Measurement of the ratio of differential cross sections for double and single ionization of He by (4–10)-MeV protons

Abstract

We have measured the ratio of differential cross sections for the production of doubly and singly ionized He by fast protons at energies between 4 and 10 MeV. The ratio was measured as a function of proton scattering angle, from which the energy transfer was calculated using binary kinematics. The ratio is found to be near 1.25%, nearly independent of either proton energy or energy transfer. This value is lower than that reported previously for a similar experiment, but in good agreement with recent Compton scattering and theoretical results.