Research Papers in Physics and Astronomy


Date of this Version



Published in Physical Review A Volume 53, Number 1, January 1996. Copyright © American Physical Society; used by permission.


Absolute cross sections, differential in energy and angle of ejection of the secondary electrons, were determined for electron emission from He+ +H2 collisions at 28–114 keV by measuring electron energy spectra from 1.5 to 300 eV at several angles from 15° to 160°. A rotatable electrostatic analyzer was used with an energy resolution of 5% and an angular acceptance of 4.6° full width at half maximum. The double-differential cross sections were integrated over angle, energy, or both to obtain single-differential and total ionization cross sections. The latter are in excellent agreement with previous experimental results. Agreement of the experimental double-differential cross sections with plane-wave Born approximation calculations is generally poor. The cross section for ejection of high-energy electrons by He+ is considerably larger than that for H+ at the same velocity. This is attributed mostly to electron emission from the projectile. The presence of prominent Doppler-shifted helium autoionization peaks in the spectra indicates an appreciable probability for electron capture by the helium ions with simultaneous double excitation.

Included in

Physics Commons