We have developed a new version of the MARY (MAmmogRaphY) pixel detector with its custom readout integrated circuit (IC) optimized for electron collection in semiconductor detectors such as CdZnTe (CZT), CdTe, a-Se and GaAs. This new pixel detector and readout IC, the MARY-N50, is essentially comprised of a 192 x 384 array of channels at a 50 μm x 50 μm pitch, which can be flip-chip bump-bonded with a matching detector pixel array. A 100 μm pitch pixel detector, the MARY-N100, was also developed, with a 64 x 192 pixel array. Standard features of both versions of MARY-N include: TDI (Time Delay Integration) or “staring” CCD readout capability; low noise and wide dynamic range; internal clock drivers; fat zero input; overflow control; multiple independent readout stages (24 for MARY-N50, 8 for MARY-N100) to accommodate large charge collection due to direct conversion.

We have developed custom two-dimensional (2-D) mixed signal readout integrated circuits (ICs) for advanced position sensitive hybrid solid-state radiation detectors. The 2-D readout ICs are an integral part of hybrid semiconductor pixel detectors developed for x-ray, gamma-ray and charged particle imaging. Different detector applications require custom IC, which is typically designed for a specific 2-D detector array. Therefore, it is challenging to develop generic ICs to meet a range of applications in different complementing fields. To approach this aim NOVA has put significant effort on developing its ICs as flexible as possible to address differences in the fields of application. Therefore, these ICs embody versatile and adaptable functions as well as selectable features. An overview of 2-D ICs recently developed at NOVA and their functionality and features will be presented. Preliminary test results will be discussed. These ICs can be used for applications ranging from x-ray astronomy and medical imaging to munitions, security and industrial inspection. Some potential applications are: gamma camera; SPECT; PET; CT; digital mammography & radiography; baggage scanner; NDI and NDE.

We have developed a new, improved version of the XENA (X-ray ENergy-binning Applications) readout IC for solid-state x-ray detector arrays, which we call XENA-2. This IC consists of 32 readout channels, each with charge-sensitive input amplifier, two-stage gain amplifier, and five comparators followed by 16-bit pulse counters. The resistive feedback of the input amplifier is provided by a transconductance circuit with continuously variable, user-controlled transconductance, which allows the amplifier’s shaping time to be varied between 100 to 150 ns and 4 μs. Two input amplitude ranges, 7 fC and 30 fC nominal (200 keV and 800 keV, respectively, for Cadmium Zinc Telluride), can be selected by switching different capacitors into the feedback path. The gain amplifier design includes a five-bit gain adjustment and a ten-bit R-2R offset DAC. The five comparator threshold voltages are supplied externally and are common to all channels; digitally controlled threshold adjustments at each comparator allow to compensate for process variations. Readout of the counters, over a 16-bit data bus, takes approximately 20 μs. Two additional analog-only channels (that is, without the comparators and counters) are provided, one at each end of the channel array; they are used for test purposes and to improve the uniformity of the full channels. Compared to XENA, this new IC’s main improvement is significantly reduced noise, which allows for lower comparator thresholds and increased count rates. XENA-2 is fully pin-compatible with XENA and replaces it as the readout IC used in NOVA’s NEXIS detector system.

We have developed a pixel detector hybrid called DANA-2 (Detector Array for Nuclear Applications). DANA-2 consists of a two-dimensional, monolithic Cadmium Zinc Telluride (CZT) detector array flip-chip bonded directly to a readout IC designed for high energy resolution. Both the detector and the IC have 16 × 16 pixels with a pitch of 0.5 mm × 0.5 mm; the detector thickness is 3 mm. Each readout channel features a low-noise, charge-sensitive input amplifier with continuous-reset feedback and two selectable energy ranges; a gain amplifier with a five-bit gain adjustment and eight-bit offset DAC; a shaper with eight selectable shaping times ranging from 0.5 μs to 4 μs; a peak detector; and a trigger comparator. The data readout is controlled by a programmable token logic, which affords the user a high degree of flexibility in the selection of nearest-neighbor channels to be read out to account for charge sharing between pixels. To process the signals from the detector cathode, one of the readout channels, which is normally connected to a corner pixel, can instead be connected to the cathode through a dedicated I/O pad. The different characteristics of these cathode signals are accommodated through user configuration options for the signal polarity and input FET size. Other features of DANA-2 include the ability to disable the trigger on any channel and thus turn off “hot” pixels, and several test features such as an AC-coupled test signal input and the option to operate any peak detector in follower mode and connect it to the analog output to continuously monitor the shaper signal. We present below details of the DANA-2 design and first results from its performance characterization.

