Measurements made during the selection and evaluation of flight CCD detectors for the XMM EPIC MOS cameras have demonstrated near Fano limited resolution at x-ray energies above approximately 3keV. At lower energies some devices exhibit a fractional charge loss which is believed to be due to recombination at the epitaxy/oxide interface. This has been modeled through a Monte-Carlo simulation by assuming that the pinning implant in the etched electrode structure can cause electrons to flow to the front surface, rather than to the buried channel. In spite of this charge loss, spectral response may be characterized using a double Gaussian with residuals of < 5 percent. Quantum efficiency has been measured using a lithium drifted silicon reference detector and these measurements combined with analytical and Monte Carlo simulation, event size ratios and cosmic ray detection, all give a value for the effective depletion depth of 30 to 35 micrometers .

The European Photon Imaging Camera (EPIC) is one of the major instruments on board the European Space Agency's X-ray Multi-Mirror cornerstone mission planned for launch at the end of the century. Ground calibrations have been performed in 1997 and 1998 on the electrical and flight models of the MOS-CCD and on the flight model of the p-n-CCD focal plane cameras at he Synchrotron facility at IAS Orsay in France. The complexity of the imaging systems required a correspondingly sophisticated calibration equipment, capable of automatically setting and calibrating the synchrotron beam at a particular energy, controlling the camera head movement in synchronism with the CCD frame readout, initializing the instrument and acquiring both the instrument data and the facility monitor data in realtime. Furthermore, always in real-time, the data stream was unpacked and stored as photon lists in FITS format and made available via NFS to the off-line analysis software. Contemporaneously, a quick look program allowed the operator to continuously monitor the calibration procedure from a scientific point of view, ensuring the correct operation of the system. The calibration system from the point of view of the instrument and the current status of the project is described.

The x-ray multi mirror (XMM) mission, the second cornerstone of the European Space Agency's Horizon 2000 program, will be launched in August 1999 and will perform high throughput imaging and spectroscopy in the energy range form 0.1 to 15 keV. One of the focal plane instruments is the EPIC pn CCD camera with a sensitive area of 60 mm by 60 mm, integrated on a single silicon wafer. The camera is divided into 4 redundant quadrants of three 10 mm by 30 mm CCDs with 64 by 200 pixels each. The thin entrance window in combination with a depletion depth out modes give the flexibility to observe targets of different source strength up to several Grab with some reduction in spectral and spatial performance. We will report on the calibration of the flight unit of the EPIC pm camera, performed at the long beam test facility Panter in Muenchen and at the Synchrotron Radiation Facility beam lines at the Istitute d'Astrophysique Spatiale in Orsay. In this paper we describe the preliminary results of the calibration of the imaging modes.

The pm-CCD camera is one of the three focal plane instruments of the European Photon Imaging Camera (EPIC) on board the x-ray multi mirror (XMM) mission scheduled for launch in August 1999. The detector consists of four quadrants of three pn-CCDs each, which are integrate don one 4 inch silicon wafer. Each CCD has 200 by 64 pixels with 280 micrometers depletion depth. One CCD of a quadrant is readout at a time, while the four quadrants can be processed independently of each other. Observations of point sources brighter than 11 mCrab in imaging mode will be effected by photon pile-up. However, special operating modes can be used to observe bright sources up to 150 mCrab in Timing Mode with 30 microsecond(s) time resolution and very bright sources up to several Crab in Burst Mode with 7 microsecond(s) time resolution. We have tested and calibrate the flight model FM of the EPIC pn-CCD camera at the long beam test facility Panter near Munich and at the synchrotron monochromators of the Institut d'Astrophysique Spatiale in Orsay, France. In this paper describe the calibration of the pn-CCD detector in high time resolution/bright source operating modes and present preliminary results on the performance in these modes.

In the frame of the XMM project, several test campaigns are accomplished to qualify the optical elements of the mission. The test described in this paper are performed on a XMM flight model mirror module added with a reflection grating assembly (RGA). The mirror module contains 58 x-ray optical quality shells, an x-ray baffle (XRB) to reduce the straylight. This complete XMM flight model mirror assembly (MA) is tested in a vertical configuration at CSL, in a full aperture or partial EUV collimated beam illumination, and with an x-ray pencil beam. One of the advantages of the EUV collimated beam is to verify the correct position of the RGA when integrated in flight configuration on the mirror module structure. This is not possible in x-ray with a finite source distance. The partial EUV illumination is performed to verify the correct integration of the RGA grating stacks. The pencil beam allows to make an accurate metrology of the XRB position, and to verify the positions of the 0, 1 and 2 diffraction order foci. In this paper, the tested module is first exposed, and the approach to qualify the instrument is described. The analysis of the results achieved over the different test configurations is presented. The impact of the environmental test on the reflection grating box is also diagnosed.

We describe simulations of the XMM EPIC instruments which suggests the correct operating mode must be chosen to ensure that spectral analysis of the data is not compromised by 'pile-up' effects. We contrast the performance with the AXAF CCD imaging spectrometer, and show that the XMM EPIC instruments will access a larger range of source fluxes due to a combination of higher effective area and better over- sampling of its mirror response function. Targets exceeding a flux of a few 10^-12 ergs cm^-2s^-1 will be compromised for spectral analysis in AXAF. For XMM, the corresponding flux levels will be 10^-11 ergs cm^-11 ergs cm^-2s^-1. This feature warrants careful attention in calibration.

Multilayer coatings with a small number of layers were designed to give an increase in normal incidence reflectance in the extreme UV over that of the available single layer coatings. Multilayer coatings based on Al, MgF₂ and SiC or B₄C showed higher reflectance than single layers of SiC and B₄C in the spectral region from 57.9 nm to 121.6 nm H Lyman (alpha) line and above. The major increase in reflectance was obtained at wavelengths close to 121.6 nm. Reflectance degraded slightly over time in the same way as single way as single layer coatings. Preliminary result have recently been obtained wit a second design based on a superposition of films of increasing refractive index form outermost to innermost layer, e.g. with multilayer coatings of SiC on B₄C on diamond-like carbon. A combination of both designs, with multilayer coatings of the type Al/MgF₂/DLC/B₄C/SiC, results in further increase in the EUV reflectance, although their stability has not been determined yet.

