D. M. Markoff
A5035029905- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Astrophysics and Cosmic Phenomena
- Nuclear Physics and Applications
- Quantum, superfluid, helium dynamics
- Nuclear physics research studies
- Radiation Detection and Scintillator Technologies
- Quantum Chromodynamics and Particle Interactions
- Nuclear reactor physics and engineering
- Particle Detector Development and Performance
- Particle accelerators and beam dynamics
- Advanced NMR Techniques and Applications
- Atomic and Molecular Physics
- NMR spectroscopy and applications
- Muon and positron interactions and applications
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- High-Energy Particle Collisions Research
- Scientific Research and Discoveries
- Advanced Chemical Physics Studies
- Gamma-ray bursts and supernovae
- Computational Physics and Python Applications
- Solar and Space Plasma Dynamics
Triangle Universities Nuclear Laboratory
2015-2024
North Carolina Central University
2015-2024
University of North Carolina at Chapel Hill
2009-2023
Duke University
2012-2023
Virginia Tech
2023
Triangle
2015
Tohoku University
2002-2015
North Carolina State University
2001-2014
University of California, Berkeley
2014
Lawrence Berkeley National Laboratory
2014
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 =...
We present an improved search for neutrinoless double-beta (0νββ) decay of ^{136}Xe in the KamLAND-Zen experiment. Owing to purification xenon-loaded liquid scintillator, we achieved a significant reduction ^{110m}Ag contaminant identified previous searches. Combining results from first and second phase, obtain lower limit 0νββ half-life T_{1/2}^{0ν}>1.07×10^{26} yr at 90% C.L., almost sixfold improvement over limits. Using commonly adopted nuclear matrix element calculations, corresponding...
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 coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross section is by far the largest all low-energy neutrino couplings. This mode interaction offers new opportunities to study properties and leads a miniaturization detector size, with potential technological applications. We observed this process at 6.7σ confidence level, using low-background, 14.6-kilogram CsI[Na] scintillator exposed emissions from Spallation Neutron...
We present results from the first phase of KamLAND-Zen double-beta decay experiment, corresponding to an exposure 89.5 kg yr $^{136}\mathrm{Xe}$. obtain a lower limit for neutrinoless half-life ${T}_{1/2}^{0\ensuremath{\nu}}>1.9\ifmmode\times\else\texttimes\fi{}{10}^{25}\text{ }\text{ }\mathrm{yr}$ at 90% C.L. The combined and EXO-200 give ${T}_{1/2}^{0\ensuremath{\nu}}>3.4\ifmmode\times\else\texttimes\fi{}{10}^{25}\text{ C.L., which corresponds Majorana neutrino mass...
The recent long-term shutdown of Japanese nuclear reactors has resulted in a significantly reduced reactor ν¯e flux at KamLAND. This running condition provides unique opportunity to confirm and constrain backgrounds for the oscillation analysis. data set also improved sensitivity other signals, particular ν¯e’s produced β-decays from U238 Th232 within Earth’s interior, whose energy spectrum overlaps with that ν¯e’s. Including constraints on θ13 accelerator short-baseline neutrino...
We present new constraints on the neutrino oscillation parameters $/textyen Delta m^{2}_{21}$, theta_{12}$, and theta_{13}$ from a three-flavor analysis of solar KamLAND data. The data set includes acquired following radiopurity upgrade amounts to total exposure $3.49 \textyen times 10^{32}$ target-proton-year. Under assumption {\textyen it CPT} invariance, two-flavor (/textyen mbox{$\textyen theta_{13} = 0$}) yields best-fit values $\textyen tan^{2} theta_{12} 0.444^{+0.036}_{-0.030}$...
We report the first measurement of coherent elastic neutrino-nucleus scattering (CEvNS) on argon using a liquid detector at Oak Ridge National Laboratory Spallation Neutron Source. Two independent analyses prefer CEvNS over background-only null hypothesis with greater than $3\ensuremath{\sigma}$ significance. The measured cross section, averaged incident neutrino flux, is $(2.2\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}39}\text{ }\text{...
The KamLAND-Zen experiment has provided stringent constraints on the neutrinoless double-beta (0νββ) decay half-life in ^{136}Xe using a xenon-loaded liquid scintillator. We report an improved search upgraded detector with almost double amount of xenon and ultralow radioactivity container, corresponding to exposure 970 kg yr ^{136}Xe. These new data provide valuable insight into backgrounds, especially from cosmic muon spallation xenon, have required use novel background rejection...
We measured the cross section of coherent elastic neutrino-nucleus scattering (CEvNS) using a CsI[Na] scintillating crystal in high flux neutrinos produced at Spallation Neutron Source Oak Ridge National Laboratory. New data collected before detector decommissioning have more than doubled dataset since first observation CEvNS, achieved with this detector. Systematic uncertainties also been reduced an updated quenching model, allowing for improved precision. With these analysis improvements,...
