  We present the results of the three-month above-ground commissioning run of
the Large Underground Xenon (LUX) experiment at the Sanford Underground
Research Facility located in Lead, South Dakota, USA. LUX is a 370 kg liquid
xenon detector that will search for cold dark matter in the form of Weakly
Interacting Massive Particles (WIMPs). The commissioning run, conducted with
the detector immersed in a water tank, validated the integration of the various
sub-systems in preparation of the underground deployment. Using the data
collected, we report excellent light collection properties, achieving 8.4
photoelectrons per keV for 662 keV electron recoils without an applied electric
field, measured in the center of the WIMP target. We also find good energy and
position resolution in relatively high-energy interactions from a variety of
internal and external sources. Finally, we have used the commissioning data to
tune the optical properties of our simulation and report updated sensitivity
projections for spin-independent WIMP-nucleon scattering.
