Projectile angular distribution in single electron capture from helium by fast protons

In addition to the Thomas peak, occurs at 0.47 mrad, another peak has been observed at approximate to 0.75 mrad in a recent measurement for projectile angular differential cross sections of single electron capture in proton-helium collision at impact energies of MeV region [M. Gudmundsson et al., J. Phys. B 43, 185209 (2010)]. Stimulated by this report, the differential cross section is calculated based on the first Born approximation for single ionization of helium by proton impact. Calculations with and without interelectron correlation give almost the same results, and the peak observed experimentally near 0.75 mrad is not accounted for in the treatment.