Evidence for Large-Molecular-Cluster Formation of Nuclear Reaction Recoils Thermalized in Helium

It has been found that nuclear reaction recoils ejected from a target and thermalized in helium attach to large molecular clusters produced from impurities by the intense ionization generated by the beam passing through helium. When the clusters containing the recoils are entrained in a room-temperature sonic helium flow, they attain kinetic energies of up to 700 keV on account of their high molecular weights which were found to be as high as ${10}^8$ u. Highly efficient separations of nuclear reaction recoils from helium carrier gas have been achieved as a result of the formation of these large clusters.