  Liquid xenon (LXe) particle detectors are a powerful technology in the field
of dark matter direct detection, having shown impressive results in recent
years and holding strong possibility for leading the field in sensitivity to
galactic weakly interacting massive particles (WIMPs) in the future. The search
for WIMPs requires the capability to detect the recoiling nuclei that result
when these particles interact with normal matter. In order to make meaningful
statements about an observed signal, or lack thereof, the energy scale of
recoiling nuclei in LXe must be known. Our understanding of this energy scale
is contained in a quantity called the relative scintillation efficiency of
nuclear recoils, or L_eff, and has been studied extensively in the literature,
producing seemingly contradictory results. I examine all the measurements of
L_eff that exist, both direct and indirect, and extract the energy dependent
behavior that is statistically consistent globally with all values.
Additionally, I examine the measurements covering low energies (>~10 keV, where
the largest disagreements exist) and attempt to diagnose the systematic effects
that have led to the observed inconsistencies. I show that virtually all major
disparity arises due to efficiency roll-off of the detectors at the low
energies, and, when taking this into account, find that the observed behavior
of L_eff supports a slowly and smoothly decreasing value with decreasing
energy. Finally, I discuss the prospects for future measurements, and derive a
practical limit to what can be achieved.
