Journal of Physics B Atomic Molecular and Optical Physics

Quantum-reflection model for Penning ionization rate coefficients in cold collisions of metastable helium and rubidium

A S Dickinson

Published Oct 21, 2010• 0 citations

Abstract

A quantum-reflection model is employed to calculate the rate coefficient for the Penning ionization of rubidium by cold metastable helium atoms in unpolarized collisions. Various results for the p-wave transmission coefficient on a 1/R-6 long-range potential are discussed. The dispersion coefficient for the interaction of these atoms is estimated as 3540 au. The calculated value of the rate coefficient is about four times lower than the recently measured value (Byron et al 2010a Phys. Rev. A 81 013405) for this process when both atoms are held in magneto-optical traps.

DOI: 10.1088/0953-4075/43/21/215302

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Journal of Physics B Atomic Molecular and Optical Physics

Quantum-reflection model for Penning ionization rate coefficients in cold collisions of metastable helium and rubidium

A S Dickinson

Published Oct 21, 2010• 0 citations

Publisher

Abstract

DOI: 10.1088/0953-4075/43/21/215302

Related papers

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arXiv:physics/0701194Physical Review AJun 29, 200713 citations

By confining

{}^{3}\mathrm{He}

and

{}^{4}\mathrm{He}

in their respective magneto-optical traps, ionization rate coefficients for Penning collisions between two cold

\mathrm{He}(2s^{3}S_{1})

atoms have been measured. At 0.5 mK, the rate coefficients obtained are $(3.8\ifmmode\pm\else\textpm\fi{}1.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}{\mathrm{cm}}^{3}/\mathrm{s}$ for

{}^{4}\mathrm{He}

{}^{4}\mathrm{He}

collisions and $(1.1\ifmmode\pm\else\textpm\fi{}0.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}{\mathrm{cm}}^{3}/\mathrm{s}$ for

{}^{3}\mathrm{He}

{}^{3}\mathrm{He}

, a difference of a factor of 3. Theoretical calculations have shown that such a large difference arises only when the lowest order partial wave alone contributes to the ionization, and that it is mainly due to the difference in the quantum statistical symmetry between

{}^{3}\mathrm{He}

and

{}^{4}\mathrm{He}

We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable

(2\phantom{\rule{0.2em}{0ex}}^{3}S_{1})

^{3}\mathrm{He}

and

^{4}\mathrm{He}

atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., Phys. Rev. A 73, 032713 (2006)]. A simple theoretical model of such collisions enables us to calculate the heteronuclear ionization rate coefficient, for our quasiunpolarized gas, in the absence of resonant light

(T=1.2\phantom{\rule{0.2em}{0ex}}\mathrm{mK})

: ${K}_{34}^{(\mathrm{th})}=2.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$. This calculation is supported by a measurement of

{K}_{34}

using magneto-optically trapped mixtures containing about $1\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms of each species, ${K}_{34}^{(\mathrm{exp})}=2.5(8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$. Theory and experiment show good agreement.