Penning collisions of laser-cooled metastable helium atoms

Abstract

We present experimental results on the two-body loss rates in a magneto-optical trap of metastable helium atoms. Absolute rates are measured in a systematic way for several laser detunings ranging from -5 to -30 MHz and at different intensities, by monitoring the decay of the trap fluorescence. The dependence of the two-body loss rate coefficient ${\hat{I}}^2$ on the excited state ($2^3{P}_2$) and metastable state ($2^3{S}_1$) populations is also investigated. From these results we infer a rather uniform rate constant $K_{sp}=(1\pm 0.4)\times 10^{-7}$ cm${}^3$/s.

8 pages, 9 figures, Revtex