25,015 research outputs found
T2K oscillation results
No full textThe T2K (Tokai-to-Kamioka) experiment is a second generation long baseline neutrino oscillation experiment that probes physics beyond the Standard Model. An off-axis neutrino beam with a peak energy of ∼0.6∼0.6 GeV is produced at the J-PARC accelerator facility, with the flavour content dominated by either muon neutrinos or muon anti-neutrinos, depending on the choice of the polarity of the magnetic focusing horns. The neutrino beam is detected first in the near detector ND280, where the flavour composition of the incoming neutrino flux is not expected to be affected by oscillation, and then travels 295 km to the far detector Super-Kamiokande, where oscillation significantly affects the flavour composition. We report the results of a joint analysis of neutrino and antineutrino oscillations at T2K with the νμνμ (ν ̄μν ̄μ) disappearance and νμνμ (ν ̄μν ̄μ) →→ νeνe (ν ̄eν ̄e) appearance channels, obtained by collecting a total statistic of 7.57×10207.57×1020 protons-on-target in νν-mode and 7.53×10207.53×1020 in ν ̄ν ̄-mode. The results in the disappearance channel shows that our data continue to prefer maximal θ23θ23 mixing (sin2θ23=0.532+0.046−0.068sin2θ23=0.532−0.068+0.046, in case of normal mass hierarchy) and no violation of the CPT theorem, while in the appearance channel, we observed a large νeνe appearance and a low ν ̄eν ̄e appearance with respect to the expectations. These results favour a δCP∼−π/2δCP∼−π/2, with a 90% confidence interval of [−3.13,−0.39][−3.13,−0.39] in normal mass hierarchy and [−2.09,−0.74][−2.09,−0.74] in inverted mass hierarchy. We comment briefly on the future prospects for T2K, including a proposal for extended running to accumulate 20×102120×1021 protons-on-target, nearly three times the currently approved amount by 2026, to gain substantial sensitivity to CP violating effects in νμνμ (ν ̄μν ̄μ) →→ νeνe (ν ̄eν ̄e) oscillations if parameters are favorable
The T2K experiment
No full textThe T2K experiment is a long baseline neutrino oscillation experiment. Its main goal is to measure the last unknown lepton sector mixing angle θ13 by observing νe appearance in a νμ beam. It also aims to make a precision measurement of the known oscillation parameters, and sin22θ23, via νμ disappearance studies. Other goals of the experiment include various neutrino cross-section measurements and sterile neutrino searches. The experiment uses an intense proton beam generated by the J-PARC accelerator in Tokai, Japan, and is composed of a neutrino beamline, a near detector complex (ND280), and a far detector (Super-Kamiokande) located 295 km away from J-PARC. This paper provides a comprehensive review of the instrumentation aspect of the T2K experiment and a summary of the vital information for each subsystem
Measurement of the nu(mu) charged current quasielastic cross section on carbon with the T2K on-axis neutrino beam
No full text17 pages, 21 figureshttp://journals.aps.org/prd/abstract/10.1103/PhysRevD.91.112002© 2015 American Physical Society17 pages, 21 figure
Measurement of neutrino oscillation parameters from muon neutrino disappearance with an off-axis beam
No full textThe T2K Collaboration reports a precision measurement of muon neutrino disappearance with an off-axis neutrino beam with a peak energy of 0.6 GeV. Near detector measurements are used to constrain the neutrino flux and cross section parameters. The Super-Kamiokande far detector, which is 295 km downstream of the neutrino production target, collected data corresponding to 3.01×1020 protons on target. In the absence of neutrino oscillations, 205±17 (syst) events are expected to be detected while only 58 muon neutrino event candidates are observed. A fit to the neutrino rate and energy spectrum, assuming three neutrino flavors and normal mass hierarchy yields a best-fit mixing angle sin2(θ23)=0.514±0.082 and mass splitting |Δm322|=2.44-0.15+0.17×10-3 eV2/c4. Our result corresponds to the maximal oscillation disappearance probability
Recent Results from the T2K ND280 Detector
No full textThe T2K near detector complex, ND280, is located at the J-PARC accelerator facility in Tokai, Japan, 280m downstream from the target. These proceedings will summarise recent physics results from ND280
First Measurement of the Electron-Neutrino Charged-Current Pion Production Cross Section on Carbon with the T2K Near Detector
No full textThe T2K Collaboration presents the first measurement of electron neutrino-induced charged-current pion production on a predominantly carbon target in a restricted kinematical phase space. This is performed using data from the 2.5° off-axis near detector, ND280. The differential cross sections with respect to the outgoing electron and pion kinematics, in addition to the total flux-integrated cross section, are obtained. Comparisons between the measured and predicted cross-section results using the neut, genie, and nuwro Monte Carlo event generators are presented. The measured total flux-integrated cross section is [2.52±0.52(stat)±0.30(syst)]×10^{-39} cm^{2} nucleon^{-1}, which is lower than the event generator predictions
