Low-energy $^{6}$He scattering in a microscopic model

TL;DR

This paper develops a microscopic model to analyze $^{6}$He scattering on various targets, accurately reproducing experimental data and revealing that breakup effects become more significant with heavier targets, especially at larger distances.

Contribution

It introduces a parameter-free microscopic CDCC model using antisymmetric 6-nucleon wave functions for $^{6}$He, providing detailed insights into breakup effects across different target masses.

Findings

Breakup effects increase with target mass.

Single-channel approximation suffices for light systems.

Polarization effects modify the Coulomb barrier.

Abstract

A microscopic version of the Continuum Discretized Coupled Channel (CDCC) method is used to investigate $^{6}$He scattering on $^{27}$Al, $^{58}$Ni, $^{120}$Sn, and $^{208}$Pb at energies around the Coulomb barrier. The $^{6}$He nucleus is described by an antisymmetric 6-nucleon wave function, defined in the Resonating Group Method. The $^{6}$He continuum is simulated by square-integrable positive-energy states. The model is based only on well known nucleon-target potentials, and is therefore does not depend on any adjustable parameter. I show that experimental elastic cross sections are fairly well reproduced. The calculation suggests that breakup effects increase for high target masses. For a light system such as $^{6}$He+$^{27}$Al, breakup effects are small, and a single-channel approximation provides fair results. This property is explained by a very simple model, based on the sharp-cut-off approximation for the scattering matrix. I also investigate the $^{6}$He-target optical potentials, which confirm that breakup channels are more and more important when the mass increases. At large distances, polarization effects increase the Coulomb barrier, and provide a long-tail absorption component in the imaginary part of the nucleus-nucleus interaction.