We have developed high energy and high spatial resolution two-dimensional (2D) solid-state imaging pixel detectors and their custom integrated circuits (ICs). Solid-state pixel detectors and their readout ICs are now regarded to be an integral part of position-sensitive semiconductor detectors such as Si, CdTe and CdZnTe for x-ray and gamma-ray imaging. These detectors have a 2D structure. We have also developed one-dimensional (ID) detectors, which are mostly used for scanning type imaging. The new 2D pixel detectors we have developed can be used for both scanning and staring mode imaging applications. Because the requirements of various detector applications tend to be diverse, a custom IC is typically designed for a specific detector array. This often lengthens the time and raises the cost of system development. To help close the readout technology gap and facilitate advances in this field, we have been formulating and implementing strategies for instrumenting different detectors of a given application category with highly versatile ICs that meet a range of requirements. The solid-state pixel detectors that have been developed within this effort are presented below.

We present the design and initial performance characterization of the XENA-2 readout IC for solid-state x-ray detector arrays. XENA-2 consists of 32 readout channels, each with charge-sensitive input amplifier, adjustable two-stage gain amplifier and five comparators with 16-bit pulse counters. Readout of the counters, over a 16-bit data bus, takes approximately 20 mu s. Compared to the XENA chip, its predecessor, this new IC's main improvement is significantly reduced noise, which allows for lower comparator thresholds and increased count rates.

497 Objectives: To develop new high spatial and energy resolution photon counting detectors for Gamma Camera and SPECT application. These detectors may also be modified and optimized for application to small animal imaging, including small animal PET. Methods: We have developed new 1D and 2D photon counting detectors with high spatial resolution of 2x2 or 0.5x0.5 mm2 pitch, respectively. The pitch has potential to be reduced even smaller if needed. To improve photon counting statistics per pixel the adjacent pixels can be added to increase statistics with some compromise on spatial resolution. For example 2x2 adjacent pixels can be combined to produce images with 1x1 mm2 pitch spatial resolution. The detector also has high energy resolution due to the use of solid state detectors. The preliminary energy resolution is 4% or 2% @ 122 keV photon energies for 1D and 2D detectors, respectively. We expect to improve on these energy resolutions for the annual meeting. A low noise 36 channel integrated readout electronics has been designed and manufactured for the 1D detector. This system is mainly developed for applications that need >1x1 mm2 pixel pitch. A 16x16=256 pixel integrated readout electronics has been designed and manufactured for the 2D detector. This detector is mainly developed for applications that use Results: We have carried out initial testing of these two detector prototypes. New second version prototypes are being manufactured and will be ready for testing by the end of January. We will report the results of our first and second version prototype detector measurements. Conclusions: The results are showing strong potential for improving both the spatial and energy resolutions of present SPECT systems. Research Support: DAAE30-02-C-1015 & DAAE30-03-C-1074

The RENA-3 (Readout Electronics for Nuclear Applications) is a 36-channel self-resetting, charge sensitive amplifier/shaper IC with trigger output, wide energy range and sparse readout designed for use with position-sensitive, spectroscopy-grade radiation detectors. It has in recent years been favored to provide the front-end electronics in prototype instruments for various applications — from space physics research through medical imaging to homeland security — that employ CZT or CdTe in the form of planar sensor assemblies or monolithic pixel/strip arrays. We will present a summary of spectroscopic data drawn from the body of RENA-3-based results obtained in our laboratories and by other RENA-3 users. Spectroscopic performance metrics will be discussed relative to the requirements of the specific application targeted in each case as well as from the general standpoint of what may be achievable within this detector-array/RENA-3 approach. A method to automate the test and calibration of RENA-3 ICs will also be described.

