A5083130000- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Astrophysics and Cosmic Phenomena
- Dark Matter and Cosmic Phenomena
- Quantum Chromodynamics and Particle Interactions
- Radiation Detection and Scintillator Technologies
- High-Energy Particle Collisions Research
- Particle Detector Development and Performance
- Atomic and Subatomic Physics Research
- Muon and positron interactions and applications
- Particle accelerators and beam dynamics
- Nuclear Physics and Applications
- Gamma-ray bursts and supernovae
- Quantum, superfluid, helium dynamics
- Particle Accelerators and Free-Electron Lasers
- Nuclear reactor physics and engineering
- Cold Atom Physics and Bose-Einstein Condensates
- Black Holes and Theoretical Physics
- Pulsars and Gravitational Waves Research
- Radiation Therapy and Dosimetry
- Superconducting Materials and Applications
- Noncommutative and Quantum Gravity Theories
- Medical Imaging Techniques and Applications
- Cosmology and Gravitation Theories
- Computational Physics and Python Applications
TRIUMF
2015-2024
Universidad Europea de Madrid
2024
University of Victoria
2024
The University of Tokyo
2021-2024
University of Toyama
2024
Chonnam National University
2013-2024
University of Bern
2023
Albert Einstein College of Medicine
2023
Eötvös Loránd University
2023
Boston University
2013-2023
We present measurements of nu_mu disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One hundred and twelve beam-originated events are observed fiducial volume Super-Kamiokande with an expectation 158.1^{+9.2}_{-8.6} without oscillation. A distortion energy spectrum is also seen 58 single-ring muon-like reconstructed energies. The probability that observations explained by for no 0.0015% (4.3sigma). In a two flavor scenario, allowed Delta m^2 region at...
We present results for ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ oscillation in the KEK to Kamioka (K2K) long-baseline neutrino experiment. K2K uses an accelerator-produced beam with a mean energy of 1.3 GeV directed at Super-Kamiokande detector. observed energy-dependent disappearance ${\ensuremath{\nu}}_{\ensuremath{\mu}}$, which we presume have oscillated ${\ensuremath{\nu}}_{\ensuremath{\tau}}$. The probability that would observe these if there is no 0.0050% ($4.0\ensuremath{\sigma}$).
Experiment E949 at Brookhaven National Laboratory has observed three new events consistent with the decay K+→π+ν¯ν in pion momentum region 140<Pπ<199 MeV/c an exposure of 1.71×1012 stopped kaons estimated total background 0.93±0.17(stat)+0.32−0.24(syst) events. This brings number to seven. Combining this observation previous results, assuming spectrum predicted by standard model, results a branching ratio B(K+→π+ν¯ν)=(1.73+1.15−1.05)×10−10. An interpretation for alternative models...
Three events for the decay K+→π+ν¯ν have been observed in pion momentum region below K+→π+π0 peak, 140<Pπ<199 MeV/c, with an estimated background of 0.93±0.17(stat.)+0.32−0.24(syst.) events. Combining this observation previously reported results yields a branching ratio B(K+→π+ν¯ν)=(1.73+1.15−1.05)×10−10 consistent standard model prediction.Received 18 August 2008DOI:https://doi.org/10.1103/PhysRevLett.101.191802©2008 American Physical Society
The weak nucleon axial-vector form factor for quasi-elastic interactions is determined using neutrino interaction data from the K2K Scintillating Fiber detector in beam at KEK. More than 12,000 events are analyzed, of which half charged-current nu-mu n to mu- p occurring primarily oxygen nuclei. We use a relativistic Fermi gas model and assume approximately dipole with one parameter, axial vector mass M_A, fit shape distribution square momentum transfer nucleus. Our best result M_A = 1.20...
Evidence of a heavy neutrino, $\nu_H$, in the $K^+\to\mu^+\nu_H$ decays was sought using E949 experimental data with an exposure $1.70\times 10^{12}$ stopped kaons. With major background from radiative $K^+\to\mu^+\nu_\mu\gamma$ decay understood and suppressed, upper limits (90% C.L.) on neutrino mixing matrix element between muon $|U_{\mu H}|^2$, were set at level $10^{-7}$ to $10^{-9}$ for mass region 175 300 MeV/$c^2$.
An experiment to search for the production of neutral penetrating particles decaying into electron-positron pairs was performed with a 2.5-GeV electron beam. A total 0.027 C injected tungsten target. No such particle is found. Constraints on coupling constants ${\ensuremath{\alpha}}_{e}$ and ${\ensuremath{\alpha}}_{\ensuremath{\gamma}}$ are given.
An additional event near the upper kinematic limit for K+-->pi(+)nunu; has been observed by experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, branching ratio is B(K+-->pi(+)nunu;)=(1.47(+1.30)(-0.89))x10(-10) based on three events in pion momentum region 211<P<229 MeV/c. At measured central value of ratio, had a signal-to-background 0.9.
