Evidence for a proton halo in 27P through measurements of reaction cross-sections at intermediate energies

Abstract

Measurements of reaction cross-sections ( σR's) for some proton-rich nuclei ( N = 11–15 isotones) on carbon target at intermediate energies have been performed on RIBLL of HIRFL. A larger enhancement of the σR for 27P has been observed than for its neighboring nuclei. A large difference between the proton and neutron density distributions (proton halo) is necessary to explain the enhanced cross-section for 27P within the framework of the Glauber model. Density distributions with HO-type core plus Yukawa-square tail and rms radii for 27P have been deduced from the measured σR data for the first time, which conform the long tail in its densities as predicted by RMF calculations.