We have developed an Application Specific Integrated Circuit (ASIC) and data acquisition system for digital X-ray Imaging. The chip consists of 16 parallel channels, each containing preamplifier, ...shaper, comparator and a 16 bit counter. We have demonstrated noiseless single-photon counting over a threshold of 7.2 keV using Silicon detectors and are presently capable of maximum counting rates of 2 MHz per channel. The ASIC is controlled by a personal computer through a commercial PCI card, which is also used for data acquisition. The content of the 16 bit counters are loaded into a shift register and transferred to the PC at any time at a rate of 20 MHz. The system is non-complicated, low cost and high performance and is optimized for digital X-ray imaging applications.
The authors characterize a 3/spl times/4 element imaging array consisting of 3/spl times/3/spl times/5 mm/sup 3/ CsI(TI) scintillator crystals individually read out by 3/spl times/3 mm/sup 2/ PIN ...silicon photodiodes. The array is a prototype for larger modules (16/spl times/16 element) for use in single photon breast cancer imaging. The photodiode output signals are amplified with a 16 channel custom IC (<3 mm on a side), after which a "Winner Take All" (WTA) custom IC (<3 mm on a side) identifies the crystal of interaction based on relative signal amplitudes. The compact nature of these readout electronics will simplify the construction of larger imaging arrays. The photodiodes were developed for low leakage current (/spl sim/50 pA) and yield a total electronic noise of 390 e- full width at half maximum (fwhm) at a shaping time of 8 /spl mu/s, with signal levels of 6600 e- for the 140 keV emissions of /sup 99m/Tc. Array pixels demonstrate an average room temperature energy resolution of 10.7/spl plusmn/0.6% fwhm for these 140 keV gamma rays. The authors observe an intrinsic spatial resolution of 3.3 mm fwhm for a 2.5 mm diameter /sup 57/Co beam on the face of the crystal array, and a system resolution of 5.9 mm fwhm for a 2 mm diameter uncollimated /sup 99m/Tc source viewed through a high resolution hexagonal hole collimator (1.5 mm hole diameter, 32 mm length, 4300 events/mCi/sec) at an imaging distance of 5 cm.
VIHI: the Visible and Infrared Hyperspectral Imager is one of the three channels of the Simbio-Sys instrument for the BepiColombo mission to Mercury. Its scientific objective is to study the hermean ...surfaces composition by sensing the photon flux reflected off the planet. VIHI works in the range of 400 to 2000 nm with a spectral resolution around a few hundreds. The particularity of this channel is the use of a single detector matrix (264 × 264) for both visible and infrared wavelengths. Getting the visible part of the detector responsivity is achieved by thinning an infrared HgCdTe matrix because visible light is completely absorbed inside the substrate. The thinning process is well controlled since a long time and was used to increase number of thermal cycle of the hybrid devices. Recently, this process is able to remove completely the substrate and, thus, open the detector to the visible range. The detector is a custom design made by Raytheon Vision System in Goleta (USA). In this paper, we will describe the expected performances of the detector which is designed to work in the very harsh radiation environment of Mercury.
We have developed an Application Specific Integrated Circuit (ASIC) and data acquisition system for digital X-ray imaging. The chip consists of 16 parallel channels, each containing preamplifier, ...shaper, comparator and a 16 bit counter. We have demonstrated noiseless single-photon counting over a threshold of 7.2 keV using Silicon detectors and are presently capable of maximum counting rates of 2 MHz per channel. The ASIC is controlled by a personal computer through a commercial PCI card, which is also used for data acquisition. The content of the 16 bit counters are loaded into a shift register and transferred to the PC at any time at a rate of 20 MHz. The system is non-complicated, low cost and high performance and is optimised for digital X-ray imaging applications.
The authors present the first images and an initial evaluation of a scanned-slot X-ray imaging system based on edge-on silicon strip detectors and high-speed low-noise parallel processing ASICs. The ...authors have demonstrated noiseless single photon counting above a minimal threshold of 7.2 keV. Edge scans show negligible cross talk between different channels in the ASIC. The Modulation Transfer Function (MTF) has been measured and found to agree with the ideal MTF for 100 /spl mu/m pixel size. The first images are obtained at very low exposures and show the high performance of the system. The authors also present a way of enhancing the X-ray flux to a slot by using a refractive X-ray lens. They believe this focusing device will significantly enhance the potential for scanned-slot X-ray imaging.
