Foreign-Gas-Induced Cesium Hyperfine Relaxation

Abstract

We have measured the hyperfine relaxation time of cesium vapor in the presence of foreign gases. We have therefore been able to measure the diffusion coefficient $D_0$ and the cross section $\sigma 〈\overrightarrow{\mathrm{S}}·\overrightarrow{\mathrm{I}}〉$ of hyperfine relaxation due to the collisions with the foreign gas. The values of $D_0$ for He, Ne, Ar, and ${\mathrm{N}}_2$ are 0.204±0.04, 0.153±0.014, 0.134±0.02, and 0.073±0.015 ${\mathrm{cm}}^2$/sec at 0°C and 760 Torr, respectively. The cross sections are 2.80±0.3, 9.27±0.9, 104±10, and 55.2±4.4 in units of ${10}^{-23\mathrm{}}$ ${\mathrm{cm}}^2$ for He, Ne, Ar, and ${\mathrm{N}}_2$, respectively. We have also improved on the measurement of the spin-exchange cross section ${\sigma }_{\mathrm{ex}}$ obtaining the value (2.18±0.12)×${10}^{-14\mathrm{}}$ ${\mathrm{cm}}^2$. We compare the problems arising in the study of hyperfine and Zeeman relaxation and we discuss the results.