EIGER is an advanced family of single photon counting hybrid pixel detectors, primarily aimed at diffraction experiments at synchrotrons. Optimization of maximal functionality and minimal pixel size (using a 0.25 μ m process and conserving the radiation tolerant design) has resulted in 75 × 75 μ m 2 pixels. Every pixel comprises a preamplifier, shaper, discriminator (with a 6 bit DAC for threshold trimming), a configurable 4/8/12 bit counter with double buffering, as well as readout, control and test circuitry. A novel feature of this chip is its double buffered counter, meaning a next frame can be acquired while the previous one is being readout. An array of 256×256 pixels fits on a ∼ 2 × 2 cm 2 chip and a sensor of ∼ 8 × 4 cm 2 will be equipped with eight readout chips to form a module containing 0.5 Mpixel. Several modules can then be tiled to form larger area detectors. Detectors up to 4×8 modules (16 Mpixel) are planned. To achieve frame rates of up to 24 kHz the readout architecture is highly parallel, and the chip readout happens in parallel on 32 readout lines with a 100 MHz Double Data Rate clock. Several chips and singles (i.e. a single chip bump-bonded to a single chip silicon sensor) were tested both with a lab X-ray source and at Swiss Light Source (SLS) beamlines. These tests demonstrate the full functionality of the chip and provide a first assessment of its performance. High resolution X-ray images and “high speed movies” were produced, even without threshold trimming, at the target system frame rates (up to ∼ 24 kHz in 4 bit mode). In parallel, dedicated hardware, firmware and software had to be developed to comply with the enormous data rate the chip is capable of delivering. Details of the chip design and tests will be given, as well as highlights of both test and final readout systems.

EIGER: Next generation single photon counting detector for X-ray applications

Eiger is a single-photon counting x-ray pixel detector being developed at the Paul Scherrer Institut (PSI) for applications at synchrotron light sources. It follows the widely utilized and successful Pilatus detector. The main features of Eiger are a pixel size of 75 × 75 μm2, high frame rate capability of 22 kHz and negligible dead time between frames of 4 μs. This article contains a detailed description of Eiger detector systems, from the 500 kpixel single-module detector to large-area multi-modules systems. The calibration and performance of the first 500 kpixel system that is in routine user operation are also presented. Furthermore, a method of calibrating the energy of single-photon counting detectors along the detector gain axis is introduced. This approach has the advantage that the detector settings can be optimized at all energies for count rate capabilities. Rate capabilities of the system are reported for energies between 6 and 16 keV.

http://iopscience.iop.org/article/10.1088/1748-0221/9/05/C05032/pdf

Eiger: a single-photon counting x-ray detector

The X-ray pixel chip with adaptable dynamics (XPAD3) circuit is the next generation of 2D X-ray photon counting imaging chip to be connected to a pixel sensor using the bump and flip-chip technologies This circuit, designed in IBM 025 μm technology, contains 9600 pixels (130 μm×130 μm) distributed into 80 columns of 120 elements each Its features have been improved to provide high-counting rate over 10 9  ph/pixel/mm 2 , high-dynamic range over 60 keV, very low-noise detection level of 100e −  rms, energy window selection and fast image readout less than 2 ms/frame An innovative architecture has been designed in order to prevent the digital circuits from bothering the very sensitive analogue parts placed in their neighbourhood This allows to read the chip during acquisition while conserving the precise setting of the thresholds over the pixel array Finally, the aim of this development is to combine several XPAD3 to form the PIXSCAN detector

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XPAD3: A new photon counting chip for X-ray CT-scanner

At X-ray synchrotron facilities, scattering experiments require detectors with a large sensitive surface, an high count rate capability, a large counter dynamics, a fast readout system and an adjustable energy threshold. X-ray pixel chip with adaptable dynamics (XPAD3) is a new pixellized photon detector based on hybrid pixel technology, which provides low noise data readout at high speed. It is designed in 0.25 μm IBM technology and contains 9600 pixels (130 μm×130 μm) distributed into 80 columns of 120 elements each. Its features have been optimized to fulfill a count rate capability up to 10+6 photons/pixel/s, an high dynamic range over 35 keV, a very low noise of 130e−, and a threshold adjustment well below 4 keV. Fast data readout below 2 ms/frame is expected. To meet these requirements, an innovative architecture has been designed that makes possible the readout the circuit during acquisition while preserving the precise setting of the thresholds all over the pixel array. The XPAD3 circuit can be bump-bonded with Si, CdTe, or GaAs sensors to optimize its detection efficiency at high X-ray energies. XPAD3 detector modules will be tiled together to form the XPIX detector with a 8 cm×12 cm sensitive area. We present first results obtained using a single-chip prototype of the XPAD3 detector.

XPAD3-S: A fast hybrid pixel readout chip for X-ray synchrotron facilities

XVAD3 is a single photon counting chip based on hybrid pixel counters, with low noise, high dynamics and high speed readout. Its features have been improved to provide an high counting rate capability, a very low threshold, an energy discrimination and a fast image readout. The chip is designed in 0.25 mum IBM technology, and contains 9600 pixels (130 mum times 130 mum) distributed into 80 columns of 120 elements each. An innovative architecture has been designed in order to prevent the digital circuits from disturbing the very sensitive analogue cells. XPAD3 was realized into two versions. The XPAD3-S version accepts positive input charges and offers an energy range from 4 keV to 40 keV with a single threshold. The XPAD3-C version accepts negative input charge and has an energy range from 6 keV to 60 keV with a windowed energy selection set by two independent thresholds. This last feature will be quite useful for experimentations where high contrast resolution is needed. The XPAD3 circuits can be bump-bonded with Si, CdTe or GaAs sensors to match detection efficiency with increasing photon energy. The aim of this development is to combine several XPAD3 circuits to build an 7.5 cm x 12 cm sensitive area for the development of a small animal micro-CT scanner, PIXSCAN and synchrotron X-ray scattering experiments. First prototypes of single chip detectors bump- bonded with a Si sensor and double chip detectors bump-bonded with a CdTe sensor have been produced and tested and preliminary results are presented.

First results of XPAD3, a new photon counting chip for X-ray CT-scanner with energy discrimination

Hybrid pixel detectors featuring a high signal to noise ratio, real 2 dimensional reconstruction and local intelligence, have now been demonstrated to be one of the most powerful trackers for high energy physics experiments. They have, therefore, gained interest in other physics fields and for medical applications. However, the conversion of pixel detectors from high energy physics to X-ray detection is not completely straightforward and new challenges appear. For example, high counting rates, wide dynamic ranges and low detection levels are required. "XPAD" (X-ray Pixel Chip with Adaptable Dynamics) is a novel concept of a pixel detector read-out chip especially developed for X-ray diffraction. This circuit, submitted in a 0.8 /spl mu/m CMOS technology, contains 600 square pixels distributed into 24 columns of 25 elements each. The analogue part, gathering 2 cascaded amplifiers, uses the automatic pole-zero cancellation technique in order to keep the baseline stable even at counting rate as high as 10/sup 7/ photons per second. A fast discriminator allows a detection level from 5 keV (1200 electrons) to 50 keV. A new read-out concept based on a special overflow mechanism has been implemented for infinite dynamic range purposes. This technique permits also data transport during acquisition and motion reconstruction provided by some level of time tagging.

L. Crest

Papers

XPAD, a new read-out pixel chip for X-ray counting