The process of observing the Sun in the x-ray and extreme UV (XUV), as we are now doing with the TRACE telescope, requires blocking the tremendous amount of visible and RI light that dominates the flux from the sun. If it is not blocked, the energy will swamp the desired spectrum and cause thermal problems inside the telescope. The most effective approach removing the energy is by filtering the incoming light. One of the best materials for eliminating the undesirable wavelengths is aluminum, which is semi- transparent to x-ray and XUV, but blocks most light with wavelength redward of 850 angstrom. Unfortunately the aluminum must be extremely must be extremely thin, < 1600 angstrom thick, to provide the necessary XUV transparency. To overcome the structural problem of supporting large areas of extremely thin aluminum, the aluminum film is bonded on a nickel mesh.

Dispersive interferometric spectroscopy using all-reflective optical elements can be applied to the far UV bandpass to provide very high spectroscopic resolution in a highly compact optical configuration. Dispersive interferometric spectroscopy is therefore well suited for UV and optical space-flight missions. We describe attributes of interferometric spectroscopy and show results from a laboratory demonstration of a high-resolution FUV dispersive interferometric spectrometer.

We report on the current status and performance of prototype hard x-ray optics we are producing for use on the high energy focusing telescope (HEFT) experiment. The baseline substrates are thermally formed glass mirrors that are overcoated with multilayers to provide good performance throughout the 20-80 keV bandpass. Progress made in the thermal forming process as well as in the multilayer performance has allowed production of optics that meet or exceed all HEFT requirements. We present metrology on the substrates and result from x-ray characterization. A novel mounting scheme for the individual telescope shells is currently being tested. If successful the mounting technique will produce a monolithic, extremely stiff and robust optic.

The importance of shields for suppressing neutron-induced background in new classes of (gamma) -ray detectors such as CZT has been emphasized for a variety of reasons. These include high cross-sections for neutron interactions in detector materials and inefficient vetoing of neutrons in conventional active shields. We previously demonstrated through Monte-Carlo simulation how our new approach, supershields, is superior to the monolithic, biatomic neutron shields which have been developed in the past. Here we show the construction of several prototype models for supershields using B and H. We verify the performance of these supershields through lab experiments using radioactive sources and monoenergetic neutron beam at the Radiological Research Accelerator Facility, and compare the results with monolithic neutron shields. We also discuss the implications of this experiment for designs of supershields in general.

The SODART x-ray telescope includes an objective crystal spectrometer (OXS) providing a high energy resolving power by Bragg reflection upon crystals. To cover a wide energy range, 3 types of natural crystals, and a Co/C multilayer structure upon Si are used in the ranges 5-11 keV, 2-5 keV, 0.5-1.2 keV, and 0.16-0.42 keV. All types of crystal besides Si being an ideal crystal have been calibrated individually and after gluing onto the Bragg panel. The x-ray calibration procedures and result are discussed below. A ray-tracing program using the OXS calibration data and simulating the x- ray photon reflection on the mentioned crystals and the multilayers has been developed and is described also.

We report the first results of the ground test of the Hard X-ray Detector (HXD) on board the Astro-E mission, by means of the newly developed Ground Support Equipment (GSE). Astro-E will be launched in 2000 by a Japanese M-V rocket. In order to verify the detector system during the limited time before launch, fast and versatile GSE is necessary. For this, we have developed a flexible test system based on nine VME I/O boards for a SUN workstation. These boards carry reconfigurable Field Programmable Gate Arrays with 50,000 gates, together with 1 Mbyte SRAM devices tightly coupled to each FPGA device. As an application of using this GSE, we have tested the performance of a phoswitch unit of the Flight Model of the HXD. In this paper, we present a schematic view of the GSE highlighting the functional design,and the result of our ground test of the HXD-sensor under the high count rate environment expected in orbit.

The Hard x-ray Detector (HXD) is one of three instruments on the fifth Japanese x-ray astronomy satellite, Astro-E, scheduled for launch in 2000. The sensitivity of the Astro-E HXD will be higher by more than one order of magnitude than that of nay previous instrument between 10 keV and several 100 keV. The electronic system is designed to handle many independent data channels from the HXD within the limitation of size and power consumption required in Astro-E. In this paper, we will present the design and the preliminary performance of the processing electronic system.

CdZnTe (CZT) is a room-temperature semiconductor well suited for high energy x-ray astronomy. Knowledge of its background properties is essential for optimizing CZT based instruments. To study its background, we flew two CZT detectors on dedicated high altitude balloon flights from Fort Sumner, NM, the first in October 1997 and the second in May 1998. The first detector is a 12 by 12 by 2 mm³ detector with orthogonal crossed strips and the second is a standard 12 by 12 by 2 mm ³ planar detector. The cross strip detector has 500 micron pitched electrodes plus anode 'steering electrodes' to improve the anode charge collection. The energy range for these flights was 20 to approximately 350 keV. We have found a preliminary background level in 20-40 keV of 8.6 by 10^-3 cts/cm²-s-keV using passive 2 mm PbSnCu shielding and 6 by 10^-4 cts/cm²-s-keV using active collimated schemes for the first position-sensitive CAT detector at balloon altitudes.

We report results of an experiment conducted in May 1997 to measure CdZnTe background and background reduction schemes in space flight conditions similar to those of proposed hard x-ray astrophysics missions. A 1 cm² CdZnTe detector was placed adjacent to a thick BGO anticoincidence shield and flown piggy backed onto the EXITE2 scientific balloon payload. The planar shield was designed to veto background counts produced by local gamma-ray production in passive material and neutron interactions in the detector. The CdZnTe and BGO were partially surrounded by a Pb-Sn-Cu shield to approximate the grammage of an x-ray collimator, although the field of view was still approximately 2 (pi) sr. At an altitude of 127000 feet we find a reduction in background by a factor of 6 at 100 keV. The non-vetoed background is 9 by 10⁴ cts cm^-2s^-1 at 100 keV, about a factor of 2 higher than that of the collimated EXITE2 phoswich detector. We compare our recorded spectrum with that expected from simulations using GEANT and find agreement within a factor of 2 between 30 and 300 keV. We also compare our results with those of previous experiments using passive lead and active NaI shields, and discus possible active shielding schemes in future astronomy mission employing large arrays of CdZnTe detectors.

The Joint Astrophysical Plasmadynamic Experiment is a high- resolution extreme UV spectrometer which operates at near- normal incidence and incorporates the most recent developments in reflecting multilayer gratings. The spectrometer comprises the following principal elements: collimators which define the 1.2 degrees field of view, a spherical multilayer-coated grating which consists of 4 segments, each 8 cm by 16 cm in area and with a focal length of 2.2 m, and a microchannel plate imaging detector. The collimator is an adaptation of a previous design which was modified to minimize the input of scattered airglow radiation while maintaining the maximum effective area within the desired field of view. This is achieved by blackening the collimator surfaces with an EBONOL-C process. In this paper we will discuss the design requirements and manufacturing techniques for the collimator.

