We report results of a search for light ( \lesssim 10 Â GeV ) particle dark matter with the XENON10 detector .
The event trigger was sensitive to a single electron , with the analysis threshold of 5 electrons corresponding to 1.4Â keV nuclear recoil energy .
Considering spin-independent dark matter-nucleon scattering , we exclude cross sections \sigma _ { n } > 7 \times 10 ^ { -42 } Â cm ^ { 2 } , for a dark matter particle mass m _ { \chi } = 7 Â GeV .
We find that our data strongly constrain recent elastic dark matter interpretations of excess low-energy events observed by CoGeNT and CRESST-II , as well as the DAMA annual modulation signal .