Speaker
Description
This paper demonstrates the application of SAMMY user-defined resolution function at the spallation neutron sources. SAMMY, a multilevel R-matrix fitting code for neutron data using Bayes' equations, has recently introduced a new format of the resolution function that describes the energy spread of neutrons at a detector due to the convolution of several effects. These effects include the time distribution of the incident proton pulse and time distributions of neutron generation and moderation. The resolution function is calculated with a Monte Carlo radiation-transport code MCNP6, using a detailed geometry model of the neutron source, and it can be imported in SAMMY in a simple point-wise format.
SAMMY provides endless opportunities to advance the field of neutron science. We discuss three distinct applications in which the user-defined resolution function has been found invaluable. The first and most relevant application focuses on validating the neutron production in the spallation source in the resonance energy region (1 eV to 1 MeV). The second application uses a well validated resolution function to determine the time distribution of the incident proton pulse, thus serving as an alternative proton beam time monitor. The last and increasingly important application focuses on recent advances in non-destructive assay techniques, specifically the neutron resonance transmission analysis with modern neutron instruments.
This investigation was carried out at the two premier spallation neutron facilities in the U.S., at the Los Alamos Neutron Science Center (LANSCE) and at the VENUS beamline of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL).
| Other | Alternative track: Target-Moderator Design or Software |
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