  Proportional scintillation in liquid xenon has a promising application in the
field of direct dark matter detection, potentially allowing for simpler, more
sensitive detectors. However, knowledge of the basic properties of the
phenomenon as well as guidelines for its practical use are currently limited.
We report here on measurements of proportional scintillation light emitted in
liquid xenon around thin wires. The maximum proportional scintillation gain of
$287^{+97}_{-75}$ photons per drift electron was obtained using 10 $\mu$m
diameter gold plated tungsten wire. The thresholds for electron multiplication
and proportional scintillation are measured as $725^{+48}_{-139}$ and
$412^{+10}_{-133}$ kV/cm, respectively. The threshold for proportional
scintillation is in good agreement with a previously published result, while
the electron multiplication threshold represents a novel measurement. A
complete set of parameters for the practical use of the electron multiplication
and proportional scintillation processes in liquid xenon was also obtained for
the first time.
