Neutron skin thickness of $^{116,118,120,122,124}$Sn determined from reaction cross sections of proton scattering

TL;DR

This paper measures neutron skin thicknesses of Sn isotopes using reaction cross sections from proton scattering and tests the Kyushu g-matrix folding model's reliability across different energies.

Contribution

It introduces a method to accurately determine neutron skin thicknesses of Sn isotopes using reaction cross sections and validates the Kyushu g-matrix folding model for this purpose.

Findings

Neutron skin thicknesses for Sn isotopes are quantified with small errors.

The Kyushu g-matrix folding model is reliable for reaction cross section calculations.

Results are consistent with previous measurements.

Abstract

The cross sections of SDR in the Sb isotopes have been measured. Within the model used, the neutron-skin thicknesses $r_{\rm skin}({\rm exp})$ deduced $0.12 \pm 0.06$fm for $^{116}$Sn, $0.13 \pm 0.06$fm for $^{118}$Sn, $0.18 \pm 0.07$fm for $^{120}$Sn, $0.22 \pm 0.07$fm for $^{122}$Sn, $0.19 \pm 0.07$fm for $^{124}$Sn. We tested the chiral (Kyushu) $g$-matrix folding model for $^{12}$C+$^{12}$C scattering, and found that the Kyushu $g$-matrix folding model is reliable for reaction cross sections $\sigma_{\rm R}$ in $30 < E_{\rm in} < 100 $MeV and $250 < E_{\rm in} < 400$MeV. We determine neutron skin thickness $r_{\rm skin}({\rm exp})$, using measured $\sigma_{\rm R}$ of $^{4}$He+$^{116,120,224}$Sn scattering. The results are $r_{\rm skin}({\rm exp})=0.242 \pm 0.140$fm for $^{116}$Sn, $r_{\rm skin}({\rm exp})=0.377 \pm 0.140$fm for $^{120}$Sn, $r_{\rm skin}({\rm exp})=0.180 \pm 0.142$fm for $^{124}$Sn. The $\sigma_{\rm R}$ are available for proton scattering on $^{116,118,120,122,124}$Sn with high accuracy. Our aim is to determine $r_{\rm skin}({\rm exp})$ for $^{116,118,120,122,124}$Sn with small errors by using the Kyushu $g$-matrix folding model. Our model is the folding model with the densities scaled from the D1S-GHFB+AMP neutron density. The proton radii of D1S-GHFB+AMP agree with those calculated with the isotope shift method based on the electron scattering. We then scale the neutron densities so as to reproduce the $\sigma_{\rm R}({\rm exp})$. In $30 < E_{\rm in} < 65$MeV, we determine $r_{\rm skin}({\rm exp})$ from measured $\sigma_{\rm R}$. The values are $r_{\rm skin}({\rm exp})=0.118 \pm 0.021$~fm for $^{116}$Sn, $0.112 \pm 0.021$fm for $^{118}$Sn, $0.124 \pm 0.021$fm for $^{120}$Sn, $0.156 \pm 0.022$fm for $^{124}$Sn. As for $^{122}$Sn, the skin value in $30 < E_{\rm in} < 50$MeV is $0.122 \pm 0.024$fm. Our results are consistent with the previous values.