used to construct multichip modules with a size of 84 x 34 mm² comprising 94'965 pixels. All calibrations and characterizations were carried out with monochromatic X-rays from a synchrotron source. In order to set any required threshold above the noise level between 2.14 keV and 22 keV the detector was calibrated with X-rays. An algorithm to adjust thresholds pixel-by-pixel and create trim files based on X-ray flat-field images was developed. The threshold dispersion was reduced from 343 eV to 36 eV by the means of trim files. An electronic noise of 447 eV has been measured. The PILATUS modules are suitable for various X-ray applications such as diffraction and imaging techniques. [ABSTRACT FROM AUTHOR]

PILATUS is a silicon hybrid pixel detector system, operating in single-photon-counting mode, that has been developed at the Paul Scherrer Institut for the needs of macromolecular crystallography at the Swiss Light Source (SLS). A calibrated PILATUS module has been characterized with monochromatic synchrotron radiation. The influence of charge sharing on the count rate and the overall energy resolution of the detector were investigated. The dead-time of the system was determined using the attenuated direct synchrotron beam. A single module detector was also tested in surface diffraction experiments at the SLS, whereby its performance regarding fluorescence suppression and saturation tolerance were evaluated, and have shown to greatly improve the sensitivity, reliability and speed of surface diffraction data acquisitionJ [ABSTRACT FROM AUTHOR]

Abstract: The Compact Muon Solenoid Experiment (CMS) will start taking data at the Large Hadron Collider (LHC) in 2007 with the largest silicon tracking detector ever built. The central components of this tracker consist of two forward/backward pixel disks on each side of the interaction region and three barrel pixel layers. The silicon pixel detector will be crucial to pattern recognition and track reconstruction in the hadronic collisions of CMS and will play a key role in the physics program of the LHC. During the 2007 pilot physics run of the LHC, CMS will run with a subset of the final detector to be installed in 2008. In this report, the final design and results from test beam runs and expected performance of the detector are given. The expected radiation tolerance and projected lifetime of the pixel detector will be discussed as well its impact on the physics program of CMS. [Copyright &y& Elsevier]

Abstract: The ATLAS experiment at the Large Hadron Collider will use a silicon pixel detector as the innermost part of its tracking system. The pixel detector is designed to operate with a 40MHz bunch crossing frequency, a high particle flux density and an unprecedentedly extreme radiation environment. The pixel detector will consist of 1744 modules for a total sensitive area of about and over 80 million read-out channels, arranged in three layers in the barrel part and three disks in the forward and backward parts. The main characteristics of the project are illustrated together with recent experimental results and construction experience. [Copyright &y& Elsevier]

Abstract: A 7-year project has been initiated to develop hybrid pixel detectors for medical radiography. Crystalline semiconductor will be bonded to a pixellated readout chip where individual integrated circuits process each event, transferring the position, energy and timing information to the data acquisition controller. Chips will be tiled to produce a large area detector, capable of energy dispersive photon counting at moderate spatial resolution. Preliminary results from studies examining the design features and operation of the device are presented. [Copyright &y& Elsevier]

Abstract: The ALICE Silicon Pixel Detector (SPD) forms the two innermost layers of the Inner Tracking System (ITS) of the ALICE experiment at LHC. The SPD is made of hybrid silicon pixel detectors with a total of readout cells. Device packaging and design of the detector were constrained by a maximum allowed module height of 2mm and an overall material budget limit of 1% per layer. The integration of the detector parts is currently carried out in order to allow installation in the experiment at the end of 2006. An overview of the production status of the individual components is presented as well as the integration activities. [Copyright &y& Elsevier]

Abstract: The ALICE Silicon Pixel Detector consists of two barrel layers of hybrid silicon pixel detectors. In total pixel cells with will provide precision tracking information in the high multiplicity environment expected in heavy ion collisions. This paper gives an overview of the system, its components and the test procedures that have been developed. [Copyright &y& Elsevier]

Abstract: The Silicon Pixel Detector (SPD) comprises the two innermost layers of the ALICE Inner Tracker System (ITS). The SPD is based on hybrid pixels and is designed to provide precise position determination in the high track density region close to the interaction point. The SPD consists of pixel cells of dimensions . Each of the 1200 chips contains a matrix of 8192 pixel cells. A test system has been developed based on a 1060nm diode laser in order to study single assemblies with an opening in the aluminum back side contact of the sensor. The test system has been used to investigate the charge sharing in adjacent pixels. The results are compared with those from recent measurements in high-energy particle beams. [Copyright &y& Elsevier]

Abstract: The ALICE Silicon Pixel Detector (SPD) forms the two innermost layers of the Inner Tracking System (ITS) of the ALICE experiment at LHC. The SPD is made of hybrid silicon pixel detectors with a total of readout cells. The total material budget per layer is limited to less than 1% . The space and material budget constraints had strict implications on the design of the detector and the device packaging. An overview of the individual components of the SPD is presented as well as the status of production. [Copyright &y& Elsevier]