In this paper will be investigated the possibility to exploit the Bragg diffraction from mosaic crystals as a reflection technique for the realization of lobster-eye telescopes for hard x-rays. In particular for our study we will assume the particular lobster-eye configuration also known as Schmidt imager. This geometry is particularly interesting not only why it can allow a 1D focusing over large fields of view but also because it is relatively easy to be realized, being based on flat reflectors. Until now lobster-eye telescopes have been mostly studied for applications in the classical x-ray band, making use of total external reflection at grazing angles mirrors. However, due to the much larger reflection angles typical of Bragg diffraction it is possible to extend the use of the Schmidt geometry also to the hard x-ray energy band. Here, in addition to a general description of the behavior of Schmidt telescopes based on the Bragg diffraction technique, we will report also some theoretical evaluations about the performances achievable with these devices.

Nb-Al-AlO_x-Al-Nb Superconducting Tunnel Junctions (SJT's) have been extensively investigated by a number of groups as potential next generation high resolution photon detectors for x-ray astronomy. The response of such devices has been studied from EUV to soft x-rays, using highly monochromatic synchrotron radiation. Based on the current understanding of the charge production and tunneling mechanisms in STJ's, it would be expected that at lower energies, the responsivity of the detector would increase as the role of self-recombination of charge carriers into Cooper pairs declines in importance. Here responsivity is simply defined as the measured charge per eV of photon energy deposited in the junction. This trend however was not observed till the lowest energies. Below a threshold energy the responsivity fell, reaching a minimum level, after which it became constant. This minimum level is lower than the responsivity at 6 keV, by a factor up to 5, leading to a clear mismatch between x-ray and EUV performance. This paper summarizes the observations, and presents quantitative explanations for the feature, based on the existence of local traps in the STJ.

The next generation of superconducting tunnel junctions based on lower critical temperature superconductors such as hafnium are now under development. Such a material with a bandgap well below a meV has the potential to provide very high wavelength resolution at soft x-ray wavelengths. In this paper we report the first results on the characteristics of hafnium thin films deposited on r-plane sapphire. The physical properties of these films together with the electrical and superconducting characteristics are described. Currently the electrical conductivity of these films are limited by scattering from the films columnar grain structure. The superconducting transition temperature has been found to vary from approximately 137-200 mK, somewhat higher than that in the bulk, while the critical magnetic field applied in a direction parallel to the film is determined to be approximately 750 gauss far, larger than that observed in bulk hafnium.

The next generation of x-ray astrophysics missions may well extend the energy range beyond the current limit of 10 keV suited by existing x-ray astrophysics space missions such as ASCA or future missions such as AXAF and XMM to be launched in the next few years. To address with a high degree of sensitivity the astrophysical problems associated with x-ray emission in the x-ray band from 10 keV to 100 keV a significant extension of the capabilities of focusing x-ray optics and imaging broad band hard x-ray detectors will be required. In this paper we present experimental result from the study of the x-ray energy response form two compounds semiconductors: GaAs and CdZnTe. The limitations on the energy resolution due to leakage current, incomplete charge collection and spatial non-uniformities are presented based on the detailed mapping of the energy response of each type of detector to highly monochromatized synchrotron radiation and radioactive sources in the photon energy range from 1 keV to 60 keV. Correlation of the observed response variations with crystal morphology and imperfections are described using collimated synchrotron radiation in the soft x-ray energy range as a diagnostic tool. Energy resolutions around and well below 1 keV have been measured at photon energies between 1 keV and 60 keV. It is clear that based on these result imaging arrays could be fabricated which will provide an important advance in the capabilities of detectors in this energy range.

The development of superconducting tunnel junction detector arrays has now reached a stage where practical applications in x-ray astrophysics can be considered. The arrays are based on tantalum devices, with operating temperatures of about 0.4 K. The energy resolution of these detectors is limited by Fano and tunnel noise to about 3 eV at 1 keV. The first result from a 6 by 6, tantalum based array are presented. These medium sized arrays have good energy resolution and adequate absorption efficiency. The possibility to operate and read out simultaneously more than one channel has been demonstrated. The uniformity of the array elements both in charge output and energy resolution is good, with the overall responsivity across the array varying by less than 5 percent. The energy resolution at x- ray energies is dominated by spatial non-uniformities in the individual pixel response. Such a performance allows us now to consider the development of a x-ray cryogenic camera based on STJ detectors. Provided the field coverage of these cameras can be extended through the development of larger format detector arrays, they have the potential to form a major basis for astrophysics instrumentation in the next century.

Hot-electron bolometers have wide applicability. Both IR bolometers as well as x-ray micro-calorimetric are currently being developed by the Space Research Organization Netherlands. The IR bolometers are equipped with space impedance matched spider web absorbers. The detectors have voltage biased superconducting transition edge thermometers. When operated in the negative feedback regime, their response time is appreciably reduced. As will be shown, electrical test give a wealth of information on the bolometer performance. In this paper typical bolometer parameters such as current-voltage characteristics, time constants and noise equivalent power are described. Electrical test results are presented. For an IR bolometer a loop gain of 500 combined with an electrical NEP of 2 by 10^-17 W/(root)Hz has been realized.

We report on the x-ray response function of the x-ray CCD camera (XIS) on-board the x-ray Astronomical Satellite, Astro-E, which will be launched in February of 2000. XIS is prepared by an international team, comprising MIT, ISAS, Osaka Univ. and Kyoto Univ. We evaluate the x-ray response on the high energy band of 1.5-10 keV. Fluorescent lines from Al, Cl, Ti, Ni, Fe, Zn are irradiated on the CCD chips, and are use to construct the response function. Details of the response function; energy-scale linearity, energy resolution, quantum efficiency and etc., are given as a function of incident x-ray energies. The response function is also demonstrated to depend largely on event-selection and re-construction criteria.

The x-ray imaging spectrometers (XIS) are x-ray CCD cameras on-board the Astro-E satellite launched in 2000. The XIS consists of 4 cameras, each of them will be installed on a focal plane of the Astro-E X-ray Telescope (XRT). The XIS not only have a higher sensitivity, which comes from a larger effective area of the XRT and thicker depletion layers of the XIS CCDs, than ASCA SIS. But also have several features that will overcome the radiation damage effects anticipated in the orbit. The calibration experiment at Osaka focuses on the soft x-ray response of the XIS. The calibration system employs a grating spectrometer which irradiates the CCD with dispersed x-rays. We have obtained preliminary results on the XIS proto model, including the energy-pulse-height relation, the energy-resolution relation, and the quantum efficiency at the energy range of 0.25-2.2 keV.

