Total cross sections for neutron-nucleus scattering

TL;DR

This paper analyzes neutron-nucleus total cross sections across a wide energy range using the Ramsauer model, emphasizing the impact of the nuclear effective radius parameter and proposing empirical formulas for improved fits.

Contribution

It introduces a global analysis of neutron total cross sections with refined Ramsauer model parameters and modifies optical model potentials for better high-energy fits.

Findings

Fitted total cross sections within ±8% using Ramsauer model.

Refined r₀ parameter improves fit to within ±4%.

Modified optical potentials enhance high-energy scattering predictions.

Abstract

Systematics of neutron scattering cross sections on various materials for neutron energies up to several hundred MeV are important for ADSS applications. Ramsauer model is well known and widely applied to understand systematics of neutron nucleus total cross sections. In this work, we examined the role of nuclear effective radius parameter (r$_0$) on Ramsauer model fits of neutron total cross sections. We performed Ramsauer model global analysis of the experimental neutron total cross sections reported by W. P. Abfalterer, F. B. Bateman, {\it et. al.,}, from 20MeV to 550MeV for nuclei ranging from Be to U . The global fit functions which can fit total cross section data over periodic table are provided along with the required global set of parameters. The global fits predict within $\pm 8%$ deviation to data, showing the scope for improvement. It has been observed that a finer adjustment of r$_0$ parameter alone can give very good Ramsauer model description of neutron total scattering data within $\pm 4%$ deviation. The required r$_0$ values for Ramsauer model fits are shown as a function of nuclear mass number and an empirical formula is suggested for r$_0$ values as a function of mass number. In optical model approach for neutron scattering, we have modified the real part of Koning-Deleroche potentails to fit the neutron total cross sections using SCAT2 code. The modified potentails have a different energy dependence beyond 200MeV of neutron energy and fit the total cross sections from Al to Pb.