Using the inherent timing stability of pulses from a mode-locked laser, we have precisely measured the cesium 6P 3/2 excited state lifetime. An initial pump pulse excites cesium atoms in two counterpropagating atomic beams to the 6P 3/2 level. A subsequent synchronized probe pulse ionizes atoms which remain in the excited state, and the photo-ions are collected and counted. By selecting pump pulses which vary in time with respect to the probe pulses, we obtain a sampling of the excited state population in time, resulting in a lifetime value of 30.462(46) ns. The measurement uncertainty (0.15%) is slightly larger than our previous report of 0.12% [Phys. Rev. A 84, 010501(R) (2011)] due to the inclusion of additional data and systematic errors. In this follow-up paper we present details of the primary systematic errors encountered in the measurement, which include atomic motion within the intensity profiles of the laser beams, quantum beating in the photo-ion signal, and radiation trapping. Improvements to further reduce the experimental uncertainty are also discussed.

We report a precision measurement of the cesium 6P 3/2 excited-state lifetime. Two collimated, counterpropagating thermal Cs beams cross perpendicularly to femtosecond pulsed laser beams. High timing accuracy is achieved from having excitation and ionization laser pulses which originate from the same mode-locked laser. Using pulse selection we vary the separation in time between excitation and ionization laser pulses while counting the ions produced. We obtain a Cs 6P 3/2 lifetime of 30.460(38) ns, which is a factor of two improvement from previous measurements and with an uncertainty of 0.12%, is one of the most accurate lifetime measurements on record.

No abstract

No abstract

No abstract