Transfer ionization in p + He collisions

Using the unique combination of the high-quality ion beams available in the heavy-ion storage ring CRYRING at the Manne Siegbahn Laboratory, Stockholm and our COLTRIMS (cold target recoil-ion-momentum spectroscopy) setup with a pulsed extraction system we have investigated the recoil-ion-momentum distributions for transfer ionization in p-He collisions at energies up to 5.8 MeV. This technique allows us to determine the separate contribution to the cross section from the Thomas p-e-e scattering mechanism. Unlike the situation at lower collision energies we find that the cross section follows the expected asymptotic v−11 scaling.