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Laboratory measurements are presented to study the effects of the physical properties of regolith on planetary soft X-ray fluorescence spectroscopy. Two laboratory setups are used to independently measure these regolith effects using lunar regolith analog samples with three different particle-size ranges. Discussion is given on the data analysis. Some of the data may be valid only for qualitative conclusions. Analytical modelling is used to separate the effects expected for a plane-parallel and homogeneous medium from those of measured regolith analogs. The surface roughness and porosity of the regolith are observed to induce an enhancement of the higher-energy part of the spectrum as a function of the incidence angle. The enhancement is larger for rougher surfaces. A brief discussion is given on the relevance of this study for future planetary missions carrying soft X-ray spectrometers.

Modern microchannel plate detectors exhibit low quantum efficiency in the extreme ultra violet range compared to those manufactured before 1990. The cause of this reduction in efficiency is unknown. We describe recent investigations into the along-channel surface compositions of a number of microchannel plates (MCPs) of varying efficiency. These compositional profiles, generated using energy-dispersive X-ray spectroscopy, provide insight into possible mechanisms underlying the efficiency reduction and may assist in efforts to restore good extreme ultraviolet (EUV) performance to MCPs through modifications to the manufacturing process.

Recent and proposed future planetary missions are becoming increasingly concerned with detailed geochemical assessment, often in a bid to ascertain the presence of water and life supporting geochemical systems. The instruments involved may use some kind of radioactive source, e.g. X-ray fluorescence spectrometry, Mossbauer spectrometry, neutron scattering. Having radioactive sources on a lander/rover poses various potential problems, in regard to both safety to personnel involved in the building of the instrument and to radiation effects on spacecraft structure and on other instruments. Indeed background radiation effects from one instrument may dominate measurements in another resulting in loss of scientific performance. Drawing on experience with the Beagle 2 probe which contained two instruments with radioactive sources, we present a discussion on the management of radiation hazards and background effects posed by radioactive sources for such planetary missions.

We report on a new optimal filtering algorithm for improved energy and position resolution in position sensitive Transition Edge Sensor (TES) based X-ray detectors. This algorithm takes account of the noise correlation between the detector outputs to minimise the variance on the estimated photon energy and position. Using numerical methods we show that improved energy and position resolution can be obtained than from previously published methods. Our simulations also reveal the trade-offs resulting from changes in the thermal conductances and heat capacities of the detector elements.

The toroidal energy- and angle-resolved electron spectrometer (TEARES) is a state-of-the-art high-resolution electron detector, which measures both the energy and ejection angle of electrons simultaneously over a range of angles. A double-focussing cylindrical slit entrance lens transports and focusses electrons that are ejected near the plane perpendicular to the main axis of the spectrometer and which originate from an interaction volume of approximately 1 mm3 to the entrance of the toroidal analyser. In addition, the lens adjusts the kinetic energy of the electrons to be analysed to match the pass energy of the analyser with a relatively constant unit magnification. The toroidal deflector analyser is comprised of an inner and an outer toroidal sector, which disperses and focuses the electrons according to their energy in the radial dimension, it is defined by a spherical radius of 125 mm, a cylindrical radius of 120 mm and a sector angle of 142°. These dimensions have been chosen to ensure optimum focussing properties. A 1 mm high entrance slit provides an analyser resolution (ΔE/PE) of 0.0081 (=1/125). A single-focussing conical slit exit lens transports, demagnifies, focuses and accelerates the electrons from the exit of the analyser onto an imaging detector. Electrons travel through the spectrometer with their initial angular direction preserved. The whole of the spectrometer has no blind spots and incorporates a working distance defined by a 38–40 mm radius. The TEARES system is designed to operate over a kinetic energy range of

A fast imaging electron detector is being developed as part of the Toroidal Energy- and Angle-Resolved Electron Spectrometer (TEARES), a high-resolution electron spectrometer for use on synchrotron sources. The analysed solid angle of TEARES is about 100 times greater than that of a conventional hemispherical analyser of similar radius and entrance slit sizes. A ‘typical’ solid sample at a third-generation synchrotron source would yield count rates in excess of 1 GHz, >10 3 times the capability of available imaging electron detectors. We describe a prototype detector based on low-resistance microchannel plates and an adaptation of the cartesian two-dimensional CODACON encoder that aims to achieve a relatively modest 2 MHz counting rate with 32 by 128 simultaneous energy and angle channels. The encoder pattern has been optimised for the output electron distribution of TEARES and directly generates a binary address for each event using simple electronics and the minimum number of signal channels.

