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Proceedings Paper

Low Noise Microchannel Plate Detectors For X-Ray Astronomy
Author(s): Michael R. Garcia; Jon H Chappell; Stephen S. Murray; W. Bruce Feller; George W. Fraser
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Paper Abstract

The dominant source of internal background in microchannel plate detectors is thought to be due to trace amount of ra-dioisotopes in the detector glass which decay through β-processes. Several manufacturers have begun programs to produce lead glass with greatly reduced amounts of radioisotopes in order to fabricate microchannel plates with lower internal background counting rates. Our laboratory measurements of such plates show that the background rates are substantially lower than in standard microchannel plates. The remaining background rate is consistent with the sum of the rates due to the residual trace level of radioisotopes, cosmic ray interactions in the microchannel plates, and a third, previously unrecognized component which is likely due to MeV γ-rays emitted by the laboratory concrete walls. We discuss the implications the measured background rates have for the sensitivity of the High Resolution Camera (HRC) to be flown on the U.S. Advanced X-ray Astrophysics Facility (AXAF). We compare these predicted rates with those measured in the High Resolution Imager (HRI) which was flown on the Einstein X-ray astronomy observatory.

Paper Details

Date Published: 27 November 1989
PDF: 5 pages
Proc. SPIE 1140, X-Ray Instrumentation in Medicine and Biology, Plasma Physics, Astrophysics, and Synchrotron Radiation, (27 November 1989); doi: 10.1117/12.961809
Show Author Affiliations
Michael R. Garcia, Smithsonian Astrophysical Observatory (United States)
Jon H Chappell, Smithsonian Astrophysical Observatory (United States)
Stephen S. Murray, Smithsonian Astrophysical Observatory, Cambridge (United States)
W. Bruce Feller, Galileo Electro-Optics Corporation (United States)
George W. Fraser, University of Leicester (United Kingdom)

Published in SPIE Proceedings Vol. 1140:
X-Ray Instrumentation in Medicine and Biology, Plasma Physics, Astrophysics, and Synchrotron Radiation
Rene Benattar, Editor(s)

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