Gas Dynamics of Pulsed Low Energy Helium Beams

We report data on pulsed atomic helium beams for use in an experiment on atomic reemission of atoms incident on a superfluid helium four sample. We used a gas dynamics code to model these pulsed low energy helium beams and found a good fit with the experimental results at low source power. The fit implies that significant collisional effects occur in these beams. Using the model for the incident pulsed beam which we obtained, we produced simulated signals from the reemitted atoms which we expect to see in the experiment in which we monitor reemission from the sample when these atomic pulses are fired at it. We find that the present experiment could detect the proposed condensate mediated transmission process but that a larger superfluid sample would give a more definitive result.