Neutron capture cross-section measurement and resolved resonance analysis of 237Np

The neutron capture cross-section of 237 Np has been measured in the neutron energy region from 10 meV to 500 eV. A neutron time-of-flight method was employed using the NaI(Tl) spectrometer in the ANNRI beamline at the Japanese Proton Accelerator Research Complex (J-PARC). The experimental capture yield was derived using the pulse-height weighting technique and an energy-dependent cross-section was obtained relative to the incident neutron spectrum derived from a 10 B(n, ) 7 Li reaction yield. The absolute cross-section was determined by normalizing the results to JENDL-4.0 cross-section data at the first resonance of 237 Np. The thermal cross-section was measured to be 177.6 ± 3.8 b. The resolved resonance region was analyzed with the REFIT code. An average radiation width = 40.3 ± 0.5 meV, a mean level spacing D 0 = 0.60 ± 0.02 eV and a neutron strength function 10 4 S 0 = 1.02 ± 0.12 were obtained.