The efficiency of lumogen coated CCDs has been measured as a function of wavelength in the range from 171 angstrom to 1800 angstrom. A decrease in efficiency has been observe as a function of exposure of the lumogen to high levels of radiation at UV and extreme UV wavelengths. The drop in efficiency was found to be most rapid at lower exposure levels, decreasing in rate as the dosage increased.

A 4096 pixel Photon Counting Chip (PCC) has been developed and tested. It is aimed primarily at medical imaging although it can be used for other applications involving particle counting. The readout chip consists of a matrix of 64 by 64 identical square pixels, whose side measures 170 micrometers and is bump-bonded to a similar matrix of GaAs or Si pixel diodes covering a sensitive area of 1.18 cm². The electronics in each cell comprises a preamplifier, a discriminator with variable threshold and a 3-bit threshold tune as well as a 15-bit counter. Each pixel can be individually addressed for electrical test or masked during acquisition. A shutter allows for switching between the counting and readout modes and the use of static logic in the counter enables long data taking periods. Electrical test of the chip have shown a maximum counting and readout modes and the use of static logic in the counter enables long data taking periods. Electrical test of the chip have shown a maximum counting rate of up to 2 MHz in each pixel. The minimum reachable threshold is 1400 e with a variation of 350 e rms that can be reduced to 80 e rms after tuning with the 3-bit adjustment. Electrical noise at the input is 170 e rms. Several read-out chips have been bump bonded to 200 micrometers thick GaAs pixel detectors. Test with (gamma) -ray and (beta) sources have been carried out. A number of objects have been imaged and a 260 micrometers thick aluminum foil which represents a contrast to the surrounding air of only 1.9 percent has been correctly imaged.

The Monolithic Systems Development Group at the Oak Ridge National Laboratory has been greatly involved in custom mixed-mode integrated circuit development for the PHIENIX detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory and position-sensitive germanium spectrometer front-ends for the Naval Research Laboratory (NRL). This paper will outline the work done for both PHENIX and the Naval Research Laboratory in the area of full-custom, mixed-signal CMOS integrated electronics. The PHENIX detector is a large multi-component detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. PHENIX has over 400,000 channels of electronics, most of which is implemented using custom integrated circuits. We presently have responsibility for developing and manufacturing electronics for the event vertexfinding subsystem, the pads tracking subsystem, the electromagnetic calorimeter subsystem, and the muon tracking/identification subsystems. We have developed an architecture utilizing simultaneous read-write analog memories used throughout the detector that allows data to be continuously taken even during event readout (a deadtime-less system). The manufacturing technologies being used range from multi-layer printed-circuit boards to multi-layer, multi-chip modules (MCMs). The germanium spectrometer electronics for the Naval Research Laboratory consist of low-noise preamplifier-shapers-peak stretchers and discriminators. The preamplifiers have been optimized for detector capacitances of approximately 10 pF and shaping times of 5-10 .ts. This paper will present the architectures chosen for the various PHENIX detectors which include position-sensitive silicon, capacitive pixel, and phototube detectors, and performance results for the subsystems as well as a system description of the NRL germanium strip system and its performance. The performance of the custom preamplifiers, discriminators, analog memories, analog-digital converters, and control circuitry for all systems will be presented.

Keywords: Physics, electronics, CMOS

Solid state solutions for imaging are mainly represented by CCDs and, more recently, by CMOS imagers. Both devices are based on the integration of the total charge generated by the impinging radiation, with no processing of the single photon information. The dynamic range of these devices is intrinsically limited by the finite value of noise. Here we present the design of an architecture which allows efficient, in-pixel, noise reduction to a practically zero level, thus allowing infinite dynamic range imaging. A detailed calculation of the dynamic range is worked out, showing that noise is efficiently suppressed. This architecture is based on the concept of single-photon counting. In each pixel, we integrate both the front-end, low-noise, low-power analog part and the digital part. The former consists of a charge preamplifier, an active filter for optimal noise bandwidth reduction, a buffer and a threshold comparator, and the latter is simply a counter, which can be programmed to act as a normal shift register for the readout of the counters' contents. Two different ASIC's based on this concept have been designed for different applications. The first one has been optimized for silicon edge-on microstrips detectors, used in a digital mammography R and D project. It is a 32-channel circuit, with a 16-bit binary static counter.It has been optimized for a relatively large detector capacitance of 5 pF. Noise has been measured to be equal to 100 + 7*Cd (pF) electron rms with the digital part, showing no degradation of the noise performances with respect to the design values. The power consumption is 3.8mW/channel for a peaking time of about 1 microsecond(s) . The second circuit is a prototype for pixel imaging. The total active area is about (250 micrometers )**2. The main differences of the electronic architecture with respect to the first prototype are: i) different optimization of the analog front-end part for low-capacitance detectors, ii) in- pixel 4-bit comparator-offset compensation, iii) 15-bit pseudo-random counter. The power consumption is 255 (mu) W/channel for a peaking time of 300 ns and an equivalent noise charge of 185 + 97*Cd electrons rms. Simulation and experimental result as well as imaging results will be presented.

The silicon microstrips tracker for CMS at LHC demands fast, radiation-hard electronics. An original solution was proposed for the processing of signals from silicon detectors. This technique allows precise reconstruction of the arrival time of the particles, even with a 'slow' shaping time and a limited power budget. This idea was already implemented in the APV6 circuit, designed in a bulk CMOS technology from Harris.In this paper, we present the version (APVD) designed in the CMOS SOI radiation hard technology DMILL by a French-British collaboration. The APVD is a 128-channel mixed analogue-digital: each channel includes a low-noise charge preamplifier, a CR-RC shaper with a peaking time of 50 ns, an analogue pipeline where the signal is sampled at 40 MHz, an analogue pulse shape processor and a current output multiplexer. The circuit integrates an 12C interface for easy control of the operating parameters. All the control current and voltages as well as a calibration pulse are generated internally by dedicated blocks. The design and first experimental results from the first version of the 128-channel APVD, will be presented in this paper. They show the circuit is fully functional and can be used for the CMS experiment.

We present a VLSI digital-analog readout electronic chain for silicon microstrip detectors. The characteristics of this circuit have been optimized for the high resolution tracker of the CERN CMS experiment. This chip consists of 128 channels at 50 micrometers pitch. Each channel is composed of a charge amplifier, a CR-RC shaper, an analog memory, an analog processor, an output FIFO which is read out serially by a multiplexer. This chip has been processed in the radiation hard technology DMILL. This paper describes briefly the architecture of the circuit and presents test results of the 128 channel full chain chip before and after irradiation up to 10 Mrad.

