A5056983440- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Radiation Detection and Scintillator Technologies
- Neutrino Physics Research
- Quantum, superfluid, helium dynamics
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Astrophysics and Cosmic Phenomena
- Nuclear reactor physics and engineering
- Radioactive Decay and Measurement Techniques
- Nuclear physics research studies
- Atmospheric Ozone and Climate
- Particle Detector Development and Performance
- Particle accelerators and beam dynamics
- Radiation Therapy and Dosimetry
- Geophysical Methods and Applications
- Cold Fusion and Nuclear Reactions
- Advanced NMR Techniques and Applications
- Quantum Chromodynamics and Particle Interactions
- Advanced Semiconductor Detectors and Materials
- Atomic and Molecular Physics
- DNA Repair Mechanisms
- Muon and positron interactions and applications
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
National Institute of Standards and Technology
2014-2024
Institute for Nuclear Research
1996-2022
Tulane University
2005-2021
Physical Measurement Laboratory
2016
National Institute of Standards
1999-2015
University of Michigan–Ann Arbor
1990-2010
University of Sussex
2005
Kurchatov Institute
2005
Rutherford Appleton Laboratory
2005
Indiana University Bloomington
2005
The Russian-American experiment SAGE began to measure the solar neutrino capture rate with a target of gallium metal in December 1989. Measurements have continued only few brief interruptions since that time. In this article we present experimental improvements its last published data summary 2001. Assuming production was constant during period collection, combined analysis 168 extractions through 2007 gives neutrinos energy more than 233 keV $65.{4}_{\ensuremath{-}3.0}^{+3.1}$ (stat)...
The solar neutrino capture rate measured by the Russian-American Gallium Experiment (SAGE) on metallic gallium during period January 1990 through December 1997 is ${67.2}_{\ensuremath{-}7.0\ensuremath{-}3.0}^{+7.2+3.5}$ SNU, where uncertainties are statistical and systematic, respectively. This represents only about half of predicted standard model 129 SNU. All experimental procedures, including extraction germanium from gallium, counting ${}^{71}\mathrm{Ge},$ data analysis, discussed in detail.
The most precise determination of the neutron lifetime using beam method was completed in 2005 and reported a result $\tau_n = (886.3 \pm 1.2 [\textrm{stat}] 3.2 [\textrm{syst}])$ s. dominant uncertainties were attributed to absolute fluence (2.7 s). measured with monitor that counted neutron-induced charged particles from absorption thin, well-characterized 6Li deposit. detection efficiency calculated areal density deposit, detector solid angle, evaluated nuclear data file, ENDF/B-VI...
The Baksan Experiment on Sterile Transitions (BEST) was designed to investigate the deficit of electron neutrinos ν_{e} observed in previous gallium-based radiochemical measurements with high-intensity neutrino sources, commonly referred as "gallium anomaly," which could be interpreted evidence for oscillations between and sterile (ν_{s}) states. A 3.414-MCi ^{51}Cr source placed at center two nested Ga volumes were made production ^{71}Ge through charged current reaction,...
The solar neutrino capture rate measured by SAGE is well below that predicted models. To check the overall experimental efficiency, we exposed 13 tonnes of Ga metal to a reactor-produced 517 kCi source ${}^{51}$Cr. ratio production from activity $0.95\ifmmode\pm\else\textpm\fi{}0.11(\mathrm{stat})+0.05/\ensuremath{-}0.08(\mathrm{syst})$. This agreement verifies efficiency correctly, establishes there are no unknown systematic errors at 10% level, and provides considerable evidence for...
The neutrino capture rate measured by the Russian-American Gallium Experiment is well below that predicted solar models. To check response of this experiment to low-energy neutrinos, a 517 kCi source ${}^{51}$Cr was produced irradiating 512.7 g 92.4%-enriched ${}^{50}$Cr in high-flux fast neutron reactor. This source, which mainly emits monoenergetic 747-keV placed at center 13.1 ton target liquid gallium and cross section for production ${}^{71}$Ge inverse beta decay $\mathrm{reaction}{...
An intense source of $^{37}\mathrm{Ar}$ was produced by the $(n,\ensuremath{\alpha})$ reaction on $^{40}\mathrm{Ca}$ irradiating 330 kg calcium oxide in fast neutron breeder reactor at Zarechny, Russia. The released from solid target dissolution acid, collected this solution, purified, sealed into a small source, and brought to Baksan Neutrino Observatory where it used irradiate 13 tonnes gallium metal Russian-American solar neutrino experiment SAGE. Ten exposures whose initial strength...
