[Abstract] The main background events seem to be caused by the low enegy atmospheric neutrinos. However, the events number can not interpleted by the expected numbers from the relevant cross sections ν_e+p→n+e^- and ν^^-_e+p→n+e^-. We show the number of background to be consistent with contribution of neutrons generated in nuclear showers initiated by muons underground, following to Ryazhskaya\u27s estimation
