Experiments with a Metastable Helium Atomic Trap
Abstract
In this work I report on the development of a Magneto Optic Trap (MOT) for metastable helium atoms (He*). The metastable helium atoms are produced in a discharge nozzle source and collimated, slowed and compressed to provide a slow bright beam for loading the trap. The trap confines approximately 107 atoms, has a diameter of about 3 mm and with temperature approximately 1 mK. The trap is used for intra-trap and electron-atom scattering experiments. The results from these two experiments are reported. The electron scattering experiment is unique and employs a He* MOT for the first time, in combination with a new diagnostic technique (Phase Modulation Spectroscopy) to measure the trap loss. The results of these experiments have yielded the first total electron-metastable atom collision cross section measurements at intermediate (10-100 eV) electron energies.