CAST solar axion search with 3He buffer gas: Closing the hot dark matter gap
Abstract not provided
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Engineering topics
Collar, J I
Publications and source records attributed to Collar, J I.
First Dark Matter Search Results from a 4-kg CF$_3$I Bubble Chamber Operated in a Deep Underground Site
New data are reported from the operation of a 4.0 kg CF{sub 3}I bubble chamber in the 6800 foot deep SNOLAB underground laboratory. The effectiveness of ultrasound analysis in discriminating alpha decay background events from single nuclear recoils has been confirmed, with a lower bound of >99.3% rejection of alpha decay events. Twenty single nuclear recoil event candidates and three multiple bubble events were observed during a total exposure of 553 kg-days distributed over three different bubble nucleation thresholds. The effective exposure for single bubble recoil-like events was 437.4 kg-days. A neutron background internal to the apparatus, of known origin, is estimated to account for five single nuclear recoil events and is consistent with the observed rate of multiple bubble events. This observation provides world best direct detection constraints on WIMP-proton spin-dependent scattering for WIMP masses >20 GeV/c{sup 2} and demonstrates significant sensitivity for spin-independent interactions.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
The Majorana Experiment
The Majorana collaboration is actively pursuing research and development aimed at a tonne-scale {sup 76}Ge neutrinoless double-beta decay ({beta}{beta}(0{nu})-decay) experiment. The current, primary focus is the construction of the Majorana Demonstrator experiment, an R and D effort that will field approximately 40 kg of germanium detectors with mixed enrichment levels. This article provides a status update on the construction of the Demonstrator.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Search for 14.4-KeV Solar Axions Emitted in the M1-Transition of Fe-57 Nuclei with CAST
We have searched for 14.4 keV solar axions or more general axion-like particles (ALPs), that may be emitted in the M1 nuclear transition of 57Fe, by using the axion-to-photon conversion in the CERN Axion Solar Telescope (CAST) with evacuated magnet bores (Phase I). From the absence of excess of the monoenergetic X-rays when the magnet was pointing to the Sun, we set model-independent constraints on the coupling constants of pseudoscalar particles that couple to two photons and to a nucleon g{sub ay}|-1.19g{sub aN}{sup 0}+g{sub aN}{sup 3}| < 1.36 x 10{sup -16} GeV{sup -1} for ma < 0.03 eV at the 95% confidence level.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Improved Limits on Spin-Dependent WIMP-Proton Interactions from a Two Liter CF{sub 3}I Bubble Chamber
Data from the operation of a bubble chamber filled with 3.5 kg of CF{sub 3}I in a shallow underground site are reported. An analysis of ultrasound signals accompanying bubble nucleations confirms that alpha decays generate a significantly louder acoustic emission than single nuclear recoils, leading to an efficient background discrimination. Three dark matter candidate events were observed during an effective exposure of 28.1 kg day, consistent with a neutron background. This observation provides strong direct detection constraints on weakly interacting massive particle (WIMP)-proton spin-dependent scattering for WIMP masses >20 GeV/c{sup 2}.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
The MAJORANA Experiment
The Majorana Collaboration is assembling an array of HPGe detectors to search for neutrinoless double-beta decay in {sup 76}Ge. Initially, Majorana aims to construct a prototype module to demonstrate the potential of a future 1-tonne experiment. The design and potential reach of this prototype Demonstrator module are presented.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Search for an Annual Modulation in a p-Type Point Contact Germanium Dark Matter Detector
Fifteen months of cumulative CoGeNT data are examined for indications of an annual modulation, a predicted signature of weakly interacting massive particle (WIMP) interactions. Presently available data support the presence of a modulated component of unknown origin, with parameters prima facie compatible with a galactic halo composed of light-mass WIMPs. Unoptimized estimators yield a statistical significance for a modulation of {approx}2.8{sigma}, limited by the short exposure.
79 ASTRONOMY AND ASTROPHYSICS↗
Consistent dark matter interpretation for CoGeNT and DAMA/LIBRA
In this paper, we study the recent excess of low-energy events observed by the CoGeNT Collaboration and the annual modulation reported by the DAMA/LIBRA Collaboration, and discuss whether these signals could both be the result of the same elastically scattering dark matter particle. We find that, without channeling but when taking into account uncertainties in the relevant quenching factors, a dark matter candidate with a mass of approximately 7 GeV and a cross section with nucleons of {sigma}{sub DM-N{approx}}2x10{sup -4} pb (2x10{sup -40} cm{sup 2}) could account for both of these observations. We also comment on the events recently observed in the oxygen band of the CRESST experiment and point out that these could potentially be explained by such a particle. Lastly, we compare the region of parameter space favored by DAMA/LIBRA and CoGeNT to the constraints from XENON10, XENON100, and CDMS (Si) and find that these experiments cannot at this time rule out a dark matter interpretation of these signals.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