Skip to main content
Open Access Publications from the University of California

UC Berkeley

UC Berkeley Electronic Theses and Dissertations bannerUC Berkeley

Precision Measurement of Neutrino Oscillation Parameters with KamLAND


This dissertation describes a measurement of the neutrino oscillation parameters $Delta m^2_{21}$, $theta_{12}$ and constraints on $theta_{13}$ based on a study of reactor antineutrinos at a baseline of $sim 180,$km with the KamLAND detector. The data presented here was collected between April 2002 and November 2009, and amounts to a total exposure of $2.64 \pm 0.07 times 10^{32}$ proton-years. For this exposure we expect $2140 \pm 74 (syst)$ antineutrino candidates from reactors, assuming standard model neutrino behavior, and $350 pm 88 (syst)$ candidates from background. The number observed is 1614. The ratio of background-subtracted candidates observed to expected is

$$frac{N_{Obs}-N_{Bkg}}{N_{Exp}} = 0.59 \pm 0.02 (stat)\pm 0.045 (syst)nonumber$$

which confirms reactor neutrino disappearance at greater than 5$sigma$ significance. Interpreting this deficit as being due to neutrino oscillation, the best-fit oscillation parameters from a three-flavor analysis are $Delta m^{2}_{21} = 7.60 ^{+0.20}_{-0.19} times 10^{-5} rm{eV^2}$, mbox{$theta_{12} = 32.5 \pm 2.9$ degrees} and $sin^{2}theta_{13} = 0.025 ^{+0.035}_{-0.035}$, the 95% confidence-level upper limit on $sin^{2}theta_{13}$ is mbox{$sin^{2}theta_{13}<0.083 $}. Assuming textit{CPT} invariance, a combined analysis of KamLAND and solar neutrino data yields best-fit values: $Delta m^{2}_{21} = 7.60 ^{+0.20}_{-0.20} times 10^{-5} rm{eV^2}$, $theta_{12} = 33.5 ^{+1.0}_{-1.1}$ degrees, and $sin^{2}theta_{13} = 0.013 pm {0.028}$ or $sin^{2}theta_{13}<0.06 $ at the 95% confidence level.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View