Doubly differential cross sections for the proton-impact double ionization of helium

A time-dependent close-coupling approach is used to investigate 6 MeV proton-impact double ionization of helium. We extract doubly differential (in the emission angles of both outgoing electrons) cross sections for comparison with recent experimental measurements. Good qualitative agreement is found between our calculations and the measurements. We also present differential cross sections for cases where the energy available to the outgoing electrons is unrestricted, which allows further information about the double escape process to be inferred.