Observations were made 1570 meters of water equivalent underground with an 8000-metric-ton water Cherenkov detector. During a live time of 80 d no events consistent with the decay p→e+π0 were found in a fiducial mass of 3300 metric tons. It is concluded that the limit on the lifetime for bound plus free protons divided by the e+π0 branching ratio is τB>6.5×1031 yr; for free protons the limit is τB>1.9×1031 yr (90% confidence). Observed cosmic-ray muons and neutrinos are compatible with expectations.
ASJC Scopus subject areas
- Physics and Astronomy(all)