A5084489116- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Neutrino Physics Research
- Radiation Detection and Scintillator Technologies
- Radioactive contamination and transfer
- Radioactivity and Radon Measurements
- Nuclear Physics and Applications
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Cosmology and Gravitation Theories
- Nuclear and radioactivity studies
- Astrophysics and Cosmic Phenomena
- Nuclear physics research studies
- Scientific Research and Discoveries
- Graphite, nuclear technology, radiation studies
- Atmospheric and Environmental Gas Dynamics
- CCD and CMOS Imaging Sensors
- Radioactive Decay and Measurement Techniques
- Muon and positron interactions and applications
- Advanced NMR Techniques and Applications
- Radiation Therapy and Dosimetry
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Astronomy and Astrophysical Research
- Radioactive element chemistry and processing
Pacific Northwest National Laboratory
2015-2024
Battelle
2012-2023
Government of the United States of America
2022
United States Department of Commerce
1996-2012
Office of Scientific and Technical Information
1996-2012
National Technical Information Service
2002-2012
Bechtel (United States)
2012
Universidad de Zaragoza
1995-2000
Institute for Nuclear Research
2000
Joint Institute for Nuclear Research
2000
We report on several features in the energy spectrum from an ultralow-noise germanium detector operated deep underground. By implementing a new technique able to reject surface events, number of cosmogenic peaks can be observed for first time. discuss irreducible excess bulklike events below 3 keV ionization energy. These could caused by unknown backgrounds, but also dark matter interactions consistent with DAMA/LIBRA. It is not yet possible determine their origin. Improved constraints are...
Fifteen months of cumulative CoGeNT data are examined for indications an annual modulation, a predicted signature weakly interacting massive particle (WIMP) interactions. Presently available support the presence modulated component unknown origin, with parameters prima facie compatible galactic halo composed light-mass WIMPs. Unoptimized estimators yield statistical significance modulation ∼2.8σ, limited by short exposure.
CoGeNT employs p-type point-contact (PPC) germanium detectors to search for Weakly Interacting Massive Particles (WIMPs). By virtue of its low energy threshold and ability reject surface backgrounds, this type device allows an emphasis on low-mass dark matter candidates (wimp mass about 10 GeV/c2). We report the characteristics PPC detector presently taking data at Soudan Underground Laboratory, elaborating aspects shielding, acquisition, instrumental stability, analysis, background...
We report the final results of Phase II SIMPLE measurements, comprising two run stages 15 superheated droplet detectors each, with second stage including an improved neutron shielding. The analyses include a refined signal analysis, and revised nucleation efficiency based on reanalysis previously reported monochromatic irradiations. combined yield contour minimum ${\ensuremath{\sigma}}_{p}=5.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }\mathrm{pb}$ at $35\text{...
The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in ^{76}Ge. Demonstrator comprises 44.1 kg (29.7 enriched ^{76}Ge) split between two modules contained a low background shield at the Sanford Underground Research Facility Lead, South Dakota. Here we present results from data taken during construction, commissioning, and start full operations. We achieve unprecedented energy resolution 2.5 keV FWHM Q_{ββ} very with no...
The International Germanium Experiment (IGEX) has analyzed 117 mol yr of 76Ge data from its isotopically enriched (86% 76Ge) germanium detectors. Applying pulse-shape discrimination to the more recent data, lower bound on half-life for neutrinoless double-beta decay is T1/2(0ν)>1.57×1025yr (90% C.L.). This corresponds an upper in Majorana neutrino mass parameter, ⟨mν⟩, between 0.33 and 1.35 eV, depending choice theoretical nuclear matrix elements used analysis.Received 29 October...
A claim for evidence of dark matter interactions in the DAMA experiment has been recently reinforced. We employ a new type germanium detector to conclusively rule out standard isothermal galactic halo weakly interacting massive particles as explanation annual modulation effect leading claim. Bounds are similarly imposed on suggestion that pseudoscalars might lead effect. describe sensitivity light achievable with our device, particular, next-to-minimal supersymmetric model candidates.