First results from the BEST Collaboration searching for short-baseline neutrino oscillations to sterile neutrinos with a high-intensity ${}^{51}$Cr monoenergetic source reaffirm that so-called gallium anomaly, deficit in electron neutrinos, persists. $4\ensuremath{\sigma}$ deficits were observed ${}^{71}$Ge production rates at two different distance scales, which could be interpreted as between an and hypothetical neutrino. The are consistent mass squared difference above about 0.5...
The Russian-American solar neutrino experiment has measured the capture rate of neutrinos on metallic gallium in a radiochemical at Baksan Neutrino Observatory. Eight years measurement give result ${67.2}_{\ensuremath{-}7.0\ensuremath{-}3.0}^{+7.2+3.5}$ units, where uncertainties are statistical and systematic, respectively. restrictions these results impose vacuum oscillation parameters given.
A measurement of the neutron lifetime ${\ensuremath{\tau}}_{n}$ performed by absolute counting in-beam neutrons and their decay protons has been completed. Protons confined in a quasi-Penning trap were accelerated onto silicon detector held at high potential counted with nearly unit efficiency. The device an efficiency inversely proportional to velocity, which cancels dwell time beam trap. result is...
Experiments using slow neutrons address a growing range of scientific issues spanning nuclear physics, particle astrophysics, and cosmology. The field fundamental physics has experienced significant increase in activity over the last two decades. This review summarizes some recent developments outlines prospects for future research.
Studies of low-energy processes, such as neutron beta-decay, contribute important information regarding different aspects physics including nuclear and particle cosmology. The from these systems is often complementary to that obtained high-energy sources. Neutron decay the most basic charged-current weak interaction in baryons. Precise measurement parameters characterizing it can be used study standard model well set limits on possible extensions it. This paper gives an overview some...
We report the first result for electron-antineutrino angular correlation ($a$ coefficient) in free neutron $\ensuremath{\beta}$ decay from aCORN experiment. uses a novel method which $a$ coefficient is proportional to an asymmetry proton time of flight events where electron and recoil are detected delayed coincidence. Data presented 15 month run at NIST Center Neutron Research. obtained...
The aCORN experiment measures the neutron-decay electron-antineutrino correlation ($a$ coefficient) using a novel method based on an asymmetry in proton time-of-flight for events where beta electron and recoil are detected delayed coincidence. We report data analysis result from second run at NIST Center Neutron Research, high-flux cold neutron beam new NG-C guide end position:...
We report the results of an improved determination triple correlation $D P \cdot(p_{e}\times p_{\nu})$ that can be used to limit possible time-reversal invariance in beta decay polarized neutrons and constrain extensions Standard Model. Our result is $D=(-0.96\pm 1.89 (stat)\pm 1.01 (sys))\times 10^{-4}$. The corresponding phase between g_A g_V $\phi_{AV} = 180.013^\circ\pm0.028^\circ$ (68 % confidence level). This represents most sensitive measurement D decay.
The standard model predicts that, in addition to a proton, an electron, and antineutrino, continuous spectrum of photons is emitted the β decay free neutron. We report on RDK II experiment which measured photon using two different detector arrays. An annular array bismuth germanium oxide scintillators detected from 14 782 keV. spectral shape was consistent with theory, we determined branching ratio 0.00335±0.00005[stat]±0.00015[syst]. A second large area avalanche photodiodes directly 0.4...
We report an upper bound on parity-violating neutron spin rotation in $^{4}\mathrm{He}$. This experiment is the most sensitive search for neutron-weak optical activity yet performed and represents a significant advance precision comparison to past measurements heavy nuclei. The was at NG-6 slow-neutron beamline National Institute of Standards Technology (NIST) Center Neutron Research. Our result angle per unit length $^{4}\mathrm{He}$...
Background: Time-reversal-invariance violation, or equivalently CP may explain the observed cosmological baryon asymmetry as well signal physics beyond Standard Model. In decay of polarized neutrons, triple correlation D<J_{n}>\cdot(p_{e}\timesp_{\nu}) is a parity-even, time-reversal- odd observable that uniquely sensitive to relative phase axial-vector amplitude with respect vector amplitude. The also possible contributions from scalar and tensor amplitudes. Final-state effects contribute D...