Spinning up and down a Boltzmann gas - art. no. 033607

Using the average method, we derive a closed set of linear equations that d escribes the spinning up of an harmonically trapped gas by a rotating aniso tropy. We find explicit expressions for the time needed to transfer annular momentum as well as the decay time induced by a static residual anisotropy . These different time scales are compared with the measured nucleation tim e and lifetime of vortices by Madison et al. We find a good agreement that may emphasize the role played by the noncondensed component in those experi ments.