The high resolution gamma imager (HRGI): a CCD based camera for medical imaging. We describe the High Resolution Gamma Imager (HRGI): a Charge Coupled Device (CCD) based camera for imaging small volumes of radionuclide uptake in tissues. The HRGI is a collimated, scintillator-coated, low cost, high performance imager using low noise CCDs that will complement whole-body imaging Gamma Cameras in nuclear medicine. Using 59.5 keV radiation from a Am-241 source we have measured the spatial resolution and relative efficiency of test CCDs from E2V Technologies (formerly EEV Ltd.) coated with Gadox (Gd2O2S(Tb)) layers of varying thicknesses. The spatial resolution degrades from 0.44 to 0.6mm and the detection efficiency increases ( x 3) as the scintillator thickness increases from 100 to 500 mum. We also describe our first image using the clinically important isotope Tc-99m. The final HRGI will have intrinsic sub-mm spatial resolution (similar to 0.7 mm) and good energy resolution over the energy range 30-160 keV. (C) 2003 Elsevier B.V. All rights reserved.

We investigate, by ray-trace simulation, two hard X-ray telescopes based on microchannel plate (MCP) optics. The first is the, by now well known, lobster-eye geometry, while the second is a novel design. The second design uses a pair of MCPs with square channels packed in a radial fashion and represents a conical approximation to the Wolter type I configuration. We show that such telescopes can provide X-ray imaging at energies up to 100 keV. Effective area may be scaled arbitrarily by co-aligning many MCP optics. As an example, we calculate that 50 parallel Wolter I units each of 60 mm diameter and 5 m focal length yield a sensitivity of 1 milli Crab at 45 keV in a 105 second integration.

The Large Observatory For X-ray Timing (LOFT) is one of the candidate missions selected by the European Space Agency for an initial assessment phase in the Cosmic Vision programme. It is proposed for the M3 launch slot and has broad scientific goals related to fast timing of astrophysical X-ray sources. LOFT will carry the Large Area Detector (LAD), as one of the two core science instruments, necessary to achieve the challenging objectives of the project. LAD is a collimated detector working in the energy range 2-50 keV with an effective area of approximately 10 m^2 at 8 keV. The instrument comprises an array of modules located on deployable panels. Lead-glass microchannel plate (MCP) collimators are located in front of the large-area Silicon Drift Detectors (SDD) to reduce the background contamination from off-axis resolved point sources and from the diffuse X-ray background. The inner walls of the microchannel plate pores reflect grazing incidence X-ray photons with a probability that depends on energy. In this paper, we present a study performed with an ad-hoc simulator of the effects of this capillary reflectivity on the overall instrument performance. The reflectivity is derived from a limited set of laboratory measurements, used to constrain the model. The measurements were taken using a prototype collimator whose thickness is similar to that adopted in the current baseline design proposed for the LAD. We find that the experimentally measured level of reflectivity of the pore inner walls enhances the off-axis transmission at low energies, producing an almost flat-top response. The resulting background increase due to the diffuse cosmic X-ray emission and sources within the field of view does not degrade the instrument sensitivity., accepted for publication in Experimental Astronomy

We report on the experimental characterisation and modelling of Transition Edge Sensor (TES)-based Distributed Read-Out Imaging Devices (DROIDs), for use as position-sensitive detectors in X-ray astronomy. Latest experimental results from prototype DROIDs using Ir TESs with Au absorbers are reported. Through modelling and the development of signal processing algorithms we are able to design the DROID for optimum spectral and spatial resolution depending upon application.

We describe the X-ray properties of alkali halide photocathodes subjected to post-evaporation thermal treatments. Measurements made in St. Petersburg on planar CsI photocathodes, over an X-ray energy range 5–10 keV, show up to a five-fold increase in current quantum yield χ c (electrons/photon) after thermal annealing. Measurements were also made at Leicester on a microchannel plate (MCP) detector bearing thermally annealed CsI and KBr photocathodes. The MCP quantum efficiency Q (counts/photon) was measured, before and after annealing, at X-ray energies of 0.28, 1.74 and 2.56 keV. A small increase in quantum efficiency was observed at large angles of incidence for the annealed photocathodes. The heat-treated CsI coated MCP half also exhibited a much enhanced mean gain. Both planar photocathode and coated MCP measurements are interpreted with the aid of a semi-empirical photocathode model and scanning electron microscope (SEM) imagery.

