Direct Observation of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">s</mml:mi></mml:math>-Wave Atomic Collisions

Abstract

We observe the angular distribution of $s$-wave scattering of Cs atoms in an atomic fountain by selecting and probing atomic velocities. At an average temperature of $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.89$ $\ensuremath{\mu}$K the scattering is predominantly $s$-wave and we have a sensitivity to $p$-wave cross sections as small as 0.1% of the $s$-wave. The cross section is $4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}\phantom{\rule{0ex}{0ex}}{\mathrm{cm}}^{2}$ for atoms in the $F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3$, ${m}_{F}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ state colliding with atoms distributed among the $F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}4$, ${m}_{F}$ states. We also demonstrate a multiply loaded magneto-optic trap and a temperature of 1.53(7) $\ensuremath{\mu}$K.