Collimated, single-pass atom source from a pulsed alkali metal dispenser   for laser-cooling experiments
  We have developed an improved scheme for loading atoms into a magneto-optical trap (MOT) from a directed alkali metal dispenser in < 10^-10 torr ultra-high vacuum conditions. A current-driven dispenser was surrounded with a cold absorbing "shroud" held at < 0 C, pumping rubidium atoms not directed into the MOT. This nearly eliminates background alkali atoms and reduces the detrimental rise in pressure normally associated with these devices. The system can be well-described as a current-controlled, rapidly-switched, two-temperature thermal beam, and was used to load a MOT with 3 x 10^8 atoms. 
Kevin L. Moore, Thomas P. Purdy, Kater W. Murch, Sabrina Leslie,   Subhadeep Gupta, and Dan M. Stamper-Kurn