MEASUREMENT OF THE 7P P-2(3 2) LEVEL LIFETIME IN ATOMIC FRANCIUM/

We present the first measurement of an atomic radiative lifetime in Fr . We use a time-correlated single photon counting technique with a col d sample of Fr-210 atoms in a magneto-optic trap. The results are a pr ecision experimental test of the atomic many-body perturbation theory applied to the heaviest alkali. The lifetime for the 7p(2)P(3/2) level of 21.02(16) ns gives a value for the reduced transition matrix eleme nt between the levels 7s(2)S(1/2) --> 7p(2)P(3/2) of 5.898(22)a(infini ty) atomic units.