The alpha magnetic spectrometer (AMS) will be attached to the International Space Station in the year 2000 for three years of operation. AMS will: (1) search for antinuclei in the cosmic rays; (2) measure the antiproton flux at the top of the earth's atmosphere; (3) measure the positron flux at the top of the earth's atmosphere; (4) measure high energy gamma rays from space; and (5) measure the isotopic composition of the light elements in the cosmic rays. In this paper we provide a general description of AMS, and a description of the antimatter, antiproton, and positron goals and performance capabilities of the instrument. The gamma ray detection capabilities are presented in another paper for this conference.

We are studying a gamma-ray burst mission concept called burst arcsecond imaging and spectroscopy (BASIS) as part of NASA's new mission concepts for astrophysics program. The scientific objectives are to accurately locate bursts, determine their distance scale, and measure the physical characteristics of the emission region. Arcsecond burst positions (angular resolution approximately 30 arcsec, source positions approximately 3 arcsec) will be obtained for approximately 100 bursts per year using the 10 - 100 keV emission. This will allow the first deep, unconfused counterpart searches at other wavelengths. The key technological breakthrough that makes such measurements possible is the development of CdZnTe room-temperature semiconductor detectors with fine (approximately 100 micron) spatial resolution. Fine spectroscopy will be obtained between 0.2 and 150 keV. The 0.2 keV threshold will allow the first measurements of absorption in our galaxy and possible host galaxies, constraining the distance scale and host environment.

Burst locations with an arc second telescope (BLAST) is a new mission concept being studied for NASA's medium explorer (MIDEX) mission opportunities. The principal scientific objectives of the BLAST mission are (1) to localize gamma- ray burst (GRB) positions to arcsec accuracy; (2) to search for enhancements in the rate of GRBs toward M31; and (3) to conduct the most sensitive sky survey to date of x-ray sources in the 7 - 200 keV regime. These objectives are achieved using a large array of position-sensitive scintillation detectors with a total area of 17,000 cm². This array is combined with a large field of view telescope (greater than 1 steradian) comprising two separate imaging systems. A coded aperture telescope provides arcminute source localization. For low energy x-rays (less than 50 keV), the aperture is also defined by phase modulation grids with provide complementary arcsecond information. The grid system consists of two aperture planes with 'checker board' patterns of slightly different pitch. The beating between the two grid pitches casts a broad interference pattern on the detector plane. Determining the phase of this interference pattern in both coordinates gives the location of a point source source in the sky, with aliased positions at approximately 1 arcmin spacing. The arcmin ambiguity is resolved by the coded aperture image. BLAST has a sensitivity to bursts of 0.03 photons cm^-2 s^-1, almost ten times more sensitive than BATSE. We expect to position 20 bursts per year to better than 2 arcsec accuracy and 35 bursts per year to better than 5 arcsec. BLAST will provide an all sky survey in hard x-rays with a sensitivity of 0.2 milliCrab at low energies.

The gamma-ray large area space telescope (GLAST) is a proposed next-generation high-energy gamma-ray telescope for studying emission from astrophysical sources in the 10 MeV to 300 GeV energy range. GLAST is currently under study as a NASA new mission concept in astrophysics. The primary scientific targets for the GLAST mission include active galactic nuclei, gamma-ray bursts, neutron stars, and the diffuse galactic and extragalactic high-energy radiation. GLAST relies on the unambiguous identification of incident gamma-rays by detection of the electron and positron that result from pair creation in a thin converter material. Measurement of the energy and direction of the electron- positron pair shower provides information about the energy and direction of the incident gamma-ray. The GLAST design utilizes modern solid-state particle detector technology and recently developed space-qualified computers. Because of the technical approach, the telescope design can be easily optimized to a range of sizes. For example, accommodation of GLAST within a Delta II size launch system results in an instrument with capabilities well beyond those of the highly successful EGRET currently operating on the Compton Observatory; namely, a broader energy range, larger effective area, wider field of view, and single-photon angular resolution 2 to 5 times more precise than EGRET's resolution. GLAST will have an effective area of 8000 cm² above 300 MeV, a field of view of 2.6 sr, and single photon angular resolution (rms projected) of 0.3 degrees at 1 GeV, approaching 0.03 degrees above 20 GeV.

The hard x-ray telescope (HXT) was selected for study as a possible new intermediate size mission for the early 21st century. Its principal attributes are: (1) multiwavelength observing with a system of focusing telescopes that collectively observe from the UV to over 1 MeV, (2) much higher sensitivity and much better angular resolution in the 10 - 100 keV band, and (3) higher sensitivity for detecting gamma ray lines of known energy in the 100 keV to 1 MeV band. The institutions collaborating in the study are: Smithsonian Astrophysical Observatory, Marshall Space Flight Center, Naval Research Laboratory, Goddard Space Flight Center, Argonne National Laboratory, Danish Space Research Institute, Osservatorio Astronomica di Brera (Merate), and Centre d'Etudes Spatiale des Rayonnements (Toulouse). This paper emphasizes the instrumentation development aspects of the concept study which is also of interest to other possible missions observing hard x rays. The instrumentation includes several grazing incidence double conical telescopes with multilayer coatings that focus up to 100 keV and a single Laue crystal telescope that functions to 1 MeV. The detectors which are relatively small thanks to focusing include CCDs, and germanium, and/or CdZnTe position sensitive arrays.

We present an instrument concept called GIPSI that uses germanium strip detectors in an imaging system to provide narrow line sensitivity less than 8.0 multiplied by 10^-6 gamma cm^-2s^-1 at 100 keV in a 2 week exposure (3 sigma), and which has a point spread function (spatial resolution of approximately 20 arc minutes rms. The germanium strip detectors also make an excellent polarimeter by capitalizing on the angular dependence of the Compton scattering cross section. Gamma-ray polarimetry in the energy band around 60 - 300 keV is an interesting area of high energy astrophysics where observations have not been possible with the technologies employed in current and past space missions. We have tested a prototype detector with polarized beams and have measured a modulation factor of approximately 0.8 at 100 keV. A sensitive instrument can be realized on a modest space mission or a long duration balloon flight. Linear polarization can be detected in sources such as the Crab Pulsar, Cen A, Cyg X-1, and solar flares down to less than 5% of the source flux. The proposed instrument would have a collecting area of 400 cm².

