Quenching of Metastable Hydrogen by Helium

Abstract

Measurements of collisional quenching of metastable hydrogen by helium in the thermal region ($v\simeq 5\times {10}^{-3\mathrm{}}$ a.u.) have been made. The resulting cross section ${\sigma }_Q\simeq 8\times {10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$ per atom is 20-25% larger than the theoretical results obtained by Byron and Gersten using a pseudopotential method.