Measurement of the neutron cross section on argon between 95 and 720 MeV

Abstract

We report an extended measurement of the neutron cross section on argon in the energy range of 95–720 MeV. The measurement was obtained with a 4.3-hour exposure of the Mini-CAPTAIN detector to the WNR/LANSCE beam at LANL. Compared to an earlier analysis of the same data, this extended analysis includes a reassessment of systematic uncertainties, in particular related to unused wires in the upstream part of the detector. Using this information we doubled the fiducial volume in the experiment and increased the statistics by a factor of 2.4. We also shifted the analysis from energy bins to time-of-flight bins. This change reduced the overall considered energy range, but improved the understanding of the energy spectrum of incoming neutrons in each bin. Overall, the new measurements are extracted from a fit to the attenuation of the neutron flux in five time-of-flight regions: 140–180 ns, 120–140 ns, 112–120 ns, 104–112 ns, 96–104 ns. The final cross sections are given for the flux-averaged energy in each time-of-flight bin with statistical and systematic (syst) uncertainties: σ(146 MeV)=0.60−0.14+0.14±0.08(syst) b, σ(236 MeV)=0.72−0.10+0.10±0.04(syst) b, σ(319 MeV)=0.80−0.12+0.13±0.040(syst) b, σ(404 MeV)=0.74−0.09+0.14±0.04(syst) b, σ(543 MeV)=0.74−0.09+0.09±0.04(syst) b.4 MoreReceived 11 January 2023Accepted 8 March 2023DOI:https://doi.org/10.1103/PhysRevD.107.072009© 2023 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNeutron physicsParticles & Fields