Mean-life Measurements in He I by the Hanle Effect on High-Velocity Atoms Excited in a Gaseous Target

Abstract
Mean lives of He I are deduced from the Hanle curves for high-velocity atoms excited in a gaseous target. For long—mean-life levels we observed oscillations in agreement with a partial precession of the dipoles around the magnetic field. For the 3pP1 level, the Hanle curve is not perturbed by self-absorption using this method, and the measured mean life (1.8±0.1 nsec) is in good agreement with the theoretical value.