Generation of an intense cold-atom beam from a pyramidal magneto-optical trap: experiment and simulation

Abstract

An intense cold-atom beam source based on a modified pyramidal magneto-optical trap has been developed and characterized. We have produced a slow beam of cold cesium atoms with a continuous flux of 2.2 ϫ 10 9 atoms/s at a mean velocity of 15 m/s and with a divergence of 15 mrad. The corresponding radiant intensity is 1.2 ϫ 10 13 atom s Ϫ1 sr Ϫ1 . We have characterized the performance of our beam source over a range of operating conditions, and the measured values for atom flux, mean velocity, and divergence are in good agreement with results from detailed Monte Carlo numerical simulations.

Two-species cold atomic beam

“…We note, however, that the fluxes reported here are still an order of magnitude lower than what we have measured previously in the single-species Cs CAB generated in this same apparatus. 18 Much of this difference can be attributed to the lower optical powers (one third to one fourth) available to the pyramidal source MOT in the present study. This dual-species beam performance could be enhanced, however, by simply employing the appropriate dichroic beam splitter and wave plates to allow a greater fraction of the available laser powers at 780 nm and 852 nm to be simultaneously directed to the source MOT.…”

“…Table 1); the Cs beam velocity, measured at a much higher laser intensity (I ϭ 3I sat ), was 15 m/s. 18 The divergence of the CAB is geometrically limited, and this divergence was previously measured to be 15 mrad for the Cs beam in the current apparatus. 18 The UHV MOT was characterized by employing two calibrated CCD cameras with narrow-band optical filters to selectively image the trapped Cs and Rb atom clouds.…”

“…18 The divergence of the CAB is geometrically limited, and this divergence was previously measured to be 15 mrad for the Cs beam in the current apparatus. 18 The UHV MOT was characterized by employing two calibrated CCD cameras with narrow-band optical filters to selectively image the trapped Cs and Rb atom clouds. The calibrated imaging system allows us to determine the atom number as well as the loading and decay rates for the UHV trap.…”

“…Recently, a high-flux twospecies Zeeman-slowed atomic beam was demonstrated by Hadzibabic et al 12 The relative advantages and disadvantages of MOT-based atomic beam sources versus other beam sources have been discussed previously. 18,19 We have utilized our two-species beam to load a mixedspecies UHV MOT, and cross-species interaction effects were observed via the measured decay rates in the UHV trap. The current experiment allows independent control of the loading and decay of each species within the UHV trap, and the effects of cold collisions in the UHV MOT are isolated from the usual losses due to thermal gas backgrounds.…”

“…18 In brief, our pyramidal trap consists of a large four-sided pyramidal mirror assembly that is truncated just before the apex. At the truncated apex, a separate retro-optic (consisting of a /4 plate with a highreflectance gold coating on the second surface) contains a 1-mm aperture.…”