Instrumentation for gamma-ray astronomy

There are three distinct energy ranges within the broad spectrum of gamma-ray astronomy, low energy (which in turn is subdivided), high energy, and very high and ultra-high energy. Each has its own unique type of instrumentation. Only in the very high-energy range do the telescopes bear any resemblence to optical telescopes; the rest appear more like instrumentation for high-energy physics. The low- and high-energy ranges are now primarly dependent on spaceflight, although some balloon altitude research is still being accomplished. Satellites planned to be launched in the next two years will carry telescopes with considerably more capability than those previously flown in space. In the very high and ultra-high energy realm, large ground based systems are used to detect the secondary radiation from interactions of the gamma radiation with the air. In all cases, software and data analysis are becoming increasingly important aspects of the subject as the data become ever greater and more complex. Beyond the telescopes to be flown in space or installed on the ground soon, instrumentation, taking advantage of new detector techniques which have come into being or older ones which now seem capable of being adapted to space, are being developed for the more distant future.     

All-sky monitors for X-ray astronomy

We discuss the rationale for a semi-permanent all-sky X-ray monitor, and investigate a variety of options for its implementation. We conclude that the Space Station offers an excellent opportunity for hosting such a monitor, and that a set of pinhole cameras can be configured to provide an effective and economical monitor system. A baseline of six independent pinhole modules, each of which requires approximately one cubic foot, 30 pounds, 2 watts, and 100 bits per second, can provide full sky coverage with scientifically interesting sensitivities. No other resources or special accommodation (such as detailed alignment registration, time-tagging or on-orbit servicing) would be required. The baseline system can locate bright sources to a few arc min, and can simultaneously measure each of the several hundred sources in the sky brighter than a few thousandths the intensity of the Crab nebula every day for decades.     

Techniques in balloon X-ray astronomy

The first balloon observation of a cosmic X-ray source, the Crab Nebula, was made in 1965, only three years after the initial discovery of such sources by rocket observations. Since then balloon data has provided much information on the positions, spectra, time variability and pulsed nature of localized sources, and on the spectrum and isotropy of diffuse galactic and universal components. Measurements are limited to energies above about 20 keV by atmospheric attenuation at 2–3 g cm ^–2 depth and to below several hundred keV by detector sensitivity. Detectors usually consist of large area NaI or CsI scintillation counters with anticoincidence collimators for rejection of charged particles and scattered X-rays. Proportional counters are occasionally used at lower energies and solid state detectors are used where extreme energy resolution is important. The instruments require a pointing capability on the order of 1.0 to 0.1°, depending on the collimator aperture. Digital data is either recorded on board or telemetered using a PCM technique. Exploratory work in the 0.2–10 MeV -ray range is starting now, and balloon observations may be expected to make important contributions in the near future.     

Position sensitive multiwire proportional counters for X-ray astronomy

The state of the art of the existing position sensitive multiwire proportional counters (PSMWPC) will be briefly reviewed. In particular taking into account the contribution these detectors have already made to our knowledge of the X-ray sky and the expected future steps that will only be possible with new detector development.Finally a new design of multiwire proportional counter will be described. The new generation of this kind of PSMWPC detectors, when operated with a modulating mask or a single grid rotation modulation collimator or, in the future, with a combination of these two techniques will provide images of the high-energy sky with an angular resolution of l min of arc.     

Wide angle X-ray optics for use in astronomy

Recently there was a suggestion in the literature to apply the principle of the lobster-eye to X-ray astronomy imaging (J.R.P. Angel, Ap. J. 233, 364, 1979). Our own suggestion for a wide angle X-ray telescope made earlier (W.K.H. Schmidt, Nucl. Instr. Meth.127, 285, 1975) is very similar to the above one. It consists of one or two sets of plane mirrors used in a grazing incidence configuration. The advantages of this type of X-ray optics over other systems for particular astronomical observations will be discussed.     

The capabilities of a gas scintillation camera for cosmic X-ray astronomy

The capabilities of a gas scintillator camera for use in X-ray astronomy are investigated. Detailed experimental results are presented on both the position and energy resolution over the energy range 0.28 to 6 keV. The energy resolution varies from 38% to 9.5% for 0.28 keV C-K and 6 keV X-rays respectively. Position resolutions of 1.8 mm and 3.5 mm for 6 keV and 1.5 keV Al-K X-rays were obtained. Image quality and uniformity over the camera aperture are also discussed, whilst further techniques leading to improvements in position resolution are outlined. Finally applications of these cameras in conjunction with grazing incidence and coded mask X-ray optics are discussed.     

Galactic X-rays observed with X-ray astronomy satellite ‘Hakucho’

Highlights of the results obtained with Japanese X-ray astronomy satellite Hakucho are reviewed. After a brief account of instrumentation (Section 2), some new features of non-bursting, non-pulsating objects are presented (Sections 3–5). The main part of the present review is devoted for X-ray bursts which are found more complex than one might have thought (Sections 6–11). The observation of X-ray pulsar, including a change of spin rate of Vela X-1, is described (Section 12). The main results obtained in the first two years are summarized in Section 13.     