The design of a ground based gamma ray telescope is presented. This telescope would be sensitive to extraterrestrial gamma rays with energies from 20 GeV to over 1000 GeV. Among other things, this telescope would be able to make improved studies of the emission mechanism of gamma rays from active galactic nuclei (AGNs), and of the interactions of gamma rays from AGNs with the intergalactic infrared radiation field (IIRF). When combined with independent measurements of the Hubble constant, these observations will enable the measurement of the IIRF.

The characteristic dependence of x-ray transition radiation on the Lorentz factor of the parent particle can be utilized in cosmic-ray observations on balloons or in space in order to discriminate between relativistic electrons and hadrons, or to determine the energy spectra of heavy cosmic-ray nuclei at very high energies. To obtain statistically meaningful results, exposure factors of the instruments of the order of 100 - 1000 m²sr days are essential. While the intrinsic weight of transition radiation detectors is low, this requires novel approaches and precludes the use of heavy pressurized containers for the instrument. We have developed a system using large arrays of xenon filled proportional tubes as detectors which can operate in a zero pressure environment. We shall discuss this design and present results from prototype evaluations. Finally, we shall describe the capabilities of a practical detector system that will measure the elemental composition and individual energy spectra of heavy cosmic ray nuclei up to energies around 10¹⁵ eV.

The measurement of particle velocities in cosmic ray experiments has largely been made by counters which determine the total amount of Cherenkov light emitted by a radiator material. Here we discuss a far more accurate technique which measures the angle of emission of individual Cherenkov photons by imaging the emission cone onto a ring. This approach has the advantage of supplying a velocity estimate from each detected photon and a large reduction in the effects of background light. As an example, we shall discuss our ring imaging Cherenkov detector (RICH) for high altitude balloon cosmic ray experiments. This instrument combines a 3 m gas Cherenkov radiator with 1.5 m multiplied by 1.5 m of position sensitive photon detectors based on TMAE gas mixtures. The photon detector assembly detects individual photons with a quantum efficiency of 10 - 20% in the UV region of the spectrum. The use of VLSI electronics provides individual readout of 18,000 1 cm by 1 cm pixels. The future application of this technique in cosmic ray instruments also is discussed.

We describe a mission concept which has as its primary objective the measurement of the elemental abundances of galactic and solar energetic nuclei over the charge range of 14 less than or equal to Z less than or equal to 92. The instruments would have sufficient collecting power to improve the number of particles collected over that of previous measurements by more than an order of magnitude and, more important, will have the capability to clearly distinguish individual elements. These measurements are of fundamental importance to an understanding of the origin, nucleosynthesis, and acceleration of energetic galactic and solar particles.

A concept for observation from space of the highest energy cosmic rays above 10²⁰ eV with a satellite-borne observatory has been considered. A maximum-energy auger (air)-shower satellite (MASS) would use segmented lenses (and/or mirrors) and an array of imaging devices (about 10⁶ pixels) to detect and record fluorescent light profiles of cosmic ray cascades in the atmosphere. The field-of-view of MASS could be extended to about (1000 km)² so that more than 10³ events per year could be observed above 10²⁰ eV. From far above the atmosphere, MASS would be capable of observing events at all angles including near horizontal tracks, and would have considerable aperture for high energy photon and neutrino observation. With a large aperture and the spatial and temporal resolution, MASS could determine the energy spectrum, the mass composition, and arrival anisotropy of cosmic rays from 10²⁰ eV to 10²² eV, a region hitherto not explored by ground-based detectors such as the fly's eye and air-shower arrays. MASS's ability to identify comic neutrinos and gamma rays may help providing evidence for the theory which attributes the above cut-off cosmic ray flux to the decay of topological defects.

The high-energy antimatter telescope (HEAT) instrument has been flown successfully by high-altitude balloon in 1994 and 1995, in a configuration optimized for the detection and identification of cosmic-ray electrons and positrons at energies from about 1 GeV up to 50 GeV and beyond. It consists of a two-coil superconducting magnet and a precision drift-tube tracking hodoscope, complemented with a time-of-flight system, a transition radiation detector and an electromagnetic shower counter. We review the design criteria for optimal e^+/- detection and identification, and assess the instruments' performance and background rejection during its first two flights. We also review the adaptation of HEAT for measurements of high-energy cosmic- ray antiprotons and for isotopic composition studies.

A new balloon instrument, the advanced thin ionization calorimeter (ATIC), is currently under development by an international collaboration involving researchers in the U.S., Germany, Korea, Russia and the Ukraine. The instrument will be used, in a series of long duration balloon flights, to investigate the charge composition and energy spectra of primary cosmic rays over the energy range from about 10¹⁰ to 10¹⁴ eV. The ATIC instrument is designed around a new technology, fully active Bismuth Germanate (BGO) ionization calorimeter that is used to measure the energy deposited by the cascades formed by particles interacting in an approximately 1 proton interaction length thick carbon target. The charge module comprises a highly segmented, triply redundant set of detectors (scintillator, silicon matrix and Cherenkov) that together give good incident charge resolution plus rejection of the 'backscattered' particles from the interaction. Trajectory information is obtained both from scintillator layers and from the cascade profile throughout the BGO calorimeter. This instrument is specifically designed to take advantage of the existing NASA long duration balloon flight capability in Antarctica and/or the Northern Hemisphere. The ATIC instrumentation is presented here, while a companion paper at this conference discusses the expected performance.

An advanced thin ionization calorimeter (ATIC) will be used to investigate the charge composition and energy spectra of ultrahigh energy primary cosmic rays in a series of long- duration balloon flights. While obtaining new high priority scientific results, this balloon payload can also serve as a proof of concept for a BGO calorimeter-based instrument on the International Space Station. The ATIC technical details are presented in a companion paper at this conference. Here we discuss the expected performance of the instrument based on a GEANT code developed for simulating nuclear- electromagnetic cascades initiated by protons. For simulations of helium and heavy nuclei, a nucleus-nucleus interaction event generator LUCIAE was linked to the GEANT based program. Using these models, the design of the ATIC detector system has been optimized by simulating the instrument response to particles of different charges over the energy range to be covered. Results of these simulations are presented and discussed.