Scintillator ageing of the T2K near detectors from 2010 to 2021
No full textThe T2K experiment widely uses plastic scintillator as a target for neutrino interactions and an active medium for the measurement of charged particles produced in neutrino interactions at its near detector complex. Over 10 years of operation the measured light yield recorded by the scintillator based subsystems has been observed to degrade by 0.9-2.2% per year. Extrapolation of the degradation rate through to 2040 indicates the recorded light yield should remain above the lower threshold used by the current reconstruction algorithms for all subsystems. This will allow the near detectors to continue contributing to important physics measurements during the T2K-II and Hyper-Kamiokande eras. Additionally, work to disentangle the degradation of the plastic scintillator and wavelength shifting fibres shows that the reduction in light yield can be attributed to the ageing of the plastic scintillator. The long component of the attenuation length of the wavelength shifting fibres was observed to degrade by 1.3-5.4% per year, while the short component of the attenuation length did not show any conclusive degradation
T2K Oscillation Analysis Results: Latest Analysis Improvements at the Far Detector
No full textT2K (Tokai to Kamioka) is a long baseline neutrino experiment that exploits a neutrino and antineutrino beam produced at the Japan Particle Accelerator Research Centre (J-PARC) to provide world-leading measurements of the parameters governing neutrino oscillation. Neutrino oscillations are analyzed by tuning the neutrino rates and spectra at a near detector complex, located at J-PARC, and extrapolating them to the water Cherenkov far detector, Super-Kamiokande, located 295 km away, where oscillations are observed. The latest T2K results include multiple analysis improvements, in particular, a new sample is added for the far detector analysis, requiring the presence of a pion in muon-neutrino interactions. This is the first time that a pion sample has been included in the study of neutrino disappearance at T2K and the first time a sample with more than one Cherenkov ring has been included in the T2K oscillation analysis, opening a road for further samples with charged and neutral pion tagging. The inclusion of such a sample enables proper control of the oscillated spectrum in a larger neutrino energy range and on subleading neutrino interaction processes. Finally, T2K is engaged with the Super-Kamiokande collaboration to combine T2K neutrino beam data and Super-Kamiokande atmospheric data to perform a joint fit of the oscillation parameters. Such a combination allows the degeneracies between the measurement of the CP-violating phase δCP and the measurement of the ordering of the neutrino mass eigenstates to be lifted. A precise evaluation of the enhanced sensitivity of this joint fit will be presented
Latest activities and results from T2K
No full textThe T2K neutrino oscillation experiment has gone through a period of renewal over the last couple of years, with several upgrades designed to improve sensitivity to leptonic CP violation. The change that most affects future analyses is the ND280 upgrade, which will constrain interaction models in new ways. At the same time the analysis continues to be developed, both by combining with the Super-Kamiokande atmospheric measurements and with refinements to the T2K-only analysis. This proceedings describes the highlights of these analyses, and the status of the various T2K upgrades.Contribution to the 2024 Electroweak session of the 58th Rencontres de Morion
First measurement of muon neutrino charged-current interactions on hydrocarbon without pions in the final state using multiple detectors with correlated energy spectra at T2K
No full textThis paper reports the first measurement of muon neutrino charged-current interactions without pions in the final state using multiple detectors with correlated energy spectra at T2K. The data was collected on hydrocarbon targets using the off-axis T2K near detector (ND280) and the on-axis T2K near detector (INGRID) with neutrino energy spectra peaked at 0.6 GeV and 1.1 GeV, respectively. The correlated neutrino flux presents an opportunity to reduce the impact of the flux uncertainty and to study the energy dependence of neutrino interactions. The extracted double-differential cross sections are compared to several Monte Carlo neutrino-nucleus interaction event generators showing the agreement between both detectors individually and with the correlated result
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