Beams of helium atoms at temperatures below 0.5° K

A cryostat containing an ellipsoidal cavity was used to produce He/sup 3/ and He/sup 4/ atomic beams. It was shown that at temperatures below 0.5 deg K the beams of atoms can be emitted from a heater, reflected from a wall, and detected by a receiver in the elliposid. The beam velocity was dependent on the input energy. Several observations were difficult to analyze because of the large number of unknown parameters. (C.E.S.)