We describe a new balloon-borne cosmic-electron telescope that incorporates a trigger system and an imaging calorimeter. It is designed to observe high-energy electrons with an energy greater than 10 GeV. The rejection of the background protons is performed by using the trigger system in real time and the off-line analysis of three-dimensional shower profiles observed in the imaging calorimeter. The calorimeter consists of scintillating-fiber belts, emulsion plates and lead plates (approximately 8r.1.thick in total). In order to observe the direction of showers, two belts in each depth are set at right angles with each other. Image intensifier is used to amplify the number of photons from scintillating fibers, and CCD camera is attached at the output window of the image intensifier. The telescope was launched at Sanriku Balloon Center, and it was flown for 12 hours at the level altitude. By preliminary analysis, we observed about 700 electrons over 10 GeV under 4g cm^-2 of average residual atmosphere. The flux of electrons is consistent with previous observations.

A hybrid detector system is being developed for measuring the cosmic ray elemental composition and energy spectra above approximately GeV/nucleon. This system employs both a conventional 'passive' emulsion chamber and an 'active' ionization calorimeter incorporating scintillating fibers. Emulsion chambers have a proton energy threshold approximately greater than 5 TeV for detectable dark spots in the x-ray films which are used as a visual 'trigger.' The central element of this hybrid system is a calorimeter which has 10 x-y hodoscopic layers of 0.5 mm scintillating fibers interspersed with 4 mm lead plates. The fibers sample the hadronic and electromagnetic showers (cascades) initiated by interactions in the overlying emulsion chamber. The cascades are recorded by two image-intensified charge-coupled device (CCD) cameras which view the ends of the fibers to present orthogonal views. These showers are located and traced with microscopes in the emulsion chamber to provide an energy calibration through standard emulsion chamber methods, and an independent confirmation of the primary particle's charge (which is also measured with a Cerenkov counter above the emulsion chamber). The hybrid system will be used this fall for a balloon-borne measurement of the cosmic ray proton and helium spectra from approximately 400 GeV/n to approximately 10 TeV/n. An 8-hour test flight was performed in September 1995. Details of the detector system and sample results from the test flight are presented.

The outstanding results of the EGRET experiment on CGRO have stimulated the search for a next generation of high-energy gamma-ray telescope. We discuss here the use of scintillating optical fibers for the development of a new type of gamma-ray telescope operating in the energy range 10 MeV and above. An all-sky high-energy monitor with ten times EGRET's sensitivity and superior detector characteristics is described. The detector is composed of layers of lead and plastic scintillating fibers that perform both the shower direction and energy measurement. We present here simulations of a system with ten radiation lengths of lead in it and show how the system achieves good directional accuracy and energy resolution. We also discuss the characteristics of a baseline technology demonstration module designed to verify the performance of the SIFTER system components.

Two-dimensional position-sensitive silicon detectors ('matrix detectors') have been designed, procured, and tested as part of the development of the solar isotope spectrometer (SIS) instrument for NASA's Advanced Composition Explorer (ACE) mission. Important characteristics of these devices include: thickness approximately 50 - 90 micrometer, active area 34 cm², 64 strips on each surface with 1 mm strip pitch. The SIS instrument uses four such detectors, processing signals from each of the 512 individual strips with a separate 12-bit pulse height analyzer implemented with custom-designed VLSI circuits. A set of 25 matrix detectors have been characterized through a variety of tests intended both toe select the best candidates for use in the flight instrument and to provide the calibrations needed to interpret flight data. We discuss the design of the SIS matrix detectors and present selected results from the detector tests that have been performed.

We report on extensive tests of large-area (10 cm diameter) high-purity ion-implanted silicon detectors for the solar isotope spectrometer (SIS), and lithium-drifted silicon detectors for the cosmic ray isotope spectrometer (CRIS), which are under development for launch on the advanced composition explorer (ACE) mission. Depletion and breakdown characteristics versus bias were studied, as were long-term current and noise stability in a thermally cycled vacuum. Dead-layer and total thickness maps were obtained using laser interferometry, beams of energetic argon nuclei and radioactive sources of alpha particles. Results, selection criteria, and yields are presented.

The scintillating optical fiber trajectory (SOFT) detector, which is the hodoscope for the cosmic ray isotope spectrometer (CRIS) on the NASA advanced composition explorer (ACE) satellite, was calibrated using 155 MeV/n He, Li, C, N, O, Ne, and Ar at the Michigan State University National Superconducting Cyclotron Laboratory (NSCL). The instrument consists of three hodoscope fiber planes and one trigger plane which are read out by an image intensified CCD camera system and by intensified photodiodes respectively. The instrument is described and the detection efficiency and spatial resolution is presented.

The INTEGRAL observatory, due for launch in 2001, will address the fine spectroscopy (2 keV FWHM 1 MeV) and accurate imaging (12 arcminute FWHM) of celestial gamma-ray sources in the important 15 keV to 10 MeV energy range. The fine spectroscopy will permit spectral features to be uniquely identified and line profiles to be determined for in-depth studies of the source regions. Fine imaging will permit the accurate location and hence identification of the sources with counterparts at other wavelengths. ESA has completed the selection process for the scientific instruments to be flown on INTEGRAL, the data center and mission scientists, and the project is in its phase B development stage. The two main instruments onboard are a spectrometer which employs high-spectral-resolution germanium detectors and an imager which employs high- spatial-resolution arrays of cadmium telluride and cesium iodide detectors. Optical and x-ray monitors complete the scientific payload.

INTEGRAL is ESA's high-energy astrophysics mission to be launched into a high eccentric orbit early in the next decade. One of the two mission's main telescopes is the gamma-ray spectrometer SPI. This instrument features a compact array of 19 high-purity germanium detectors shielded by a massive anticoincidence system. A coded aperture of the HURA type modulates the astrophysical signal. We present the spectrometer system and its characteristics and discuss the choices that led to the present design. The instrument properties like imaging capability, energy resolution and sensitivity have been evaluated by extensive Monte-Carlo simulations. The expected performance for narrow-line spectroscopy is characterized by an energy resolution of approximately 1.6 keV at 1 MeV, an angular resolution of approximately 2 degrees within a totally coded field of view of approximately 15 degrees, and a sensitivity of (2 - 5) multiplied by 10^-6 gamma/(cm² s) for 4 multiplied by 10⁶ s observation time in the nominal energy range from approximately 20 keV and approximately 8 MeV. With these characteristic features it will be possible for the first time to explore the gamma-ray sky in greater depth and detail than it was possible with previous gamma- ray telescopes like SIGMA, OSSE and COMPTEL. In particular the field of nuclear astrophysics will be addressed with an unprecedented combination of sensitivity and energy. Especially the high-energy resolution allows for the first time measuring gamma-ray line profiles. Such lines are emitted by the debris of nucleosynthesis processes, by the annihilation process near compact objects and by the nuclear interaction between cosmic rays and interstellar matter. Lines of all these processes have been measured so far, but, owing to the relatively poor energy resolution, details of the emission processes in the source regions could not be studied. With the high-resolution spectroscopy of SPI such detailed investigations will be possible opening a wealth of astrophysical investigations.

