Magneto-optical trap for thulium atoms

Thulium atoms are trapped in a magneto-optical trap using a strong transition at 410 nm with a small branching ratio. We trap up to 7 x 10(4) atoms at a temperature of 0.8(2) mK after deceleration in a 40-cm-long Zeeman slower. Optical leaks from the cooling cycle influence the lifetime of atoms in the magneto-optical trap which varies between 0.3 and 1.5 s in our experiments. The lower limit for the leaking rate from the upper cooling level is measured to be 22(6) s(-1). The repumping laser transferring the atomic population out of the F = 3 hyperfine ground-state sublevel gives a 30% increase for the lifetime and the number of atoms in the trap.