The XENON100 experiment , in operation at the Laboratori Nazionali del Gran Sasso in Italy , is designed to search for dark matter WIMPs scattering off 62 \mathrm { kg } of liquid xenon in an ultra-low background dual-phase time projection chamber .
In this letter , we present first dark matter results from the analysis of 11.17 live days of non-blind data , acquired in October and November 2009 .
In the selected fiducial target of 40 \mathrm { kg } , and within the pre-defined signal region , we observe no events and hence exclude spin-independent WIMP-nucleon elastic scattering cross-sections above 3.4 \times 10 ^ { -44 } \mathrm { cm } ^ { 2 } for 55 \mathrm { GeV / c ^ { 2 } } WIMPs at 90 \% confidence level .
Below 20 \mathrm { GeV / c ^ { 2 } } , this result constrains the interpretation of the CoGeNT and DAMA signals as being due to spin-independent , elastic , light mass WIMP interactions .