  LUX, the world's largest dual-phase xenon time-projection chamber, with a
fiducial target mass of 118 kg and 10,091 kg-days of exposure thus far, is
currently the most sensitive direct dark matter search experiment. The initial
null-result limit on the spin-independent WIMP-nucleon scattering cross-section
was released in October 2013, with a primary scintillation threshold of 2 phe,
roughly 3 keVnr for LUX. The detector has been deployed at the Sanford
Underground Research Facility (SURF) in Lead, South Dakota, and is the first
experiment to achieve a limit on the WIMP cross-section lower than $10^{-45}$
cm$^{2}$. Here we present a more in-depth discussion of the novel energy scale
employed to better understand the nuclear recoil light and charge yields, and
of the calibration sources, including the new internal tritium source. We found
the LUX data to be in conflict with low-mass WIMP signal interpretations of
other results.
