An experimental investigation of the trap-dynamics of a cesium magneto-optical trap at high laser intensities

Abstract

We have developed Pakistan’s first magneto optical trap (MOT) in which we were able to capture as many as 2.8 × 109 Cs atoms and attain densities as high as 2 × 1011 atoms/cm3. The trap performance was optimized by varying the laser intensity from 50 mW/cm2 to 500 mW/cm2 as well as the magnetic field gradient from 5 G/cm to 20 G/cm. We have fully investigated the dynamics of the cesium vapor cell magneto-optical trap (VCMOT) by determining the capture rate L (atoms s−1), background collisional loss rate γ (s−1) and intra-trap excited-state collisional loss parameter β (cm3 s−1) of the cesium atoms in the trap. Also, the cloud expansion and compression with trap laser intensity and magnetic field gradient was observed. The MOT dynamics at high intensities is characterized by high capture rate (4 × 109 atoms/s), high densities, enhanced collisional losses (β ∼ 10−11 cm3 s−1) and cloud expansion due to radiation trapping. The intensities used in this study are the highest ever reported with the cesium MOT.