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Segmented Ge detector rejection of internal beta activity produced by neutron irradiationFuture Ge spectrometers flown in space to observe cosmic gamma-ray sources will incorporate segmented detectors to reduce the background from radioactivity produced by energetic particle reactions. To demonstrate the effectiveness of a segmented Ge detector in rejecting background events due to the beta decay of internal radioactivity, a laboratory experiment has been carried out in which radioactivity was produced in the detector by neutron irradiation. A Cf-252 source of neutrons was used to produce, by neutron capture on Ge-74 (36.5 percent of natural Ge) in the detector itself, Ge-75 (t sub 1/2 = 82.78 min), which decays by beta emission with a maximum electron kinetic energy of 1188 keV. By requiring that an ionizing event deposit energy in two or more of the five segments of the detector, each about 1-cm thick, the beta particles, which have a range of about 1-mm, are rejected, while most external gamma rays incident on the detector are counted. Analysis of this experiment indicates that over 85 percent of the beta events from the decay of Ge-75 are rejected, which is in good agreement with Monte Carlo calculations.
Document ID
19910057859
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Varnell, L. S.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Callas, J. L.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Mahoney, W. A.
(JPL Pasadena, CA, United States)
Pehl, R. H.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Landis, D. A.
(Lawrence Berkeley Laboratory Berkeley, CA, United States)
Date Acquired
August 15, 2013
Publication Date
April 1, 1991
Publication Information
Publication: IEEE Transactions on Nuclear Science
Volume: 38
ISSN: 0018-9499
Subject Category
Spacecraft Instrumentation
Accession Number
91A42482
Distribution Limits
Public
Copyright
Other

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