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Low-inelastic-rate Atom-Molecule Collisions in a Magnetic Trap
The study of low-temperature molecular collisions is a key step to understanding the fundamental processes in archetypal few-body systems, but also as a stepping stone to further cooling, whether sympathetic or evaporative. With the aim of building on our buffer-gas-loaded BEC work with metastable helium, we studied, both theoretically and experimentally, the collisional properties of the N-NH system. It was hoped that due to the low polarizability of atomic nitrogen and high rotational constant of NH, that the inelastic spin-relaxation cross-section would be significantly lower than the important, cooling, elastic rate. This is what was found and lays the foundation for further cooling of this system. Our methods are unique and allow us to work with unqiue and useful atoms, such as atomic nitrogen. The measure value for the loss rate for N-NH collisions due to NH spin depolarization is k = 9(5)(3) X 10-13 cm3s-1.