Magneto-optical trapping of optically pumped metastable europium

We demonstrate laser cooling and magneto-optical trapping of europium. The atoms are optically pumped to a metastable state and then loaded from an atomic-beam source via conventional Zeeman slowing and magneto-optical trapping techniques using a J=13/2↔J=15/2 quasicyclic transition. The trapped populations contained up to 1×10⁷ atoms, and a two-body loss rate is estimated as 1×10^-100.28em0excm³/s from the nonexponential loss of atoms at high densities. We also observed leakage out of the quasicyclic transition to the two metastable states with $J=9/2$ and $11/2$, which is adequate to pump the laser-cooled atoms back to the $J=7/2$ ground state.