Accounting for the Thermal Neutron Flux Depression in Voluminous Samples for Instrumental Neutron Activation Analysis
作者:
OverwaterR. M. W.,
HoogenboomJ. E.,
期刊:
Nuclear Science and Engineering
(Taylor Available online 1994)
卷期:
Volume 117,
issue 3
页码: 141-157
ISSN:0029-5639
年代: 1994
DOI:10.13182/NSE94-A28530
出版商: Taylor&Francis
数据来源: Taylor
摘要:
AbstractAt the Delft University of Technology Interfaculty Reactor Institute, a facility has been installed to irradiate cylindrical samples with diameters up to 15 cm and weights up to 50 kg for instrumental neutron activation analysis (INAA) purposes. To be able to do quantitative INAA on voluminous samples, it is necessary to correct for gamma-ray absorption, gamma-ray scattering, neutron absorption, and neutron scattering in the sample. The neutron absorption and the neutron scattering are discussed. An analytical solution is obtained for the diffusion equation in the geometry of the irradiation facility. For samples with known composition, the neutron flux—as a function of position in the sample—can be calculated directly. Those of unknown composition require additional flux measurements on which least-squares fitting must be done to obtain both the thermal neutron diffusion coefficient Dsand the diffusion length Lsof the sample. Experiments are performed to test the theory.
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