Measurement of theAm242mneutron-induced reaction cross sections

Abstract

The neutron-induced reaction cross sections of 242m Am were measured at the Los Alamos Neutron Science Center using the Detector for Advanced Neutron-Capture Experiments array along with a compact parallel-plate avalanche counter for fission-fragment detection. A new neutron-capture cross section was determined, and the absolute scale was set according to a concurrent measurement of the well-known 242m Am(n,f) cross section. The (n,γ) cross section was measured from thermal to an incident energy of 1 eV at which point the data quality was limited by the reaction yield in the laboratory. Our new 242m Am fission cross section was normalized to ENDF/B-VII.1 to set the absolute scale, and it agreed well with the (n,f) cross section reported by Browne et al. from thermal energy to 1 keV. The average absolute capture-to-fission ratio was determined from thermal to En = 0.1 eV, and it was found to be 26(4)% as opposed to the ratio of 19% from the ENDF/B-VII.1 evaluation.

ComprehensiveAm242mneutron-induced reaction cross sections and resonance parameters

“…Our 242m Am(n,f) cross section agrees well with the Browne et al (1984) cross section over this large energy interval. The new neutron-capture cross section measurement complements and agrees well with our recent results reported below 1 eV in Buckner et al (2017). This new work comprises the most comprehensive study of 242m Am(n,γ) above thermal energy.…”

“…The capture-to-fission ratio was found to be 26(4)% from thermal to 0.1 eV in this recent study [30]. The Buckner et al [30] study comprises the first measurement of the 242m Am neutron-capture cross section above thermal energy.…”

“…The current work is an extension of the Buckner et al [30] 242m Am neutron-capture cross section measurement. New, concurrent measurements of the 242m Am(n,f) and 242m Am(n,γ) cross sections were made at LANSCE using the DANCE array [38] in combination with a parallelplate avalanche counter (PPAC) [39] for fission fragment detection.…”

“…The 242m Am(n,γ) cross section also factors into calculations of heavy actinide concentrations in nuclear fuel [27], nuclear waste recycling, and isotope production [5,28,29]. Recently, the neutron-capture cross section was directly measured at the Los Alamos Neutron Science Center (LANSCE) with the Detector for Advanced Neutron-Capture Experiments (DANCE) by Buckner et al [30] from thermal to 1 eV. The capture-to-fission ratio was found to be 26(4)% from thermal to 0.1 eV in this recent study [30].…”

“…Recently, the neutron-capture cross section was directly measured at the Los Alamos Neutron Science Center (LANSCE) with the Detector for Advanced Neutron-Capture Experiments (DANCE) by Buckner et al [30] from thermal to 1 eV. The capture-to-fission ratio was found to be 26(4)% from thermal to 0.1 eV in this recent study [30]. The Buckner et al [30] study comprises the first measurement of the 242m Am neutron-capture cross section above thermal energy.…”