Absence of the Thomas peak in the classical-trajectory Monte Carlo calculations for proton-hydrogen collisions in the MeV region.

Abstract

Large-scale classical-trajectory Monte Carlo calculations are executed in three-dimensional space for proton-hydrogen collisions at 2.8 and 5 MeV. The Thomas peak that has been confirmed in the experimental data and in the quantal calculations is invisible in the classical calculations. This unexpected result is due to the peculiar character of classical bound states that have no minimum binding energy. The Oppenheimer-Brinkmann-Kramers-type capture by means of the velocity-matching mechanism dominates even in the MeV region owing to this classical peculiarity, and the Thomas double-scattering contribution is embedded in this background.