Precision lifetime measurement of the cesium $6P_{3/2}$ level using ultrafast pump-probe laser pulses

摘要

Using the inherent timing stability of pulses from a mode-locked laser, wehave precisely measured the cesium $6P_{3/2}$ excited state lifetime. Aninitial pump pulse excites cesium atoms in two counter-propagating atomic beamsto the $6P_{3/2}$ level. A subsequent synchronized probe pulse ionizes atomswhich remain in the excited state, and the photo-ions are collected andcounted. By selecting pump pulses which vary in time with respect to the probepulses, we obtain a sampling of the excited state population in time, resultingin a lifetime value of 30.462(46) ns. The measurement uncertainty (0.15%) islarger 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 thisfollow-up paper we present details of the primary systematic errors encounteredin the measurement, which include atomic motion within the intensity profilesof the laser beams, quantum beating in the photo-ion signal, and radiationtrapping. Improvements to further reduce the experimental uncertainty are alsodiscussed