A spin flipper for reversal of polarisation in a thermal atomic beam

By using the method of diabatic passage, the authors have developed a spin flipper which allows a rapid and convenient reversal of the atomic spins. The spin flipper was tested with a polarised lithium atomic beam by analysing the atomic beam polarisation with the help of a second spin-flip region and a sextupole magnet. The reversal efficiency was measured to be 0.98 which is in agreement with the calculation. The flipper is especially useful in low-energy electron-atom crossed-beam collision studies. The experimental arrangement used also allows a precise determination of the atomic beam polarisation.