We are investigating Transition-Edge Sensors (TESs) for future X-ray Astronomy missions. In this paper, we report the first X-ray results from a one-dimensional imaging spectrometer or Distributed Read-Out Imaging Device (DROID). The DROID consists of two Iridium TESs with transitions temperatures of ∼172 mK, at the ends of a 250 μm by 4.7 mm Gold absorber. The event position can be determined from pulse height and rise/fall time information. Initial results were obtained by reading one end of the DROID only.

The Extreme Physics Explorer (EPE) is a concept timing/spectroscopy mission that would use micro-channel plate optics (MCPO) to provide 4 square meters effective area focused to ~1 arc-min onto an X-ray calorimeter. We describe science drivers for such a mission, possible designs for the large area MCPO needed for EPE, and the challenges of the large area MCPO design., Comment: 12 pages, 9 figures, to appear in proceedings of SPIE V8147, "Optics for EUV, X-ray, and Gamma-Ray Astronomy V"

The Wide Field Imager (WFI) of the International X-ray Observatory (IXO) is an X-ray imaging spectrometer based on a large monolithic DePFET (Depleted P-channel Field Effect Transistor) Active Pixel Sensor. Filling an area of 10 x 10 cm2 with a format of 1024 x 1024 pixels it will cover a field of view of 18 arcmin. The pixel size of 100 x 100 μm2 corresponds to a fivefold oversampling of the telescope's expected 5 arcsec point spread function. The WFI's basic DePFET structure combines the functionalities of sensor and integrated amplifier with nearly Fano-limited energy resolution and high efficiency from 100 eV to 15 keV. The development of dedicated control and amplifier ASICs allows for high frame rates up to 1 kHz and flexible readout modes. Results obtained with representative prototypes with a format of 256 x 256 pixels are presented.

Two rhesus monkeys were trained to move a cursor using neural activity recorded with silicon arrays of 96 microelectrodes implanted in the primary motor cortex. We have developed a method to extract movement information from the recorded single and multi-unit activity in the absence of spike sorting. By setting a single threshold across all channels and fitting the resultant events with a spline tuning function, a control signal was extracted from this population using a Bayesian particle-filter extraction algorithm. The animals achieved high-quality control comparable to the performance of decoding schemes based on sorted spikes. Our results suggest that even the simplest signal processing is sufficient for high-quality neuroprosthetic control.

As part of a comprehensive study of X-ray emission from planetary surfaces and in particular the planet Mercury, we have measured fluorescent radiation from a number of planetary analog rock samples using monochromatized synchrotron radiation provided by the BESSY II electron storage ring. The experiments were carried out using a purpose built X-ray fluorescence (XRF) spectrometer chamber developed by the Physikalisch-Technische Bundesanstalt, Germany’s national metrology institute. The XRF instrumentation is absolutely calibrated and allows for reference-free quantitation of rock sample composition, taking into account secondary photon- and electron-induced enhancement effects. The fluorescence data, in turn, have been used to validate a planetary fluorescence simulation tool based on the GEANT4 transport code. This simulation can be used as a mission analysis tool to predict the time-dependent orbital XRF spectral distributions from planetary surfaces throughout the mapping phase.

In order to keep up with the large improvements in synchrotron radiation, we have developed a toroidal‐based electron spectrometer capable of collecting electrons emitted over a large angular range, whilst preserving emission direction information. This system has an analyser defined by spherical radius of 125 mm, cylindrical radius of 120 mm, sector angle of 142°, and useable azimuthal angle of ∼230°. A 1 mm high analyser entrance slit provides a theoretical analyser resolution (ΔE/PE) of 0.0081. The spectrometer has no blind spots and incorporates a working distance defined by a ∼40 mm radius. It operates over the kinetic energy range

APEX is a proposed mission for a Small Explorer (SMEX) satellite. APEX will investigate the density, temperature, composition, magnetic field, structure, and dynamics of hot astrophysical plasmas (log T = ~5-7), which emit the bulk of their radiation at EUV wavelengths and produce critical spectral diagnostics not found at other wavelengths. APEX addresses basic questions of stellar evolution and galactic structure through high-resolution spectroscopy of white dwarf stars, cataclysmic variables, the local interstellar medium, and stellar coronae. Thus APEX complements the Chandra , Newton-XMM , FUSE , and CHIPS missions. The instrument is a suite of 8 near-normal incidence spectrometers (~90-275 Angstroms, resolving power ~10,000, effective area 30-50 cm 2 ) each of which employs a multilayer-coated ion-etched blazed diffraction grating and a microchannel plate detector of high quantum efficiency and high spatial resolution. The instrument is mounted on a 3-axis stabilized commercial spacecraft bus with a precision pointing system. The spacecraft is launched by a Taurus vehicle, and payload size and weight fit comfortably within limits for the 2210 fairing. Of order 100 targets will be observed over the baseline mission of 2 years. These are selected carefully to maximize scientific return, and all were detected in the EUVE and the ROSAT WFC surveys.

