[en] An ASIC for the readout of signals from X-ray Active Matrix Pixel Sensor (XAMPS) detectors to be used at the Linac Coherent Light Source (LCLS) is presented. The X-ray Pump Probe (XPP) instrument, for which the ASIC has been designed, requires a large input dynamic range on the order of 104 photons at 8 keV with a resolution of half a photon FWHM. Due to the size of the pixel and the length of the readout line, large input capacitance is expected, leading to stringent requirement on the noise optimization. Furthermore, the large number of pixels needed for a good position resolution and the fixed LCLS beam period impose limitations on the time available for the single pixel readout. Considering the periodic nature of the LCLS beam, the ASIC developed for this application is a time-variant system providing low-noise charge integration, filtering and correlated double sampling. In order to cope with the large input dynamic range a charge pump scheme implementing a zero-balance measurement method has been introduced. It provides an on chip 3-bit coarse digital conversion of the integrated charge. The residual charge is sampled using correlated double sampling into analog memory and measured with the required resolution. The first 64 channel prototype of the ASIC has been fabricated in TSMC CMOS 0.25 (micro)m technology. In this paper, the ASIC architecture and performances are presented

[en] We have developed a high-speed system for collecting x-ray fluorescence microprobe data, based on ASICs developed at BNL and high-speed processors developed by CSIRO. The system can collect fluorescence data in a continuous raster scan mode, and present elemental images in real time using Ryan's Dynamic Analysis algorithm. We will present results from a 32-element prototype array illustrating the concept. The final instrument will have 384 elements arranged in a square array around a central hole

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[en] We describe an application specific integrated circuit (ASIC) for 3D position-sensitive detectors. It was optimized for pixelated CZT sensors, and it measures, corresponding to an ionizing event, the energy and timing of signals from 121 anodes and one cathode. Each channel provides low-noise charge amplification, high-order shaping, along with peak- and timing-detection. The cathode's timing can be measured in three different ways: the first is based on multiple thresholds on the charge amplifier's voltage output; the second uses the threshold crossing of a fast-shaped signal; and the third measures the peak amplitude and timing from a bipolar shaper. With its power of 2 mW per channel the ASIC measures, on a CZT sensor Connected and biased, charges up to 100 fC with an electronic resolution better than 200 e^- rms. Our preliminary spectral measurements applying a simple cathode/mode ratio correction demonstrated a single-pixel resolution of 4.8 keV (0.72 %) at 662 keV, with the electronics and leakage current contributing in total with 2.1 keV

[en] The LCLS-II Free Electron Laser (FEL) will produce X-ray pulses with a repetition rate of up to 1 MHz and energies between 250 eV and 5 keV. Experiments conducted at LCLS-II will require 2D imaging detectors with a unique set of features, such as high-spatial resolution, low-noise performance, high-dynamic range and high-frame rates up to 1 MHz. We present the design of ePixM, a fully-depleted monolithic CMOS detector tailored for soft X-rays applications at high-repetition rates FEL. It consists of an array of 384×192 active pixel sensors, with a pixel size of 50×50 μm² and a total sensitive area of 2×1 cm². ePixM has been designed in a 150 nm CMOS technology on high-resistivity substrate to achieve full depletion of the substrate. Each pixel includes a Charge Sensitive Amplifier (CSA) with gain auto-ranging capability and a noise-shaper performing Correlated Double Sampling (CDS). A novel technique named correlated pre-charging removes the excess noise introduced by the gain-switching mechanism. The performance of the design has been evaluated through post-layout simulations. The Equivalent Noise Charge (ENC) of 11.3 electrons enables single-photon detection at X-ray energies down to 250 eV, and the dynamic range exceeds 10³ photons at 500 eV thanks to the auto-ranging circuitry.

[en] ePix is a novel class of ASIC architectures, based on a common platform, optimized to build modular scalable detectors for LCLS. The platform architecture is composed of a random access analog matrix of pixel with global shutter, fast parallel column readout, and dedicated sigma-delta analog-to-digital converters per column. It also implements a dedicated control interface and all the required support electronics to perform configuration, calibration and readout of the matrix. Based on this platform a class of front-end ASICs and several camera modules, meeting different requirements, can be developed by designing specific pixel architectures. This approach reduces development time and expands the possibility of integration of detector modules with different size, shape or functionality in the same camera. The ePix platform is currently under development together with the first two integrating pixel architectures: ePix100 dedicated to ultra low noise applications and ePix10k for high dynamic range applications.

[en] After improving the PCB level electronics the next step in our continuing upgrade program of LCLS Cornell-SLAC Pixel Array Detector (CSPAD) cameras is the use of a new improved ASIC named CSPAD V1.5. The upgraded ASIC includes on chip DACs to set the bias currents of all amplifiers. The new chip also supports power cycling by design. Together this simplifies the PCB level complexity and eases the integration of many ASICs into one camera. Homogeneity across the full reticle size chip was improved by redesigning the power distribution. The upgrade included modifications of the gain latches and the per pixel comparators. Results from the upgraded cameras used at LCLS will be presented and discussed.

[en] X-ray Active Matrix Pixel Sensors (XAMPS) were designed and fabricated at Brookhaven National Laboratory. Devices based on J-FET technology were produced on 100 mm high-resistivity silicon, typically 400 μm-thick. The prototypes are square matrices with n rows and n columns with n = 16, 32, 64, 128, 256, 512. Each pixel of the matrix is 90 x 90 μm² and contains a JFET switch to control the charge readout. The XAMPS is a position sensitive ionization detector made on high resistivity silicon. It consists of a pixel array detector with integrated switches. Pixels are isolated from each other by a potential barrier and the device is fully depleted by applying a high voltage bias to the junction on the entrance window of the sensor. The small features of the design presented some technological challenges fully addressed during this production. The first prototypes were tested at the National Synchrotron Light Source (NSLS) with a monochromatic beam of 8 keV and millisecond readout and exhibit good performances at room temperature.

[en] A multilayer stacked X-ray camera concept is described. This type of technology is called '4H' X-ray cameras, where 4H stands for high-Z (Z>30) sensor, high-resolution (less than 300 micron pixel pitch), high-speed (above 100 MHz), and high-energy (above 30 keV in photon energy). The components of the technology, similar to the popular two-dimensional (2D) hybrid pixelated array detectors, consists of GaAs:Cr sensors bonded to high-speed ASICs. 4H cameras based on GaAs also use integration mode of X-ray detection. The number of layers, on the order of ten, is smaller than an earlier configuration for single-photon-counting (SPC) mode of detection [1]. High-speed ASIC based on modification to the ePix family of ASIC is discussed. Applications in X-ray free electron lasers (XFELs), synchrotrons, medicine and non-destructive testing are possible.

[en] The ePix100 x-ray camera is a new system designed and built at SLAC for experiments at the Linac Coherent Light Source (LCLS). The camera is the first member of a family of detectors built around a single hardware and software platform, supporting a variety of front-end chips. With a readout speed of 120 Hz, matching the LCLS repetition rate, a noise lower than 80 e-rms and pixels of 50 µm × 50 µm, this camera offers a viable alternative to fast readout, direct conversion, scientific CCDs in imaging mode. The detector, designed for applications such as X-ray Photon Correlation Spectroscopy (XPCS) and wavelength dispersive X-ray Emission Spectroscopy (XES) in the energy range from 2 to 10 keV and above, comprises up to 0.5 Mpixels in a very compact form factor. In this paper, we report the performance of the camera during its first use at LCLS.