Prompt fission neutron anisotropy in low-multiplying subcritical plutonium metal assemblies [electronic resource]
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| Online Access: |
Full Text (via OSTI) |
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| Format: | Government Document Electronic eBook |
| Language: | English |
| Published: |
Washington, D.C. : Oak Ridge, Tenn. :
United States. National Nuclear Security Administration ; distributed by the Office of Scientific and Technical Information, U.S. Department of Energy,
2018.
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| Subjects: |
| Abstract: | Fission neutron anisotropy, due to the kinematics of the fission process, has been studied for non-multiplying sources and highly multiplying subcritical plutonium metal assemblies (i.e. relatively long fission chains). The studies on highly multiplying assemblies show that the observed neutron-neutron angular distribution appear isotropic, while the studies on non-multiplying sources show that the neutron-neutron angular distribution appear anisotropic. No measured data exists, however, that investigates the dependence of neutron anisotropy on multiplication for low-multiplying assemblies. We have experimentally characterized the dependence of fission neutron anisotropy on multiplication for low-multiplying plutonium metal assemblies. Here, an array of 16 organic scintillators was used to measure plutonium metal assemblies (95% <sup>239</sup>Pu, by mass) exhibiting a leakage multiplication of 1.0722(3) to 1.6006(4). Full neutron-neutron angular distributions were measured, and the fission neutron anisotropy was quantified with the ratio of neutron-neutron coincidences observed at 180° and 90°. The results show that the neutron-neutron angular distribution becomes more isotropic as the multiplication increases. Additionally, energy-angle correlations were also characterized showing that the angular distributions are more anisotropic when observing neutrons of higher energy. |
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| Item Description: | Published through SciTech Connect. 09/27/2018. Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment 915 C ISSN 0168-9002 AM. Tony H. Shin; Angela Di Fulvio; Shaun D. Clarke; David L. Chichester; Sara A. Pozzi. Univ. of Michigan, Ann Arbor, MI (United States) |
| Physical Description: | p. 110-115 : digital, PDF file. |