The ANTARES neutrino telescope is a large photomultiplier array designed to detect neutrino-induced upward-going muons by their Cherenkov radiation. Understanding the absorption and scattering of light in the deep Mediterranean is fundamental to optimising the design and performance of the detector. This paper presents measurements of blue and UV light transmission at the ANTARES site taken between 1997 and 2000. The derived values for the scattering length and the angular distribution of particulate scattering were found to be highly correlated, and results are therefore presented in terms of an absorption length λ abs and an effective scattering length λ eff sct . The values for blue (UV) light are found to be λ abs ≃ 60(26) m, λ eff sct ≃ 265(122) m, with significant (∼15%) time variability. Finally, the results of ANTARES simulations showing the effect of these water properties on the anticipated performance of the detector are presented.

We present a new dataset analysis of the neutrino experiment at the Baksan Underground Scintillator Telescope with muon energy threshold about 1 GeV for the longest exposure time toward the Sun. In search for a signal from self-annihilations of dark matter particles in the center of the Sun we use an updated sample of upward through-going muons for 24.12 years of live time. No observable excess has been found in measured muons relative to expected background from neutrinos of atmospheric origin. We present an improved data analysis procedure and describe it in detail. We set the 90% C.L. new upper limits on expected neutrino and muon fluxes from dark matter annihilations in the Sun, on the corresponding annihilation rates and cross sections of their elastic scattering off proton.Keywords: high energy neutrinos, dark matter. †Dedicated to the memory of Stas Mikheyev.

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We have analyzed a data set taken over 2.76 years live time with the Baikal neutrino telescope NT200. The goal of the analysis is to search for neutrinos from dark matter annihilation in the center of the Sun. Apart from the conventional annihilation channels bb, W + W − and τ + τ − we consider also the annihilation of dark matter particles into monochromatic neutrinos. From the absence of any excess of events from the direction of the Sun over the expected background, we derive 90% upper limits on the fluxes of muons and muon neutrinos from the Sun, as well as on the elastic cross sections of dark matter scattering on protons.

The Prototyping phase of the BAIKAL-GVD project has been started in April 2011 with the deployment of a three string engineering array which comprises all basic elements and systems of the Gigaton Volume Detector (GVD) in Lake Baikal. In April 2012 the version of engineering array which comprises the first full-scale string of the GVD demonstration cluster has been deployed and operated during 2012. The first stage of the GVD demonstration cluster which consists of three strings is deployed in April 2013. We review the Prototyping phase of the BAIKAL-GVD project and describe the configuration and design of the 2013 engineering array.