Polarization of Lyman-$\alpha$ Radiation Produced in Charge-Transfer Collisions between Protons and the Inert Gases

The polarization of Lyman-$\alpha$ radiation arising from charge-transfer collisions between protons and helium, argon, and neon has been measured for incident proton energies from 0.6 to 24 keV. A lithium fluoride crystal set at the Brewster's angle was used to measure the polarization of the radiation. Structure has been observed in the energy dependence of the polarization fraction for ${\mathrm{H}}^{+}$-Ne and ${\mathrm{H}}^{+}$-Ar collisions which reflects the structure in the total cross sections for electron capture into the $2P$ state of atomic hydrogen for these collisions. The present results are in poor agreement with those of Gaily et al.