PRECISION LIFETIME MEASUREMENTS USING LASER EXCITATION OF A FAST ATOMIC-BEAM

We employ resonant laser excitation of a fast atomic beam to measure e xcited state lifetimes by observing the decay-in-flight of the emitted fluorescence. Our program includes lifetime measurements of the low l ying p states in alkali and alkali-like systems. This work was initiat ed by the motivation to test the atomic many-body-perturbation theory that is necessary for interpretation of parity nonconservation experim ents in cesium. We report new measurements of the 6p P-2(1/2) and 6p P -2(3/2) state lifetimes in the Cs-133 atom to be 34.934 +/- 0.094 ns a nd 30.499 +/- 0.070 ns respectively. With mine; changes to the apparat us, we have extended our measurement capabilities to include the 2p P- 2(1/2,3/2) states of lithium. We present comparisons between measureme nts and relativistic calculations of atomic transition matrix elements .