The XENON1T experiment is currently in the commissioning phase at the Laboratori Nazionali del Gran Sasso, Italy. In this article we study the experiment's expected sensitivity to the spin-independent WIMP-nucleon interaction cross section, based on Monte Carlo predictions of the electronic and nuclear recoil backgrounds.The total electronic recoil background in 1 tonne fiducial volume and (1, 12) keV electronic recoil equivalent energy region, before applying any selection to discriminate between electronic and nuclear recoils, is (1.80 ± 0.15) · 10⁻⁴(kg·day·keV)⁻¹, mainly due to the decay of²²²Rn daughters inside the xenon target. The nuclear recoil background in the corresponding nuclear recoil equivalent energy region (4, 50) keV, is composed of (0.6 ± 0.1) (t·y)⁻¹from radiogenic neutrons, (1.8 ± 0.3) · 10⁻²(t·y)⁻¹from coherent scattering of neutrinos, and less than 0.01 (t·y)⁻¹from muon-induced neutrons. The sensitivity of XENON1T is calculated with the Profile Likelihood Ratio method, after converting the deposited energy of electronic and nuclear recoils into the scintillation and ionization signals seen in the detector. We take into account the systematic uncertainties on the photon and electron emission model, and on the estimation of the backgrounds, treated as nuisance parameters. The main contribution comes from the relative scintillation efficiency ℒ_eff, which affects both the signal from WIMPs and the nuclear recoil backgrounds. After a 2 y measurement in 1 t fiducial volume, the sensitivity reaches a minimum cross section of 1.6 · 10⁻⁴⁷cm²at m_χ = 50 GeV/c².

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 $8.8\times {10}^{-44}{\mathrm{cm}}^2$ for a WIMP mass of $100\mathrm{GeV}/c^2$, and $4.5\times {10}^{-44}{\mathrm{cm}}^2$ for a WIMP mass of $30\mathrm{GeV}/c^2$. This result further constrains predictions of supersymmetric models.

We report results of a search for light ($\lesssim 10\mathrm{GeV}$) 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 ${\sigma }_n>7\times {10}^{-42}{\mathrm{cm}}^2$, for a dark matter particle mass $m_{\chi }=7\mathrm{GeV}$. 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.

We present new experimental constraints on the elastic, spin-dependent WIMP-nucleon cross section using recent data from the XENON100 experiment, operated in the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 224.6 live $\mathrm{\text{days}}\times 34\mathrm{kg}$ of exposure acquired during 2011 and 2012 revealed no excess signal due to axial-vector WIMP interactions with ${}^{129}\mathrm{Xe}$ and ${}^{131}\mathrm{Xe}$ nuclei. This leads to the most stringent upper limits on WIMP-neutron cross sections for WIMP masses above $6\mathrm{GeV}/c^2$, with a minimum cross section of $3.5\times {10}^{-40}{\mathrm{cm}}^2$ at a WIMP mass of $45\mathrm{GeV}/c^2$, at 90% confidence level.

53 pages. Submitted to Nuclear Instruments and Methods in Physics Research Section AInternational audienceThe Pierre Auger Observatory is a hybrid detector for ultra-high energy cosmic rays. It combines a surface array to measure secondary particles at ground level together with a fluorescence detector to measure the development of air showers in the atmosphere above the array. The fluorescence detector comprises 24 large telescopes specialized for measuring the nitrogen fluorescence caused by charged particles of cosmic ray air showers. In this paper we describe the components of the fluorescence detector including its optical system, the design of the camera, the electronics, and the systems for relative and absolute calibration. We also discuss the operation and the monitoring of the detector. Finally, we evaluate the detector performance and precision of shower reconstructions