Using Monte-Carlo simulations, an optimization of the mass distribution of the scintillator crystals, which constitute the veto shield of the spectrometer SPI on board of INTEGRAL, has been performed. Special emphasis was put on a realistic model for the radiation environment in the satellite orbit. All the components of the radiation (gamma- rays, protons and electrons) in space were taken into account regarding their relative fluxes. Furthermore the radiation produced by nuclear reactions within the spacecraft structure was estimated using a separate computer code. A simple realistic mass model of the spectrometer with special consideration of the holding structure of the crystals and other material within the opening angle of the spectrometer, was implemented. Different geometries for background reduction were analyzed and the results are presented. Experiments concerning the behavior of the radiation damage in the scintillator crystals are presented. They give important hints for methods to avoid an increase in the background due to the radiation induced degradation of the crystals.

To follow up on the remarkable discoveries of the Compton Gamma Ray Observatory and GRANAT, the International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission was selected by ESA as part of the agency's 'HORIZON 2000' strategic plan. It is scheduled to begin detailed gamma ray spectral and imaging studies, of unprecedented resolution, in the year 2001. One of the two main INTEGRAL instruments is a high performance imager. It features a coded aperture mask and a novel large area multilayer detector which utilizes both cadmium telluride and cesium iodide elements to deliver the fine angular-resolution approximately 12 arcmin, wide spectral response (15 keV to 10 MeV) and high resolution spectroscopy (6% at 100 keV) required to satisfy the mission's imaging objectives.

The INTEGRAL soft gamma-ray imager (ISGRI) is a large and thin CdTe array. Operating at room temperature, this gamma camera covers the lower part (below 200 keV) of the energy domain (20 keV - 10 MeV) of the imager on board the INTEGRAL Satellite (IBIS). The ASIC's front-end electronics features particularly a low noise preamplifier, allowing a threshold below 20 keV and a pulse rise-time measurement which permits a charge loss correction. The charge loss correction and its performances are presented as well as the results of various studies on CdTe thermal behavior and radiation hardness. At higher energy (above 200 keV) ISGRI will operate in conjunction with PICsIT, the IBIS CsI gamma camera. A selection among the events in coincidence performed on the basis of the Compton scattering properties reduces strongly the background. This allows an improvement of the sensitivity and permits short term imaging and spectral studies (high energy pulsars) which otherwise would not have fit within the IBIS telemetry allocation.

IBIS is one of the two main instruments onboard the INTEGRAL gamma-ray satellite. IBIS will produce images of the gamma- ray sky in the region between 15 keV and 10 MeV by means of a coded mask coupled to a double-layer position sensitive detector. PICsIT is the detection layer optimized for high energy. It has a total area of 3065 cm² and is composed by 4096 individual pixels made of CsI(Tl) crystal, each one with its proper electronic chain. The single units are 0.75 cm² in area, and 3 cm thick. The front end electronics are designed so that analogue circuits, with their low noise figure, will allow the exploitation of the spectroscopic characteristics of the detector. The digital circuits will allow PICsIT to operate in anticoincidence with an active shield, and to deliver the interaction time of occurrence of the events.

The multi-layer discrete structure of the IBIS telescope onboard the INTEGRAL gamma-ray satellite allows the application of the Compton kinematics for improving the signal to noise ratio of the images which are obtained by mens of a coded mask coupled to a position sensitive detector. Two steps of data selection based on Compton kinematics are envisaged: one to be operated aboard the satellite and the other one which will be applied on ground. The possible reduction of data volume to be transmitted to ground, background rejection, and signal to noise enhancement are shown.

A passive shield will be implemented on the IBIS instrument in order to reduce at low and medium energies the cosmic diffuse background and the source fluxes contribution outside the field of view. The collimator device originally proposed has been reviewed against an alternative option consisting of a box-type lateral shield. Advantages and disadvantages of the two system are analyzed in view of different optimization criteria including background, sensitivity and imaging performance as a function of energy.

JEM-X will extend the energy range of the gamma ray instruments on ESA's INTEGRAL mission (SPI, IBIS) to include the x-ray band. JEM-X will provide images with arcminute angular resolution in the 2 - 60 keV band. The baseline photon detection system consists of two identical, high pressure, imaging microstrip gas chambers, each with a collecting area of 500 cm². They view the sky through a coded aperture mask (0.5 mm tungsten) at a separation of 3.4 m. The two detector boxes are formed from 2 mm thick stainless steel plate and are filled with 5 bar Xe. The field of view is defined by the collimator mounted on top of the detector. Each collimator consists of an array of bonded square tubes of Mo. The internal surface of these tubes is covered by a graded shield. The collimator provide also the support for the detector windows which are made out of 250 micrometer thick beryllium foils. The detector sensor elements consists of microstrip plates shaped as regular octagons with a diameter of 292 mm. The basic microstrip pattern is similar to the one chosen for the HEPC/LEPC detector system on SRG. The detector position resolution will be sufficient to ensure an angular resolution for JEM-X of better than 3 arcmin throughout the 2 - 60 keV band.

The JEM-X (joint European x-ray monitor) experiment will be flown onboard the ESA's INTEGRAL satellite. The instrumental background level of the two JEM-X twin detectors will depend on several parameters, among which the satellite orbit and mass distribution, and the detectors materials play a major role. Based on the information available at the present stage of the emission design, we have computed the instrumental background to be expected because of two main background components: direct diffuse x-ray background and secondary photons originated by the interactions of the primary cosmic rays with the spacecraft structures. This calculation has been carried out by means of a Monte Carlo simulation using the code MCNP. The background due to on- orbit material activation and to the primary cosmic rays direct interactions with the detecting medium has not been considered. The INTEGRAL satellite structure is only now being completely defined and the details of the instrument design are still under evolution. The present background estimation can therefore be only preliminary and based on some reasonable approximations on the radiation environment in which the INTEGRAL experiments will operate.

