Accumulation of chromium metastable atoms into an Optical Trap

We report the fast accumulation of a large number of metastable Cr atoms in a mixed trap, formed by the superposition of a strongly confining optical trap and a quadrupolar magnetic trap. The steady state is reached after about 400 ms, providing a cloud of more than one million metastable atoms at a temperature of about 100 μK, with a peak density of 10 atoms.m. We have optimized the loading procedure, and measured the light shift of the D4 state by analyzing how the trapped atoms respond to a parametric excitation. We compare this result to a theoretical evaluation based on the available spectroscopic data for chromium atoms. PACS. 32.80.Pj Optical Cooling of atoms; trapping – 32.10.Dk Electric and magnetic moments, polarizability – 42.50.Vk Mechanical effects of light on atoms, molecules, electrons, and ions