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The results of electrical characterisation and X-ray detection measurements of two different active area (0.06 mm 2 and 0.5 mm 2 ) commercial 4H-SiC Schottky photodiodes at room temperature are reported. The devices exhibited low dark currents (less than 10 pA) even at a high electric field strengths (403 kV/cm for 0.06 mm 2 diodes; 227 kV/cm for 0.5 mm 2 diodes). The results of the X-ray measurements indicate that the diodes can be used as photon counting spectroscopic X-ray detectors with modest energy resolutions: FWHM at 5.9 keV of 1.8 keV and 3.3 keV, for the 0.06 mm 2 and 0.5 mm 2 devices, respectively. Noise analysis of the photodiodes coupled to a custom low noise charge sensitive preamplifier is also presented. [ABSTRACT FROM AUTHOR]

A second generation of the Rapid readout electronics has been designed, built and commissioned at Daresbury Laboratory. The first application is for a 1D small- and wide-angle scattering X-ray detection system on the new multipole wiggler 6.2 beam-line at the SRS. The ADC per channel system interpolates and yields typically 32 pixels per channel. The wide-angle detector uses 128 channels of electronics to produce 4096 pixels with a FWHM of four pixels, i.e. demonstrates an ability to resolve 1024 peaks across the detector. This corresponds to an FWHM of 400 μm over a 384 mm long (60°) curved detector. A second group of 128 channels instrument the 200-mm-radius quadrant detector for simultaneous small-angle scattering measurements. System rate of over 2×107 events/s for each detector is predicted. A description of the new pipelined digital processing of detected events is given, together with initial beam-line test results. [Copyright &y& Elsevier]

Abstract: A soft X-ray scintillator phosphor (Gd2O2S:Pr) has been synthesised which is composed of discrete crystals of 120×150nm average size. This material has been deposited onto a transparent substrate so that it can be used to detect X-rays generated by a laser generated plasma. A photodiode has then been used to quantify the intensity of emission by the phosphor slide. This nano-crystalline Gd2O2S:Pr phosphor shows greatly enhanced signal over a commercially available phosphor with larger particle size. [Copyright &y& Elsevier]

Abstract: We report on the detection of hard X-rays using a GaP Schottky diode at the HASYLAB synchrotron radiation research facility. Exposure to alpha particles from an 214Am source showed that the device was spectroscopic at room temperature with a FWHM energy resolution of 3.5% at 5.5MeV. It was also found to be responsive to X-rays in the range 11–100keV. Although individual energies are not spectrally resolved there is a proportionality of response to increasing X-ray energy. A two-dimensional scan of the sensitive area using a 30×30μm2 30keV pencil beam showed the spatial response of the detector to be uniform at the few percent level, consistent with statistics. [Copyright &y& Elsevier]

We report on the performance of a micro-hole and strip plate, fabricated with standard gas electron multiplier-production procedures, presenting 40-μm hole-diameter and 30-μm wide anode strips. Multiplication factors of 5×104 were reached in an Ar/Xe (95/5) atmosphere at about 1 bar; the energy resolution is of the order of 14% (FWHM) for 5.9-keV X-rays. [Copyright &y& Elsevier]

This study describes development work in which systematic changes in the pitch of the electrode pattern of a Microstrip Gas Counter (MSGC) are explored in the search for higher gas gains and enhanced stability. We investigated the gas gain, soft X-ray energy resolution and the detector noise with pitch values set between 300 μm and 1200 μm. With the cathode width set to half of the pitch and anode width at 5 μm, gas gains exceeding 50,000 were comfortably achieved. We present the optimised MSGC geometry which permits radiation detection in the sub-keV X-ray region. [Copyright &y& Elsevier]

