In-situ measurements of optical parameters in Lake Baikal with the help of a Neutrino Telescope

Abstract

We present results of an experiment performed in Lake Baikal at a depth of about 1 km. The photomultipliers of an underwater neutrino telescope under construction at this site have been illuminated by a distant laser. The experiment not only provided a useful cross-check of the time calibration of the detector, but also allowed to determine inherent optical parameters of the water in a way complementary to standard methods. In 1997, we have measured an absorption length of 22 m and an asymptotic attenuation length of 18 m. The effective scattering length was measured as 480 m. Using <cos theta > = 0.95 (0.90) for the average scattering angle, this corresponds to a geometrical scattering length of 24 (48) m.