Loading of a far off resonance dipole force trap for stable ³⁹K

The TRIumf Neutral Atom Trap (TRINAT) group is performing precision measurements to test the standard model of the weak interaction. Nuclear β decay asymmetry experiments are carried out on radioactively decaying potassium isotopes, trapped in a Magneto Optical Trap (MOT). In order to accurately test whether parity is fully violated, atoms of well defined polarisation are required. A useful tool which can achieve a high level of polarisation is a Circularly polarized Far Off Resonance dipole Force Trap (CFORT). This work is the first step in its development; building the necessary components in order to successfully load stable ³⁹K into a linearly polarised FORT from a MOT, where the atoms are pre-cooled to a temperature of a few hundred μK. The FORT consists of 700mW of light from a Titanium Sapphire ring laser, linearly polarized and focused with a 200mm achromatic lens to a waist of 35μm. The light is detuned between 1 and 20nm from the D₁ transition and this gives rise to trap depths in the region of a few millikelvin. A characterisation of the FORT loading efficiency and lifetime as a function of FORT beam detuning, power and ellipticity are studied.Science, Faculty ofPhysics and Astronomy, Department ofGraduat