Robert J. Rafac

Construction of fiber-optic bundle light-collection systems and calculations of collection efficiency

This paper describes the position-sensitive light-collection system that we use in our fast-beam laser experiments. The collection system consists of fiber-optic bundles whose facets are arranged to accept light emitted from a beam of fluorescent atoms. The flexibility of the fiber bundles allows their use in scanning collection systems with precise position sensitivity. We describe calculations of geometrical collection efficiency using a numerical integration scheme and compare the results with measurements. We also compare the collection efficiencies of the different fiber bundle arrangements that we used as our apparatus evolved with the implementation of various improvements.

Laser Doppler velocimetry of a fast beam with a temperature stabilized solid etalon

Abstract We report a precise velocity measurement of a fast atomic lithium beam using a calibrated solid etalon. This technique is important to our program of precision atomic lifetime measurements which includes the 2p states of neutral 7Li. For our lifetime measurements, we use a dye laser crossed with a fast lithium beam to selectively excite the 2 p 2 P 1 2 , 3 2 states from the 2 s 2 S 1 2 ground state, and photon-counting detectors record the decay in flight of the fluorescence. With the laser aligned antiparallel to the atomic beam direction, we use a calibrated solid etalon to measure the Doppler shift of the 2 s 2 S 1 2 → 2 p 2 P 3 2 resonance to be 1742.67(53) GHz. The resulting velocity converts our position scale to a time scale with a precision of 0.03%.

Precision lifetime measurements using laser excitation of a fast atomic beam

Abstract We employ resonant laser excitation of a fast atomic beam to measure excited state lifetimes by observing the decay-in-flight of the emitted fluorescence. Our program includes lifetime measurements of the low lying p states in alkali and alkali-like systems. This work was initiated by the motivation to test the atomic many-body-perturbation theory that is necessary for interpretation of parity nonconservation experiments in cesium. We report new measurements of the 6p 2 P 1 2 and 6p 2 P 3 2 state lifetimes in the 133Cs atom to be 34.934 ± 0.094 ns and 30.499 ± 0.070 ns respectively. With minor changes to the apparatus, we have extended our measurement capabilities to include the 2p 2 P 1 2 , 3 2 states of lithium. We present comparisons between measurements and relativistic calculations of atomic transition matrix elements.