Cadmium Resonance Parameters from Neutron Capture and Transmission Measurements at the RPI LINAC

Abstract

Cadmium has been used historically as an important component of integral experiments because of its high thermal neutron absorption cross section. Correct interpretation of such experiments depends on accurate differential neutron cross section measurements. The 60 MeV electron accelerator at the Gaerttner LINAC Center was used to generate neutrons for neutron capture and total cross section measurements of natural Cd. Measurements were performed in the thermal and epithermal resonance range with sample thicknesses ranging from 1 x 10-4 to 4 x 10-2 atoms per barn. A full resonance region analysis was performed in order to determine the thermal cross sections and resonance integrals of the cadmium isotopes. The Bayesian R-Matrix code SAMMY 8.0 was used to shape fit the data and extract the resonance parameters. Resonance parameter and cross section uncertainties were determined from their primary components: transmission background, capture normalization, experimental resolution function, burst width, sample thickness, and counting statistics. The experiments were analyzed for consistency within the measured capture and transmission using multiple sample thicknesses. Results are compared to previously published measurements and evaluated nuclear libraries. No major changes to the thermal cross section or the first resonance in Cd113 were identified from the consensus achieved from measurements and evaluations over the past decade.