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First Dark Matter Results from the XENON100 Experiment

The XENON100 Collaboration, E. Aprile, K. Arisaka, F. Arneodo, A. Askin, L. Baudis, A. Behrens, E. Brown, J. M. R. Cardoso, B. Choi, D. B. Cline, S. Fattori, A. D. Ferella, K. -L. Giboni, K. Hugenberg, A. Kish, C. W. Lam, J. Lamblin, R. F. Lang, K. E. Lim, J. A. M. Lopes, T. Marrodán Undagoitia, Y. Mei, A. J. Melgarejo Fernandez, K. Ni, U. Oberlack, S. E. A. Orrigo, E. Pantic, G. Plante, A. C. C. Ribeiro, R. Santorelli, J. M. F. dos Santos, M. Schumann, P. Shagin, A. Teymourian, D. Thers, E. Tziaferi, H. Wang, C. Weinheimer

TL;DR

First dark matter results from the analysis of 11.17 live days of nonblind data are presented, which constrains the interpretation of the CoGeNT and DAMA signals as being due to spin-independent, elastic, light mass WIMP interactions.

Abstract

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 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 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 x 10^-44 cm^2 for 55 GeV/c^2 WIMPs at 90% confidence level. Below 20 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.

First Dark Matter Results from the XENON100 Experiment

TL;DR

First dark matter results from the analysis of 11.17 live days of nonblind data are presented, which constrains the interpretation of the CoGeNT and DAMA signals as being due to spin-independent, elastic, light mass WIMP interactions.

Abstract

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 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 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 x 10^-44 cm^2 for 55 GeV/c^2 WIMPs at 90% confidence level. Below 20 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.

Paper Structure

This paper contains 5 figures.

Figures (5)

  • Figure 1: Global fit to all $\mathcal{L}_{\text{eff}}$ measurements with fixed neutron energies between $5\, \mathrm{keV_{nr}}$ and $100\, \mathrm{keV_{nr}}$, together with $90\%$ confidence contours (solid lines) and extrapolations to lower energies (dashed lines).
  • Figure 2: Electronic (top) and nuclear (bottom) recoil bands from $^{60}\text{Co}$ and $^{241}\mathrm{AmBe}$ calibration data, respectively, after data selection and the $40\, \mathrm{kg}$ fiducial volume cut. Colored lines correspond to the median $\log_{10}(\mathrm{S2/S1})$ values of the electronic (blue) and nuclear (red) recoil bands. The WIMP search energy window $8.7-32.6\, \mathrm{keV_{nr}}$ (vertical, dashed) and S2 software threshold of $300\, \mathrm{PE}$ (long dashed) are shown.
  • Figure 3: Cut acceptance (top, not including 50% acceptance from $\mathrm{S2/S1}$ discrimination) and $\log_{10}(\mathrm{S2/S1})$ (bottom) as functions of nuclear recoil energy for events observed in the $40\, \mathrm{kg}$ fiducial volume during 11.17 live days. Lines as in figure \ref{['fig:bands']}.
  • Figure 4: Distribution of all events (dots) and events below the nuclear recoil median (red circles) in the TPC (grey line) observed in the $8.7-32.6\, \mathrm{keV_{nr}}$ energy range during 11.17 live days. No events below the nuclear recoil median are observed within the $40\, \mathrm{kg}$ fiducial volume (dashed).
  • Figure 5: $90\%$ confidence limit on the spin-independent elastic WIMP-nucleon cross section (solid and long dashed), together with the best limit to date from CDMS (dotted) Ahmed:2010, re-calculated assuming an escape velocity of $544\, \mathrm{km/s}$ and $v_0 = 220\, \mathrm{km/s}$. Expectations from a theoretical model Trotta:2008bp, and the areas ($90\%$ CL) favored by CoGeNT (green) Aalseth:2010vx and DAMA (red/orange) Savage:2008er are also shown.