Search for Neutrinos from the Core of the Earth with the Baikal Underwater Detector NT-36

Abstract

The first stage of the Baikal Neutrino Telescope NT-200, the detector NT-36, was operated from 1993 to 95. The data obtained with this small array were analysed to search for vertically upward muons. Apart from neutrinos generated in the atmosphere at the opposite side of the Earth, such muons might be due to neutrinos produced in neutralino annihilations in the center of the Earth. We have selected two clear neutrino candidates. From this, an 90%CL upper limit of 1.3 x 10^-13 muons cm^(-2) sec^(-1) in a cone with 15 degree half-aperture around the opposite zenith is obtained for muons due to neutralino annihilation.