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

Neutrino Telescope in Lake Baikal: Present and Nearest Future

“…Additional technical strings equipped with high-power pulsed lasers are installed in-between the GVD clusters. These are used for detector calibration [8] and light propagation studies [10]. The lake is covered with thick ice (up to ~ 1m) from February to mid-April, providing a convenient solid platform for detector deployment and maintenance operations.…”

Measuring muon tracks in Baikal-GVD using a fast reconstruction algorithm

“…Additional technical strings equipped with high-power pulsed lasers are installed in-between the GVD clusters. These are used for detector calibration [6] and light propagation studies [8]. The lake is covered with thick ice (up to ≈ 1 m) from February to mid-April, providing a convenient solid platform for detector deployment and maintenance operations.…”

GUT-Monopole Searches by Means of Deep Underwater Baikal Neutrino Telescope

“…The mean cosine cos (θ) also provides useful information about angular characteristics of scattering. Many years of measurements of optical parameters of the aqueous medium at the location of the Baikal neutrino telescope (see, for example, [2,[11][12][13][14][15][16]) have shown that the absorption length changes only sightly over a year, and one can take, for different years, 21 m as a characteristic value of λ abs in the wavelength range between 470 and 500 nm (that is, at the transparency maximum). On the contrary, the scattering length and the scattering function may change greatly from one month to another and from one year to another, but the effective scattering length defined as…”