Small-Angle Charge-Exchange Scattering ofHe+by He, Ne, and Kr at Energies between 1.00 and 3.00 keV

Abstract

The scattering of ${\mathrm{He}}^{+}$ by He, Ne, and Kr is studied in the energy range 1.00-3.00 keV and in an angular region from 0° to about 3°. These studies yield information on the probability of charge exchange $P_0$ as a function of beam energy and scattering angle. For the ${\mathrm{He}}^{+}$ + He case, the positions of the maxima and minima of $P_0$ generally agree with those of previous experiments. A wider range of $P_0$ values is obtained, however, and the current results lend more credence to a two-state resonant-charge-exchange theory for the ${\mathrm{He}}^{+}$ + He collision. In the ${\mathrm{He}}^{+}$ + Ne collision, the charge-exchange differential cross section is found to increase with increasing energy, while the non-charge-exchange differential cross section decreases. An unexpected result of the current studies on Ne is that the positions of the maxima and minima of the scattered neutral He (and of $P_0$) are independent of energy. These results are not consistent with a curve-crossing model for the charge-exchange process, which predicts an angular structure dependent on energy. Studies of the ${\mathrm{He}}^{+}$ + Kr collision show a broad forward He peak with no pronounced structure in the energy and angular region investigated.