arXiv subjects

R. J. Gaitskell

Publications and source records attributed to R. J. Gaitskell.

101 records · Page 6Linked to original sources

arXiv2008

The scintillation and ionization yield of liquid xenon for nuclear recoils

XENON10 is an experiment designed to directly detect particle dark matter. It is a dual phase (liquid/gas) xenon time-projection chamber with 3D position imaging. Particle interactions generate a primary scintillation signal (S1) and ionization signal (S2), which are both functions of the deposited recoil energy and the incident particle type. We present a new precision measurement of the relative scintillation yield \leff and the absolute ionization yield Q_y, for nuclear recoils in xenon. A dark matter particle is expected to deposit energy by scattering from a xenon nucleus. Knowledge of \leff is therefore crucial for establishing the energy threshold of the experiment; this in turn determines the sensitivity to particle dark matter. Our \leff measurement is in agreement with recent theoretical predictions above 15 keV nuclear recoil energy, and the energy threshold of the measurement is 4 keV. A knowledge of the ionization yield \Qy is necessary to establish the trigger threshold of the experiment. The ionization yield \Qy is measured in two ways, both in agreement with previous measurements and with a factor of 10 lower energy threshold.

astro-ph↗

arXiv2008

Limits on spin-dependent WIMP-nucleon cross-sections from the XENON10 experiment

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 -2 TeV as a dark matter candidate under standard assumptions for its density and distribution in the galactic halo.

astro-ph↗

arXiv2007

First Results from the XENON10 Dark Matter Experiment at the Gran Sasso National Laboratory

The XENON10 experiment at the Gran Sasso National Laboratory uses a 15 kg xenon dual phase time projection chamber (XeTPC) 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 x 10^{-44} cm^2 for a WIMP mass of 100 GeV/c^2, and 4.5 x 10^{-44} cm^2 for a WIMP mass of 30 GeV/c^2. This result further constrains predictions of supersymmetric models.

astro-ph↗

arXiv2007

Deep Underground Science and Engineering Lab: S1 Dark Matter Working Group

A study of the current status of WIMP dark matter searches has been made in the context of scientific and technical planning for a Deep Underground Science and Engineering Laboratory (DUSEL) in the U.S. The table of contents follows: 1. Overview 2. WIMP Dark Matter: Cosmology, Astrophysics, and Particle Physics 3. Direct Detection of WIMPs 4. Indirect Detection of WIMPs 5. Dark Matter Candidates and New Physics in the Laboratory 6. Synergies with Other Sub-Fields 7. Direct Detection Experiments: Status and Future Prospects 8. Infrastructure 9. International Context 10. Summary and Outlook 11. Acknowledgments

astro-ph↗

arXiv2006

3D Position Sensitive XeTPC for Dark Matter Search

The technique to realize 3D position sensitivity in a two-phase xenon time projection chamber (XeTPC) for dark matter search is described. Results from a prototype detector (XENON3) are presented.

astro-ph↗

arXiv2005

Beyond the CDMS-II Dark Matter Search: SuperCDMS

Presently the CDMS-II collaboration's Weakly Interacting Massive Particle (WIMP) search at the Soudan Underground Laboratory sets the most stringent exclusion limits of any WIMP cold dark matter direct-detection experiment. To extend our reach further, to WIMP-nucleon cross sections in the range $10^{-46} - 10^{-44}$cm$^2$, we propose SuperCDMS, which would take advantage of a very deep site. One promising site is the recently approved SNOLab facility in Canada. In this paper we will present our overall plan, identify primary issues, and set the goals that need to be met prior to embarking upon each phase of SuperCDMS.

astro-ph↗

arXiv2002

Expected Performance of CryoArray

WIMP-nucleon cross sections below 10^(-9) pb may be probed by ton-scale experiments with low thresholds and background rates ~20 events per year. An array of cryogenic detectors ("CryoArray") could perform well enough to reach this goal. Sufficient discrimination and background suppression of photons has already been demonstrated. Reduction of neutron backgrounds may be achieved by siting the experiment deep enough. Removal of the surface-electron backgrounds alone has not yet been demonstrated, but the reductions required even for this troublesome background are quite modest and appear achieveable.

astro-ph↗

arXiv2002

XENON: a 1 tonne Liquid Xenon Experiment for a Sensitive Dark Matter Search

XENON is a novel liquid xenon experiment concept for a sensitive dark matter search using a 1-tonne active target, distributed in an array of ten independent time projection chambers. The design relies on the simultaneous detection of ionization and scintillation signals in liquid xenon, with the goal of extracting as much information as possible on an event-by-event basis, while maintaining most of the target active. XENON is expected to have effective and redundant background identification and discrimination power, higher than 99.5%, and to achieve a very low threshold, on the order of 4 keV visible recoil energy. Based on this expectation and the 1-tonne mass of active xenon, we project a sensitivity of 0.0001 events/kg/day, after 3 yr operation in an appropriate underground location. The XENON experiment has been recently proposed to the National Science Foundation (NSF) for an initial development phase leading to the development of the 100 kg unit module.

astro-ph↗

arXiv2002

Comment on "Evidence for Neutrinoless Double Beta Decay"

We comment on the recent claim for the experimental observation of neutrinoless double-beta decay. We discuss several limitations in the analysis provided in that paper and conclude that there is no basis for the presented claim.

hep-ex↗

arXiv2001

Towards One Tonne Direct WIMP Detectors: Have we got what it takes?

Experimentally have we got what it takes to pursue the direct observation of WIMP interactions down to sensitivities of a few events /100 kg/year? For a Ge target with a low energy threshold (<20 keVr) this corresponds to a WIMP-nucleon sigma~10^-46 cm^2. A number of recent theoretical papers, making calculations in SUSY-based frameworks, show many (>5) orders of magnitude spread in the possible interaction rates for models consistent with existing Cosmology and Accelerator bounds. Some theorists, but certainly not all, are able to generate models, that lead to interaction rates at the few /kg/day that would be implied by the current DAMA annual modulation signal. All theorists demonstrate models that generate much lower interaction rates. This paper takes an unashamed experimentalist`s view of the issues that arise when looking forward to constructing 1 tonne WIMP detectors.

astro-ph↗

arXiv2000

A New Model-Independent Method for Extracting Spin-Dependent Cross Section Limits from Dark Matter Searches

A new method is proposed for extracting limits on spin-dependent WIMP-nucleon interaction cross sections from direct detection dark matter experiments. The new method has the advantage that the limits on individual WIMP-proton and WIMP-neutron cross sections for a given WIMP mass can be combined in a simple way to give a model-independent limit on the properties of WIMPs scattering from both protons and neutrons in the target nucleus. Extension of the technique to the case of a target material consisting of several different species of nuclei is discussed.

hep-ph↗