We describe the design of Lobster-ISS, an X-ray imaging all-sky monitor (ASM) to be flown as an attached payload on the International Space Station. Lobster-ISS is the subject of an ESA Phase-A study which will begin in December 2001. With an instantaneous field of view 162 x 22.5 degrees, Lobster-ISS will map almost the complete sky every 90 minute ISS orbit, generating a confusion-limited catalogue of ~250,000 sources every 2 months. Lobster-ISS will use focusing microchannel plate optics and imaging gas proportional micro-well detectors; work is currently underway to improve the MCP optics and to develop proportional counter windows with enhanced transmission and negligible rates of gas leakage, thus improving instrument throughput and reducing mass. Lobster-ISS provides an order of magnitude improvement in the sensitivity of X-ray ASMs, and will, for the first time, provide continuous monitoring of the sky in the soft X-ray region (0.1-3.5 keV). Lobster-ISS provides long term monitoring of all classes of variable X-ray source, and an essential alert facility, with rapid detection of transient X-ray sources such as Gamma-Ray Burst afterglows being relayed to contemporary pointed X-ray observatories. The mission, with a nominal lifetime of 3 years, is scheduled for launch on the Shuttle c.2009.

We describe HERMES (High Energy Remote-Sensing of Mercury's Surface), a novel X-ray imaging spectrometer for potential accommodation in the Mercury Planetary Orbiter (MPO) component of ESA's BepiColombo mission to Mercury. The instrument combines recently developed micro channel plate optics with large-format compound semiconductor imaging arrays. MCP optics offer the distinct advantage of a large collecting area coupled to arcminute angular resolution in a light-weight package and short focal length. Measurements on a prototype optic indicate it should be possible to achieve an angular resolution below 1 arcmin over a fov of 1 degree(s). Energy resolution of 270 eV FWHM at 5.9 keV has been achieved at room temperature for a prototype GaAs array. We estimate that HERMES will detect ~2000 x-ray fluorescent photons s-1 from the surface of Mercury during solar quiet conditions at the pericenter of the orbit. The maximum expected surface spatial resolution from this altitude is ~200m and the fov 40 km2. Over the orbiter's 2 year mission life, HERMES will provide the first very high resolution compositional maps of any planetary surface.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have fabricated the four flight gratings for a sounding rocket high-resolution spectrometer using a holographic ion-etching technique. The gratings are spherical (4000-mm radius of curvature), large (160 mm x 90 mm), and have a laminar groove profile of high density (3600 grooves/mm). They have been coated with a high-reflectance multilayer of Mo5C/Si/Mo2Si. Using an atomic force microscope, we examined the surface characteristics before and after multilayer coating. The average roughness is approximately 2-3A rms after coating, somewhat smoothened by the multilayer. Using synchrotron radiation, we completed an efficiency calibration map of each grating over the wavelength range 225-245A. At an angle of incidence of 5 degree(s) and a wavelength of 234A, the average efficiency peaks in the first inside order at 10.3+/- 0.6% for Grating 1, 7.3+/- 0.9% for Grating 6, 7.2+/- 1.2% for Grating 3, and 9.0+/- 1.5% for Grating 4. These values exceed all previously published results for a high density grating. The first order groove efficiency for Grating 1 is 34.4+/- 1.9%, in good agreement with the best value obtained from similar test gratings and close to the theoretical limit of 40.5%.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Using the technology that has been developed over many years for the fabrication of glass micro-channel plates, a prototype micro-pore optic has been produced that is a very light and compact implementation of a Wolter-I optic for X-ray imaging. With this prototype true Wolter-I imaging has been observed for the first time in a micro-pore optic. Individual fibers in the plates are found to be quite good, with a surface roughness permitting application at medium X-ray energies. The image quality and effective area is however seriously reduced by random tilt errors of multifibers in the plates. If this limitation can be overcome, this technology would allow very light and compact X-ray telescopes to be built. A design is presented that already provides a considerable effective area for soft X-rays using the properties of the surfaces obtained in this program.