Status of the digital pixel array detector for protein crystallography Datte, P.; Birkbeck, A.; Beuville, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/1999, Letnik:
421, Številka:
3
Journal Article
Recenzirano
A two-dimensional photon counting digital pixel array detector is being designed for static and time resolved protein crystallography. The room temperature detector will significantly enhance ...monochromatic and polychromatic protein crystallographic through-put data rates by more than three orders of magnitude. The detector has an almost infinite photon counting dynamic range and exhibits superior spatial resolution when compared to present crystallographic phosphor imaging plates or phosphor coupled CCD detectors. The detector is a high resistivity N-type Si with a pixel pitch of 150×150
μm, and a thickness of 300
μm, and is bump bonded to an application specific integrated circuit. The event driven readout of the detector is based on the column architecture and allows an independent pixel hit rate above 1 million photons/s/pixel. The device provides energy discrimination and sparse data readout which yields minimal dead-time. This type of architecture allows a continuous (frameless) data acquisition, a feature not found in any current detector being used for protein crystallographic applications. For the targeted detector size of 1000×1000 pixels, average hit rates greater than 8 billion photons/s for the complete detector appears achievable. This paper will present a review of the 8×8 detector array pixel performance which includes the analog amplifier response and the photon counting capabilities. In addition, operational results of a 16×16 detector array prototype, that includes both the analog amplifier and digital readout circuitry functioning together on one integrated circuit.
We present performance measurements of a "Winner-Take-All" (WTA) CMOS integrated circuit to be used with a pixel based PET detector module. Given n input voltages, it rapidly determines the input ...with the largest voltage, and outputs the encoded address of this input and a voltage proportional to this largest voltage. This is more desirable than a threshold approach for applications that require exactly one channel to be identified or when noise is a significant fraction of the input signal. A sixteen input prototype has been fabricated using two 1.2 /spl mu/m processes (HP linear MOS capacitance and Orbit double-poly capacitance). ICs from both processes reliably identify (within 50 ns) the maximum channel if /spl Delta/V (the difference between the two highest channels) is >20 mV. The key element in the WTA circuit is an array of high gain non-linear current amplifiers. There is one amplifier for each input channel, and each amplifier is composed of only two FETs. All amplifiers are supplied by a common, limited current source, so the channel with the largest input current takes all of this supply current while the other channels receive virtually none, Thus, these amplifier outputs become a set of logical bits that identify the maximum channel, which is encoded and used to select a multiplexer input. A voltage to current converter at each input channel turns this into a voltage sensitive device. This circuit uses very little power, drawing approximately 100 /spl mu/A at 5 V.
Indigo Operations, subdivision of FLIR Systems, has designed, fabricated, and tested a mixed-signal readout integrated circuit (ROIC), the ISC9717, for instrumentation and flat panel X-ray ...applications. This off-the-shelf, high performance, low-noise, 128-channel device is fully programmable with a multistage pipelined architecture and a 9 to 14-bit programmable A/D converter per channel, making it suitable for numerous instrumentation detector types, especially for X-ray imaging applications. Each 80-micron pitch amplification channel includes a low noise integrator, a low pass filter with programmable time constant, a correlated double sampling to remove kTC and 1/f noise, and a programmable A/D converter (9 to 14-bit). Both integrator and correlated double sampling have programmable gains to cover a wide range of input signal dynamic range. The ISC9717 integrates both charge polarities, making it suitable for silicon (Si), amorphous silicon, gallium arsenide (GaAs), cadmium zinc telluride (CdZnTe) detector materials and selenium (Se) or cesium iodide (CsI) flat panel arrays. The ROIC is designed to interface along one or two sides of the detector or flat panels like TFT, where ROICs are abutted, each reading out charge from pixels multiplexed on to 128 read lines.
Gas microstrip detectors have been integrated with low noise preamplifier and shaper electronics on a common silicon substrate. These devices were fabricated at the Hewlett-Packard company using a ...standard 0.8
μm process. This unique approach offers advantages over conventional microstrip design: ease of fabrication, lower noise, and higher channel density. The detector/electronics assembly was tested in a small drift chamber. An energy resolution of 18% FWHM and a noise level of 80
e
− r.m.s per channel were obtained with a gas gain of about 200. These integrated microstrip detectors are being developed as the readout devices for a small, high-resolution Time Projection Chamber (MicroTPC). Low mass and high resolution make the MicroTPC well suited for use as a vertex detector, especially in high track-density environments such as RHIC and the LHC.
A digital pixel address generator for pixel array detectors Datte, P.; Beuville, E.; Millaud, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/1999, Letnik:
421, Številka:
3
Journal Article
Recenzirano
An 8×8 analog pixel array detector prototype has been constructed for characterizing a larger 50×50 digital pixel array detector (DPAD) that will be used for protein crystallography. Each detector ...readout element in the array consists of a preamplifier and shaper, with adjustable reset and shaping times. The readout array is bump-bonded to a Si pixel array detector and provides 64 independent analog output channels for data processing. This paper describes the digital processing electronics which is used for mapping the prototype pixel detector characteristics. The event driven digital encoding circuitry processes each photon hit by grouping each pixel into a column of 8 pixels and then grouping each column into an array of 8 columns forming an 8×8 pixel array. The logic is inexpensive and easy to implement. Results from these measurements were used as an aid in the design of the DPAD detector and DPAD ASIC.
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