Lifetime of the2S1State of He

Abstract

A traveling Auger detector is used to measure the attenuation of a cooled thermal beam of He $2^{1}S$ atoms in a vacuum of 1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}8}$ Torr. Its velocity is determined by a time-of-flight technique. The lifetime obtained is (38 \ifmmode\pm\else\textpm\fi{} 8)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ sec.