The use of diamond turned & replicated wolter 1 telescopes for high sensitivity X-ray astronomy

Following the success of Einstein, it is clear that telescopes of very large area (10 cm) with angular resolution (20) are needed for deep X-ray surveys and other observations. After a discussion of these objectives, which form the basis of the NASA LAMAR mission, the design & performance of a five mirror telescope is described. The system was studied for possible flight on Spacelab to undertake observations & to act as a prototype module for LAMAR. Both diamond turning & replication methods of mirror production are discussed. The performance of a single Wolter I telescope with diamond turned mirrors will be described.     

Infrared astronomy

This review paper is a survey of infrared astronomy up to early 1969. The techniques and photometric standards are mentioned briefly, and results cover solar, lunar, and planetary observations. Point sources and extended sources both within and beyond the Galaxy are included, ending with the problem of cosmic background radiation. It is concluded that great progress will be possible when large infrared telescopes are placed above the atmosphere in orbit for extended periods of time.This work was conducted under the McDonnell Douglas Corporation Independent Research and Development Program.     

Gamma-ray line astronomy

Recent gamma-ray line observations and their interpretations are reviewed and prospects for future line detections are discussed.     

Aspects of neutrino astronomy

A broad overview of the current status of experimental neutrino astronomy is presented. Particular emphasis is given to the major recent developments that have occurred during the last few years. It is concluded that these developments and the next generation of experiments currently being installed signifies the coming of age of neutrino astronomy.     

A high-resolution Ge spectrometer for Gamma-Ray burst astronomy

The Transient Gamma-Ray Spectrometer (TGRS) to be flown aboard the WIND spacecraft is primarily designed to perform high resolution spectroscopy of transient -ray events, such as cosmic -ray bursts and solar flares over the energy range 25 keV to 8.2 MeV with an expected spectroscopic resolution of 3 keV at 1 MeV. The detector itself consists of a 215 cm³ high purityn-type Ge crystal kept at cryogenic temperatures by a passive radiative cooler. The geometric field of view defined by the cooler is 1.8 steradian. To avoid continuous triggers by soft solar events, a thin BeCu Sun-shield around the sides of the cooler has been provided. A passive Mo/Pb occulter, which modulates signals from within ±5° of the ecliptic plane at the spacecraft spin frequency, is used to identify and study solar flares, as well as emission from the galactic plane and center. Thus, in addition to transient event measurements, the instrument will allow the search for possible diffuse background lines and monitor the 511 keV positron annihilation radiation from the galactic center. In order to handle the typically large burst count rates, which can be in excess of 100 kHz, burst data are stored directly in an onboard 2.75 Mbit burst memory with an absolute timing accuracy of ±1.5 ms after ground processing. The memory is capable of storing the entire spectral data set of all but the largest bursts. WIND is scheduled to be launched on a Delta II launch vehicle from Cape Canaveral on November 1, 1994. After injection into a phasing orbit, the spacecraft will execute a double lunar swing-by before being moved into a controlled halo orbit about theL1 Lagrangian point (250R _e towards the Sun). This will provide a 5 light-second light travel time with which to triangulate gamma-ray burst sources with Earth-orbiting systems, such as those on-board the Gamma-Ray Observatory (GRO). The response of instrument to transient -ray events such as GRB's and solar flares will be presented as well as the expected response to steady state point sources and galactic center line emission.     

Extragalactic γ-ray astronomy

Space Science Reviews - Extragalactic γ-ray astronomy is in its infancy. In this paper a review is presented of the γ-ray emission of the few individual objects observed to date and some...     

On-Line Computer for Transient Turbine Cascade Instrumentation

A 32-channel computer based data acquisition and processing system em has been developed for use with the new type of transient cascade facility at Oxford. This is used for testing turbine blades and nozzle guide vanes at full-scale engine Reynolds and Mach numbers ers with correct wallto-flow temperature ratios. A novel technique for processing transient heat transfer data from thin film surface resistance thermometers has been developed. Measurements of surface ace pressure around blades, and of the upstream turbulence level have been made. The cascade and instrumentation are shown to have advantages both in cost and effectiveness over continuous running cascades.     

Stellar infrared astronomy with EDISON

In this review the IR emission from circumstellar material is discussed, both of ionized gas and dust grains, and the astrophysical information that can be extracted from such observations. Some emphasis is placed on the possibilities of stellar IR astronomy using a large space-borne telescope, especially with respect to the much better spatial and spectral resolution of such a telescope compared to the current generation of ground-based and space IR telescopes.     

航空发动机高能X射线测试系统

综合介绍了高能X射线测试系统在航空发动机试验中的作用和基本组成以及国内外高能X射线测试技术开发应用情况。