The function of the radiation monitoring system Radiation Monitoring System Applicable to Fusion Experiments (RMSAFE) is well verified to detect burst radiation, that is, radiation generated suddenly and explosively. When an increase in 50 ms integrated count from a radiation monitor, which is recorded and updated every 10 ms in the system CPU, is encountered to exceed a pre-set level, RMSAFE recognizes it as an outbreak of burst radiation and alters its recording mode so that the burst event data is saved in a specified file. In this study, we detected X-rays arising from Compact Helical System (CHS), a high-temperature plasma experimental device, in order to verify that RMSAFE is able to detect radiation bursts successfully and accurately. Increases in the dose of radiation due to X-rays from CHS were observed concurrently at various observation points in several plasma shots. The weekly accumulated values of radiation dose observed by RMSAFE in the CHS torus hall were consistent with the results of integrated dose measurements by thermoluminescent dosimeter (TLD) and by radiophotoluminescent dosimeter (RPLD), and furthermore, the general decreasing tendency of the observed dose with the distance from the CHS torus was clearly seen, though detailed radiation patterns might be dependent on source plasma and other conditions. These results support our conclusion that RMSAFE is able to successfully detect burst X-rays. [Copyright &y& Elsevier]

We have studied the current–voltage and capacitance–voltage characteristics of p/i/n structures made on non-intentionally doped epitaxial GaAs layers grown by the chemical reaction method. Deep level transient spectroscopy demonstrates that these layers contain a low defect concentration. X-ray photoconductivity shows that the diffusion length is large. The homogeneity of the properties of these layers, which has been evaluated over large area (cm2), is confirmed by photoluminescence mapping. [Copyright &y& Elsevier]

Abstract: We report on preliminary alpha particle and X-ray measurements on a number of prototype GaN PIN diodes. The aim of the study was to investigate the potential use of GAN based radiation detectors for radiation hard, high temperature, solar blind space applications. The devices have a planar structure consisting of a 2μm epitaxial GaN layer grown on a highly doped n-type Al x Ga1−x N nucleation layer, which in turn is deposited on a p-type 4H–SiC substrate. Au ohmic contacts were applied to the top of the GaN layer and the bottom of the substrate. A number of different sized devices were tested with contact diameters ranging from 0.4mm to 0.7mm. All devices showed good diode behaviour with reverse leakage currents in the tens to hundreds of micro-amp range. C–V measurements showed that the GaN layers were fully depleted for biases >20V. When exposed to a 5.5MeV alpha particle source, the devices showed a spectroscopic response with energy resolutions of ∼25% FWHM at room temperature (RT) and 10V bias and 20% FWHM at −50°C. These values are consistent with the previous measurements. No response to 60keV photons could be measured. [Copyright &y& Elsevier]

Abstract: A set of double-sided 3D silicon detectors have been fabricated, bump bonded to single-photon-counting Medipix2 readout chips, and tested using X-ray sources. When tested with monochromatic X-rays, the 3D detectors show reduced charge sharing compared with standard planar pixel detectors [Copyright &y& Elsevier]

State-of-the art X-ray imaging cameras using silicon sensors for X-ray detection have demonstrated a frame-rate of 10 MHz and excellent performance for X-ray energies below 20 keV. We proposed a pixelated ultrafast inorganic scintillator-based front imager for GHz hard X-ray imaging. The proposed imager is featured with a total absorption for hard X-ray photons, and provides sub-ns scintillation pulse width crucial for X-ray bunches of a few ns spacing foreseen at the proposed MaRIE facility. We measured temporal response of a dozen ultrafast and fast inorganic scintillators at the 10-ID-B site of the Advanced Photon Source (APS) of ANL. Crystal's response to hybrid X-ray beam of 30 keV, consisting of singlet bunches of 50 ps width and septuplet bunches of 27 ps width with 2.83 ns bunch spacing, was measured. Ultrafast inorganic scintillators, such as BaF 2 :Y and ZnO:Ga, show clearly resolved X-ray bunches for septuplets, as well as no degradation of amplitude for continuous eight septuplets, providing a proof of principle for the ultrafast inorganic scintillator-based total absorption front imager for the proposed MaRIE project. [ABSTRACT FROM AUTHOR]

