Comparison of Neutron Pulse Height Distributions from Organic Scintillators Calculated by Geant4 and MCNPX-PoliMi

Year
2012
Author(s)
S. D. Clarke - Department of Nuclear Engineering & Radiological Sciences, University of Michigan
S. A. Pozzi - Department of Nuclear Engineering & Radiological Sciences, University of Michigan
S.F. Naeem - Department of Nuclear Engineering and Radiological Sciences, University of Michigan
J. Dolan - Department of Nuclear Engineering and Radiological Sciences, University of Michigan
Abstract
Organic liquid scintillators are sensitive to fast neutrons, and hence are instrument of choice for non-proliferation applications. The energy distribution of neutrons is indirectly measured by characterizing the pulse height distribution of light output produced through nuclear reactions within the detectors. However, the complexity of the light generation on these detectors makes simulating their response difficult with standard Monte Carlo techniques. This paper presents the response of 7.62-by-7.62 cm 2 and 12.7-by-12.7 cm 2 EJ-309 cylindrical liquid scintillators, simulated using the Geant4 and MCNPX-PoliMi Monte Carlo codes. Monoenergetic neutrons in the energy range of 0.2 to 15 MeV are used in these simulations. The energy deposition of neutrons in organic liquid scintillators is dependent upon their collisions with hydrogen and carbon nuclei; therefore accurately simulating neutron collisions on an event-by-event basis is crucial to generating neutron pulse height distributions. Geant4 (ver. 9.4) and MCNPX-PoliMi (ver. 2.0) generated neutron pulse height distributions are compared. Furthermore, experimental measurements are carried out in our laboratory to validate the simulations.