Measurement of the Am242m neutron-induced reaction cross sections

The neutron-induced reaction cross sections of (242)mAm 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 (242)mAm(n, f) cross section. The (n,gamma) cross section was measured from thermal energy to an incident energy of 1 eV at which point the data qualitywas limited by the reaction yield in the laboratory. Our new (242)mAmfission cross sectionwas 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. (1984) from thermal energy to 1 keV. The average absolute capture-to-fission ratio was determined from thermal energy to E-n = 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.