Narrow-line magneto-optical trap for europium

We report on the realization of a magneto-optical trap (MOT) for europium atoms using narrow-line cooling transition with natural linewidth 97 kHz. Our starting point is continuous capturing and optically pumped metastable atoms. have employed simultaneous MOT ground-state The trapped are successively back to ground state then continuously loaded MOT, where up $4.7\times10^7$ captured. A spin-polarized sample at temperature $6\,\mathrm{\mu K}$ peak number density $2.2\times10^{11}\,\mathrm{cm^{-3}}$ obtained through compression process, resulting in phase space $3\times10^{-5}$.