| In the first section of this thesis, I describe an experimental apparatus designed to cool a gas of sodium atoms from 600K to below 10–6 K at a density high enough to form a Bose Einstein condensate. Especially novel elements include the atomic source, vacuum chamber, and the “4-Dee” magnetic trap. The benefits of the magnetic trap include large magnetic gradients and curvature for deep trapping, parallel water flow for efficient cooling, and easy access, since it resides outside the vacuum chamber. The vacuum chamber allows near-360° optical access to the trapped atoms. I also present the design of feedback circuitry which maintains a stable magnetic trapping field and the design of a transistor switch that turns off the field quickly.; In the second section, I present measurements made using the apparatus described above. In the first, nearly pure condensates are used to determine the s-wave scattering length for sodium atoms in the 3S, F = 1, mF = –1 atomic state. The value obtained is a = 26.6 ± 0.6 Å, which is the most precise measurement published to date. In the second experiment we study the dynamics of the interface region between the Bose condensed and noncondensed components of expanding atomic clouds at finite temperature. We show that the time dependent density profile is highly sensitive to the effects of interactions between the two components. The measurements are compared to calculations based on Hartree-Fock-Bogoliubov mean field theory, from which a value for the spatial second order correlation function for noncondensed atoms of = 1.8 ± 0.3 can be deduced. |
