  The scintillation properties of liquid helium upon the recoil of a low energy
helium atom are discussed in the context of the possible use of this medium as
a detector of dark matter. It is found that the prompt scintillation yield in
the range of recoil energies from a few keV to 100 keV is somewhat higher than
that obtained by a linear extrapolation from the measured yield for an 5 MeV
alpha particle. A comparison is made of both the scintillation yield and the
charge separation by an electric field for nuclear recoils and for electrons
stopped in helium.
