Neutron total and scattering cross sections of niobium in the continuum region

Abstract

Neutron total and elastic and inelastic scattering cross sections of niobium are measured in the incident energy interval 0.25 to 0.5 MeV. Total neutron cross sections are determined to a few percent accuracy throughout the energy interval. Differential elastic and inelastic neutron scattering cross sections are measured at ≈ 20 scattering angles distributed between 20 and 160 degrees and at incident neutron energy intervals of 0.1 MeV from 1.8 to 4.0 MeV. The cross sections for the inelastic neutron excitation of 11 states withQ- values of → 2520 keV are quantitatively measured and the excitation of an additional 8 states qualitatively observed. Calculations based upon a selected optical potential give a good description of total neutron cross sections to 20.0 MeV and of elastic scattering cross sections extending from low energies where compound-nucleus processes are prominent to high energies where “shape” scattering predominates. Inelastic neutron scattering cross sections are calculated from the optical potential and statistical theory and comparison with the corresponding experimental values suggests the spins and parities of the low-energy excited states.