Comprehensive Am 242 m neutron-induced reaction cross sections and resonance parameters

The Am-242 metastable isomer's neutron-induced destruction mechanisms were studied at the Los Alamos Neutron Science Center using the Detector for Advanced Neutron-Capture Experiments array with a compact parallel-plate avalanche counter. New Am-242m neutron-capture cross sections were determined from 100 meV to 10 keV, and the absolute scale was set with respect to a concurrent measurement of the well-known Am-242m neutron-induced-fission cross section. The new fission cross section spans an energy range from 100 meV to 1 MeV and was normalized to the ENDF/B-VII. 1 evaluated cross section to set the absolute scale. Our Am-242m(n, f) cross section agrees well with the cross section of Browne et al. [Phys. Rev. C 29, 2188 (1984)] over this large energy interval. The new neutron-capture cross sectionmeasurement complements and agrees well with our recent results reported below 1 eV in Buckner et al. [Phys. Rev. C 95, 024610 (2017)]. This new work comprises the most comprehensive study of Am-242m(n,.) above thermal energy. Neutron-induced resonance energies and parameters were deduced with the SAMMY R-matrix code for incident neutron energies up to 45 eV, and the new average inverted right perpendicular(gamma) is 13% higher than the evaluated average. width.