Neutron skins of $^{208}$Pb and $^{48}$Ca from pionic probes

TL;DR

This paper investigates neutron skins of lead-208 and calcium-48 using pionic probes, providing new measurements that align with existing data from other experimental methods.

Contribution

It introduces neutron skin measurements from pionic atoms and reaction cross sections, expanding the methods used to study neutron distributions in nuclei.

Findings

Neutron skin of $^{208}$Pb consistent with previous measurements.

Neutron skin of $^{48}$Ca agrees with pion and alpha scattering data.

Pionic probes effectively determine neutron skin thicknesses.

Abstract

The neutron skin of $^{208}$Pb has received considerable attention in recent years. A variety of strongly-interacting probes depict a rather consistent picture but pionic probes have not been referred to in this context. We present here neutron-skin values from pionic atoms and from total reaction cross sections of $\pi ^+$ between 0.7 and 2 GeV/c which fit well into the picture. In addition we show that a neutron skin for $^{48}$Ca can be obtained from existing data on pionic atoms and the result agrees with pion scattering experiments and with the scattering of $\alpha $ particles.