The PILATUS 1M detector is a hybrid pixel array detector with over one million pixels that operate in single photon counting mode. The detector, designed for macromolecular crystallography, is the largest pixel array detector currently in use at a synchrotron. It is a modular system consisting of 18 multichip modules covering an area of 21 cm × 24 cm. The design of the components as well as the manufacturing of the detector including the bump-bonding was performed at the Paul Scherrer Institute (PSI). The use of a single photon counting detector for protein crystallography requires detailed studies of the charge collection properties of the silicon sensor. The 18 modules are read out in parallel, leading to a full frame readout-time of 6.7 ms. This allows crystallographic data to be acquired in fine-ϕ-slicing mode with continuous rotation of the sample. The detector was tested in several experiments at the protein crystallography beamline X06SA at the Swiss Light Source at PSI. Data were collected both in conventional oscillation mode using the shutter, as well as in a fine-ϕ-slicing mode. After applying all the necessary corrections to data from a thaumatin crystal, the processing of the conventional data led to satisfactory merging R-factors of the order of 8.5%. This allows, for the first time, determination of a refined electron density map of a macromolecular biological crystal using a silicon pixel detector. [ABSTRACT FROM AUTHOR]

Abstract: The ALICE SPD (Silicon Pixel Detector) forms the two innermost layers of the Inner Tracking System (ITS) of the ALICE experiment at LHC. After several years of development the production of the modules is starting. The present article provides an overview of the different elements that will be used in the SPD with special emphasis given to testing of wafers and bump-bonded ladders. [Copyright &y& Elsevier]

Abstract: A simulation tool has been developed for the analysis of the performance of an X-ray imaging hybrid pixel detector. The photon transport and charge collection were simulated with the aid of the Monte Carlo based code GEANT and the readout signal processing was simulated in a program written in the LabView programming environment. Results of the spatial frequency-dependent detective quantum efficiency are presented and the influence of charge sharing, the threshold settings, level of exposure, the noise sources on the detector performance are studied. The detector was found to operate quantum limited down to an exposure of 0.08μGy, below which it is limited by the readout noise. The threshold setting has a strong influence on both the efficiency and the spatial resolution due to charge sharing, and a compromise between the two is necessary. The optimized threshold value corresponds to half of the mean energy of the input spectrum. [Copyright &y& Elsevier]

Linear systems theory is used for the numerical assessment of the detective quantum efficiency (DQE) of the hybrid semiconductor pixel detector DIXI. The Monte Carlo based code GEANT is used to simulate the photon transport in the sensor, charge transport modeling is treated analytically and the readout chip is simulated using PSPICE. The DQE for two differently shaped X-ray spectra of the same quality and for different operational conditions of the readout chip regarding the discrimination level are computed in order to validate the model. The model described in this paper can be adopted for optimizing the detector. [ABSTRACT FROM AUTHOR]

The CMS experiment will operate at the Large Hadron Collider (LHC). A hybrid pixel detector located close to the interaction region of the colliding beams will provide high resolution tracking and vertex identification which will be crucial for b quark identification. Because of the radiation environment of the LHC, the performance of the sensors must be carefully evaluated up to a fluence of 6×1014 neq cm−2. We expect that the sensors will be operated partially depleted during their operation at the LHC and we have implemented an n+ on n sensor design. We have irradiated prototype sensors to a dose of 1×1015 neq cm−2. We present the results of our testing before and after irradiation. [Copyright &y& Elsevier]

System prototyping of the ALICE silicon pixel detector (SPD) is well underway. The ALICE SPD consists of two barrel layers with 9.83 million channels in total. These are read out by the ALICE1LHCb pixel chip, which has been developed in a commercial 0.25 μm process with radiation hardening by design layout. The readout chip contains 8192 pixel cells each with a fast analog preamplifier and shaper followed by a discriminator and digital delay lines. Test results show a pixel cell noise of about 110 electrons rms and a mean minimum threshold of about 1000 electrons rms before threshold fine tuning. Several readout chips have been flip-chip bonded to detectors using two different bump-bonding techniques (solder, indium). Results of radioactive source measurements of these assemblies are presented for 90Sr and 55Fe sources. Several chip-detector assemblies have been tested in a 150 GeV/c pion beam at CERN where an online efficiency of about 99% across a wide range of detector bias and threshold settings was observed. All preliminary investigations confirm the functionality of the chip and the chip-detector assemblies for the ALICE experiment. [Copyright &y& Elsevier]

A photon-counting hybrid pixel detector (Medipix-1) has been characterized using a synchrotron X-ray source. The detector consists of a readout ASIC with 64×64 independent photon-counting cells of 170×170 μm2 pitch, bump-bonded to a 300 μm thick silicon sensor, read out by a PCIbus-based electronics, and a graphical user interface (GUI) software. The intensity and the energy tunability of the X-ray source allow characterization of the detector in the time, space, and energy domains. The system can be read out on external trigger at a frame rate of 100 Hz with 3 ms exposure time per frame. The detector response is tested up to more than 7×105 detected events/pixel/s. The point-spread response shows <2% crosstalk between neighboring pixels. Fine scanning of the detector surface with a 10 μm beam reveals no loss in sensitivity between adjacent pixels as could result from charge sharing in the silicon sensor. Photons down to 6 keV can be detected after equalization of the thresholds of individual pixels. The obtained results demonstrate the advantages of photon-counting hybrid pixel detectors and particularly of the Medipix-1 chip for a wide range of X-ray imaging applications, including those using synchrotron X-ray beams. [Copyright &y& Elsevier]