# Neutron gas and pairing

## TL;DR

This paper investigates neutron gas effects in nuclei with large neutron excess using the BCS approach, finding that positive energy states contribute negligibly to observable properties.

## Contribution

It provides a detailed analysis showing that neutron gas effects are numerically insignificant in Ni and Sn isotopes within the BCS framework.

## Key findings

- Neutron gas effects are negligible for studied isotopes.
- Positive energy states do not significantly influence observables.
- Results support simplified models ignoring neutron gas effects.

## Abstract

We study the emergence of neutron gas effects in the description of nuclei with large neutron excess within the Bardeen-Cooper-Schrieffer approach. We consider Ni and Sn isotopes where, in the literature, these effects have been found. We investigate the role of the single particle states with positive energy generating the neutron gas, and we find that the contribution of these states is numerically irrelevant for the various observables that we evaluate.