Antineutrino Science in KamLAND

Abstract

The primary goal of KamLAND is a search for the oscillation of ${\bar{\nu }}_{\mathrm{e}}$${}^{\prime }$s emitted from distant power reactors. The long baseline, typically 180 km, enables KamLAND to address the oscillation solution of the solar neutrino problem with ${\bar{\nu }}_{\mathrm{e}}$ under laboratory conditions. KamLAND found fewer reactor ${\bar{\nu }}_{\mathrm{e}}$ events than expected from standard assumptions about ${\bar{\nu }}_{\mathrm{e}}$${}^{\prime }$s propagation at more than 9 σ confidence level (C.L.). The observed energy spectrum disagrees with the expected spectral shape at more than 5 σ C.L., and prefers the distortion from neutrino oscillation effects. A three-flavor oscillation analysis of the data from KamLAND and KamLAND + solar neutrino experiments with CPT invariance, yields $\Delta {\mathrm{m}}_{21}^2=[{7.54}_{0.18}^{+0.19},{7.53}_{0.18}^{+0.19}]$ $\times {10}^{-5}{\mathrm{eV}}^2$, ${\tan }^2{\theta }_{12}=[{0.481}_{-0.080}^{+0.092},{0.437}_{-0.026}^{+0.029}]$, and ${\sin }^2{\theta }_{13}=[{0.010}_{-0.034}^{+0.033},{0.023}_{-0.015}^{+0.015}]$. All solutions to the solar neutrino problem except for the large mixing angle (LMA) region are excluded. KamLAND also demonstrated almost two cycles of the periodic feature expected from neutrino oscillation effects. KamLAND performed the first experimental study of antineutrinos from the Earth${}^{\prime }$s interior so-called geoneutrinos (geo ${\bar{\nu }}_{\mathrm{e}}$${}^{\prime }$s), and succeeded in detecting geo ${\bar{\nu }}_{\mathrm{e}}$$‘$s produced by the decays of ${}^{238}$U and ${}^{232}$Th within the Earth. Assuming a chondritic Th/U mass ratio, we obtain ${116}_{-27}^{+28}$ ${\bar{\nu }}_{\mathrm{e}}$ events from ${}^{238}$U and ${}^{232}$Th, corresponding a geo ${\bar{\nu }}_{\mathrm{e}}$ flux of ${3.4}_{-0.8}^{+0.8}\times {10}^6{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ at the KamLAND location. We evaluate various bulk silicate Earth composition models using the observed geoneutrino rate.

References in corpus (29)

• Evidence for oscillation of atmospheric neutrinos
• First Results from KamLAND: Evidence for Reactor Anti-Neutrino Disappearance
• Observation of Reactor Electron Antineutrino Disappearance in the RENO Experiment
• Indication of Electron Neutrino Appearance from an Accelerator-produced Off-axis Muon Neutrino Beam
• Limits on Neutrino Oscillations from the CHOOZ Experiment
• Measurement of Neutrino Oscillation with KamLAND: Evidence of Spectral Distortion
• Precision Measurement of Neutrino Oscillation Parameters with KamLAND
• Measurement of the Total Active 8B Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity
• Improved search for muon-neutrino to electron-neutrino oscillations in MINOS
• New solar opacities, abundances, helioseismology, and neutrino fluxes
• Measurement of the solar neutrino capture rate with gallium metal. III: Results for the 2002--2007 data-taking period
• Precision measurement of the 7Be solar neutrino interaction rate in Borexino
• Electron Energy Spectra, Fluxes, and Day-Night Asymmetries of ${}^8$B Solar Neutrinos from the 391-Day Salt Phase SNO Data Set
• Observation of Tau Neutrino Interactions
• Solar neutrino measurements in Super-Kamiokande-I
• Limit on Neutrinoless ββ Decay of Xe-136 from the First Phase of KamLAND-Zen and Comparison with the Positive Claim in Ge-76
• Reactor electron antineutrino disappearance in the Double Chooz experiment
• Final results from the Palo Verde Neutrino Oscillation Experiment
• Improved Measurement of Electron Antineutrino Disappearance at Daya Bay
• Getting the most from the statistical analysis of solar neutrino oscillations
• Probing possible decoherence effects in atmospheric neutrino oscillations
• Observation of Geo-Neutrinos
• Neutrino Decay as an Explanation of Atmospheric Neutrino Observations
• Geophysical and geochemical constraints on geoneutrino fluxes from Earth's mantle
• Antineutrinos from Earth: A reference model and its uncertainties
• The reaction 13C(alpha,n)16O: a background for the observation of geo-neutrinos
• Antineutrino Geophysics with Liquid Scintillator Detectors
• How accurately can one test CPT conservation with reactor and solar neutrino experiments?
• A simple model of reactor cores for reactor neutrino flux calculations for the KamLAND experiment

Cited by in corpus (12)

• Solar neutrinos and neutrino physics
• Limits on astrophysical antineutrinos with the KamLAND experiment
• Embedded Readout Electronics R&D for the Large PMTs in the JUNO Experiment
• Theoretical prediction of presupernova neutrinos and their detection
• Search for Low-energy Electron Antineutrinos in KamLAND Associated with Gravitational Wave Events
• First measurement of the strange axial coupling constant using neutral-current quasielastic interactions of atmospheric neutrinos at KamLAND
• Combined Pre-Supernova Alert System with Kamland and Super-Kamiokande
• Experimental Aspects of Geoneutrino Detection: Status and Perspectives
• Scintillation Balloon for Neutrinoless Double-Beta Decay Search with Liquid Scintillator Detectors
• Search for supernova neutrinos and constraint on the galactic star formation rate with the KamLAND data
• New Signal of Atmospheric Tau Neutrino Appearance: Sub-GeV Neutral-Current Interactions in JUNO
• Search for Solar Flare Neutrinos with the KamLAND detector