The RENA-3 (Readout Electronics for Nuclear Applications) is a multi-channel mixed-signal integrated circuit (IC) developed for the readout of position-sensitive solid-state detectors with excellent energy resolution. We will present results of experiments characterizing its performance as used with a variety of spectroscopy-grade detectors currently available in the industry, notably CZT pixel arrays as well as other detector configurations. The merits of specific RENA-3 design features vis-a-vis different detector applications will also be discussed.

A multi-channel front-end readout IC is developed for position sensitive solid-state detectors. It is called RENA-3. It has 36 low noise channels. Each channel has externally selectable input polarity. The channel inputs are optimized for 2 or 9 pF detector capacitance, which is externally selectable. It also has selectable dual energy range, 56K and 338K electrons (250 keV and 1.5 Mev for CZT, respectively). A fast trigger output is provided applications that require timing. A novel circuit produces arrival time difference measurement for each channel. It is developed to serve as front-end readout electronics for a variety of position-sensitive solid-state semiconductor detectors such as CdZnTe, Si, GaAs and HgI2. It also has flexibility for use with other types of solid-state detectors such as Ge, Se, PbI2 and CdTe in a multichannel strip or pixel geometry to detect and image x-rays and gamma-rays with energies up to 1.3 MeV. Also a novel register circuit and process allows nearest neighbor readout capability for pixel detectors. Combination of RENA-3 chips with a variety of semiconductor detectors would be suitable for numerous applications in astrophysics, nuclear physics, nuclear medicine, security and industrial imaging. Some possible applications include gamma camera, SPECT, small animal PET and SPECT, nuclear source detection and spectroscopy, space x-ray and gamma-ray astronomy missions, NDE and NDI.

We have developed high energy and high spatial resolution 1D and 2D solid state imaging detectors and their custom integrated circuits (ICs). Readout ICs are now regarded to be an integral part of position-sensitive semiconductor detectors, especially for Si and CdZnTe for x-ray and gamma-ray imaging. These detectors have a 1D or 2D structure. The 1D structure types are mostly used for scanning purposes with some staring type imaging while 2D pixel detectors can be used for both scanning and staring mode imaging applications. Because the requirements of various detector applications tend to be diverse, a custom IC is typically designed for a specific detector array. This often lengthens the time and raises the cost of system development. To help close the readout technology gap and facilitate advances in this field, we have been formulating and implementing strategies for instrumenting different detectors of a given application category with highly versatile ICs that meet a range of requirements. The solid-state detectors and their ICs that have been developed within this effort are presented.

We have developed a multi-channel, mixed-signal integrated circuit (IC) as part of a resource-conserving approach to the design of instruments for missions flown under the Geospace Missions Network (GMN) of NASA's Living With a Star (LWS) program. Specifically, the IC was designed to read out microchannel plates (MCPs) which allow detection of single hot plasma particle by emitting a pulse of charge when struck by the plasma particle. The IC, named AIDA (AlowbarmplIlowbarfier Dlowbariscriminator AlowbarSIC) includes several Charge-Amplifier Discrminators in one package without sacrificing performance, thus simplifying the MCP electronics and saving on space, power and cost. Reduction of power and mass requirements by several tens of percent relative to existing MCP instrument electronics was the primary goal. A secondary goal was to integrate the pulse counting function into the IC, thereby eliminating the need for additional counters and conserving resources further. We present the features and capabilities of the AIDA IC and evaluation system, and initial characterization data for the chip.