Organometal halide perovskites have proven to be potential materials for X-ray detection due to their great photoelectric properties, high radiation attenuation and low-cost preparation. However, ion migration is one of the obstacles for its applications, especially, ion migration via surface is much easier in single crystal materials than bulk diffusion which could significantly degrade the device performances. In this paper, the KCl passivation layer is prepared by the thermal evaporation method and inserted between crystal and electrode The trap density and μ τ product of pristine and KCl passivated MAPbI 3 devices are compared, and the results demonstrate KCl as a passivation layer can effectively passivate the surface traps and improve electrical performance. The KCl passivated MAPbI 3 detector exhibits a high X-ray sensitivity of 3700 μ C Gy air − 1 cm −2 under −20 V bias. [ABSTRACT FROM AUTHOR]

Recently, halide hybrid perovskites have emerged as an attractive material for radiation detection due to their high atomic numbers and resistivity, large μ τ product (μ is the carrier mobility; τ is the carrier lifetime). However, the sensitivity and stability of perovskite X-ray detectors were limited by ion migration in the perovskites. In this paper, the guanidinium ionic (Gua +) doped MAPbI 3 single crystals were successfully obtained with the solution-processed method. (Gua) 0.06 (MA) 0.94 PbI 3 single crystal shows an activation energy of 589 meV. The X-ray detector with Au/(Gua) 0.06 (MA) 0.94 PbI 3 /Ga structural exhibited a high X-ray sensitivity of 2903 μ C Gy air − 1 cm−2 and a low limit of detection of 7.2 nGy air s − 1. This work shows that a certain amount of Gua + doping into MAPbI 3 could inhibit the ion migration, and significantly improve the X-ray detection performance. [ABSTRACT FROM AUTHOR]

Abstract: Pixel sensors have been calibrated using both fluorescence X-ray photons and an X-ray beam obtained by the transmission technique. The X-rays were generated by an Amptek EDIX 40 X-ray tube (maximum voltage 40kV). During the fluorescence calibration the pixel sensor was placed in front of the target in an off-beam position; the resulting photons hitting the detector were emitted by fluorescence in all directions with an energy which is typical of the fluorescence lines of the target material. During the calibration in the transmission mode the detector was placed behind the target, acting now as a filter, and the energy of the photons was tuned by adjusting the voltage of the tube and the thickness of the target. In this paper the comparison between the two methods will be shown. From the results of this test, it is possible to infer that transmission is more efficient (higher photon yield) and flexible (more energy points are possible) but produces broader spectral lines while fluorescence has a better energy definition. A reasonable strategy to benefit from both methods is using fluorescence to calibrate a spectrometer that will be used to evaluate the energy of the X-rays emitted in the transmission mode. The results of this calibration will be shown in this paper. [Copyright &y& Elsevier]

In this paper, we present a multi-voltage threshold (MVT) digitizer using a time-varied threshold and investigate the feasibility of using this digitizer to develop the data acquisition system for photon-counting X-ray security inspection imaging. This digitizer compares the scintillation pulse with a preset time-varied voltage signal and records the time information of the intersections. As the amplitude of the threshold varies as a function of time, the voltage values of the intersections could be calculated using the recorded time, and the energy information could be extracted via the acquired time–voltage samples. Unlike the constant voltage thresholds MVT digitizer requiring multiple voltage comparators, this method needs only one voltage comparator, which notably reduces the complexity in configuration. We demonstrate the development of such an MVT digitizer using a sine signal threshold and evaluate its energy performance with a yttrium orthosilicate (YSO) scintillator and Silicon Photomultiplier (SiPM) detector (designed for X-ray detection). The digitizer obtains energy resolutions of 41.4%, 26.6%, and 25.5% at 30, 59.5, and 80.9 keV, respectively. For comparison, the YSO/SiPM detector is also evaluated with a high-speed oscilloscope, and measured energy resolutions are 40.6%, 26.5%, and 25.1% at 30, 59.5, and 80.9 keV, respectively. These results indicate that the proposed MVT digitizer using a time-varied threshold is a promising method for developing a YSO/SiPM-based photon-counting X-ray detector. [ABSTRACT FROM AUTHOR]

