Production and Loss of Fast Metastable Helium Atoms in Collisions with Permanent Gases

Cross sections for production and destruction of fast ${\mathrm{He}}^0$ atoms in triplet states have been measured for 10- to 30-keV ${\mathrm{He}}^{+}$ ions incident on gas targets of Kr, ${\mathrm{N}}_2$, and Ne. Values of the fractions of neutral ${\mathrm{He}}^0$ atoms in the triplet metastable state emerging from thin targets of Kr, ${\mathrm{N}}_2$, and Ne are 0.12±0.005, 0.06±0.03, and 0.03±0.02, respectively, for incident ${\mathrm{He}}^{+}$ energies of 30 keV.