Recently polycrystalline mercuric iodide have become available, for room temperature radiation detectors over large areas at low cost. Though the quality of this material is still under improvement, ceramic detectors have been already been successfully tested with dedicated low-noise, low-power mixed signal VLSI electronics which can be used for compact, imaging solutions. The detectors used are of different kinds: microstrips and pixels; of different sizes, up to about 1 square inch; and of different thickness, up to 600 microns. The properties of this first-generation detectors are quite uniform from one detector to another. Also for each single detector the response is quite uniform and no charge loss in the inter-electrode space have been detected. Because of the low cost and of the polycrystallinity, detectors can be potentially fabricated in any size and shape, using standard ceramic technology equipment, which is an attractive feature where low cost and large area applications are needed.

Recently the need for a higher level of integration in x-ray and gamma ray sensor systems has lead to several approaches of integrating read out electronics in a monolithic integrated circuit (IC). Typically these ICs are limited in their application to a specific problem. The Readout Electronics for Nuclear Applications (RENA) Integrated Circuit, presented here, is targeted for use in many energy sensor applications. The RENA IC has 32 parallel signal channels with, signal polarity control for use with either electron or hole collection from detectors. The input amplifier is optimized for a detector capacitance of 6 pF, but may be used with detector capacitances up to 50 pF. The Shapers' peaking time is digitally selectable, for optimum noise filtering, with peaking times geometrically spaced from 400 ns to 6 microsecond(s) . Up to 16 RENA ASICs may be daisy chained together to make a system with 512 detector channels. Various trigger modes are available with a user- defined threshold over the full signal range of 50K electronics. The circuits in the RENA are designed to be stable with no 'tweaking' control,s which allows an easy user interfaces.

A mixed signal Application Specific Integrated Circuit chip for front end readout electronics of position sensitive solid state detectors has been developed. It is called RENA. This chip can be used for large number of channels and high energy resolution astrophysics and nuclear physics detectors. It can also be used for medical and industrial imaging of x-rays and gamma rays. The RENA chip is a monolithic integrated circuit and has 32 channels with low noise charge sensitive amplifiers followed by a polarity amplifier and a high quality shaper circuit. It works in pulse counting mode with good energy resolution. It also has a self triggering output which is essential for nuclear applications when the incident radiation arrives at random. Different, externally selectable, operational modes that include a sparse readout mode are available to increase data throughput. It also has externally selectable shaping times. A full scale prototype RENA chip has been manufactured. The preliminary results of test done on the prototype chip are presented.

Two identical CsI-coated, low noise microchannel plate (MCP) detectors were taken to the Daresbury Synchrotron Radiation Source (SRS) to measure their quantum efficiencies over two different energy ranges - 450 eV to 1200 eV and 4.5 eV to 9.5 eV. The SRS was run in low ring current with the beam flux monitored using single wire gas proportional counters. We present accurate measurements of edge-related absolute quantum efficiency features due to the CsI photocathodes. This data will be incorporated into the calibration program of the Advanced X-ray Astrophysical Facility High Resolution Camera.

We report upon our continued investigation of a chemical treatment method for improving the quantum detection efficiency and gain of photon counting microchannel plate detectors for vacuum UV and soft x-radiation. The process improved MCP quantum detection efficiency for approximately 100-1200 angstrom radiation by a factor of 1.5-2. The performance results of DIP treated microchannel plates are summarized.

Microchannel plate (MCP), detectors are currently being used with great success on many recent NASA and ESA missions. These include SOHO, ALEXIS, EUVE, ACE, ORFEUS and sounding rocket experiments. Similar devices are in preparation for satellites such as IMAGE, FUSE, COS-HST, and the GALEX mission. For some of these missions we have pioneered the development of planar and multilayer centroid position readout anodes in the form of delay line image readout system for high resolution, large format, photon counting MCP detectors. Derived from these concepts we have devised a new type of readout system, the cross strip anode, for future mission applications which may offer significantly performance advances. Our objective is to provide a highly adaptable sensor for sub-orbital and satellite instruments which combines very high sped photon counting with high spatial resolution, low power, low mass/volume, high sensitivity, low background and high time resolution. The multilayer crossed strip position encoding anode uses two sets of orthogonal strip arrays to collect charge from a microchannel plate stack. Event position centroids are then computed using multichannel high sped electronics. A prototype system is currently under evaluation and we ultimately expect to achieve high resolution at low gain, with low power, high counting rates and low mass for a wide range of adaptable senor formats.

We have developed compact microchannel plate detectors utilizing a cross delay line readout system for the IMAGE- FUV Spectrographic Imager. We present a description of the detector head assembly and performance data typical for both detectors. Both detectors are nearly identical, the only different being the position of the input window on the front cover. Each detector, optimized for operation in the far UV with a KBr photocathode, provides high spatial resolution and good linearity over a 20 mm square format.

The FUV Spectrometer Imager for IMAGE is designed to simultaneously take aurora images at 1218 and 1356 angstrom. This paper describes the alignment procedure and performance results. The Spectrograph alignment requires to efficiently reject the Lyman-(alpha) line at 1216 angstrom. The imager alignment requires to tune optical components until finest imaging.

The IMAGE FUV-SI is simultaneously imaging auroras at 121.8 nm and 135.8 nm. The spectrograph design challenge is the efficient rejection of the intense Lyman-alpha emission at 121.6 nm while passing its Doppler-shifted component at 121.8 nm. The FUV-SI opto-mechanical design, analysis integration, and verification of performances against environment are discussed in this paper. In absence of STM environmental constraints at subsystem levels are derived analytically from F.E.M. and used for pre-qualifying optical subsystems.

Minisat 01 is the first of a series of small satellites developed by INTA in Spain. In this case, it as a multi- purpose scientific mission. It was successfully launched on April 21 of last year using a Pegasus rocket. Minisat 01 caries on-board a payload with two astronomical instruments: EURD and LEGRI. EURD is a high sensitivity double spectrometer for the measurement of diffuse cosmic radiation in the extreme UV range, from 350 to 1100 angstrom. LEGRI is a hard x-ray imaging telescope with a coded mask and an array of HgI₂ and CdZnTe detectors. News about the performance of Minisat 01 in orbit and its scientific results are presented together with a brief description of the instrumental and their main objectives. The continuation of the program is ensured by several future Minisat missions, now under development or study.