The development of nanoscale X-ray sensors is of crucial importance to achieve higher spatial resolution in many X-ray-based techniques playing a key role in materials science, healthcare, and security. Here, we demonstrate X-ray detection using individual CdS, SnO 2 , and ZnO nanowires (NWs). The NWs were produced via vapor–liquid–solid technique and characterized using X-ray diffraction, scanning, and transmission electron microscopy. Electrical measurements were performed under ambient conditions while exposing two-terminal NW-based devices to X-rays generated by a conventional tungsten anode X-ray tube. Fast and stable nanoampere-range X-ray beam induced current (XBIC) in response to X-ray illumination was observed. The high XBIC measured in the NW devices could be attributed to the efficient transport and collection of generated charge carriers due to the single-crystalline nature of NWs and the short NW length. Such fast-response and high-sensitivity nanoscale X-ray detectors can find applications in sub-micron resolution imaging and nanofocused beam shape measurements. [Display omitted] • Vapor–liquid–solid synthesis of single-crystalline CdS, SnO 2 and ZnO nanowires. • Individual nanowire two-terminal devices were exposed to X-rays. • Fast and stable nanoampere-range X-ray beam induced current was observed. [ABSTRACT FROM AUTHOR]

The CRYSTAL EYE detector is proposed as a space-based X and gamma ray all-sky monitor to be active from 10 keV up to 30 MeV. In its full scale configuration, it consists in a 40 cm diameter hemisphere, made by 112 pixels, with an overall weight lower than 50 kg, wide Field Of View (FOV, about 6 sr), full sky coverage and very large effective area (about 6 times higher than Fermi-GBM at 1 MeV) in the energy range of interest. Each pixel consists of two layers of scintillating LYSO crystals, read out by arrays of Silicon PhotoMultipliers (SiPMs), equipped with a segmented anticoincidence detector for charged Cosmic Ray (CR) identification and hard X-ray detection. The primary scientific goals include the observation of transient X and gamma flashes from Gamma Ray Bursts (GRBs), Gravitational Wave (GW) follow up, Supernovae (SN) explosions, etc. and stable gamma-ray source observation in the MeV energy range. The pioneering design optimizes these observations in terms of localization of the source and timing. By using specific triggers for charged particles, solar flares and space weather phenomena could also be studied. A pathfinder mission is foreseen onboard of the Space Rider vehicle run by European Space Agency (ESA), allowing technology tests, qualification and both deep space and Earth observation during the mission. We here present the CRYSTAL EYE technology. [ABSTRACT FROM AUTHOR]

XRPIX is the monolithic X-ray SOI (silicon-on-insulator) pixel detector, which has a time resolution better than 10 μ s as well as a high detection efficiency for X-rays above 10 keV. XRPIX is planned to be installed on future X-ray satellites. To mount on satellites, it is essential that the ADC (analog-to-digital converter) be implemented on the detector because such peripheral circuits must be as compact as possible to achieve a large imaging area in the limited space in satellites. Thus, we developed a new XRPIX device with the on-chip ADC, and evaluated its performances. As the results, the integral non-linearity was evaluated to be 6 LSB (least significant bit), equivalent to 36 eV. The differential non-linearity was less than 0.7 LSB, and input noise from the on-chip ADC was 5 e −. Also, we evaluated end-to-end performance including the sensor part as well as the on-chip ADC. As the results, energy resolution at 5.9 keV was 294 ± 4 eV in full-width at half maximum for the best pixel. [ABSTRACT FROM AUTHOR]

