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

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 $R_{\mathrm{m}}=2.42(4)$ fm for ${}^7$Be and $R_{\mathrm{m}}=2.58(6)$ fm for ${}^8$B were obtained. The radial density distribution deduced for ${}^8$B exhibits a proton halo structure with the rms halo radius $R_{\mathrm{h}}=4.24(25)$ fm. A comparison of the deduced experimental radii is displayed with existing experimental and theoretical data.