Excitation of thenS1States of Helium by Proton Impact

The first Born-approximation cross sections for proton excitation of helium from the ground state to the $n{}_{}{}^1{}_{}{}^{}S(n=4\mathrm{} \mathrm{to} 7)$ states are calculated using a 53-term correlated ground-state wave function and 40-term correlated wave functions for the excited states. Generalized oscillator strengths for the respective transitions are also given. The results are compared with the only previous theoretical calculation and with existing experimental values. The agreement between theory and experiment is poor for absolute values, but the curves obtained from $log\sigma$ vs $logE$ plots have the same slope at large impact energies.