The lifetimes of the $3{}_{}{}^1{}_{}{}^{}S$, $3{}_{}{}^1{}_{}{}^{}D$, $4{}_{}{}^1{}_{}{}^{}D$, $4{}_{}{}^1{}_{}{}^{}F$, and $5{}_{}{}^1{}_{}{}^{}F$, states of He have been determined experimentally to be 54.5±0.8, 16.7±0.8, 36.4±1.2, 67±10, and 142±20 nesc, respectively. The measurements were made at several incident electron energies using a pulsed-electron time-delayed-coincidence technique.

• Received 13 February 1978

DOI:https://doi.org/10.1103/PhysRevA.18.559