Abstract: We report on the characterization of four Teledyne Imaging Systems HAWAII Hybrid Si CMOS detectors designed for X-ray detection. Three H1RG detectors were studied along with a specially configured H2RG. Read noise measurements were performed, with the lowest result being 7.1e− RMS. Interpixel capacitive crosstalk (IPC) was measured for the three H1RGs and for the H2RG. The H1RGs had IPC upper limits of 4.0–5.5% (up & down pixels) and 8.7–9.7% (left & right pixels), indicating a clear asymmetry. Energy resolution is reported for two X-ray lines, 1.5 & 5.9keV, at multiple temperatures between 150 and 210K. The best resolution measured at 5.9keV was 250eV (4.2%) at 150K, with IPC contributing significantly to this measured energy distribution. The H2RG, with a unique configuration designed to decrease the capacitive coupling between ROIC pixels, had an IPC of 1.8±1.0% indicating a dramatic improvement in IPC with no measurable asymmetry. We also measured dark current as a function of temperature for each detector. For the detector with the lowest dark current, at 150K, we measured a dark current of 0.020±0.001 (e− s−1 pixel−1). There is also a consistent break in the fit to the dark current data for each detector. Above 180K, all the data can be fit by the product of a power law in temperature and an exponential. Below 180K the dark current decreases more slowly; a shallow power law or constant must be added to each fit, indicating a different form of dark current is dominant in this temperature regime. Dark current figures of merit at 293K are estimated from the fit for each detector. [Copyright &y& Elsevier]

Abstract: In this paper we discuss two novel methods of measuring afterglow in scintillators. One method is designed for X-ray detection and the other for neutron detection applications. In the first method a commercial fan-beam scanner of basic design similar to those seen at airports is used to deliver a typically 12ms long X-ray pulse to a scintillator by passing the test equipment through the scanner on the conveyor belt. In the second method the thermal neutron beam from a research reactor is incident on the scintillator. The beam is cut-off in about 1ms using a 10B impregnated aluminum pneumatic shutter, and the afterglow is recorded on a dual range storage oscilloscope to capture both the steady state intensity and the weak decay. We describe these measurement methods and the results obtained for a range of developmental ceramic and glass scintillators, as well as some standard scintillators such as NaI(Tl), LiI(Eu) and the plastic scintillator NE102A. Preliminary modeling of the afterglow is presented. [Copyright &y& Elsevier]

Abstract: The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 ×32 pixels covering about 1cm2 active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4×4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed. [ABSTRACT FROM AUTHOR]

Abstract: We first briefly review the performances for X-ray detection which are obtained using thin epitaxial GaAs layers. We then show that good detectors can be realized on thick and large area epitaxial GaAs layers which are now available, making them suitable for X-ray imaging. We finally discuss the main limitation imposed by the epitaxial nature of this new material and ways to overcome it. [Copyright &y& Elsevier]

Abstract: The aim of this study was to examine Y3Al5O12:Ce (also known as YAG:Ce) powder scintillator under X-ray imaging conditions. This material shows a very fast scintillation decay time and it has never been used in X-ray medical imaging. In the present study various scintillator layers (screens) with coating thickness ranging from 13 to 166mg/cm2 were prepared in our laboratory by sedimentation of Y3Al5O12: Ce powder. Optical emission spectra and light emission efficiency (spectrum area over X-ray exposure) of the layers were measured under X-ray excitation using X-ray tube voltages (80–120kVp) often employed in general medical radiography and fluoroscopy. Spectral compatibility with various optical photon detectors (photodiodes, photocathodes, charge coupled devices, films) and intrinsic conversion efficiency values were determined using emission spectrum data. In addition, parameters related to X-ray detection, energy absorption efficiency and K-fluorescence characteristic emission were calculated. A theoretical model describing radiation and light transfer through scattering media was used to fit experimental data. Intrinsic conversion efficiency and light attenuation coefficients were derived through this fitting. Y3Al5O12:Ce showed peak emission in the wavelength range 530–550nm. The light emission efficiency was found to be maximum for the 107mg/cm2 layer. Due to its “green” emission spectrum, Y3Al5O12:Ce showed excellent compatibility (of the order of 0.9) with the sensitivity of many currently used photodetectors. Taking into account its very fast response Y3Al5O12:Ce could be considered for application in X-ray imaging especially in various digital detectors. [Copyright &y& Elsevier]