JEM-X is the x-ray monitor serving the two gamma-ray experiments imager and spectrometer onboard the ESA's INTEGRAL satellite. Due to the intrinsic weakness of the celestial sources in the gamma energy range they will need very long integration times. During these long pointings JEM-X will be able to detect very small variations on most x-ray sources, but only if accurately calibrated. The in- flight calibration system of the JEM-X experiment is devoted to measure the response of the detection chain (detector plus electronics) in a small set of positions and energies. The data from this system, together with on ground calibrations and simulations, must provide the capability to deconvolve pulse height spectra of celestial sources. The baseline for the in-flight calibration system foresees a set of four radioactive sources, maybe by Fe⁵⁵ and Cd¹⁰⁹ nuclides, and a pair of Amptek Cool-X15 X-ray generators. The latter is a novel product, based on a pyroelectric crystal used to generate energetic electrons that produce fluorescence lines by hitting a metallic target. We plan to use the four low intensity radioactive sources for monitoring the four independent anode chains, and the two x- ray tubes, one with a copper and the other with a molybdenum target, shared on the two twin detectors, for a flat illumination of the whole detectors area.

The INTEGRAL Science Data Center (ISDC) is the interface between the scientific payload of the INTEGRAL gamma-ray satellite and the astronomical community. This center will process INTEGRAL data, to the point where they can be meaningfully interpreted by scientists unfamiliar with the instrumentation, and provide the necessary support for the full scientific exploitation of these data. Astronomers of many different field will be able to use INTEGRAL data, and multiwavelength studies will be facilitated. The sky at gamma-ray energies is highly variable. At the ISDC a rapid preliminary analysis of the data will be performed to detect whether unexpected events have occurred in the INTEGRAL field of view. In case of a detection, the foreseen observation plan may be modified accordingly. An ISDC software system will be developed to pre-process the satellite data, archive it together with the ancillary data necessary to understand the observations, process the data to obtain images of the sky, energy spectra of the sources and time profiles. The results of this analysis and the pre- processed data will be made available to the observers and stored in the INTEGRAL archive, where they will become public after one year.

Astro-E is the x-ray satellite to be launched in the year 2000 by Inst. of Space & Astronautical Science. This report deals with the design and expected performance of the hard x-ray detector (HXD), one of the 3 experiments aboard Astro- E. The HXD is a combination of GSO/BGO well-type phoswich counters and silicon PIN diodes: the two combined will cover a wide energy band of 10 - 700 keV. The detector is characterized by its low background of approximately 10^-5/s/cm²/keV and its sensitivity higher than any past missions between a few 10 keV and several 100 keV. Combined with the other 2 experiments, a micro-calorimeter array (XRS) and 4 CCD arrays (XIS), both with x-ray mirrors, the mission will cover the soft and hard x-ray range at a highest sensitivity.

The MART-LIME is a large area x-ray experiment planned to be launched on board the Russian satellite Spectrum X-Gamma, as the high energy imager of a complement of broad band co- aligned x-ray telescopes. The energy range covered is 5 - 150 keV with an angular resolution of 8.6 arcminutes. The final detector configuration is now in its testing phase and includes the high pressure window comprising the 6 by 6 degree collimator, and the multiwire proportional counter (MWPC). The response to x-ray sources was investigated during the tests carried out at the Daresbury Laboratory (Warrington, UK) facilities The MWPC was filled up by a xenon-argon-isobutane gas mixture in order to evaluate the efficiency of the detector and in particular its linearity over the whole approximately 2,000 cm² sensitive area. At the same time the various parts of the apparatus have been simulated by using a Monte Carlo program. Results on the detector response and simulations are presented.

As part of our ongoing research program to develop a liquid xenon gamma-ray imaging telescope (LXe-GRIT) for medium energy astrophysics, we have built a liquid xenon time projection chamber (LXeTPC) with a total volume of 10 liters and a sensitive are of 20 cm by 20 cm. The detector has been successfully tested with gamma-ray sources in the laboratory and is currently being prepared as balloon-borne payload for imaging MeV gamma-ray emission from the Crab Nebula, Cygnus X-1 and the Orion molecular cloud region. The LXe-TPC, sensitive to gamma-rays from 300 keV to 30 MeV, measures the energy and the 3-D location of each gamma-ray interaction with a resolution of 6% FWHM and 1 mm RMS at 1 MeV, within a 1 sr FOV. Its detection efficiency for Compton events is about 4% in the 1 - 3 MeV, an energy band of great astrophysical interest for both continuum and line emission. Its 3 sigma continuum sensitivity of 1.8 multiplied by 10^-7 ph cm^-2s^-1keV^-1 for a nominal 10 hr observation time, will allow us to study a variety of sources with an imaging accuracy as good as 1 degree. We plan to pursue a vigorous program of balloon flights with this telescope to achieve the maximum science return while continuing a strong R&D laboratory program on LXe technology. The ultimate goal is an optimized design of a satellite implementation of a liquid xenon gamma-ray imaging instrument that will lead to drastic improvements in sensitivity and angular resolution in the 0.3 - 30 MeV band and beyond.

We are working on the development of a new balloon-borne telescope, MARGIE (minute-of-arc resolution gamma ray imaging experiment). It will be a coded aperture telescope designed to image hard x-rays (in various configurations) over the 20 - 600 keV range with an angular resolution approaching one arc minute. MARGIE will use one (or both) of two different detection plane technologies, each of which is capable of providing event locations with sub-mm accuracies. One such technology involves the use of cadmium zinc telluride (CZT) strip detectors. We have successfully completed a series of laboratory measurements using a prototype CZT detector with 375 micron pitch. Spatial location accuracies of better than 375 microns have been demonstrated. A second type of detection plane would be based on CsI microfiber arrays coupled to a large area silicon CCD readout array. This approach would provide spatial resolutions comparable to that of the CZT prototype. In one possible configuration, the coded mask would be 0.5 mm thick tungsten, with 0.5 mm pixels at a distance of 1.5 m from the central detector giving an angular resolution of 1 arc-minute and a fully coded field of view of 12 degrees. We review the capabilities of the MARGIE telescope and report on the status of our development efforts and our plans for a first balloon flight.

