A5022624338- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Nuclear physics research studies
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Quantum Chromodynamics and Particle Interactions
- Atomic and Molecular Physics
- Muon and positron interactions and applications
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Subatomic Physics Research
- Quantum, superfluid, helium dynamics
- Advanced NMR Techniques and Applications
- Nuclear Physics and Applications
- Advanced Chemical Physics Studies
- Radioactive Decay and Measurement Techniques
- X-ray Diffraction in Crystallography
- Particle accelerators and beam dynamics
- Nuclear reactor physics and engineering
- Crystallization and Solubility Studies
- Computational Physics and Python Applications
- Particle Detector Development and Performance
- Electron and X-Ray Spectroscopy Techniques
- Nuclear and radioactivity studies
- Gamma-ray bursts and supernovae
- Scientific Research and Discoveries
California Institute of Technology
2015-2024
Comenius University Bratislava
2011-2018
Dubna State University
2018
Czech Technical University in Prague
2018
Los Alamos National Laboratory
2016
University of Washington
1997-2007
Stanford University
2004-2006
University of Cologne
2005
University of North Carolina at Chapel Hill
1996-2004
European Space Research and Technology Centre
2004
KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected standard assumptions about propagation at 99.95% C.L. In a 162 ton.yr exposure ratio observed inverse beta-decay to number without disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for energies >3.4 MeV. context two-flavor neutrino oscillations with CPT invariance, all solutions solar problem except "large mixing angle" region are excluded.
We present results of a study neutrino oscillation based on 766 ton-year exposure KamLAND to reactor anti-neutrinos. observe 258 \nuebar\ candidate events with energies above 3.4 MeV compared 365.2 expected in the absence oscillation. Accounting for 17.8 background events, statistical significance \nuebar disappearance is 99.998%. The observed energy spectrum disagrees spectral shape at 99.6% and prefers distortion from effects. A two-neutrino analysis data gives \DeltaMSq =...
The KamLAND experiment has determined a precise value for the neutrino oscillation parameter Deltam21(2) and stringent constraints on theta12. exposure to nuclear reactor antineutrinos is increased almost fourfold over previous results 2.44 x 10(32) proton yr due longer livetime an enlarged fiducial volume. An undistorted nu[over]e energy spectrum now rejected at >5sigma. Analysis of above inverse beta decay threshold, including geoneutrinos, gives best fit...
The reaction $\bar{\nu}_e + p \to e^+ n$ is very important for low-energy ($E_\nu \lesssim 60$ MeV) antineutrino experiments. In this paper we calculate the positron angular distribution, which at low energies slightly backward. We show that weak magnetism and recoil corrections have a large effect on making it isotropic about 15 MeV forward higher energies. also behavior of cross section distribution can be well-understood analytically $E_\nu by calculating to ${\cal O}(1/M)$, where $M$...
The motivation, present status, and future plans of the search for neutrinoless double beta decay are reviewed. It is argued that, motivated by recent observations neutrino oscillations, there a reasonable hope that corresponding to mass scale suggested <m_{\nu}> about 50 meV, actually exists. challenges achieve sensitivity this scale, overcome them, described.
The nuclear matrix element for 2\ensuremath{\nu} double-beta decay is calculated within the quasiparticle random-phase approximation. It shown that passes through zero as a function of strength ${g}^{\mathrm{pp}}$ particle-particle component spin-isospin polarization force, neglected previously. analysis electron capture/${\ensuremath{\beta}}^{+}$ rates semimagic neutron-deficient nuclei suggests values in very vicinity this zero, which gives rise to long lifetimes. qualitative features...
It has been suggested that an apparent correlation of the flux detected solar neutrinos with activity is due to a neutrino magnetic moment. Here several terrestrial experiments might observe moment are considered, emphasis on those employing reactor neutrinos. The charge radius, and prospects for observing it, also discussed. An appendix collects all relevant scattering cross sections.
We report on a search for neutrinoless double-beta decay of $^{136}$Xe with EXO-200. No signal is observed an exposure 32.5 kg-yr, background ~1.5 x 10^{-3} /(kg yr keV) in the $\pm 1\sigma$ region interest. This sets lower limit half-life $T_{1/2}^{0\nu\beta\beta}$($^{136}$Xe) > 1.6 10$^{25}$ (90% CL), corresponding to effective Majorana masses less than 140-380 meV, depending matrix element calculation.
