Abstract

T2K is a second-generation long-baseline neutrino-oscillation experiment using the new high-intensity muon-neutrino beam produced at Japan Proton Accelerator Research Complex (JPARC). Sitting 295 km away, at an off-axis angle of 2.5 degrees, the giant Super-Kamiokande water Cherenkov detector sees a narrow-band beam peaked at 600 MeV. The baseline to energy ratio is finely tuned for studying neutrino-oscillations at the so-called atmospheric-neutrino squared-mass splitting. The beam is also sampled 280 m downstream of the neutrino production target by a series of finely-segmented solid-scintillator and time-projection-chamber detectors. Observing changes in the neutrino beam between the two detectors allows oscillation parameters to be extracted. The main goal of the T2K experiment is to produce the first measurement of the neutrino mixing angle theta13 and precise measurements of the mixing angle theta23 and of the atmospheric squared-mass splitting. I will present results from the oscillation analysis on the full dataset collected up to the time of the major earthquake that struck Japan on March 2011. This dataset corresponds to an integrated JPARC neutrino-beam exposure of 1.431E+20 protons-on-target. This analysis provided the first significant indication for a non-zero theta13 angle.