We are studying high pressure (20 atmospheres) xenon gas scintillation drift chambers for use in hard x-ray astronomy. These detectors combine the concepts of the gas scintillation proportional counter and the time projection chamber, with the scintillation light read out using waveshifting fibers or plane parallel proportional counters with CsI photocathodes. We have operated both a small technical prototype and a large flight prototype chamber. The CSI photocathodes have consistently given quantum efficiencies near 30% for the detection of xenon scintillation light and plane parallel proportional counters filled with methane have provided gains better than 10⁶. The small GSDC with a CsI readout has a measured energy resolution of 6.0% FWHM at 30 keV, within about a factor of two and a half of the ultimate resolution obtainable in the device. The resolution is currently limited by spread of the incident x-ray beam causing a variable fraction of scintillation light to be observed for each event. We report on the development status of this technology.

Until recently, focusing of gamma-radiation was regarded as an impracticable task. Today, gamma-ray lenses have become feasible and present promising perspectives for future instrumentation. For the first time in high energy astronomy the signal/noise ratio will be dramatically improved as gamma-rays are collected on the large area of a lens from where they are focused onto a small detector. Besides an unprecedented sensitivity, such instruments feature very high angular and energy resolution.

This paper presents some of the imaging analysis techniques which are currently used to investigate COMPTEL 1.8 MeV gamma-ray line data. In the first part of this paper, an algorithm is presented which allows the accurate prediction of the background distribution at a specific line energy using measurements at adjacent energy intervals. The second part deals with the different image reconstruction methods which are applied to COMPTEL data, namely the maximum entropy method, the Richardson-Lucy algorithm and Pixon- based image reconstruction. We conclude that after 5 years of experience with COMPTEL, 1.8 MeV gamma-ray line imaging techniques are well established allowing a comprehensive study of cosmic gamma-ray line emission.

A crystal diffraction lens was constructed at Argonne National Laboratory for use as a telescope to focus nuclear gamma rays. It consists of 600 single crystals of germanium arranged in 8 concentric rings. The mounted angle of each crystal was adjusted to intercept and diffract the incoming gamma rays with an accuracy of a few arcsec. The performance of the lens was tested in two ways. In one case, the gamma rays were focused on a single medium size germanium detector. In the second case, the gamma rays were focused on the central germanium detector of a 3 multiplied by 3 matrix of small germanium detectors. The efficiency, image concentration and image quality, and shape were measured. The tests performed with the 3 by 3 matrix detector system were particularly interesting. The wanted radiation was concentrated in the central detector. The 8 other detectors were used to detect the Compton scattered radiation, and their energy was summed with coincident events in the central detector. This resulted in a detector with the efficiency of a large detector (all 9 elements) and the background of a small detector (only the central element). The use of the 3 multiplied by 3 detector matrix makes it possible to tell if the source is off axis and, if so, to tell in which direction. The crystal lens acts very much like a simple convex lens for visible light. Thus if the source is off to the left then the image will focus off to the right illuminating the detector on the right side: telling one in which direction to point the telescope. Possible applications of this type of crystal lens to balloon and satellite experiments are discussed.

Grazing incidence hard x-ray multilayer structures require the capability to deposit ultra-thin (of the order of monolayers, i.e. single angstrom), ultra-smooth (of the order of an angstrom rms value), uniform, alternating films of high Z and low Z materials, with sharp interfaces and no interdiffusion between the layers. Vapor phase deposition processes such as evaporation and sputtering can not achieve all the above goals. We have developed a new deposition process which does not involve the use of vacuum, is performed at a low temperature, can be scaled up to large surface areas and to curved substrates, is low cost, and results in ultra thin (monolayers), ultra smooth, uniform, high density films with sharp interfaces. This is optimal for the construction of multilayer x-ray optical components. Multilayer structures of various High Z/ low Z materials were deposited using our new deposition process. The surface characterization and x-ray reflectivity of these multilayer structures are presented.

For a sufficiently short gamma pulse, pile-up prohibits conventional PHA spectroscopy, which depends on temporal separation to distinguish individual counts. For such pulse applications, we are developing a spectrometer which detects and records individual gamma photon signals simultaneously in independent parallel channels. This is a two-dimensional array of BGO scintillation elements, each of which is a high-aspect ratio, square-section cylinder. The elements are closely packed in a regular rectangular array, and separated by reflective walls which optically isolate the elements and channel the visible light to the end. The array is oriented with the elements end-on to the gamma source. The downstream array face is imaged, and a histogram of the light levels of the individual elements corresponds to a gamma spectrum. We report on tests performed on the array component intended for such a system.

Radioactivity induced in detectors by protons and secondary neutrons is the major background source of gamma-ray telescopes. A significant background reduction will be achieved by the use of an anticoincidence shield surrounding the Ge detector of the INTEGRAL spectrometer (SPI). An important aspect in the design of SPI was therefore to find the optimum thickness of the shield. In general, the hadronic interactions triggered by energetic cosmic rays in the detector are very difficult to simulate with good accuracy. Now, however, the TIERCE code developed at CEA/DAM Bruyeres-le-Chatel enables us to make these computations with a good accuracy. It is indeed a Monte Carlo code which transports hadrons, neutrons, electrons and gamma, based upon cross sections measurements obtained in accelerators in parallel with the program conception. In that sense, it is one of the only code able to simulate correctly the spallation reactions. We have then used this code to evaluate the neutron production induced in the SPI anticoincidence shield by the cosmic GeV protons, and to deduce information about the positron and neutron fluence, the activation products in Ge for different BGO shield thickness and to determine the impacts of the shield on the induced background.

A charge coupled device is under development with fast timing capability (15 millisecond full frame readout, 30 microsecond resolution for measuring the time of individual pixel hits). The fast timing CCD will be used in conjunction with a CsI microfiber array or segmented scintillator matrix detector to detect x rays and gamma rays with submillimeter position resolution. The initial application will be in conjunction with a coded aperture hard x ray/gamma ray astronomy instrument. We describe the concept and the readout architecture of the device.

Anticoincidence detectors are required for a variety of satellite instruments, including high energy gamma-ray telescopes, in order to differentiate ambient background radiation from signals of interest. Presently, most anticoincidence systems use scintillators coupled to photomultiplier tubes. We have demonstrated that it is now possible to use very high gain solid state avalanche photodiodes (APDs) as photodetectors for this application. A single APD coupled to a 30 cm multiplied by 30 cm multiplied by 0.95 cm plastic scintillator tile demonstrated 100% detection efficiency for minimum ionizing particles, with a low false positive rate. Multiple APDs enhance the signal to noise ratio in addition to providing redundancy. Relative to PMTs, APDs are compact, low power, and mechanically robust devices. Ground test data of APDs for anticoincidence shields is presented.

