LASER-DOPPLER VELOCIMETRY OF A FAST BEAM WITH A TEMPERATURE STABILIZED SOLID ETALON

We report a precise velocity measurement of a fast atomic lithium beam using a calibrated solid etalon. This technique is important to our p rogram of precision atomic lifetime measurements which includes the 2p states of neutral Li-7, For our lifetime measurements, we use a dye l aser crossed with a fast lithium beam to selectively excite the 2p P-2 (1/2,3/2) states from the 2s S-2(1/2) ground state, and photon-countin g detectors record the decay in flight of the fluorescence. With the l aser aligned antiparallel to the atomic beam direction, we use a calib rated solid etalon to measure the Doppler shift of the 2s S-2(1/2) --> 2p P-2(3/2) resonance to be 1742.67(53) GHz. The resulting velocity c onverts our position scale to a time scale with a precision of 0.03%. (C) 1997 Elsevier Science B.V.