HEXIS is a MIDEX-class mission concept for x-ray astronomy. Its objectives are to improve our knowledge of the high energy x-ray sky by increasing the number of sources above 20 keV to > 2,000, discovering transient sources such as x-ray novae and gamma-ray bursts, and making spectral and temporal studies of the sources. With mission life > 3 years, a 1-year all-sky survey sensitivity of approximately 0.3 mCrab, and continuous monitoring of the entire visible sky, HEXIS will provide unprecedented capabilities. Source positions will be determined to accuracies of a few arcmin or better. Spectra will be determined with an energy resolution of a few keV and source variability will be studied on time scales from < 1 sec to years. In addition, 10 times more sensitive studies of limited fields will be performed at the same time. Gamma-ray bursts will be detected about 4 times/week at about the same sensitivity as BATSE and the sensitivity to nova-like x-ray transients will be approximately 6 mCrab in one day. HEXIS contains a set of coded mask imagers that use position-sensitive CZT detectors operating from approximately 5 keV to 200 keV. Detector planes are built with 41 cm² CZT detector modules which employ crossed-strip readout to obtain a pixel size of 0.5 mm. Nine modules are grouped in a 369 cm² array for each imager. In the past 2 years significant progress has been made on techniques requires for HEXIS: position-sensitive CZT detectors and ASIC readout, coded mask imaging, and background properties at balloon altitudes. Scientific and technical details of HEXIS are presented together with result form tests of detectors and a coded mask imager.

We report preliminary measurements of the air UV fluorescence light yield as a function of pressure using as a stimulus hard x-rays. For comparison measurements in pure nitrogen are also reported. Knowledge of the air UV fluorescence light yield induced by hard x-rays is needed in order to evaluate the capability to detect, in an AIRWATCH FROM SPACE experiment, Gamma Ray Burst (GRB) events. The experiment was carried out a the LAX x-ray facility in Palermo, by using an high flux collimated x-ray photon beam. The experimental result indicate that the fluorescence yield is inversely proportional to the filling pressure. At pressures below 30 mbar, corresponding to the value for the upper atmospheric layers in which the X and gamma ray photons of the GRBs are absorbed, about 0.1 percent of the total energy of a GRB is transformed in UV photons. This makes possible the observation of the GRBs with the technique proposed in the AIRWATCH FROM SPACE experiment.

The design of an Airwatch type space mission can greatly benefit from a flexible simulation code for establishing the values of the main parameters of the experiment. We present her a code written for this purpose. The cosmic ray primary spectrum at very high energies, the atmosphere modeling,the fluorescence yield, the photon propagation and the detector response are taken into account in order to optimize the fundamental design parameters of the experiment, namely orbit height, field of view, mirror radius, number of pixels of the focal plane, threshold of photo-detection. The optimization criterion will be to maximize counting rates versus mission cost, which imposes limits both on weight and power consumption. Preliminary result on signals with changing energy and zenith angel of incident particles are shown.

A basic problem in an AIRWATCH based experiment is the development of suitable trigger, read-out and data handling techniques. Considering a matrix of image elements to read- out, ideally one would like to have as many position and timing channels as pixels in the image, but for obvious practical and cost reasons, this solution is not always applicable. In fact the complexity of the electronics demanding a huge amount of channels, is not generally suitable for mission base don satellites, where stringent limitations are present for what concerns power supply, weight and telemetry. One way to deal with such a problem, in the assumption of using a fast detector capable of detecting single photoelectron, is to reduce the number of position and timing channels without significant loss of performance. We present a modular read-out electronics system called 'FIRE'. The modular hierarchical organization of FIRE allow to register X-Y position and arrival time of the single photoelectrons. To check the validity of the method, a set of simulated data was produced and analyzed. Results are illustrated both for the read-out performance and the event reconstruction efficiency.

The discovery of the extreme energy cosmic rays (EERC) with energy greater than 10²⁰ eV has opened a new research branch of astrophysics on both observational and interpretative point of views. Together with the EECR one has also to consider the neutrino component which, independently on its primary or secondary origin, can reach comparable energies. These particles can be detected through the giant showers (EAS) produced in the Earth atmosphere and the induced fluorescent molecular nitrogen emission. Observing the EECR 'signals' is very difficult; we need forefront technology or new developments. The main reason is that their flux is very weak, typically of the order of a few events/year/1000 km² per EECR of E approximately equals 10²⁰ eV. The proposed Airwatch mission, base don a single orbiting telescope which can measure both intensity and direction of the EAS, impose new concepts for the detectors; single photon sensitivity, fast response of the order of few microseconds with sampling times of tenths of nanoseconds, low noise and good S/N ratio, large area, adaptability to a curved surface. Fortunately the spatial resolution requirements are somehow relaxed. The peculiar characteristics of this application are such that no available detectors satisfies completely the requirements. Therefore the final detector has to be the result of a R and D program dedicated to the specific problem. In this paper we survey a number of possible detectors and identify their characteristics versus the Airwatch mission requirements.

The Airwatch optical system is shown to have minimal resolution requirements while requiring both a large entrance aperture and a simple configuration. Several single and double element optical systems are discussed, and Fresnel lenses are shown to be a promising candidate for the Airwatch optical system. Design techniques of Fresnel lens systems are presented, and it is shown how complex Fresnel lenses systems can be modeled and analyzed using commercially available ray tracing programs. It is then demonstrated how the performance of the single element system can be improved through the use of a two element configuration. Specifically, focal surface curvature can be eliminated, and the FOV of a single aperture can be increased by switching to the two element design. Techniques for reducing the size of the focal surface are also discussed. Finally, current research efforts involving the construction of prototype Fresnel lens system are explained.

One of the most challenging tissues in Astroparticle Physics is represented today by the observation of the energy spectrum of the Extreme Energy Cosmic Radiation. The very existence of particles with energy above 10²⁰ eV and of neutrinos of comparable energy raises fundamental scientific questions in connection with their origin and propagation in the interstellar/intergalactic space. These particles can be detected through the gain showers produced in the Earth Atmosphere. The shower development is accompanied by emission of fluorescence in the atmosphere, in particular that induced in Nitrogen with characteristics spectral lines in the UV. Following a first suggestion by J. Linsley in the early 1980's, taken over by Y/ Takahashi, the fluorescence observation can be advantageously carried out by space. By using wide angel optics with large collecting surface, we can monitor a target area of atmosphere of the order of millions square kilometers x sr and corresponding mass above 10¹³ tons, allowing the detection of the very small flux values typical of the EECR and making possible the search of the elusive high energy neutrinos. AIRWATCH follows this approach. We describe the main scientific goals for the investigation of the EECR, High Energy neutrinos and of the Gamma Ray Bursts, together with the relevant connections to the problem of their origin. The experimental framework is outlined and a description is given of the space mission and of the observational strategy.

