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

Cross sections for production and destruction of fast He⁰ atoms in triplet states have been measured for 10- to 30-keV He⁺ ions incident on gas targets of Kr, N₂, and Ne. Values of the fractions of neutral He⁰ atoms in the triplet metastable state emerging from thin targets of Kr, N₂, and Ne are 0.12±{}0.005, 0.06±{}0.03, and 0.03±{}0.02, respectively, for incident He⁺ energies of 30 keV.