2014/03/18 by A. Renshaw, Renshaw, Andrew
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Atmospheric Ozone and Climate #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Instrumentation and Detectors (physics.ins-det) #Neutrino Physics Research
paper · pdf · doi:10.48550/arxiv.1403.4575
openalex publication_date 2014/03/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Super-Kamiokande-IV (SK-IV) data taking began in September of 2008, after upgrading the electronics and data acquisition system. Due to these upgrades and improvements to water system dynamics, calibration and analysis techniques, a solar neutrino signal could be extracted at recoil electron kinetic energies as low as 3.5 MeV. When the SK-IV data is combined with the previous three SK phases, the SK extracted solar neutrino flux is found to be [2.37±0.015(stat.)±0.04(syst.)]×106/(cm2sec). The combination of the SK recoil electron energy spectra slightly favors distortions due to a changing electron flavor content. Such distortions are predicted when assuming standard solar neutrino oscillation solutions. An extended maximum likelihood fit to the amplitude of the expected solar zenith angle variation of the neutrino-electron elastic scattering rate results in a day-night asymmetry of [-3.2±1.1(stat.)±0.5(syst.)]%. A solar neutrino global oscillation analysis including all current solar neutrino data, as well as KamLAND reactor antineutrino data, measures the solar mixing angle as sin2θ12=0.305±0.013, the solar neutrino mass squared splitting as Δm221=7.49+0.19-0.17×10-5eV2 and sin2θ13=0.026+0.017-0.012.