We show that, within the quasiparticle random phase approximation (QRPA) and renormalized QRPA (RQRPA) based on Bonn-CD nucleon-nucleon interaction, competition between pairing neutron-proton particle-particle particle-hole interactions causes contributions to neutrinoless double-beta decay matrix element nearly vanish at internucleon distances of more than 2 or 3 fermis. As a result, is sensitive short-range/high-momentum physics one naively expects. analyze various ways treating that...
Within the quasiparticle random-phase approximation (QRPA) we achieve partial restoration of isospin symmetry and hence fulfillment requirement that $2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ Fermi matrix element ${M}_{F}^{2\ensuremath{\nu}}$ vanishes, as it should, unlike in previous version method. This is accomplished by separating renormalization parameter ${g}_{pp}$ particle-particle proton-neutron interaction into isovector isoscalar parts. The ${g}_{pp}^{T=1}$ needs to be...
A search for neutrinoless double-beta decay ($0\nu\beta\beta$) in $^{136}$Xe is performed with the full EXO-200 dataset using a deep neural network to discriminate between $0\nu\beta\beta$ and background events. Relative previous analyses, signal detection efficiency has been raised from 80.8% 96.4$\pm$3.0% energy resolution of detector at Q-value improved $\sigma/E=1.23\%$ $1.15\pm0.02\%$ upgraded detector. Accounting new data, median 90% confidence level half-life sensitivity this analysis...
Results from a search for neutrinoless double-beta decay (0νββ) of ^{136}Xe are presented using the first year data taken with upgraded EXO-200 detector. Relative to previous searches by EXO-200, energy resolution detector has been improved σ/E=1.23%, electric field in drift region raised 50%, and system suppress radon volume between cryostat lead shielding implemented. In addition, analysis techniques that improve topological discrimination 0νββ background events have developed....
The ${\overline{\ensuremath{\nu}}}_{e}$ flux and spectrum have been measured at a distance of about 800 m from the reactors Palo Verde Nuclear Generating Station using segmented Gd-loaded liquid scintillator detector. Correlated positron-neutron events reaction ${\overline{\ensuremath{\nu}}}_{e}\stackrel{\ensuremath{\rightarrow}}{p}{e}^{+}n$ were recorded for period 200 d including 55 with one three off refueling. Backgrounds accounted by making use reactor-on reactor-off cycles, also novel...
The analysis and results are presented from the complete data set recorded at Palo Verde between September 1998 July 2000. In experiment, ${\overline{\ensuremath{\nu}}}_{\mathrm{e}}$ interaction rate has been measured a distance of 750 890 m reactors Nuclear Generating Station for total 350 days, including 108 days with one three off refueling. Backgrounds were determined by (a) $\mathrm{swap}$ technique based on difference signal background under reversal positron neutron parts correlated...
This biennial Review summarizes much of Particle Physics. Using data from previous editions, plus 2205 new measurements 667 papers, we list, evaluate, and average measured properties gauge bosons, leptons, quarks, mesons, baryons. We also summarize searches for hypothetical particles such as Higgs heavy neutrinos, supersymmetric particles. All the particle search limits are listed in Summary Tables. give numerous tables, figures, formulae, reviews topics Standard Model, detectors,...
Using the quasiparticle random phase approximation, we calculate nuclear matrix elements governing two-neutrino and neutrinoless double-beta decay. We show that a consistent treatment, including both particle-hole particle-particle interactions, helps to resolve longstanding discrepancy between experimental calculated decay rates. The force, which allows us bring EC/${\ensuremath{\beta}}^{+}$ rates in semimagic nuclei into closer agreement with experiment, is large part responsible for...
We report on the initial results from a measurement of antineutrino flux and spectrum at distance about 800 m three reactors Palo Verde Nuclear Generating Station using segmented gadolinium-loaded scintillation detector. find that agrees with predicted in absence oscillations excluding 90% C.L. nu;(e)-nu;(x) Deltam(2)>1.12x10(-3) eV(2) for maximal mixing sin (2)2straight theta>0.21 large Deltam(2). Our support conclusion atmospheric neutrino observed by Super-Kamiokande do not involve nu(e).