Observations on lifetimes and excitation processes for the upper states in atomic helium

Lifetime observations have been made on 49 energy levels of helium. Good overall agreement with theory is obtained, with significant exceptions, the most striking of which are the 31D and 33D states, where 50% discrepancies with theory and some of the older measurements are found. The new measurements are, however, in harmony with recent results using the Hanle effect. The existance of the upper-state process is clearly delineated by the results of n>6. (author)