Excitation and Ionization of He Atom by Positron Impact

Abstract

The 2¹S-excitation cross-section Q_exc and the ionization cross-section Q_ion of He atom by positron impact were obtained in the range of 24∼120 eV positron energies by the time spectrum in the retarding potential-TOF method. The excitation cross-section is consistent with those by Coleman and Hutton at the energies below 31 eV. The values of Q_ion agreed with those by electron-collision measurements.