The Baikal Neutrino Telescope - Results and Plans

New results from the Baikal neutrino telescope NT200, based on the first 5 years of operation (1998-2003), are presented. We derive an all-flavor limit on the diffuse flux of astrophysical neutrinos between 20 TeV and 50 PeV, extract an enlarged sample of high energy muon neutrino events, and obtain limits on the flux of high energy atmospheric muons. In 2005, the upgraded telescope NT200+ will be commissioned: 3 additional distant strings with only 12 photo-multipliers each will rise the effective volume to 20 Mton at 10 PeV for this largest running neutrino telescope in the Northern hemisphere

A device for detection of acoustic signals from super high energy neutrinos.

We present the design of a device for detection of acoustic signals from high energy particle showers. The module will be stationary installed above the Baikal Neutrino Telescope NT-200+

Searches for almost vertically upgoing muons in a Lake Baikal deep-underwater experiment

A method for selecting collisions involving atmospheric neutrinos and resulting in the emission of almost vertically upgoing muons is proposed and implemented by analyzing data from the deep-underwater neutrino telescopes NT-36 and NT-96. On the basis of data collected by the deep-underwater neutrino telescope NT-96 over a 0.192-year operation period, an upper limit has been imposed on the flux of muons that may originate from the annihilation of neutralino pairs in the core of the Earth

In-situ measurements of optical parameters in Lake Baikal with the help of a neutrino telescope

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 = 0.95 (0.90) for the average scattering angle, this corresponds to a geometrical scattering length of 24 (48) m