The SUMER spectrograph on the Solar and Heliospheric Observatory utilizes two cross delay-line (XDL) microchannel plate (MCP) photon counting detectors. Detailed housekeeping telemetry from SUMER allow us to track many characteristics of its in-orbit detector behavior. Since there is a finite quantity of charge that can be extracted form an MCP detector, we observe some variation in the response of such a detector over the course of its lifetime. Information from the housekeeping data reveals the expected variation in gain for both spectral and spatial dimensions. We also present SUMER history memory files which illustrate the pattern of count extraction arising from repeated observations of emission line spectra. In addition, we compare pre-flight and in-flight flat fields for both SUMER detectors. The in- flight flat fields include features corresponding to regions of high charge extraction. Evidence for displacement of low gain events is also presented, and the importance of performing a pre-launch MCP 'scrub' is emphasized.

The Naval Research Laboratory has built five UV spectrographs for the Air Force Defense Meteorological Satellite Program. These sensors, known as the Special Sensor UV Limb Imager, will provide limb observation of airglow emissions from 75 to 750 km over the spectral range of 800 to 1700 angstroms. Each spectrograph employs an imaging detector with a micro-channel plate intensifier and a wedge and strip anode. The detectors are windowless and require a hermetically sealed door mechanisms to prevent water vapor from destroying the Cesium Iodide photocathode. Although the first of these sensors will not be launched until 2001, they are being maintained for flight readiness at NRL. An ongoing effort at NRL is to determine the senor deficiencies and investigate possible improvements. Since the performance of the spectrograph is strongly dependent on the quality of the detector, NRL has identified the refurbishment of the detector as the highest priority to improve the overall capabilities of the sensor. The goals of the refurbishment was to improve the detector imaging quality, counting efficiency, resolution, background uniformity, long term vacuum storage, and serviceability.

THe resolution and sensitivity of the special sensor UV limb imager (SSULI) spectrograph depend strongly on the quality of the detector. As a result, the Naval Research Laboratory (NRL) has given high priority to the refurbishment of a damaged detector and tow spares to evaluate possible improvements to the overall capabilities of the SSULI sensor. The goal of the detector refurbishment is to improve the detector imaging quality, counting efficiency, resolution, background uniformity, long term vacuum storage, and serviceability. Estimated improvement sin the sensor performance will be used to determine the feasibility of refurbishing all the remaining detectors and spectrographs. The NRL is currently refurbishing a SSULI detector. The completion of the detector refurbishment includes a detailed analysis of the detector performance. This paper describes the performance of the refurbished SSULI detector and a comparison tot he original detectors. Included is a detailed description of the testing methods and result as well as the impact to the performance of the SSULI spectrograph. The test that will be reported are counting efficiency, image uniformity and quality, gain variability, background uniformity, and anode alignment.

Traditional charge division readouts used in microchannel plate detectors, such as the Wedge and Strip anode, while simple in operation, can suffer from positional nonlinearities and instability in absolute positioning. The cause of both effects is due to the ratio of charges collected on the individual electrodes not accurately representing the electrode geometry. This is primarily a result of redistribution of secondary electron is produced from the anode surface among the anode electrodes. The Vernier position readout is an analogue charge division electronic readout capable of exceptional position resolution and linearity. In order to exploit this performance to the full and produce a device with absolute position stability, the problem of second are electron redistribution has had to be overcome. We describe the result of a series of experiments to determine the physical processes producing charge redistribution in the Vernier anode. Understanding of the mechanisms underlying this phenomenon has allowed the modification of the detector, anode pattern design and data acquisition software to alleviate the limitations imposed. These modifications are also applicable to other anodes relying on analogue charge division and provide improvements in absolute positional stability and linearity. We present measurements of the imaging performance of a microchannel plate detector using the Vernier anode. These results show the high spatial resolution, improved positional stability and linearity that can be achievable by controlling secondary electron redistribution.

We investigate the role of the mechanical and chemical composition of the anode on the performance of charge division readout systems in microchannel plate (MCP) based detectors. Typically, in these detectors, electrons from the MCP gain stage have sufficient energy to excite secondary electrons from the anode surface. Normally, these are recollected by the anode and can thus modify the effective charge footprint. These secondary electrons can also mediate charge redistribution between the anode electrodes in the presence of differential voltages. We describe an experiment to investigate the error in electrode charge ratio of a charge division anode pattern. The detector used, comprised a microchannel plate intensifier stack with an intermediate grid between MCP and anode for secondary electron control and measurement. The intermediate grid is used to either suppress or collect secondary electrons produced by the anode depending on the configuration of detector voltages. Anode patterns were manufactured on a variety of substrates. One anode pattern design was used for all experiments and consisted of several sets of fixed electrode ratios. The effect of the anode surface finish and electrode composition on the charge ratios was measured for different substrates.

IBIS is an instrument designed to produce images of the gamma-ray sky in the 15 keV to 10 MeV energy range with few arcminute resolution over a wide field of view. This will be obtained by deconvolving the shadowgram projected by a coded mask onto two pixelated detectors layers. One, ISGRI is made of 16384 CdTe elements operating in the low energy range, the other, PICsIT is made with 4096 CsI scintillating crystals coupled to PIN Photodiodes and it operates in the high energy range. Theoretical performances of the overall increments have been described in a dedicated session at SPIE in August 1996. Now, after a short description of the detector assembly and test procedures, the performances of a significant number of the PICsIT detector units are reported.

We have built a back-illuminated, silicon x-ray pixel detector which is bump bonded to an array of readout electronics. The system is intended for x-ray spectroscopy measurement in the 1 keV-25keV range with a resolution of 250eV FWHM. The readout electronics consists of an array of 16 by 16 preamplifiers on the bump bonded integrated circuit, this unit is wire bonded to two 128 channel integrated circuits which have signal shaping, peak-hold and sparcification logic. This paper describes the construction of the silicon detector, the readout electronics and the performance of these components. The energy range of the detector system can be increased by using a GaAs or CdZnTe detector instead of the 300 micrometers -500 micrometers thick silicon pixel detector described here.

Orbiting x-ray and XUV observatories are pushing the achievable image resolution and with it, the requirements on mounted mirror performance. The transitional region and coronal explorer (TRACE) observatory uses a center mounted primary mirror that must maintain its orientation in roll as well as pitch and way. A conformable bedding was used to support the mirror against the expected launch loads in a re-assembled mount, without inducing unacceptable mirror distortion. The novel mirror mount design is discussed, and its resulting performance described. This paper outlines the TRACE primary mirror assembly design. The evolution of the design from the Space Weather and Terrestrial Hazards assembly to the TRACE baseline design is presented.

