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[47.01] Evidence for Reactor Anti-Neutrino Disappearance at KamLAND

J.M. Goldman (Tohoku University), KamLAND Collaboration

KamLAND, the first terrestrial experiment with direct sensitivity to the Large Mixing Angle (LMA) solution to the solar neutrino problem, has measured the flux of electron anti-neutrinos produced by distant (flux-weighted baseline of approximately 180 km) nuclear reactors. Fewer electron anti-neutrino events are observed in this measurement than are predicted by the Standard Solar Model and the non-oscillation hypothesis at the 99.95% C.L. Using data corresponding to a period of 162 ton-years, KamLAND has found the ratio of the measured number of anti-neutrino events to the expected number of anti-neutrino events to be equal to 0.611±0.085(stat)±0.041(syst) for anti-neutrino energies greater than 3.4 MeV. With the assumption of CPT invariance and a two-flavor oscillation formalism, this measurement excludes all solutions to the solar neutrino problem other than LMA.

Bulletin of the American Astronomical Society, 35#2
© 2003. The American Astronomical Soceity.