Charge-changing cross-section measurements of 12-16C 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 (sigma(CC)) of (12-16)Con a C-12 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 (sigma(R)) and sigma(CC) measurements at incident energies from 10A to 2100A MeV. Adopting the proton-density distribution of C-12 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 beta(pn) of the proton-neutron elastic differential cross section so as to reproduce the existing sigma(R) and interaction cross-section data for C-12+ C-12 over a wide range of incident energies. The Glauber model thus formulated is applied to calculate the sigma(R)'s of C-12 on a Be-9 and Al-27 targets at various incident energies. Our calculations show excellent agreement with the experimental data. Applying our model to the s(R) and sigma(CC) for the so-called neutron-skin C-16 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 sigma(CC)'s and the existing s(R) data. The results for C12-14 are consistent with the values from the electron scatterings, demonstrating the feasibility, usefulness of the sigma(CC) measurement, and the present Glauber model.