Comments on the super Kamiokande project (next-generation underground facility at KAMIOKA)

Summary

After proposing Grand Unification Theory, many experiments for the search of nucleon decay events and the search of GUT monopoles have been done in the whole world. At the present stage, however, there are no nucleon decay events and no GUT monopoles up to the upper limits of the present technical level of detectors. It should be necessary to have some new developments of detectors for the second-generation experiments, not simply enlargement of the present detectors. As a next-generation underground experiment, a large water Ĉerenkov detector with a total mass of 32000 tons is proposed at Kamioka, called Super Kamiokande. The physics potential of Super Kamiokande lies in the detection of phenomena predicted by grand unified theories and neutrino astronomy, particularly the search for nucleon decay, and the detection of⁸B solar neutrinos via electron-neutrino electron scattering. The authors comment on background events in the search for nucleon decay in all decay modes measured by the Kamiokande I and II detectors, and by reason of circular statistical tests, on the angular distributions of low-energy electrons produced by solar electron-neutrinos as observed in Kamiokande II. On the basis of these discussions about the measured experimental results of the Kamiokande I and II detectors, we present some critical comments on the detection capability and physics potential of the proposed experiment.