XENON100 is a direct WIMP dark matter search experiment deploying
a dual-phase xenon Time Projection Chamber (TPC) underground at
the Laboratori Nazionali del Gran Sasso of INFN, Italy. The
detector features a 62 kg liquid xenon target, which is sensitive
to both scintillation and ionization and is surrounded by a 99 kg
optically isolated liquid xenon volume as active veto. The TPC
enables 3D interaction position reconstruction with millimeter
precision allowing the selection of only the innermost 48 kg as
ultra-low background fiducial target. The yield difference
between scintillation and ionization discriminates nuclear recoil
signal from electronic recoil background.
I will discuss various aspects of the XENON100 detector, as well as present the most recent results from 100.9 live days of data, acquired between January and June 2010. No evidence for dark matter is found. Three candidate events were observed in a pre-defined signal region with an expected background of (1.8 ± 0.6) events. This leads to the most stringent limit on dark matter interactions to date excluding spin-independent elastic WIMP-nucleon scattering cross-sections above 7.0e-45 cm2 for a WIMP mass of 50 GeV/c2 at 90% confidence level.