  We report the first measurement of discrimination between low-energy helium
recoils and electron recoils in liquid xenon. This result is relevant to
proposed low-mass dark matter searches which seek to dissolve light target
nuclei in the active volume of liquid-xenon time projection chambers.
Low-energy helium recoils were produced by degrading $\alpha$ particles from
$^{210}$Po with a gold foil situated on the cathode of a liquid xenon
time-projection chamber. The resulting population of helium recoil events is
well separated from electron recoils and is also offset from the expected
position of xenon nuclear recoil events.
