DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Prompt fission neutron anisotropy in low-multiplying subcritical plutonium metal assemblies

Journal Article · · Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment
 [1];  [1];  [1];  [2];  [1]
  1. Univ. of Michigan, Ann Arbor, MI (United States)
  2. Idaho National Lab. (INL), Idaho Falls, ID (United States)

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% 239Pu, 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.

Research Organization:
Univ. of Michigan, Ann Arbor, MI (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA), Office of Nonproliferation and Verification Research and Development (NA-22)
Grant/Contract Number:
NA0002534
OSTI ID:
1525316
Journal Information:
Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 915, Issue C; ISSN 0168-9002
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 6 works
Citation information provided by
Web of Science

References (18)

Models for a three-parameter analysis of neutron signal correlation measurements for fissile material assay journal November 1986
Statistical estimation of the performance of a fast-neutron multiplicity system for nuclear material accountancy
  • Chichester, David L.; Thompson, Scott J.; Kinlaw, Mathew T.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 784 https://doi.org/10.1016/j.nima.2014.09.027
journal June 2015
Velocity and Angular Distributions of Prompt Neutrons from Spontaneous Fission of Cf 252 journal June 1962
Angular Correlation of Neutrons from Spontaneous Fission of Cf 252 journal December 1975
Simultaneous investigation of fission fragments and neutrons in 252Cf (SF) journal December 1988
Neutron-neutron angular correlations in spontaneous fission of 252Cf journal June 2008
Correlated Neutron Emissions from 252 Cf journal October 2014
Neutron angular distribution in plutonium-240 spontaneous fission
  • Marcath, Matthew J.; Shin, Tony H.; Clarke, Shaun D.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 830 https://doi.org/10.1016/j.nima.2016.05.064
journal September 2016
Neutron-neutron angular correlations in spontaneous fission of Cf 252 and Pu 240 journal April 2018
Using anisotropies in prompt fission neutron coincidences to assess the neutron multiplication of highly multiplying subcritical plutonium assemblies
  • Mueller, J. M.; Mattingly, J.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 825 https://doi.org/10.1016/j.nima.2016.04.027
journal July 2016
Passive assay of plutonium metal plates using a fast-neutron multiplicity counter
  • Di Fulvio, A.; Shin, T. H.; Jordan, T.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 855 https://doi.org/10.1016/j.nima.2017.02.082
journal May 2017
MCNPX-PoliMi for nuclear nonproliferation applications
  • Pozzi, S. A.; Clarke, S. D.; Walsh, W. J.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 694 https://doi.org/10.1016/j.nima.2012.07.040
journal December 2012
Pulse Shape Discrimination in a Plastic Scintillator journal June 1960
An algorithm for charge-integration, pulse-shape discrimination and estimation of neutron/photon misclassification in organic scintillators
  • Polack, J. K.; Flaska, M.; Enqvist, A.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 795 https://doi.org/10.1016/j.nima.2015.05.048
journal September 2015
Evaluation of neutron light output response functions in EJ-309 organic scintillators
  • Norsworthy, Mark A.; Poitrasson-Rivière, Alexis; Ruch, Marc L.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 842 https://doi.org/10.1016/j.nima.2016.10.035
journal January 2017
Characterizing subcritical assemblies with time of flight fixed by energy estimation distributions
  • Monterial, Mateusz; Marleau, Peter; Pozzi, Sara
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 888 https://doi.org/10.1016/j.nima.2018.01.080
journal April 2018
Measurements of angular and energy distributions of prompt neutrons from thermal neutron-induced fission
  • Vorobyev, A. S.; Shcherbakov, O. A.; Pleva, Yu. S.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 598, Issue 3 https://doi.org/10.1016/j.nima.2008.10.017
journal January 2009
Neutron cross-talk characterization of liquid organic scintillators conference October 2015

Cited By (1)

Simulation of the Nondestructive Assay of 237 Np Using Active Neutron Multiplicity Counting journal September 2019

Figures / Tables (12)


Similar Records

Using anisotropies in prompt fission neutron coincidences to assess the neutron multiplication of highly multiplying subcritical plutonium assemblies
Journal Article · 2016 · Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment · OSTI ID:1438391

Multiplication and Presence of Shielding Material from Time-Correlated Pulse-Height Measurements of Subcritical Plutonium Assemblies
Journal Article · 2017 · Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment · OSTI ID:1340272

Neutron Number Probability Distributions in a Subcritical System Using the Forward Master Equation
Journal Article · 2016 · Transactions of the American Nuclear Society · OSTI ID:22991994