# Nuclear-matter distribution in the proton-rich nuclei $^7$Be and $^8$B from intermediate energy proton elastic scattering in inverse kinematics

## TL;DR

This study measured elastic proton scattering on $^7$Be and $^8$B at 0.7 GeV/u to determine their nuclear matter radii and revealed a proton halo structure in $^8$B, contributing to understanding exotic nuclear configurations.

## Contribution

First measurement of elastic proton scattering on $^7$Be and $^8$B at intermediate energy to extract nuclear matter radii and identify halo structures.

## Key findings

- RMS matter radius of $^7$Be is 2.42 fm.
- RMS matter radius of $^8$B is 2.58 fm.
- $^8$B exhibits a proton halo with a radius of 4.24 fm.

## Abstract

Absolute differential cross sections for elastic $p^7$Be and $p^8$B small-angle scattering were measured in inverse kinematics at an energy of 0.7 GeV/u at GSI Darmstadt. The hydrogen-filled ionization chamber IKAR was used as an active target to detect the recoil protons. The projectile tracking and isotope identification were performed with multi-wire proportional chambers and scintillation detectors. The measured cross sections were analysed using the Glauber multiple-scattering theory. The root-mean-square (rms) nuclear matter radii $R_{\rm m} = 2.42 (4)$ fm for $^7$Be and $R_{\rm m} = 2.58 (6)$ fm for $^8$B were obtained. The radial density distribution deduced for $^8$B exhibits a proton halo structure with the rms halo radius $R_{\rm h} = 4.24 (25)$ fm. A comparison of the deduced experimental radii is displayed with existing experimental and theoretical data.