New diagnostic technique for Zeeman-compensated atomic beam slowing: technique and results

We have developed a new diagnostic tool for the study of Zeeman-compensated slowing of an alkali atomic beam. Our time-of-flight technique measures the longitudinal veloc- ity distribution of the slowed atoms with a resolution below the Doppler limit of 30 cm/s. Furthermore, it can map the position and velocity distribution of atoms in either ground hyperfine level inside the solenoid without any devices inside the solenoid. The technique reveals the optical pumping ef- fects, and shows in detail how the slowing within the solenoid proceeds. We find that most atoms in the chosen hyperfine state are decelerated in the slowing process. The width of the velocity distribution is mainly determined by inhomogeneities in the slowing laser beam, and after expanding the laser beam, the width is reduced to 2.5 m/s, corresponding to 3.2 mK. Fi- nally, we discuss and show a method to produce a beam with two-velocity components for the study of head-tail low energy collisions