We report on the performance of 6 micrometer pore diameter Microchannel Plates (MCPs) fabricated in 50 X 50 mm2 format, from both standard and radio-isotope free low noise glass, by Photonis SAS for a European Space Agency Technology Research Program. We compare them to MCPs manufactured by Photonis (the former Philips Photonics) for the High Resolution Camera (HRC) on NASA's Chandra X-ray observatory. The new MCPs represent a significant advance in MCP technology, having a much larger area than previously reported 6 micrometer plates, and demonstrating low noise 6 micrometer technology for the first time. The 6 micrometer plates are shown to be, mechanically, exceptionally well made with a defect density reduced by a factor of 2 - 5 compared to samples from the HRC flight blocks. They exhibit excellent gain and the expected 0.28 keV (Carbon K) X-ray quantum efficiency. The low noise plates have a very uniform response to X-rays but the standard glass MCPs do show inhomogeneity on both the global and multifiber scales.

We describe the development of an imaging microchannel plate detector for a new class of high resolution EUV spectrometer. The detector incorporates a front MCP coated with a CsI photocathode to enhance quantum efficiency, while the rear MCP, supplied by Photonis SAS for a European Space Agency Technology Research Program, represents one of the first uses of a 6 micron pore device in astronomy. The detector uses a unique design of charge division anode, the Vernier readout, enabling it to deliver a spatial resolution better than 15 microns FWHM. The detector forms an integral component of J- PEX, a sounding rocket EUV spectrometer operating at near- normal incidence, using multilayer coated gratings to deliver a resolution and effective area 10 times that of EUVE in the 225 - 245 angstrom band.

In this paper we present and compare flight results with the latest results of the ground calibration for the HRC-I detector. In particular we will compare ground and in flight data on detector background, effective area, quantum efficiency and point spread response function.

A novel type of micro-pore optics for the X-ray regime has been developed. These optics have a radial design instead of the square packing in the more traditional Lobster-eye optics. With such a design true imaging, without a crucifix in the focus, can be achieved. We demonstrate that the walls inside the square pores are good enough to produce sub- arcminute focussing up to photon energies above 10 keV. The current performance of the optics is limited by large-scale distortions of the plates, probably caused by the method to fuse the fibers together.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The High Resolution Camera (HRC) is one of two focal plane instruments on the NASA Chandra X-ray Observatory which was successfully launched on July 23, 1999. The Chandra X-ray Observatory was designed to perform high resolution spectroscopy and imaging in the X-ray band of 0.07 to 10 keV. The HRC instrument consists of two detectors, HRC-I for imaging and HRC-S for spectroscopy. Each HRC detector consists of a thin aluminized polyimide blocking filter, a chevron pair of microchannel plates and a crossed grid charge readout. The HRC-I is an approximately 100 X 100 mm detector optimized for high resolution imaging and timing, the HRC-S is an approximately 20 X 300 detector optimized to function as the readout for the Low Energy Transmission Grating. In this paper we discuss the in-flight performance of the HRC-S, and present preliminary analysis of flight calibration data and compare it with the results of the ground calibration and pre-flight predictions. In particular we will compare ground data and in-flight data on detector background, quantum efficiency, spatial resolution, pulse height resolution, and point spread response function.

The High Resolution Camera (HRC) is one of the two focal plane instruments on NASA's Chandra X-ray Observatory which was successfully launched July 23, 1999. The Chandra Observatory will perform high resolution spectroscopy and imaging in the X-ray band of 0.1 to 10 keV. The HRC instrument consists of two detectors, the HRC-I for imaging and the HRC-S for spectroscopy. In this paper we present an overview of the in-flight performance of the High Resolution Camera and discuss some of the initial scientific results.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This chapter describes, with an emphasis on physical principles, satellite-borne instrumentation for cosmic X-ray spectroscopy. Both wavelength dispersive spectrometers and energy dispersive detectors are considered; the potential and problems of new forms of cryogenic detector are examined in particular detail.

Lobster-eye optics have been proposed as an exciting development in the field of x-ray all-sky monitors. However, to date their potential has mainly been analyzed in the context of an all-sky monitor for a small satellite mission. We examine the wide range of parameters available for lobster-eye optics with different configurations. The sensitivity of the various schemes is calculated. We have also examined the current state of the art in actual lobster-eye optics. We present our experimental results and discuss realistic targets for manufacture. The impact of these targets on the calculated sensitivities is also described.

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.

