Optical molasses loaded from a low-velocity intense source of atoms: an atom source for improved atomic fountains

We demonstrate the efficient capture of cesium atoms from a low-velocity intense source (LVIS) of atoms into an optical molasses. The high load rates that are achievable with the technique can potentially improve the stability of and reduce collisional shifts in atomic fountain clocks. An LVIS is an atomic beam created from a small hole in one of the retroreflectors in an otherwise ordinary magnetooptical trap (MOT). Our typical LVIS flux was 10¹⁰ atoms/s. The asymptotic value for the number of atoms captured in the optical molasses was 1.1(1) × 10⁹ atoms, and the fill time constant was τ = 290(30) ms. The initial molasses fill rate was R_t=0 = 3.8(5) × 10⁶ atoms/ms. At this rate, it would require 24 ms to capture and launch 10⁷ state-selected atoms in an atomic fountain. The fill rate at short times indicates that approximately 40% of the LVIS atoms were being captured in the optical molasses.