Baryon-Conservation Limit

Abstract

An improved lower limit of >2 × ${10}^{30}$ yr against baryon-conservation-violating nucleon decay has been obtained for modes which produce $\mu \to e$ decays. The detector, employing a 20-ton large-area (180 ${\mathrm{m}}^2$) liquid scintillator, was operated deep underground (3.2 km) to eliminate stopping muons from cosmic rays, leaving only the background from muons produced by atmospheric neutrinos. A run length of 2.7 yr was required to achieve the sensitivity quoted.