Design aspects of a cold neutron irradiator

Journal Article · Sun Dec 31 04:00:00 EST 1995 · Transactions of the American Nuclear Society

OSTI ID:411613

Atwood, A G; Clark, D D; Hossain, T Z; Spern, S A ^[1]

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1. Cornell Univ., Ithaca, NY (United States)

Design work on a cold-neutron irradiator (CNI) is being pursued at Cornell University. Prompt gamma neutron activation analysis (PGNAA) by means of cold neutron absorption is the objective of the CNI. Using cold neutrons instead of thermal neutrons to cause neutron capture in the sample, the CNI is a logical extension of the concept of a thermal neutron irradiator. Since the neutron capture cross section for most nuclei varies as 1/v, augmentation of the neutron capture reaction rate is achieved in the sample by a factor of {approximately}2.3. The statistical precision with which one can measure the mass of a particular element in the sample is enhanced in a CNI, in comparison with a thermal neutron irradiator, by a factor of between 2.3 and the square of 2.3. The exact factor by which the statistical precision is enhanced depends on the energy of the PGNAA photopeak at which one is looking and on the extent to which the photon background measured by the photon detector is dominated by either the {sup 252}Cf spontaneous fission photons or by the neutron capture photons from the CNI structural materials. Within the context of the optimization of the elemental sensitivity of the CNI system, the CNI must efficiently deliver cold neutrons from the {sup 252}Cf fast neutron source to the sample and must efficiently deliver the PGNAA gamma rays of the sample to the high-purity germanium (HPGe) photon detector while maintaining reasonable fast neutron and gamma-ray backgrounds at the detector.

• OSTI ID: 411613
• Report Number(s): CONF-951006--
• Journal Information: Transactions of the American Nuclear Society, Journal Name: Transactions of the American Nuclear Society Vol. 73; ISSN 0003-018X; ISSN TANSAO
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
22 GENERAL STUDIES OF NUCLEAR REACTORS
66 PHYSICS
CALIFORNIUM 252
COLD NEUTRONS
CORNELL TRIGA-MK-2 REACTOR
M CODES
MODERATORS
NEUTRON ACTIVATION ANALYSIS
NEUTRON SOURCE FACILITIES
NEUTRON SOURCES
RADIATION TRANSPORT