We report here the experimental result between the x-ray interaction location and the split event. The x-ray interaction position can be localized in subpixel scale using the mesh experiment. We found that the center of gravity of the split even well correlated with the x-ray interaction position. We analyzed the data using two models, assuming the charge cloud shape: one is the rectangular model and the other is the Gaussian model. Although we could not distinguish between them, we obtained the standard deviation of the charge cloud shape of 1-2 micrometers for x-rays of Y-L, Ag-L and Ti-K. When the x-rays enter near the pixel boundary, the charge splits into adjacent pixel, in which we can achieve the accuracy of the x-ray interaction position of subpixel spatial resolution of 1.5-2.2 micrometers . We expect that the x-ray CCD can function as x-ray imager with subpixel resolution useful for the high spatial resolution optics.

The EUV grating spectrograph (EGS) as part of the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) solar EUV experiment (SEE) presents a number of performance challenges for its microchannel plate (MCP)- based detector. The EGS measures the solar spectral irradiance from 25 to 200 nm. The intensities of the line and continuum emissions over this spectral range vary by up to five orders of magnitude. While a variety of transmission filters are strategically used to bring the signal over the entire spectrum into the dynamic range of a single chevron pair of MCPs, a number of concerns regarding the characteristic behavior of MCPs remain. The nominal TIMED mission is two years while the extended mission potentially doubles to four years. Over this period, the MCP response is expected to change to some extent. Detailed changes in MCP performance are notoriously application dependent,however. In order to better anticipate and accommodate these changes over the duration of the mission as well as to potentially enhance detector performance, we are performing a series of life-tests on a variety of MCPs. In these tests we characterize MCP gain, pulse height distribution, quantum detection efficiency, and linearity as function of accumulated charge and exposure to atmosphere. Here we report on the result of these test.s

An x-(gamma) ray detector constituted by a 1 mm² Schottky junction on Vapor Phase Epitaxy gallium arsenide is presented. The junction has been characterized by means of capacitance and current vs. voltage analyses, finding a good agreement with the theory. Thanks to the low impurity concentration of the undoped epitaxial layer, an active region depth of 20 micrometers is reached at 100 V bias voltage. A reverse current density of 18 nA/cm² has been measured at 290 K in operating condition. The detector has been tested at room temperature with a ²⁴¹Am X-(gamma) source; the pulser line shows 1.41 keV FWHM and the 59.54 keV line shows 1.47 keV FWHM, corresponding to an energy resolution of 2.5 percent.

The Global UV imager (GUVI) is an imaging spectrometer on the NASA TIMED spacecraft. GUVI produces simultaneous monochromatic images at five 'colors' as its field of view is scanned from horizon to horizon. The instrument consists of a scan mirror feeding a parabolic telescope and Rowland circle spectrometer, with a wedge-and-strip detector at the focal plane. We describe the design, and give an overview of the environmental parameters that will be measured. GUVI is a modified version of the Special Sensor UV Spectrographic Imager (SSUSI), which will fly on the DMSP Block 5D3 satellites S-16 through S-20, We present some results from the optical calibration of the five SSUSI units.

The performance of a new slotted electron sieve design in an integrated photo-sensor for use in xenon gas proportional scintillation detectors is described. The new design exhibits an enhanced photoelectron collection when compared to the earlier circular holes design, used for the first time in such application. The present design uses an electron sieve composed of a 50-micrometers pitch. The front surface is made photosensitive with a 150-thick CsI film. When an appropriate voltage is applied between the copper electrodes, the resulting electric field directs photoelectrons produced on the front surface through the holes in the sieve and onto a wire chamber where charge amplification occurs. Positive feedback is essentially eliminated since the charge amplification stage is optically decoupled from the photo-cathode. The electron sieve also provides a small amount of charge gain up to 2.8. The measured effective quantum efficiency, namely the number of photoelectrons traversing the electron sieve holes per incident 170-nm scintillation photon, as measured under present conditions, is about 8.3 percent. A discussion of the results is presented.

The result obtained in the course of the characterization of a photon-counting ICCD prototype. The detector consists of a 40 mm diameter, Z stack, high gain microchannel plate intensifier, endowed with a RbTe photocathode. The intensifier electron cascade is transduced, via a phosphor screen and a 1:3.6 fiber optics reducer, into a 3 by 3 pixel, quasi-gaussian charge distribution on a 512 by 512 pixel format CCD matrix with square pixels of 15 micrometers . The CCD is read out, in the frame-transfer mode, through a single output amplifier at a frequency of 20 MHz. The data flow is acquired serially and fed to a virtual shift- register system, as to generate a 3 by 3 pixel even sash that sweeps dynamically the CCD matrix at the 50 ns clock pace. Each and every events has is searched for the presence of events whose integral charge distribution lie within set threshold levels, and satisfy given morphological rules, i.e. a single-peaked charge profile. The centroid coordinates of identified events are then determined with sub-pixel accuracy and subsequently stored in an external, high resolution memory. Detective quantum efficiency, spatial resolution and dynamic range obtained for the prototype system in the 150-600 nm spectral domain, are given and discussed, together with the up-graded performance expected for a second-generation prototype, presently being assembled.

A custom analog VLSI chip is being developed for the readout of pixelated CdZnTe detectors in the focal plane of an astronomical hard x-ray telescope. The chip is intended for indium bump bonding to a pixel detector having pitch near 0.5 mm. A complete precision analog signal processing chain, including charge sensitive preamplifier, shaping amplifiers and peak detect and hold circuit, is provided for each pixel. Here we describe the circuitry and discus the performance of a functional prototype fabricated in a 1.2 micrometers CMOS process at Orbit Semiconductor. Dynamic performance is found to be close to SPICE model predictions over a self-triggering range extending from 1 to 50 keV. Integral non-linearity and noise while acceptable ar not as god as predicted. Power consumption is only 250 uW per pixel. Layout and design techniques are discussed which permit successful self-triggering operation at the low 1 keV threshold.

We have characterized the intrinsic 1/f noise of ion- implanted silicon thermistors in the 0.05-0.5 K temperature range. This noise can have a significant effect on detector performance and needs to be taken into account in the design optimization of IR bolometers and x-ray microcalorimeters. The noise can be reasonably well fit as (Delta) R/R fluctuations whose spectral density varies as 1/f and increases steeply with lower doping density and lower temperatures. The observed 1/f noise can be approximated as a resistance fluctuations.