Theory of evaporative cooling with energy-dependent elastic scattering cross section and application to metastable helium
Paul J. J. Tol, W. Hogervorst, W. Vassen
The kinetic theory of evaporative cooling developed by Luiten et al. [Phys. Rev. A 53, 381 (1996)] is extended to include the dependence of the elastic scattering cross section on collision energy. We introduce a simple approximation by which the transition range between the low-temperature limit and the unitarity limit is described as well. Applying the modified theory to our measurements on evaporative cooling of metastable helium, we find a scattering length $\ensuremath{\mid}a\ensuremath{\mid}=10(5)\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$.
arXiv:cond-mat/0312223•Physical Review A•Jul 8, 2004•24 citations