Charge-changing cross-section measurements of C 12-16 at around 45A MeV and development of a Glauber model for incident energies 10A-2100A MeV

We have measured for the first time the charge-changing cross sections (σCC) of C12-16 on a C12 target at energies below 100A MeV. To analyze these low-energy data, we have developed a finite-range Glauber model with a global parameter set within the optical-limit approximation which is applicable to reaction cross section (σR) and σCC measurements at incident energies from 10A to 2100A MeV. Adopting the proton-density distribution of C12 known from the electron-scattering data, as well as the bare total nucleon-nucleon cross sections and the real-to-imaginary-part ratios of the forward proton-proton elastic scattering amplitude available in the literatures, we determine the energy-dependent slope parameter βpn of the proton-neutron elastic differential cross section so as to reproduce the existing σR and interaction cross-section data for C12+C12 over a wide range of incident energies. The Glauber model thus formulated is applied to calculate the σR's of C12 on a Be9 and Al27 targets at various incident energies. Our calculations show excellent agreement with the experimental data. Applying our model to the σR and σCC for the so-called neutron-skin C16 nucleus, we reconfirm the importance of measurements at incident energies below 100A MeV. The proton root-mean-square radii of C12-16 are extracted using the measured σCC's and the existing σR data. The results for C12-14 are consistent with the values from the electron scatterings, demonstrating the feasibility, usefulness of the σCC measurement, and the present Glauber model.