We report results of a search for light (10 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 1.4 keV nuclear recoil energy. Considering spin-independent dark matter-nucleon scattering, we exclude cross sections n>7×10-42 cm2, for a dark matter particle mass m=7 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.

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The XENON10 experiment at the Gran Sasso National Laboratory uses a 15 kg xenon dual phase time projection chamber to search for dark matter weakly interacting massive particles (WIMPs). The detector measures simultaneously the scintillation and the ionization produced by radiation in pure liquid xenon to discriminate signal from background down to 4.5 keV nuclear-recoil energy. A blind analysis of 58.6 live days of data, acquired between October 6, 2006, and February 14, 2007, and using a fiducial mass of 5.4 kg, excludes previously unexplored parameter space, setting a new 90% C.L. upper limit for the WIMP-nucleon spin-independent cross section of 8.8x10(-44) cm2 for a WIMP mass of 100 GeV/c2, and 4.5x10(-44) cm2 for a WIMP mass of 30 GeV/c2. This result further constrains predictions of supersymmetric models.

XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso Underground Laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulation data. The results on the detector's energy threshold, position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10 keVr) and low background rate achieved.Design and Performance of the XENON10 Dark Matter Experiment XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso underground laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulations data. The results on the detector's energy threshold, energy and position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10 keVr) and the excellent energy resolution achieved by combining the ionization and scintillation signals, detected simultaneously.PACS numbers: 95.35.+d, 29.40.Mc, 95.55.Vj

XENON10 is an experiment to directly detect weakly interacting massive particle (WIMPs), which may comprise the bulk of the non-baryonic dark matter in our Universe. We report new results for spin-dependent WIMP-nucleon interactions with 129 Xe and 131 Xe from 58.6 live-days of operation at the Laboratori Nazionali del Gran Sasso (LNGS). Based on the non-observation of a WIMP signal in 5.4 kg of fiducial liquid xenon mass, we exclude previously unexplored regions in the theoretically allowed parameter space for neutralinos. We also exclude a heavy Majorana neutrino with a mass in the range of ∼10 GeV/c 2 -2 TeV/c 2 as a dark matter candidate under standard assumptions for its density and distribution in the galactic halo.PACS numbers: 95.35.+d, 29.40.Mc, 95.55.Vj Evidence for a significant cold dark matter component in our universe is stronger than ever [1, 2, 3], a wellmotivated particle candidate being the lightest neutralino from super-symmetric extensions to the Standard Model [4]. Such a particle is neutral, non-relativistic, stable, and more generally classified as a Weakly Interacting Massive Particle (WIMP). The open question of the nature of WIMPs is being addressed by numerous direct and indirect detection experiments [5,6,7].Among these, the XENON10 experiment aims to directly detect galactic WIMPs scattering elastically from Xe atoms. Moving with velocities around 10 −3 c, WIMPs can couple to nucleons via both spin-independent and spin-dependent (axial vector) interactions. Spinindependent WIMP-nucleon couplings are in general smaller than axial vector couplings [4]. However, for low momentum transfer, they benefit from coherence across the nucleus, and therefore the overall event rate for WIMP interactions is expected to be dominated by the spin-independent coupling for target nuclei with A≥30. The sensitivity of XENON10 to spin-independent interactions is published in [8].We report here on a spin-dependent analysis of 58.6 live-days of WIMP-search data, taken in low-background conditions at LNGS, which provides ∼3100 meters water equivalent rock overburden. XENON10 is a dual phase (liquid and gas) xenon time projection chamber, discriminating between the predominantly electron-recoil background and the expected nuclear-recoil WIMP signal via the distinct ratio of ionization to scintillation for each type of interaction [8]. A nuclear recoil energy threshold of 4.5 keV was achieved, and 10 candidate events were recorded for an exposure of about 136 kg days after analysis cuts (the fiducial mass was 5.4 kg). Although all observed events are consistent with expected background from electron recoils (see [8] for details on the analysis and the candidate events), no background subtraction is employed for calculating the WIMP upper limits. In the following analysis, we use identical data quality, fiducial volume, and physics cuts as reported in [8].For axial WIMP-nuclei interactions, the WIMPs couple to the spins of the nucleons. Although the interaction with the nucleus is coherent (as it is in the s...