Optimizing the production of metastable calcium atoms in a magneto-optical trap

We investigate the production of long lived metastable (3P2, n=4) calcium atoms in a magneto-optical trap operating on the 1S0 to 1P1 transition at 423 nm. For excited 1P1-atoms a weak decay channel into the triplet states 3P2 and 3P1 exists via the singlet 1D2 (n=3) state. The undesired 3P1-atoms decay back to the ground state within 0.4 ms and can be fully recaptured if the illuminated trap volume is sufficiently large. We obtain a flux of above 10^10 atoms/s into the 3P2-state. We find that our MOT life time of 23 ms is mainly limited by this loss channel and thus the 3P2-production is not hampered by inelasic collisions. If we close the loss channel by repumping the 1D2-atoms with a 671 nm laser back into the MOT cycling transition, a non-exponential 72 ms trap decay is observed indicating the presence of inelastic two-body collisions between 1S0 and 1P1 atoms.