Cryogenic buffer-gas loading and magnetic trapping of CrH and MnH molecules

We report on the buffer- gas cooling and trapping of CrH and MnH molecules in a magnetic quadrupole trap with densities on the order of 10(6) cm(-3) at a temperature of 650 mK. Storage times of up to 180 ms have been observed, corresponding to a 20- fold lifetime enhancement with respect to the field- free diffusion through the He-3 buffer- gas. Using Monte Carlo trajectory simulations, inelastic molecule-He-3 collision cross sections of 1.6 x 10(-18) and 3.1 x 10(-17) cm(2) are extracted for CrH and MnH, respectively. Furthermore, elastic molecule-He-3 collision cross sections of 1.4(+/- 0.5) x 10(-14) cm(2) are determined for both species. We conclude that the confinement time of these molecules in a magnetic trapping field is limited by inelastic collisions with the helium atoms leading to Zeeman relaxation.