We have investigated at optimal temperature the X-ray detection characteristics of two TlBr crystals by the Traveling Molten Zone (TMZ) technique. The resistivities were typically 1.5×1010 Ω cm at room temperature, increasing to (1.1–1.7)×1012 Ω cm at −15°C. In the temperature range −0°C to −50°C, both crystals exhibited mobility-lifetime products of ∼8×10−5 cm2V−1 and ∼1.5×10−5 cm2V−1, for electrons and holes respectively. From these crystals, two detectors were packaged and X-ray metrology carried out. For the best detector, the measured energy resolutions at an operating temperature of −15°C and 500 V bias were 1.0 keV at 5.9 keV; 1.1 at 13.9 keV; 2.5 at 59.54 keV; 3.3 keV at 88 keV; 4 keV at 122 keV and 27.7 keV at 662 keV.A comparative analysis of the characteristics of detectors grown by TMZ to those grown by the Bridgeman–Stockbarger method is given. [Copyright &y& Elsevier]

Systematic measurements of the energy resolution available from a Micro-Strip Gas Counter (MSGC) are presented. The effect of factors such as bias potential, gas filling and strip geometry on the energy resolution are examined in detail and related to a simple model. The geometry of the MSGC is adapted to permit “wall-less” detection of X-rays and this results in useful improvements in the pulse height spectra. [Copyright &y& Elsevier]

Semiconductor sensors based on the rad-optic effect enable ultra-fast detection of X-rays and play an important role in fusion diagnostics. Obtaining the responsivity of the semiconductor ultrafast response material is an important part of characterization. In this work, the refractive index change mechanism of the semiconductor under X-ray irradiation was analyzed, and the quantitative relationship between the diffraction efficiency and the X-ray photon energy was established through the LT-AlGaAs diffraction imaging experiments. The impulse responses of LT-AlGaAs under 1 keV–10 keV X-ray radiation were calculated, revealing the variation of responsivity with radiated photon energy. Imaging experiments of LT-AlGaAs were performed by bombarding an Al target to generate 1.5 keV X-rays. The diffraction images were obtained in agreement with the simulations. The responsivity of the semiconductor chip increases with the square of the incident X-ray power density. This study provides meaningful analyses for the development of ultra-fast X-ray imaging systems based on the rad-optic effect. [ABSTRACT FROM AUTHOR]

To obtain both a high count rate of >10 7 s −1 and a detection efficiency sufficient for high-energy X-rays of >30 keV, we propose a scintillation timing detector using a proportional-mode silicon avalanche photodiode (Si-APD) for synchrotron radiation nuclear resonant scattering. We here present results obtained with a prototype detector using a lead-loaded plastic scintillator (EJ-256) mounted on a proportional-mode Si-APD (active area size: 3 mm in diameter). The detector was operated at ‒35 °C for a better signal-to-noise ratio. Using synchrotron X-rays of 67.41 keV, which is the same energy as the first excited level of 61 Ni, we successfully measured pulse-height and time spectra of the scintillation light. A good time resolution of 0.50±0.06 ns (full width at half-maximum) was obtained for 67.41 keV X-rays with a scintillator 3 mm in diameter and 2 mm thick. [ABSTRACT FROM AUTHOR]

Abstract: The properties of a novel X-ray diffraction (XRD) technique having very low sensitivity to the sample morphology were previously elucidated through theoretical considerations and model simulations (Hansford, 2011 [1]). This technique opens up the possibility of mineralogical analysis by XRD without sample preparation. Here, the results of proof-of-principle experimental tests are presented. Two sets of experiments were performed using a vacuum chamber equipped with an X-ray tube source, sample holder and charge-coupled detector. Firstly, a pressed-powder pellet of α-quartz was placed in three different positions relative to the X-ray source and detector. The changes in position represent gross sample movements which would be inconceivable in conventional XRD analysis. The resulting back-reflection energy-dispersive spectra show a very high degree of correspondence other than an overall intensity factor dependent on the distance between the sample and detector. Secondly, the back-reflection spectrum of an unprepared limestone hand specimen, having mm-scale surface morphology, was compared to the spectrum of a calcite pressed-powder pellet. The correspondence of the diffraction peaks in the spectra demonstrate that the limestone is comprised dominantly of calcite. In both cases, the claims of the earlier paper are fully supported by the results of these experimental tests. [Copyright &y& Elsevier]