A new mixed signal front-end readout electronics integrated circuit (IC) called HILDA (Hyperspectral Imaging with Large Detector Arrays) has been developed for two-dimensional CdZnTe (CZT) pixel detector arrays. The CZT array is directly bonded on top of the IC. The CZT array and the HILDA-IC have matching geometric pixel/channel structure and dimensions, a 16times16 array of 0.5 mm times 0.5 mm pitch. They are mounted together using flip-chip bump bonding. The pixel detector and readout IC are designed for high-rate photon counting independently for each channel/pixel and multiple-energy binning up to eight energy bands. Therefore, eight images can be produced that represent identical slices in time and space but different energy bands. Several HILDA CZT pixel detector hybrids have been fabricated and tested. The CZT pixel detector, the readout IC and preliminary test results are presented in this paper. The main potential applications envisioned for this chip are industrial non-destructive inspection, security applications and CT scanners.

Using the density functional theory in the local density approximation the pressure dependence of the structural, dynamical, and electronic properties of the SnP2S6 layered semiconductor in the pressure range up to 35 GPa is investigated. The pressure dependence of the lattice parameters is well described by the Murnaghan equation of state. The nonmonotonic pressure dependence of the structural polarization is obtained. The SnP2S6 compound is predicted to be an indirect-gap semiconductor. At a pressure of above 10 GPa, an indirect-direct bandgap crossover is observed. The pressure dependence of the long-wavelength lattice vibration frequencies is calculated and compared with experimental results from Raman spectroscopy in the pressure range 0-21.5 GPa. Full phonon dispersion curves do not indicate mode softening over the entire range of the Brillouin zone. The stability of the structure under pressure is discussed.

Multiple-site interactions initiated by Compton scattering are the primary interaction processes of gamma-rays in CZT in ~0.2 - several MeV range. Thus, exploiting gamma-rays as directional and spectral diagnostic probes requires detectors with 3-D resolution that resolve and measure individual interaction site's locations and energies. Desirable capabilities for Compton telescopes appear to be a spatial resolution of ~1 mm and an energy resolution of ~1 percent. Such capabilities are also important for coded mask imagers above 250 keV, where 3-D resolution can greatly improve the identification of a gamma-ray's initial interaction site, which is crucial for imaging. Significantly improved spectral resolution can be anticipated with CZT when multi-site interactions are resolved. This will allow each site's energy signals to be corrected for the site's specific signal loss characteristics, and the summed energies will then provide an accurate measure of the incident gamma-ray energy. We report on progress toward the development of 5 - 10 mm thick CZT detectors and electronics that are pursuing these objectives. Position sensing is provided by anode pixels with ~1 mm pitch for x-y positions and charge drift times for z-positions. Detectors are read out with the new RENA-2 ASIC. This chip contains preamplifiers, shaping amplifiers, threshold triggering, and peak detection for each of its 36 channels. To optimize energy resolution for various detector types and event rates, the RENA-2's peaking times and other parameters are adjustable. Each channel has a novel fast time stamp function that can record interaction times to ~10 nsec, allowing precise measurements of charge drift times and making PET imaging possible. The detector and ASIC designs are described and results are presented on tests of thresholding, energy resolution, and time resolution

A new mixed signal integrated circuit (IC) for front-end readout electronics of position sensitive solid state detectors has been developed. It is called RENA-2 and can be used for readout of position sensitive solid state detectors such as CdTe, CdZnTe, Ge, GaAs, HgI 2 , PbI 2 , Se and Si strip, pad and pixel detectors, with large numbers of channels. It is designed to have very low noise and, therefore, high energy resolution. It has numerous possible applications in astrophysics, medical and industrial imaging, security such as baggage inspection and nuclear physics. The RENA-2 chip is a monolithic integrated circuit and has 36 channels with low noise, high input impedance charge sensitive amplifiers. The RENA-2 chip can be optimized for individual applications

We have developed compact detector modules for high-resolution PET imaging. The modules consist of arrays of four by four 20 mm long LYSO crystals whose scintillation signals are read by avalanche photodiode arrays. The scintillator arrays are instrumented at both ends to facilitate depth-of-interaction determination by measuring the pulse-height ratio between the two ends of the LYSO crystal. To process the diode signals, we have developed a custom multi-channel integrated readout chip designed for excellent coincidence time resolution and low power dissipation. The IC offers various configuration options to allow for a high degree of flexibility in the design of the imaging system