KamLAND, designed to explore the neutrino oscillation of over(ν, -)e's from reactors, showed the improved results with enhanced statistics of 2881 ton-yr data set, added data lowering the energy threshold, and suppressed systematic uncertainties. As a result, a scaled reactor spectrum with no distortion is excluded at more than 5σ, and the best-fit of oscillation parameters gives Δ m212 = 7.58- 0.20+ 0.21 × 10- 5 eV2 and tan2 θ12 = 0.56- 0.09+ 0.14. The improved analysis measured the mass-square difference of neutrino oscillation parameters at a precision of 2.8%, and also observed two cycles of oscillatory shape expected from neutrino oscillation. The geo neutrino flux, measured at the same time, is consistent with expectation based on an earth model within the statistical uncertainty.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics