Fast Neutron Sensitivity with HPGe

Conference · Tue Jan 22 00:00:00 EST 2008 · Nuclear Science Symposium Conference Record, 2007. NSS 07'. IEEE

DOI:https://doi.org/10.1109/NSSMIC.2007.4437216· OSTI ID:946671

Seifert, Allen ^[1]; Hensley, Walter K. ^[1]; Siciliano, Edward R. ^[1]; Pitts, W. K. ^[1]

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1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

In addition to being excellent gamma-ray detectors, germanium detectors are also sensitive to fast neutrons. Incident neutrons undergo inelastic scattering {Ge(n,n')Ge*} off germanium nuclei and the resulting excited states emit gamma rays or conversion electrons. The response of a standard 140% high-purity germanium (HPGe) detector with a bismuth germanate (BGO) anti-coincidence shield was measured for several neutron sources to characterize the ability of the HPGe detector to detect fast neutrons. For a sensitivity calculation performed using the characteristic fast neutron response peak that occurs at 692 keV, the 140% germanium detector system exhibited a sensitivity of ~175 counts / kg of WGPu_metal in 1000 seconds at a source-detector distance of 1 meter with 4 in. of lead shielding between source and detector. Theoretical work also indicates that it might be possible to use the shape of the fast-neutron inelastic scattering signatures (specifically, the end-point energy of the long high energy tail of the resulting asymmetric peak) to gain additional information about the energy distribution of the incident neutron spectrum. However, the experimentally observed end-point energies appear to be almost identical for each of the fast neutron sources counted. Detailed MCNP calculations show that the neutron energy distributions impingent on the detector for these sources are very similar in this experimental configuration, due to neutron scattering in a lead shield (placed between the neutron source and HPGe detector to reduce the gamma ray flux), the BGO anti-coincidence detector, and the concrete floor.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 946671
• Report Number(s): PNNL-SA-58127; DP4011020; TRN: US0900990
• Journal Information: Nuclear Science Symposium Conference Record, 2007. NSS 07'. IEEE, Vol. 2; Conference: 2007 IEEE Nuclear Science Symposium Conference Record, Honolulu, HI (United States), 26 Oct-3 Nov 2007; ISSN 1095-7863
• Publisher: IEEE Service Center, Piscataway, NJ, United States
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BISMUTH GERMANATES
CONCRETES
CONFIGURATION
ELECTRONS
ENERGY SPECTRA
EXCITED STATES
FAST NEUTRONS
GE SEMICONDUCTOR DETECTORS
GERMANIUM
INELASTIC SCATTERING
NEUTRON SOURCES
NEUTRONS
NUCLEI
SCATTERING
SENSITIVITY
SHAPE
SHIELDING
SHIELDS
HPGe
fast neutron
spectroscopy