Continuous propagation and energy filtering of a cold atomic beam in a long high-gradient magnetic atom guide

We demonstrate the continuous injection and propagation of a cold atomic beam in a high-gradient (up to 2.7 kG∕cm) magnetic guide of 1.7 m length. Continuous injection is accomplished using a side-loading scheme that involves a sequence of two modified magneto-optic traps. Methods are developed to measure the atomic-flow temperatures and the flux under steady-state conditions. In the high-gradient portion of the guide, the guided atomic beam has a transverse temperature of 420 μK±40 μK, a longitudinal temperature of 1 mK, and an average velocity of order 1 m∕s. Using a radio-frequency current of a fixed frequency ν coupled directly into the guide wires, atoms exceeding a transverse energy of hν can be continuously and selectively removed from the atomic beam.