Magneto-optical trapping of chromium atoms

We have constructed a magneto-optical trap for chromium atoms. Using trapping light at 425 nm and two repumping lasers tuned to intercombination transitions, over 10⁶ atoms were trapped and average densities of over 10¹⁶ m^-3 were obtained. Nonexponential loss of atoms is observed at high densities indicating inelastic collisions between trapped atoms. Over a range of trapping conditions, the density-dependent trap loss rate constant β is extracted from fluorescence decay curves and found to have values in the range of 10^-15 m³ s^-1, much larger than is observed in alkali-metal traps.