We present results from the KamLAND-Zen double-beta decay experiment based on an exposure of 77.6 days with 129 kg $^{136}$Xe. The measured two-neutrino half-life $^{136}$Xe is $T_{1/2}^{2\nu} = 2.38 \pm 0.02(stat) 0.14(syst) \times 10^{21}$ yr, consistent a recent measurement by EXO-200. also obtain lower limit for neutrinoless half-life, $T_{1/2}^{0\nu} > 5.7 10^{24}$ yr at 90% confidence level (C.L.), which corresponds to almost five-fold improvement over previous limits.
Radioactive isotopes produced through cosmic muon spallation are a background for rare-event detection in $\nu$ detectors, double-$\beta$-decay experiments, and dark-matter searches. Understanding the nature of cosmogenic backgrounds is particularly important future experiments aiming to determine pep CNO solar neutrino fluxes, which dominated by production $^{11}$C. Data from Kamioka liquid-scintillator antineutrino detector (KamLAND) provides valuable information better understanding these...
We present the results of a search for extraterrestrial electron antineutrinos ('s) in energy range using KamLAND detector. In an exposure 4.53 kton-year, we identify 25 candidate events. All events can be attributed to background, most importantly neutral current atmospheric neutrino interactions, setting upper limit on probability 8B solar νe's converting into 's at 5.3 × 10−5 (90% CL), if assume undistorted shape. This corresponds flux 93 cm−2 s−1 or event rate 1.6 (kton − year)−1 above...
The COHERENT Collaboration searched for scalar dark matter particles produced at the Spallation Neutron Source with masses between 1 and 220 MeV/c^{2} using a CsI[Na] scintillation detector sensitive to nuclear recoils above 9 keV_{nr}. No evidence is found we thus place limits on allowed parameter space. With this low-threshold detector, are coherent elastic scattering nuclei. cross section process orders of magnitude higher than other processes historically used accelerator-based...
Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used search for nu;(e)'s in the energy range 8.3<E(nu;(e))<14.8 MeV. No candidates were found an expected background 1.1+/-0.4 events. This result can be obtain limit on nu;(e) fluxes any origin. Assuming that all flux its origin Sun and characteristic 8B solar nu(e) spectrum, we upper 3.7 x 10(2) cm(-2) s(-1) (90% C.L.) flux. We interpret this limit, 2.8 10(-4) standard model flux, framework spin-flavor precession...
We present limits on Majoron-emitting neutrinoless double-beta decay modes based an exposure of 112.3 days with 125 kg Xe-136. In particular, a lower limit the ordinary (spectral index n = 1) half-life Xe-136 is obtained as T_{1/2}^{0\nu\chi^{0}} > 2.6 x 10^{24} yr at 90% C.L., factor five more stringent than previous limits. The corresponding upper effective Majoron-neutrino coupling, using range available nuclear matrix calculations, <g_{ee}> < (0.8 - 1.6) 10^{-5}. This excludes previously...
We report a measurement of the neutrino-electron elastic scattering rate from ${}^{8}$B solar neutrinos based on 123 kton-day exposure KamLAND. The background-subtracted electron recoil rate, above 5.5-MeV analysis threshold is 1.49 $\ifmmode\pm\else\textpm\fi{}$ 0.14(stat) 0.17(syst) events per kton-day. Interpreted as due to pure flavor flux with neutrino spectrum, this corresponds spectrum integrated 2.77 0.26(stat) 0.32(syst) $\ifmmode\times\else\texttimes\fi{}$10${}^{6}$...
We report a measurement of the neutrino-electron elastic scattering rate 862 keV 7Be solar neutrinos based on 165.4 kton-day exposure KamLAND. The observed is 582 +/- 90 (kton-day)^-1, which corresponds to neutrino flux (3.26 0.50) x 10^9 cm^-2s^-1, assuming pure electron flavor flux. Comparing this with standard model prediction and further three mixing, nu_e survival probability 0.66 0.14 determined from KamLAND data. Utilizing global oscillation analysis, we obtain total (5.82 0.98)...
We present a precision analysis of the $^{136}$Xe two-neutrino $\beta\beta$ electron spectrum above 0.8 MeV, based on high-statistics data obtained with KamLAND-Zen experiment. An improved formalism for rate allows us to measure ratio leading and subleading $2\nu\beta\beta$ nuclear matrix elements (NMEs), $\xi^{2\nu}_{31} = -0.26^{+0.31}_{-0.25}$. Theoretical predictions from shell model majority quasiparticle random-phase approximation (QRPA) calculations are consistent experimental limit....