Coherent K-Ionization Using a H2+ Beam

A 1.0 MeV H2+ beam from the University of Delaware van de Graaff accelerator was used to bombard a thin Nickel target. Characteristic K X-ray from Ni was measured with a thin NaI(Tl) detector in coincidence with protons scattered into 90° and 165° lab angles. The energy of the protons detected in those angles corresponds to the elastic scattering of 0.5 MeV incident H+ beam because of the negligible (2.65 eV) bound energy between H and proton in H2+. However, the ionization probabilities measured in the 1 MeV H2+ beam case differ from that measured with a 0.5 MeV proton beam. While the ionization probability for the 165° scattering is increased with the H2+ beam, the reverse is true for the 90° scattering. Possible coherent effect is being considered.