Experimental separation of the Thomas charge-transfer process in high-velocityp−Hecollisions

Abstract

We present differential cross sections of electron capture in $7.5\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ and $12.5\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ proton-helium collisions. Complete experimental separations of the Thomas and the kinematic single electron capture processes in the two-dimensional ${\mathrm{He}}^{+}$ momentum distribution in the plane perpendicular to the fast ion beam have been achieved. We compare the resulting projectile angular differential cross section with the two most recent theoretical calculations and expose significant deviations.