We have studied a general technique for laser cooling a cloud of polarizedtrapped atoms down to the Doppler temperature. A one-dimensional opticalmolasses using polarized light cools the axial motional degree of freedom ofthe atoms in the trap. Cooling of the radial degrees of freedom can be modelledby reabsorption of scattered photons in the optically dense cloud. We presentexperimental results for a cloud of chromium atoms in a magnetic trap. A simplemodel based on rate equations shows quantitative agreement with theexperimental results. This scheme allows us to readily prepare a dense cloud ofatoms in a magnetic trap with ideal starting conditions for evaporativecooling.
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