A new type of gas proportional counter employing a capillary plate has been developed. The capillary plate consists of a bundle of fine glass capillaries with electrodes on both the inlet and the outlet. The capillaries are 100 micrometer in diameter and 800 micrometer in length and gas multiplication occurs in each capillary. The operational conditions of the electric fields in the drift region were investigated by applying the drift potential. The better electric fields were around 0.28 volts/cm(DOT)Torr for argon+10%methane at the pressure of 760 Torr. The energy resolution was 21% for 5.9 keV x rays at the gas gain of 3,000. The gas gain, the energy resolution and the detection efficiency were uniform at the radial positions in diameter of 16 mm for the capillary plate of 20 mm in diameter. The non-uniformity was within 2% of the average for the gas gain. We can expect imaging detectors with the capability of fine position resolution as an application.

Design of the cylindrical ionization chamber with shielding mesh is considered. The chamber has sensitive volume 5 liters and is filled with xenon at the pressure about 35 atm. Main characteristics of this detector are submitted: the energy resolution, efficiency of detection and position of the peak of full absorption for various energies of gamma-rays. It is shown that the energy resolution at 662 keV is 2.9% at the optimum electrical field in the chamber. Prospects of use of cylindrical compressed xenon ionization chamber with a shielding mesh in various fields of science and engineering are considered.

The most important observational challenges remaining in cosmic ray composition will require much increased detector areas to collect rare events while maintaining or improving upon present detector resolution. These goals include extending isotopic abundance measurements to higher energies, measuring isotopes beyond the Fe peak, and making elemental studies with single charge unit resolution through the Pb peak and beyond. Unfortunately, solid state cosmic ray spectrometers have, for practical purposes, approached their limit in collecting area. the fiber optic Cherenkov integrating system (FOCIS) could answer this need. Historically, most cosmic-ray Cherenkov detectors have been of the light-integrating type. The University of Chicago RICH experiment and the CAPRICE experiment are notable exceptions. These instruments measure the Cherenkov light cone to determine the incident particle velocity, avoiding the areal non-uniformities and time-dependent gain variations inherent in light-integrating Cherenkov detectors. FOCIS would use an array of special optical fibers to measure the light cone. These fibers would be simple and robust, could operate over a wide range of temperatures, and would not require onboard consumables (i.e., ionization gas). Fibers can also be left open to vacuum conditions. Thus FOCIS is well suited to balloon flights and long duration space-craft applications. Though the light collection efficiency of FOCIS would be vastly less than RICH or CAPRICE, it would otherwise share their advantages over light-integrating Cherenkov detectors and would be applicable to heavy ion studies. Monte-Carlo simulations of a FOCIS detector are presented. These simulations indicate that FOCIS would have a relatively flat resolution over a range of energies, in distinct contrast to conventional light-integrating Cherenkov detectors.

Current trends in the design new missions and mission concepts for space-borne high-energy astrophysics research concentrate on the development of advanced detection systems. While progress in detector research and development is critical to the future success of space astrophysics, tremendous advances in communications technology stand ready to breathe new life into stable and established detector technology and detection schemes. Very high rate telemetry systems have a proven record in space-based Earth science missions, yet have been largely overlooked by space astrophysics researchers. By employing advanced telemetry systems, such currently available detector technologies as NaI can now be used to build high-energy astrophysics experiments that open a vast new phase space of astrophysical research. As a context for our discussion, we describe a proposed medium explorer-class mission called ALLEGRO (all-sky low energy gamma ray observatory), a high time and energy resolution experiment that uses high rate telemetry to provide a virtual 'photon pipe' in the 7 - 200 keV energy range.

Gamma-ray bursts remain one of the outstanding unsolved mysteries of astronomy. The next generation of instruments will address specific aspects of the gamma-ray burst problem and attempt to answer fundamental questions such as the distance scale. However, missing from the crop of planned or proposed instruments is one which combines high sensitivity and a large field of view, so that detailed studies can be performed on a large sample of weak bursts. Such a combination is difficult to obtain at a reasonable cost with the techniques currently used. We describe a novel application of the Compton telescope technique to the energy range 50 - 300 keV which can, in principle, provide the required capabilities using position sensitive semiconductor detectors.

Zn_xCd_1-xTe is an important crystal used in room temperature x-ray and gamma ray detectors. Zn_xCd_{1- x}Te single crystals with varying values of x were grown using the traveling heater method and were purchased from a commercial vendor. The crystals were cleaved and etched. Electrical contact layers of Au were deposited to form a radiation detector. In order to reduce defect formation under the contact layer, we have developed a new deposition process which does not involve the use of vacuum, is performed at a low temperature, is low cost, and results in thin, ultra smooth, uniform, high density films with sharp interfaces. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to characterize the chemical composition and surface morphology of the thin film of Au. The surface characterization and radiation response properties of these crystals are presented and discussed.

Many future space missions will use cadmium zinc telluride (CdZnTe) gamma-ray detectors because their operation at room temperature makes compact, lightweight detector systems possible. Even though instruments for space using CdZnTe detectors have already been built, the effect of the high- energy particle space environment on these detectors has not been measured. To determine the effect of energetic charged particles on these detectors, we have bombarded several CdZnTe detectors with 199 MeV protons at the Indianan University Cyclotron Facility. Planar detectors of area 1 cm² and thickness 2-3 mm from both eV products and Digirad were irradiated, along with a 2 multiplied by 2 array of proprietary design from Digirad. Using standard gamma-ray sources, the response of the detectors was measured before and after bombardment in steps up to fluences of 5 multiplied by 10⁹ p cm^-2. Significant effects from the proton irradiation were observed in the gamma-ray spectra. In particular, the peak positions of the lines in the spectrum were shifted downward proportional to the fluence. The explanation is almost certainly the production of electron traps by the high energy proton interactions, resulting in a decrease of the mobility-lifetime ((mu) (tau) ) product of the electrons. Calculations were made to model the effect of a decrease in electron trapping length on the spectrum.