Abstract: This paper presents the results of the characterisation of a back-illuminated pixel sensor manufactured in Silicon-on-Insulator technology on a high-resistivity substrate with soft X-rays. The sensor is thinned and a low energy phosphorus implantation is performed on the back-plane. The response to X-rays from 2.12 to 8.6keV is evaluated with fluorescence radiation at the LBNL Advanced Light Source. [Copyright &y& Elsevier]

Abstract: Fourth generation accelerator-based light sources, such as VUV and X-ray Free Electron Lasers (FEL), deliver ultra-brilliant (∼1012–1013 photons per bunch) coherent radiation in femtosecond (∼10–100fs) pulses and, thus, require novel focal plane instrumentation in order to fully exploit their unique capabilities. As an additional challenge for detection devices, existing (FLASH, Hamburg) and future FELs (LCLS, Menlo Park; SCSS, Hyogo and the European XFEL, Hamburg) cover a broad range of photon energies from the EUV to the X-ray regime with significantly different bandwidths and pulse structures reaching up to MHz micro-bunch repetition rates. Moreover, hundreds up to trillions of fragment particles, ions, electrons or scattered photons can emerge when a single light flash impinges on matter with intensities up to 1022 W/cm2. In order to meet these challenges, the Max Planck Advanced Study Group (ASG) within the Center for Free Electron Laser Science (CFEL) has designed the CFEL-ASG MultiPurpose (CAMP) chamber. It is equipped with specially developed photon and charged particle detection devices dedicated to cover large solid-angles. A variety of different targets are supported, such as atomic, (aligned) molecular and cluster jets, particle injectors for bio-samples or fixed target arrangements. CAMP houses 4π solid-angle ion and electron momentum imaging spectrometers (“reaction microscope”, REMI, or “velocity map imaging”, VMI) in a unique combination with novel, large-area, broadband (50eV–25keV), high-dynamic-range, single-photon-counting and imaging X-ray detectors based on the pnCCDs. This instrumentation allows a new class of coherent diffraction experiments in which both electron and ion emission from the target may be simultaneously monitored. This permits the investigation of dynamic processes in this new regime of ultra-intense, high-energy radiation—matter interaction. After an introduction into the salient features of the CAMP chamber and the properties of the redesigned REMI/VMI spectrometers, the new 1024×1024 pixel format pnCCD imaging detector system will be described in detail. Results of tests of four smaller format (256×512) devices of identical performance, conducted at FLASH and BESSY, will be presented and the concept as well as the anticipated properties of the full, large-scale system will be elucidated. The data obtained at both radiation sources illustrate the unprecedented performance of the X-ray detectors, which have a voxel size of 75×75×450μm3 and a typical read-out noise of 2.5 electrons (rms) at an operating temperature of −50°C. [Copyright &y& Elsevier]

Abstract: Since diagnostic X-rays have been proven to be a cause of cancer, some precautions are essential to reduce the dose delivered to patients. In this paper, an idea to reduce the dose by a new type of X-ray computed tomography (CT) using silicon strip detectors is discussed. Thin tungsten plates placed between edge-on silicon strip detectors are the key element to reduce the background of scattered X-rays and improve the image contrast with low dose. The initial results of a feasibility study are also reported. [Copyright &y& Elsevier]

A study of a dual-GEM detector coupled to a strip readout anode is described. The effects of the induction electric field and GEM-to-anode gap are presented, for an operation in atmospheric pressure Ar/CO2 (70/30) and Ar/CH4 (95/5). Visible gain and anode signal pulse-shapes, measured with 5.9 keV X-rays are presented for 1–6 mm wide induction gaps and for induction fields ranging up to 6 kV cm−1. The spatial distribution of the anode charge is provided for induction gaps of 2–12 mm. The results are useful for matching the detector parameters to the position recording circuit requirements. [Copyright &y& Elsevier]