Measurements of neutron total and capture cross sections of $^{139}$La and evaluation of resonance parameters

TL;DR

This study measured neutron cross sections of La-139 at J-PARC, revealing significant differences from evaluated libraries and providing new resonance parameters and scattering radius data.

Contribution

It presents new experimental measurements of La-139 neutron cross sections and resonance parameters, highlighting discrepancies with existing evaluated data.

Findings

Total cross section differs from evaluated libraries between 80-900 eV.

Resonance parameters for four resonances were determined.

Scattering radius larger than in evaluated libraries.

Abstract

Neutron total and capture cross sections of Lanthanum(La)-139 were measured at the Accurate Ne-utron-Nucleus Reaction measurement Instrument (ANNRI) of the Materials and Life Science Experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC). The total cross section was largely different from that in evaluated libraries, such as JENDL-5, in the energy range from 80 to 900~eV. Resonance parameters for four resonances including one negative resonance were obtained using a resonance analysis code, REFIT. The resonance analysis revealed discrepancies in several resonance parameters with the evaluated libraries. Furthermore, the information about the scattering radius was also extracted from the results of the total cross section. The obtained scattering radius was larger than that recorded in the evaluated libraries.