Abstract
The goal of the Chi-Nu experiment at the Los Alamos Neutron Science Center is to measure the prompt fission neutron spectra from major actinides using a double time-of-flight method with a pulsed, white incoming neutron source. Fission events are detected with a parallel-plate avalanche counter and outgoing neutrons are detected with either a 6Li-glass or liquid scintillator detector array for low- or high-energy neutrons, respectively. A detector response matrix for the interaction of neutrons with the experimental environment for neutrons measured with the Chi-Nu 6Li-glass detector array has been calculated to obtain a full understanding of the measured Chi-Nu data and also to allow for nearly instantaneous production of simulated Chi-Nu data spectra. Prompt fission neutron spectra corresponding to 19 incoming neutron energy ranges from 0.7-20 MeV have been extracted using the ratio-of-ratios method with Chi-Nu 6Li-glass data on the neutron-induced fission of 235U.
Highlights
Accurate measurements of neutrons emitted promptly following neutron-induced fission of major actinides are required in order to understand the behavior of energetic nuclear systems and they are of interest for many other related applications
Nuclear data evaluations are in need of new, high-precision measurements of prompt fission neutron spectra for 239Pu and 235U to differentiate between discrepant data sets and evaluations [1]
The Chi-Nu experiment is located on the 15L beamline at the Weapons Neutron Research (WNR) Facility at the Los Alamos Neutron Science Center (LANSCE)
Summary
Accurate measurements of neutrons emitted promptly following neutron-induced fission of major actinides are required in order to understand the behavior of energetic nuclear systems and they are of interest for many other related applications. Nuclear data evaluations are in need of new, high-precision measurements of prompt fission neutron spectra for 239Pu and 235U to differentiate between discrepant data sets and evaluations [1]. The ratio-of-ratios method, a simple method for determining the underlying prompt fission neutron spectrum without assuming anything about the shape of said spectrum, is described in Sect. 4. results for the 235U prompt fission neutron spectrum for outgoing neutron energies from 0.01-2.5 MeV are shown in Sect.
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