Figure 1

Charge yield ($Q_y$) as a function of energy for nuclear recoils (keV). This analysis employs the conservative nuclear recoil charge yield model of Bezrukov et al. (electric field independent) [2], given by the green line. It agrees with the measurement of XENON100 ($\mathrm{E}=0.53\mathrm{kV}/\mathrm{cm}$) [3] (red triangles). The NEST model ($\mathrm{E}=0.73\mathrm{kV}/\mathrm{cm}$) [4] (dashed black) and the recent measurement of LUX ($\mathrm{E}=0.18\mathrm{kV}/\mathrm{cm}$) [1] (blue points) predict slightly higher yields. To account for the mild discrepancies below 3 keV, we use the model from Bezrukov et al. and conservatively assume $Q_y=0$ below 0.7 keV.