The evaporative cooling of a gas of caesium atoms in the hydrodynamic regime

We study the efficiency of evaporative cooling of a trapped gas of caesium atoms in the hydrodynamic regime by the numerical solution of classical kinetic theory equations. The results of the numerical simulation are compared to our experimental observations of evaporative cooling of magnetically trapped ¹³³Cs atoms in the F = 3, m_F = −3 state. The simulation accurately reproduces our experimental performance and indicates that the reduction in cooling efficiency as the gas enters the hydrodynamic regime is the main obstacle to the realization of Bose–Einstein condensation (BEC) in this state. The simulation is used to explore alternative routes to BEC.