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CdZnTe background measurement at balloon altitudes with an active BGO shield

Bloser, P. and Grindlay, J. and Narita, T. and Harrison, F. (1998) CdZnTe background measurement at balloon altitudes with an active BGO shield. In: EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy IX. Proceedings of SPIE. No.3445. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, pp. 186-196. ISBN 9780819429001.

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We report results of an experiment conducted in May 1997 to measure CdZnTe background and background reduction schemes in space flight conditions similar to those of proposed hard x-ray astrophysics missions. A 1 cm^2 CdZnTe detector was placed adjacent to a thick BGO anticoincidence shield and flown piggy backed onto the EXITE2 scientific balloon payload. The planar shield was designed to veto background counts produced by local gamma-ray production in passive material and neutron interactions in the detector. The CdZnTe and BGO were partially surrounded by a Pb-Sn-Cu shield to approximate the grammage of an x-ray collimator, although the field of view was still approximately 2 π sr. At an altitude of 127000 feet we find a reduction in background by a factor of 6 at 100 keV. The non-vetoed background is 9 X 10^(-4) cts cm^(-2) s^(-1) at 100 keV, about a factor of 2 higher than that of the collimated (4.5° FWHM) EXITE2 phoswich detector. We compare our recorded spectrum with that expected from simulations using GEANT and find agreement within a factor of 2 between 30 and 300 keV. We also compare our results with those of previous experiments using passive lead and active NaI shields, and discus possible active shielding schemes in future astronomy mission employing large arrays of CdZnTe detectors.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Grindlay, J.0000-0002-1323-5314
Harrison, F.0000-0003-2992-8024
Additional Information:© 1998 Society of Photo-Optical Instrumentation Engineers (SPIE). We thank B. Matthews for work on the CdZnTe detector, T. Gauron and J. Grenzke for work on the flight electronics and software, and K. Lum for work on the data analysis software. This work was supported in part by NASA grant NAG5-5103. P. Bloser acknowledges support from NASA GSRP grant NGT5-50020.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
NASA Graduate Student Research FellowshipNGT5-50020
Subject Keywords:CdZnTe, background, shielding, balloon flights, hard X-ray astronomy, instrumentation
Series Name:Proceedings of SPIE
Issue or Number:3445
Record Number:CaltechAUTHORS:20180110-155845293
Persistent URL:
Official Citation:Peter Forbes Bloser, Jonathan E. Grindlay, Tomohiko Narita, Fiona A. Harrison, "CdZnTe background measurement at balloon altitudes with an active BGO shield", Proc. SPIE 3445, EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy IX, (10 November 1998); doi: 10.1117/12.330275;
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84238
Deposited By: George Porter
Deposited On:11 Jan 2018 16:36
Last Modified:15 Nov 2021 20:18

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