Atomic beam measurement of the lifetime of the3 P 1 metastable states of Mg and Ca

Abstract

The lifetime of the metastable level3P1 of Mg and Ca have been measured in an atomic beam experiment. We excite the atoms to the3P1 state by electron collisions and we measure the decay length of the light emitted by the beam. The velocity distribution of the atoms is also measured by a time-of-flight technique. The decay length and the velocity measurements are then combined to compute the required lifetimes. The results are (2.4±0.2)×10−3 sec for Mg and (0.55±0.04)×10−3 sec for Ca.