Showing papers by "T. J. Sumner published in 1991"
TL;DR: In this article, a preliminary observation of a small section of the sky, carried out over July 11-16 (the mini-survey) showed all ROSAT systems to be functioning well and has allowed predictions to be made on the ultimate productivity of both ROSAT all-sky surveys.
Abstract: Following a successful launch on 1990 June 1, the ROSAT spacecraft and its payload, consisting of an X-ray and an EUV telescope, underwent two months of in-orbit calibration and detailed performance checks. A preliminary observation of a small section of the sky, carried out over July 11-16 (the mini-survey) showed all ROSAT systems to be functioning well and has allowed predictions to be made on the ultimate productivity of both ROSAT all-sky surveys. An analysis of the mini-survey data from the UK Wide Field Camera, has revealed 35 EUV sources, including several white dwarf stars, a variety of active cool stars and several other objects. In all, 23 sources have probable optical counterparts
5 citations
01 Dec 1991-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the design and performance of individual bolometers, using doped layers with a thickness in the range 0.2 to 2 μm, were described, and the use of epitaxial growth to replace ion implantation for improved performance was discussed.
Abstract: Silicon bolometers are currently under development for milliKelvin operation; these devices are being produced using Si wafer fabrication technology. The design and performance of individual bolometers, using doped layers with a thickness in the range 0.2 to 2 μm are described. The use of epitaxial growth to replace ion implantation for improved performance is discussed.
For future use in space based X-ray astronomy, such devices could be fabricated as complete one or two dimensional arrays with integrated isolation and support. The proposed fabrication method for such arrays is outlined.
3 citations
TL;DR: In this paper, two types of drift devices, namely photodiodes and position sensitive drift chambers with segmented anode and cathode structures, have been studied at room temperature and below.
Abstract: Two types of drift device, namely photodiodes and position sensitive drift chambers with segmented anode and cathode structures, have been studied at room temperature and below. Leakage current and electron mobility have been investigated at low temperature for the drift photodiodes. Self-triggering has been achieved for the position sensitive drift chambers using 60 keV photons, and differences in arrival time between the prompt trigger signal from the cathode and the delayed anode signal have been studied as a function of drift distance and temperature. The response of the photodiodes when coupled to a CsI scintillator at room temperature has been assessed.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
2 citations
TL;DR: In this paper, the Schottky diodes on LEC and HB starting material were used as x-ray detectors for high energy physics applications and dark matter searches, including their low temperature operation.
Abstract: Recent developments in the manufacture of GaAs detectors for high energy physics applications and dark matter searches have resulted in working devices made from LEC and HB starting material This offers the promise of routine manufacture of reproducible devices at a modest cost The most advanced of the techniques is that of Schottky diodes on LEC material Results are presented demonstrating the performance of such devices (30 mm X 50 mm X 200 micrometers ) as x-ray detectors, including their low temperature operation An alternative technique using charge collection in bulk HB material at temperatures down to liquid helium also is briefly described
2 citations
TL;DR: In this paper, the design and performance of individual bolometers, using doped layers with a thickness in the range 0.1 to 3 (mu), are described and the use of epitaxial growth to replace ion implantation for improved performance is described.
Abstract: Silicon bolometers are currently under development for milliKelvin operation; these devices are being produced using Si wafer fabrication technology. The design and performance of individual bolometers, using doped layers with a thickness in the range 0.1 to 3 (mu) , are described. The use of epitaxial growth to replace ion implantation for improved performance is described and initial results reported.
TL;DR: In this paper, a review of work done by several people in the UK Interstellar Medium/Diffuse Emission ROSAT Special Interest Group is presented, focusing on the preliminary results from this instrument on which the review focuses.
01 Jan 1991
TL;DR: Early results from observations made by the UK's imaging EUV telescope, the Wide Field Camera (WFC), are presented in this paper, which highlights the importance of WFC observations for the study of white dwarfs and related objects.
Abstract: We present early results from observations made by the UK’s imaging EUV telescope, the Wide Field Camera (WFC). This telescope is being flown aboard the West German satellite ROSAT. In conjunction with a large X-ray telescope, built by the West Germans, the WFC is conducting a survey of the whole sky. This is the first in the EUV waveband. Afterwards ROSAT will be devoted to pointed observations of specific objects. We use results from the earliest phases of the ROSAT mission to highlight the importance of WFC observations for the study of white dwarfs and related objects such as the central stars of planetary nebulae.