Measurement of reaction cross section for proton-rich nuclei ( A

Abstract

Radioactive ion beams were produced through the projectile fragmentation induced by 69 MeV/ nucleon 36Ar primary beam on a 9Be target. Measurements of reaction cross sections ( σ R 's) for 44 nuclei with A<30 (mostly proton-rich), on carbon were performed on RIBLL (Radioactive Ion Beam Line in Lanzhou) of HIRFL (Heavy Ion Research Facility in Lanzhou) at intermediate energies around 30 MeV/nucleon by a transmission method. The experimental σ R values for 23Al and 27P are abnormally large compared with their neighboring nuclei. Together with the previous experimental facts such as the binding energy and ground state data, it suggests anomalously large matter root-mean-square radii and proton halo structure in 23Al and in 27P. There is an enhancement for the σ R of 17F + 12C compared with the neighboring isotopes. Considering that the ground state of 17F is 1 d 5/2, this can indicate that there is a proton skin in 17F. The calculation of relativistic density-dependent Hartree model (RDDH) shows that the nuclei 23Al and 27P may have proton-halo structure and 17F may have proton-skin structure. The significance of these measurements is discussed.