Optical and evaporative cooling of caesium atoms in the gravito-optical surface trap

We report on cooling of an atomic caesium gas closely above an evanescent-w ave atom mirror. At high densities, optical cooling based on inelastic refl ections is found to be limited by a density-dependent excess temperature an d trap loss due to ultracold collisions involving repulsive molecular state s. Nevertheless, very good starting conditions for subsequent evaporative c ooling are obtained. Our first evaporation experiments show a temperature r eduction from 10 muK down to 300 nK along with a gain in phase-space densit y of almost two orders of magnitude.