Measuring the Enhanced Scattering Rate in a Bose-Einstein condensate

Abstract

In this thesis we measure and calculate the enhanced scattering rate for both cold thermal clouds and Bose-Einstein condensates. For Bose-Einstein condensates we find that the scattering rate is enhanced, due to the large densities and a temperature just below the critical temperature. The enhancement under typical experimental conditions with a Bose-Einstein condensate is up to a factor 3, while there is no enhancement for thermal clouds. The scattering rate influences both the number of particles and the average energy per particle. For both the energy and the number of particles a theoretical prediction is compared with an experimental result. For the number of particles in a cloud both with and without a Bose-Einstein condensate and the energy in a cloud without a Bose-Einstein condensate, we find that theory and experiment agree within their uncertainties. In the case of the energy per particle in a cloud with a Bose-Einstein condensate, we included a cooling effect for condensed atoms that become thermal, however our experimental results are not sufficient to confirm this theory.