Absolute triple-differential cross sections for ionization-excitation of helium

Triple-differential cross sections (TDCSs) for electron-impact ionization of He(1s(2))S-1 leading to He+(1s) are calculated using the highly accurate convergent close-coupling (CCC) method for incident projectile energies of 268.6 and 112.6 eV, with at least one of the outgoing electrons having an energy of 44 eV. These results are used to obtain absolute TDCSs from the recent experimental data [Bellm , Phys. Rev. A 75, 042704 (2007)] for TDCS ratios of ionization with no excitation to ionization with excitation resulting in He+(n=2,3,4). The TDCSs can be used as comparison benchmarks in future studies, and already allow us to test the accuracy of the TDCSs obtained from the hybrid distorted-wave+R-matrix (close-coupling) model, which was fairly successful in predicting the ratios, using CCC for n=1 and experimental results for n=2,3,4.