The high resolution camera (HRC) will be one of the two focal plane instruments on the Advanced X-ray Astrophysics Facility, (AXAF). AXAF will perform high resolution spectrometry and imaging in the X-ray band of 0.1 to 10 keV. The HRC instrument consists of two detectors, the HRC-I for imaging and the HRC-S for spectroscopy. Each HRC detector consists of a thin aluminized polyimide window, a chevron pair of microchannel plates (MCPs) and a crossed grid charge readout. The HRC-I is a 100 by 100 mm detector optimized for high resolution imaging and timing, the HRC-S is an approximately 30 by 300 mm detector optimized to function as the readout for the low energy transmission grating spectrometer (LETGS). In this paper we present the absolute quantum efficiency, spatial resolution, point spread response function and count rate linearity of the HRC-I detector. Data taken at the HRC laboratory and at the Marshall Space Flight Center X-ray Calibration Facility are presented. The development of the HRC is a collaborative effort between The Smithsonian Astrophysical Observatory, University of Leicester UK and the Osservatorio Astronomico, G.S. Vaiana, Palermo Italy.

The high resolution camera (HRC) is one of two focal plane detector systems that will be flown on the Advanced X-ray Astrophysics Facility (AXAF). The HRC consists of two microchannel plate (MCP) detectors: one to provide large area, high position resolution imaging and timing (HRC-I), and a second (HRC-S) to provide a readout for the AXAF low energy transmission gratings. Each detector is composed of a chevron pair of CsI coated MCPs with a crossed grid charge detector and an Al/polyimide UV/ion shield. In this paper, we describe the operation, performance and calibration of the spectroscopic detector. In particular, we discuss the absolute quantum efficiency calibration, the point spread function of the instrument combined with the AXAF telescope, the count rate linearity, the spatial linearity, and the internal background of the instrument. Data taken in the laboratory and at the x-ray Calibration Facility at Marshall Space Flight Center are presented.

The high resolution camera (HRC) is a microchannel plate based imaging detector for the Advanced X-Ray Astrophysics Facility (AXAF) that will be placed in a high earth orbit scheduled for launch in August, 1998. An end-to-end calibration of the HRC and the AXAF high resolution mirror assembly (HRMA) was carried out at the Marshall Space Flight Center's X-Ray Calibration Facility (XRCF). This activity was followed by several modifications to the HRC to improve its performance, and a series of flat field calibrations. In this paper, and the following companion papers, we discuss the calibration plans, sequences, and results of these tests. At the time of this conference, the HRC has been fully flight qualified and is being integrated into the science instrument module (SIM) in preparation for integration into the AXAF spacecraft.

A proposal for an x-ray optics test facility based at a synchrotron radiation source is presented. The facility would incorporate a clean preparation area, and a large evacuable test area. The advantages of using a synchrotron as the source of the test radiation are discussed. These include the ability to produce a highly parallel beam of monochromatic x rays ranging from 200 eV to around 70 keV.

We discuss the current status of the Advanced X-ray Astrophysics Facility (AXAF) High Resolution Camera (HRC) quantum efficiency (QE) calibration. The absolute quantum efficiency of flight candidate, CsI coated HRC microchannel plates (MCPs) for the imaging detector (HRC-I) manufactured by Galileo Electro-Optics Corporation (GEOC) has been measured at several energies. We find the absolute QE of these MCPs (measured at SAO) to be 0.41 at C Kalpha (E equals 277 eV) and 0.28 at Al Kalpha (E equals 1487) eV). The absolute QE of flight-like HRC-I MCPs manufactured by Phillips Components (measured at the University of Leicester) is approximately 0.40 at both C Kalpha and Si Kalpha (E equals 1739 eV). We are now in the process of measuring the absolute QE of both the HRC-I and HRC-S flight detectors at 22 different energies at 4 azimuthal and 5 polar angles. A summary of planned measurements is presented. In addition, we present data taken at the Daresbury Synchrotron Radiation Source to map out the detailed edge structure of the MCP glass and coatings. In particular, we present measurements of the relative QE of CsI coated MCPs around Cs and I M edges, and absolute measurements around the K K and Cs LIII edges. The absolute measurements of the flight instrument at the 22 discrete energies will be combined with the relative synchrotron measurements of flight-like detectors to produce the absolute QE of the HRC over the entire AXAF bandpass (0.1 to 10 keV).© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Reducing plate resistance is one of the possible ways to increase the count rate capability of microchannel plates (MCPs). Bonding a low-resistance plate to a cooled substrate provides a conductive path for heat transport an prevents thermal runaway. MCPs of very low resistance (less than or equal to 500 k(Omega) ), bonded to a Peltier cooler, were tested using different bonding techniques. Stable, reproducible operation of a rear-cooled MCP (60:1, 10 micrometer channels) was achieved for biases up to 1320 volts (RMCP equals 260 k(Omega) at that voltage), when the MCP bias current was as high as 5.1 mA and the heat generated by the plate was 0.78 W cm-2. The count rate reached the value of 108 cm-2s-1 limited not by the plate recharge time, but by the intensity of the mercury vapor UV lamp (2540 angstrom) used for illumination. The dark noise, at the same time, was less than 1 cm-2s-1. A thermal model of such conductively cooled MCPs is described. The count rate characteristic of a microchannel plate is well-known to depend on the pattern of illumination. This paper updates our previous investigation of radial gain depression in the vicinity of high count rate point-like illumination.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The high resolution camera (HRC) will be one of the two focal plane instruments on the Advanced X-ray Astrophysics Facility, (AXAF). AXAF is a major NASA space observatory and is scheduled for launch in 1998. AXAF will perform high resolution spectrometry and imaging in the x-ray band of 0.1 to 10 keV. The HRC instrument consists of two detectors, the HRC-I for imaging and the HRC-S for spectroscopy. Each HRC detector consists of chevron pairs of microchannel plates (MCPs) and a crossed grid charge readout. Spatial resolutions of the HRC detectors are less than 25 micrometer (less than 0.5'). The HRC-I is a 100 by 100 mm detector primarily for imaging, the HRC-S is an approximately 30 by 300 mm detector which is optimized to function as the readout for the low energy transmission grating spectrometer (LETGS). The development of the HRC is a collaborative effort between the Smithsonian Astrophysical Observatory, University of Leicester UK and the Osservatorio Astronomico, G.S. Vaiana, Palermo Italy. In this paper we present the most recent design, development and testing of the HRC instrument.

