A novel gravito-optical trap (GOT) consisting of a dark hollow-divergent laser beam (DHB) either from a collimated and focused doughnut beam or from the output beam of the LP01 mode in a hollow optical fiber is presented. The cold atoms are loaded into the DHB from a magneto-optical trap (MOT). As the atoms bounce in the DHB, it experience Sisyphus cooling and geometrical cooling induced by the blue detuned DHB and a very weak repumping beam propagating downward into the DHB. Taking into the consideration of the Sisyphus and geometrical cooling along with the spontaneous-emission heating, equations are derived to estimate the final equilibrium rms momentum for the atoms in the DHB trap.
