Fragmentation Cross Sections of 290 and 400 MeV/nucleon 12C Beams on Elemental Targets

Charge-changing and fragment production cross sections at 0 circ have been obtained for interactions of 290 MeV/nucleon and 400 MeV/nucleon carbon beams with C, CH2, Al, Cu, Sn, and Pb targets. These beams are relevant to cancer therapy, space radiation, and the production of radioactive beams. We compare to previously published results using C and CH2 targets at similar beam energies. Due to ambiguities arising from the presence of multiple fragments on many events, previous publications have reported only cross sections for B and Be fragments. In this work we have extracted cross sections for all fragment species, using data obtained at three distinct values of angular acceptance, supplemented by data taken with the detector stack placed off the beam axis. A simulation of the experiment with the PHITS Monte Carlo code shows fair agreement with the data obtained with the large acceptance detectors, but agreement is poor at small acceptance. The measured cross sections are also compared to the predictions of the one-dimensional cross section models EPAX2 and NUCFRG2; the latter is presently used in NASA's space radiation transport calculations. Though PHITS and NUCFRG2 reproduce the charge-changing cross sections with reasonable accuracy, none of the models is able to accurately predict the fragment cross sections for all fragment species and target materials