Soft x-ray optics based on slumped, profiled microchannel plates (MCPs) are under development. Their purpose is to collimate the expanding beam from a laser-plasma x-ray source, resulting in a parallel beam suitable for lithography of semiconductor devices. We present a prototype design for such an optic with a radius of curvature optimized for maximum beam intensity. The plate thickness (and hence the channel length) is varied as a function of distance from the plate center. The resulting plate profile is determined by the radius of curvature but not by the x- ray energy. This design is shown by Monte Carlo ray-trace modeling to give a circular illuminated field with a diameter of 36mm for 1 keV x-rays. The calculated intensity of the beam is equivalent to that of the divergence beam at a distance of 0.35m from the source. We also present preliminary x-ray measurements from the optic. These optics, while designed with the semiconductor industry in mind, may find application in any field where a uniform or parallel soft x-ray or VUV beam is required.

Microsphere plates (MSPs), a new type of electron multiplier, consisting of sintered disks of glass beads, have recently become available from El-Mul Technologies Ltd. The principles of MSP operation are similar to those of microchannel plates (MCPs). This paper reports a survey of the gain, resistance, dark noise, count rate capability, charge abstraction lifetime, and image characteristics of a number of standard 33 mm diameter microsphere plates (of thickness 0.7 and 1.4 mm), operated both singly and as two-stage multipliers. We also describe a simple Monte-Carlo model of MSP operation, which enables us to estimate numerically a number of MSP characteristics, including (1) output pulse height distributions (PHDs), (2) output electron spatial and energy distributions, and (3) transit time distributions.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Advanced X-ray Astrophysics Facility (AXAF) is a major NASA space observatory and is scheduled for launch in 1998. AXAF will perform high spatial and spectral resolution observations of celestial sources in the soft x-ray band 0.1 - 10 keV. The high resolution camera (HRC) is one of two focal plane instruments being developed for the AXAF. The HRC will be capable of observing point and extended sources with high sensitivity and high spatial resolution and will be used to record the high resolution spectra produced by an objective transmission grating. The HRC is based on microchannel plates (MCPs). We describe the design and development of the HRC, its expected performance, and some of its observational goals. The HRC consists of two separate detectors, HRC-I (imaging) and HRC-S (spectroscopy). HRC-I is used for imaging and has a field of view of 31 arc min by 31 arc min and a spatial resolution of less than 25 micrometers (equivalent to less than 0.5 arc sec). HRC- S is optimized to readout the spectrum of AXAF's low energy transmission grating (LETG) and this combination will achieve resolving powers in excess of 1000 at low energies and cover a wavelength range of 4 to 140 angstroms.

