Angular differential and total cross sections for the excitation of atomic hydrogen to itsn=2state by helium ions

Differential cross sections for 15-100 keV ${\mathrm{He}}^{+}$ excitation of atomic hydrogen to its $n=2\mathrm{}$ level have been determined for c.m. angles from 0 to 8 mrad. The differential cross sections are obtained from an analysis of the angular distribution of the scattered ions which have lost an energy corresponding to the excitation of the target to its $n=2\mathrm{}$ level. The shape of the differential cross section changes rapidly with increasing incident energy. At 15 keV, the differential cross section falls off by a factor of 5 in 6 mrad. At 100 keV, the differential cross section decreases by nearly six orders of magnitude in the same angular range. The higher-energy results are in fair agreement with a recent symmetrized first-order Glauber approximation calculation of the process. Total cross section results are given for the same process in the 15-200 keV range.