The Latest Results from K2K Experiment

The K2K experiment is the first long baseline neutrino oscillation experiment. At this moment, 2.29 × 10¹⁹ protons on target were accumulated, which was about 20 % of the goal of the experiment. We observed 27 fully-contained events at Super-Kamiokande(in the 22.5 kton fiducial mass) and the expected number of events is 40.3^+4.7_-4.6 in the case of no oscillation.