We report on the results of a synchrotron calibration of two identical microchannel plate (MCP) detectors carried out at the CCL Daresbury synchrotron radiation source (SRS). The SRS was run with low ring current to allow operation of the detectors in photon-counting mode. Both detectors were half coated with KBr and half with CsI. Detector 1 was calibrated, for both photocathodes, in 1 eV steps over the energy range 50 - 350 eV, on SRS beamline 6.1. We present measurements of edge-related absolute quantum efficiency features arising from both the photocathodes and the underlying lead silicate glass. We also describe the results of charge abstraction lifetests of Detector 1, made possible by the small cross section and relatively high peak count rate of the line 6.1 x-ray beam. A preliminary analysis of the calibration of detector 2 in 3 eV steps over the energy range 2000 - 6000 eV (on IRC beamline 4.2) is also presented.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The high resolution camera (HRC) will be one of the two focal plane instruments on the Advanced X-ray Astrophysics Facility (AXAF). AXAF is a major NASA space observatory and is scheduled for launch in 1998. The essential elements of the HRC instruments are chevron pairs of microchannel plates (MCPs). The HRC MCPs provide x ray conversion and electron multiplication while maintaining high spatial and temporal resolution. In addition, the HRC MCPs will be the largest format, the lowest internal background, and the highest resolution of any MCP-based x-ray imaging detector. This paper presents results obtained in testing and evaluating flight candidate MCPs with emphasis on their low internal background out-of-band (high energy) response and their spatial uniformity.

Focused x-ray images are reported for 21 X 21mm2 microchannel plate (MCP) optics having an eleven micron square-channel geometry. These are the smallest channel size square-pore MCPs yet evaluated. Because the limiting focal spot size in such optics is twice the channel width, their construction represents a significant advance towards focusing elements capable of very high intensification. The MCPs were fabricated with channel length- to-diameter ratios of 40 to 1 and 75 to 1; with an open area fraction of 85%. X-ray images were first obtained at 0.28keV and 1.74keV using a planar MCP geometry with a zero degree bias angle. These images indicate that subtle deviations from an ideal square channel geometry (i.e. vertex 'radiusing') can strongly influence the focal spot structure. Finally, one of the MCPs was spherically 'slumped' to a 1m radius and remeasured in x-rays, demonstrating for the first time the operation of a slumped square-channel MCP.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A brief review is given of position-sensitive detector systems for thermal neutron imaging, highlighting novel techniques and the goal of sub-mm spatial resolution. The links between position-sensitive neutron detection and soft x-ray imaging are emphasized.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We describe an experiment to quantify reflected X-ray Absorption Fine Structure (XAFS) in the mirrors to be used on the Joint European X-ray Telescope (JET-X). This instrument is due to be launched on the Russian Spectrum-X platform into deep orbit in December 1995. As part of the calibration program, samples of the Wolter type I, X-ray mirrors were taken to the Synchrotron Radiation Source at the Daresbury Laboratory and exposed to monochromatic X- rays across the energy range of the gold MI - MV edges (2 keV to 3.5 keV). We outline our research program and present preliminary results of both direct and reflected XAFS measurements at a variety of incident angles. We find that, while the position of the MII edge occurs within 3 eV of its tabulated value, the MI, MIII, MIV and MV edges are shifted to higher energies by approximately 10 eV, 13 eV, 40 eV and 40 eV, respectively. We attribute these discrepancies to inaccuracies in the field equations used to generate atomic and nuclear data tables.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We describe our recent synchrotron measurements of microchannel plate (MCP) quantum detection efficiency made in pulse-counting mode in a 40-300 eV band containing the L shell absorption edges of silicon. The significance of this data for the calibration of the HRC-S transmission grating detector for the AXAF-I X-ray observatory is discussed.

In the present paper, we describe X-ray images obtained using planar, square pore MCPs in `point-to-point' focusing mode. Angular resolution of 5 arcminutes fwhm has now been measured for full-field illumination of a hydrogen-reduced Galileo MCP (29 mm active diameter; approximately 44,000 active channels). Secondly, we report some preliminary metrology of square-pore microchannel plates using atomic force, scanning electron and optical microscopies. Finally, we extend our study of spherically-slumped, round-pore Philips MCPs operated as X-ray `beam expanders'.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Microchannel plates (MCPs) are compact electron multipliers of high gain, widely used for the high resolution imaging of charged particles and photons. In this paper, we consider the use of lead glass MCPs for the imaging of thermal neutrons. Two contrasting techniques are described. The first method involves direct neutron detection within a special channel plate structure containing lithium and/or boron. We review the constraints of glass chemistry on the attainable lithium oxide and boron oxide fractions and, hence, on the maximum neutron detection efficiency. The second method involves the detection, using MCPs of standard glass composition, of the internal conversion electrons from a thin gadolinium foil. We present the first measurements of the detection efficiency, pulse height resolution and imaging properties of a pulse-counting MCP/Gd detector system.