A dramatic reduction in background was achieved the latest Pacific Northwest Laboratory--University of South Carolina germanium detectors. Two 1.05-kg natural-isotopic-abundance detectors were operated for 1.92 kg yr. The residual spectrum, after straightforward corrections, has a significant region resembling theoretical spectrum two-neutrino \ensuremath{\beta}\ensuremath{\beta} decay $^{76}\mathrm{Ge}$. fit to data yields...
We comment on the recent claim for experimental observation of neutrinoless double-beta decay. discuss several limitations in analysis provided that paper and conclude there is no basis presented claim.
Weakly Interacting Massive Particles (WIMPs) are well-established dark matter candidates. WIMP interactions with sensitive detectors expected to display a characteristic annual modulation in rate. We release dataset spanning 3.4 years of operation from low-background germanium detector, designed search for this signature. A previously reported persists, concentrated region the energy spectrum populated by an exponential excess unknown origin. Its phase and period agree phenomenological...
The International Germanium Experiment (IGEX) has six HPGe detectors, isotopically enriched to 86% in ${}^{76}\mathrm{Ge},$ containing approximately 90 active moles of ${}^{76}\mathrm{Ge}.$ Three detectors 2 kg each operate the Canfranc Underground Laboratory (Spain) with pulse-shape analysis electronics. One detector (\ensuremath{\sim}0.7 volume) been operating Baksan Low-Background for several years, and two additional similar will Baksan. A maximum likelihood 74.84 mole years data yields...
Results are reported of an experimental search for the unique, rapidly varying temporal pattern solar axions coherently converting into photons via Primakoff effect in a single crystal germanium detector when incident at Bragg angle with crystalline plane. The analysis 1.94 kg yr data from 1 DEMOS Sierra Grande, Argentina, yields new laboratory bound by axion-photon coupling...
We report results of a 14.1 kg d measurement with 15 superheated droplet detectors total active mass 0.208 kg, comprising the first stage 30 Phase II experiment. In combination neutron-spin sensitive XENON10 experiment, these yield limit |a(p)|<0.32 for M(W)=50 GeV/c² on spin-dependent sector weakly interacting massive particle-nucleus interactions 50% reduction in previously allowed region phase space, formerly defined by XENON, KIMS, and PICASSO. spin-independent sector, 2.3×10⁻⁵ pb at...
CoGeNT has taken data for over 3 years, with 1136 live days of accumulated as April 23, 2013. We report on the results a maximum likelihood analysis to extract any possible dark matter signal present in collected data. The extraction uses 2-dimensional probability density functions (PDFs) characterize anticipated variations interaction rates given observable nuclear recoil energies during differing periods Earth's annual orbit around Sun. Cosmogenic and primordial radioactivity backgrounds...
Background: The MAJORANA DEMONSTRATOR , a modular array of isotopically enriched high-purity germanium (HPGe) detectors, was constructed to demonstrate backgrounds low enough justify building tonne-scale experiment search for the neutrinoless double-beta decay ($\beta\beta(0\nu)$) $^{76}\mathrm{Ge}$. Purpose: This paper presents description instrument, its commissioning, and operations. It covers electroforming, underground infrastructure, enrichment, detector fabrication, low-background...
One IGEX 76Ge double-beta decay detector is currently operating in the Canfranc Underground Laboratory a search for dark matter WIMPs, through Ge nuclear recoil produced by WIMP elastic scattering. A new exclusion plot, σ(m), has been derived WIMP-nucleon spin-independent interactions. To obtain this result, 40 days of data from (energy threshold Ethr∼4 keV), recently collected, have analyzed. These improve limits all other ionization germanium detectors mass region 20 to 200 GeV, where...
Two independent axion searches have been carried out near a well-shielded radioactive $^{65}\mathrm{Zn}$ source (\ensuremath{\sim}15 kCi). One experiment used four NaI(Tl) scintillators to detect coincident photons generated in the decay a\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}. The second shielded 145-${\mathrm{cm}}^{3}$ low-background intrinsic-Ge detector single produced by ``Compton'' interactions with electrons and Primakoff conversion off Ge nuclei Pb shield. We...