Because of its high atomic number and convenient room temperature operation, CdZnTe has great potential for use in both balloon and space borne hard x-ray (5 - 200 keV) astrophysics experiments. Here we present preliminary results from the first CdZnTe background measurements made by a balloon instrument. Measurements of the CdZnTe internal background are essential to determine which physical processes make the most important background contributions and are critical in the design of future scientific instruments. The PoRTIA CdZnTe balloon instrument was flown three times in three different shielding configurations. PoRTIA was passively shielded during its first flight from Palestine, Texas and actively shielded as a piggyback instrument on the GRIS balloon experiment during flights 2 and 3 from Alice Springs, Australia. PoRTIA flew twice during the Fall 1995 Alice Springs, Australia campaign using the thick GRIS NaI anticoincidence shield. A significant CdZnTe background reduction was achieved during the third flight with PoRTIA placed completely inside the GRIS shield and blocking crystal, and thus completely surrounded by 15 cm of NaI. These background results are presented and contributions from different background processes are discussed.

Cadmium zinc telluride (CdZnTe) is a room temperature solid state material with many properties attractive to space- borne astrophysical instrumentation. Irradiation of monolithic CdZnTe detectors with 199 MeV protons shows that proton-induced radiation damage causes an increase in electron trapping in the material. Small-pixel and strip CdZnTe detectors which rely on efficient electron collection are particularly sensitive to changes in the electron mean free path, which can result in significant changes in the spectral response. Using a charge transport model, we calculate the effects of the observed radiation damage on spectral response for pixel detectors of several geometries. A degradation in spectral response is observed which is most pronounced for small-pixel detectors. The magnitude of the effects indicate that depending on pixel size and the desire for good spectral performance annealing may be necessary to maintain good detector performance after approximately 1 - 2 years in low-earth orbit.

We describe research on developing more effective means to shield gamma-ray detectors from neutron-induced background. Conventional active shields are very inefficient in vetoing neutrons. Neutron-induced background is exacerbated in new classes of gamma-ray detectors such as CZT, which have large neutron interaction cross-sections. An approach to this problem is supershields, which contain separate layers to moderate and absorb neutrons. We show how supershields are superior to monolayer neutron shields which have been studied previously.

Model calculations for a next generation telescope for high resolution gamma-ray spectroscopy are presented: the sensitivity for narrow lines is based on estimates of the background level and the detection efficiency. The instrumental background rates (continuum and lines) are explained as a sum of various components that depend on cosmic-ray intensity and spectrometer characteristics (e.g. mass distribution around the Ge detectors, passive material, characteristics of the detection system and background reduction techniques). Extended background calculations have been performed both with Monte-Carlo simulations and using empirical, semi-empirical and calculated neutron and proton cross-sections. In order to improve the spectrometer sensitivity several design and background reduction techniques (shield thickness, passive material, active or passive coded mask, enriched or natural Ge detectors) have been compared for an instrument with a fixed detector volume.

The background spectrum in balloon and satellite Ge spectrometers consists of a continuum with discrete nuclear gamma-ray lines superimposed. Although many background lines can be distinguished in a Ge background spectrum, only a few are at energies of astrophysical interest. In this work, tools for estimating these background lines in different spectrometer configurations are provided. The 511 keV background line is studied in detail since it is one of the most intense background features. This line can be described as the sum of three components: (1) atmospheric 511 keV photons entering through the aperture of the instrument; (2) 511 keV photons produced in the (beta) ⁺ decays of unstable nuclei in the passive material inside the shield; and (3) 511 keV photons coming from outside that pass through the shield without scattering and are completely absorbed in the detector. The variation of the different components as a function of the passive material and shield characteristics is studied to provide techniques to determine the instrument configuration that minimizes the background line intensity. The mechanisms producing the 1809 keV Al background line are not as numerous. The background line can be described as the sum of a delayed component originating inside the shield and a prompt component from outside the shield. The use of a thick shield seems to be an appropriate way to reduce this background line. However, the lack of information about relevant cross sections has not allowed us to perform accurate modeling. Finally, the mechanisms that cause other narrow background lines at energies of astrophysical interest (i.e., the 476 keV Be line, 844 keV Al line, 847 Fe line, 1157 keV Ti line, 4.439 MeV C line, and 6.129 MeV O line) are briefly described.

For actively shielded, narrow aperture germanium spectrometers at balloon or spacecraft altitudes, the beta decay of radio-active nuclei is the dominant source of background in the 0.2 to 2 MeV energy range. This component of the background is internal to the germanium detectors (GeDs) and results from the activation of Ge nuclei by cosmic ray secondaries. The sensitivity of GeD spectrometers can be improved by rejecting beta-decay events, which deposit energy at a single site in the detector, while retaining photon events, which are predominantly multiple site at these energies. Pulse shape discrimination (PSD) techniques can distinguish between single- and multiple-site events by analyzing the shape of GeDs' current pulses. Here we present results of laboratory tests of PSD with a newly developed narrow-inner-bore (0.6 cm diameter) coaxial GeD and compare them to numerical simulations.

For the measurement of astronomical gamma ray radiation in the energy range 50 keV to several MeV usually photomultiplier tubes (PMT) with scintillation crystals are used. However, due to the internal detection mechanism high voltage and single photon counting are required leading to heavy and structurally unpractical systems. Even APD's (avalanche photodiodes) do not circumvent the problem of the high voltage. Recent improvements in the performance of semiconductor detectors allow the use of large area and low noise pin photodiodes as innovative scintillation detectors with 40 - 100 V operating voltage only. Tl-doped CsI as scintillation crystal with a superior light yield has not only a much higher photon output compared to the light yield of pure CsI and BGO crystals which are used for the gamma ray detection with PMTs, but has also a perfect matching of spectral properties of the photodiode. This paper presents a comprehensive comparison with conventional PMT scintillation detector systems and the development activities of full size breadboards with such a photodiode/CsI(Tl) detector set-up. The relevant functional performance test results have shown the high technical maturity of this detector system and the principal feasibility for the application either in the INTEGRAL spectrometer and imager anticoincidence shield (ACS) or in image central detector system. The dedicated ACS configuration design featuring optimized mass budget combined with high gamma ray stopping efficiency is figured.

CdZnTe strip detectors have been fabricated and tested to show the ability for arc second imaging and spectroscopy. Two dimensional CdZnTe strip detectors with 100 micron pitch have been fabricated and wire bonded to readout electronics to demonstrate the ability to localize 22 to 122 keV photons to less than 100 microns. Good spectral resolution has also been achieved. The uniformity and relative efficiency of the strip detector are discussed. Radiation damage effects by intermediate energy neutrons and low energy protons on the surface and bulk performance of CdZnTe devices have been investigated and are presented. Activation and annealing of radiation effects have been seen and are discussed.