Lifetime measurements on atomic states of He I

Lifetimes of He I states (n = 3, 4 and 5) have been measured by the beamfoil technique. For most states the experimental accuracy is of the same order as that of the theory. Some lifetimes differ significantly from theoretical predictions: tausub(ex)(31S) = (50.3 +- 2.3) ns, tausub(th)(31S) = (55.2 +- 1.7) ns, tausub(ex)(41S) = (77.9) +- 3.5) ns, tausub(th)(41S) = (89.8 +-4.0) ns, tausub(ex)(51S) = (109 +- 16) ns, tausub(th)(51S) = (150 +- 12) ns. The lifetimes of the states 4sup(1,3)F have been measured for the first time. (author)