Recent Results from KamLAND

TL;DR

The KamLAND experiment measured reactor electron anti-neutrino oscillations over 1490 days, providing precise oscillation parameters and strong statistical evidence for neutrino disappearance, confirming neutrino oscillation phenomena.

Contribution

This study presents the first detailed measurement of neutrino oscillation parameters using a large liquid scintillator detector over an extended period.

Findings

Oscillation parameters: Delta m^2_21 = 7.58 x 10^-5 eV^2

Statistical significance of neutrino disappearance: 8.8 sigma

Undistorted spectrum disfavored at > 5 sigma

Abstract

The main goal of the KamLAND reactor electron anti-neutrino experiment is a search for electron anti-neutrino oscillation using inverse-beta decay reaction in 1,000 ton of ultra-pure liquid scintillator. The data-set is 1490.8 days from Mar. 2002 to May 2007. The best-fit oscillation parameters are Delta m^{2}_{21} = 7.58^{+0.14}_{-0.13} (stat.) +/- 0.15 (syst.) x 10$^{-5} eV^{2} and tan^{2}theta_{12} = 0.56^{+0.10}_{-0.07} (stat.) ^{+0.10}_{-0.06} (syst.). The statistical significance for reactor electron anti-neutrino disappearance is 8.8 sigma, and an undistorted electron anti-neutrino energy spectrum is disfavored at > 5 sigma.