Additional evidence for the rare kaon decay K+-->pi+nu(nu) has been found in a new data set with comparable sensitivity to previously reported result. One event was observed pion momentum region examined, 211<P<229 MeV/c, bringing total combined two. Including all taken, backgrounds were estimated contribute 0.15+/-0.05 events. The branching ratio is B(K+-->pi+nu(nu)) = 1.57(+1.75)(-0.82)x10(-10).
An event consistent with the signature expected for rare kaon decay ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ has been observed. In pion momentum region examined, $211<P<230\mathrm{MeV}/c$, backgrounds are estimated to contribute $0.08\ifmmode\pm\else\textpm\fi{}0.03$ events. If is due ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}$, branching ratio...
The JHF-Kamioka neutrino project is a second generation long base line oscillation experiment that probes physics beyond the Standard Model by high precision measurements of masses and mixing. A intensity narrow band beam produced secondary pions created proton synchrotron at JHF (JAERI). energy tuned to maximum ~1 GeV for baseline length 295 km towards world largest water Cerenkov detector, Super-Kamiokande. Its excellent resolution particle identification enable reconstruction initial...
We report the result from a search for charged-current coherent pion production induced by muon neutrinos with mean energy of 1.3 GeV. The data are collected fully active scintillator detector in K2K long-baseline neutrino oscillation experiment. No evidence is observed, and an upper limit set on cross section ratio to total interaction at 90% confidence level. This first experimental charged region few
Experiment E949 at Brookhaven National Laboratory studied the rare decay \$K^+\to\pi^+\nu\bar{\nu}$ and other processes with an exposure of $1.77\times 10^{12}$ $K^+$'s. The data were analyzed using a blind analysis technique yielding one candidate event estimated background $0.30\pm0.03$ events. Combining this result observation two events by predecessor experiment E787 gave branching ratio ${\calB}(K^+\to\pi^+\nu\bar{\nu})=(1.47^{+1.30}_{-0.89})\times 10^{-10}$, consistent Standard Model...
We report the results of a search for decay ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ in kinematic region with ${\ensuremath{\pi}}^{+}$ momentum $140<P<195\mathrm{MeV}/c$ using data collected by E787 experiment at BNL. No events were observed. When combined our previous this region, one candidate event an expected background $1.22\ifmmode\pm\else\textpm\fi{}0.24$ 90% C.L. upper limit...
A search for additional evidence the rare kaon decay K+-->pi(+)nunu; has been made with a new data set comparable in sensitivity to previous exposure that produced single event. No events were found pion momentum region examined, 211<P<229 MeV/c. Including reanalysis of original set, backgrounds estimated contribute 0.08+/-0.02 events. Based on one observed event, branching ratio is B(K+-->pi(+)nunu;) = 1.5(+3.4)(-1.2)x10(-10).
We installed a source for ultracold neutrons at new, dedicated spallation target TRIUMF. The was originally developed in Japan and uses superfluid-helium converter cooled to 0.9$\,$K. During an extensive test campaign November 2017, we extracted up 325000 after one-minute irradiation of the target, over three times more than previously achieved with this source. corresponding ultracold-neutron density whole production guide volume is 5.3$\,$cm$^{-3}$. storage lifetime initially 37$\,$s...
We performed an improved search for ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{e}$ oscillation with the KEK to Kamioka (K2K) long-baseline neutrino experiment, using full data sample of $9.2\ifmmode\times\else\texttimes\fi{}{10}^{19}$ protons on target. No evidence a ${\ensuremath{\nu}}_{e}$ appearance signal was found, and we set bounds parameters. At $\ensuremath{\Delta}{m}^{2}=2.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{...
Single charged pion production in charged-current muon neutrino interactions with carbon is studied using data collected the K2K long-baseline experiment. The mean energy of incident neutrinos 1.3 GeV. used this analysis are mainly from a fully active scintillator detector, SciBar. cross section for single π+ resonance region (W<2 GeV/c2) relative to quasielastic found be 0.734−0.153+0.140. energy-dependent ratio also measured. results consistent previous experiment and prediction our...
As long-baseline neutrino experiments enter the precision era, difficulties associated with understanding interaction cross sections on atomic nuclei are expected to limit experimental sensitivities oscillation parameters. In particular, ability relate observables energy in previous has relied solely theoretical models of neutrino-nucleus interactions, which currently suffer from very large uncertainties. By observing charged current $ν_μ$ interactions over a continuous range off-axis angles...
The first observation of the decay K^+ --> pi^+ gamma is reported. A total 31 events was observed with an estimated background 5.1 +- 3.3 in pi+ momentum range from 100 MeV/c to 180 MeV/c. corresponding partial branching ratio, B(K+ -> gamma, < P_pi^+ MeV/c), (6.0 1.5 (stat) 0.7 (sys)) x 10^{-7}. No region greater than 215 spectrum compared predictions chiral perturbation theory.