Monte Carlo Simulations of an Experimental Method for Measuring Charge-Changing Cross Sections

Measurements of charge-changing cross-sections were developed as a method for determining proton radii, particularly for unstable, short-lived nuclei. Such cross-sections must be measured with high precision to determine the precise charge radii. However, there are complexities in the experimental method and leading to uncertainties in determining precise nuclear radii. Therefore, good models describing the complex physics of charged-particle interactions are needed in order to validate the experimental method and to estimate the contribution of systematic uncertainties. GEANT4 is a Monte Carlo simulation code that can describe elementary-particles and heavy-ion interactions in a broad range from typical atomic to cosmic-ray energies. An experiment has been performed to measure charge-changing cross-section of carbon isotopes, namely 10,11,12C nuclei, on different secondary reaction targets using the fragment separator FRS at GSI, Darmstadt. This work presents a comparison between the measured spectra of that experiment and the corresponding GEANT4 simulations.