An approach allowing one to calculate the spatiotemporal intensity distribution of light from a point source with the use of integral scattering characteristics is considered. Using this approach in practice has an undeniable advantage because it does not require knowing the scattering function for the whole range of angles, in particular, in the region of small angles where the measurement of the scattering phase function for media with predominantly forward scattering involves considerable experimental difficulties.

The procedure for Grand Unified Theory (GUT) monopole searches by means of the NT200 Baikal neutrino detector is described. Event-selection and background-suppression algorithms are discussed in detail. Limits on the flux of slow monopoles are presented and are compared with theoretical predictions and with the results of other experiments.

We consider issues related to the determination of integral characteristics of the scattering phase function for media with a highly forward directed scattering function. We show that, as a rule, the standard method of calculation of the average cosine of the scattering angle does not take into account the contribution that is important for scattering in the direction of small angles. We present a technique that makes it possible to obtain necessary corrections for the integral scattering characteristics in this case.

We have analyzed the neutrino events recoded in the deep-water neutrino experiment NT200 in Lake Baikal in five years of observations toward dark dwarf spheroidal galaxies (dSphs) in the southern hemisphere and the Large Magellanic Cloud (LMC). This analysis completes the series of works based on NT200 data in the search for a dark matter annihilation signal in astrophysical objects. We have found no significant excess in the number of observed events relative to the expected background from atmospheric neutrinos in all tested directions, in 22 dSphs and the LMC. For a sample of five selected dwarf galaxies we have performed a joint analysis of the data by the maximum likelihood method. We have obtained a correspondence of the observational data to the null hypothesis about the presence of only background events and established 90% confidence-level upper limits for the annihilation cross sections of dark matter particles with a mass from 30 GeV to 10 TeV in several annihilation channels both in the joint analysis of the selected sample of galaxies and in the analysis toward the LMC. The strongest constraints at a level of 7 × 10–21 cm3 s–1 have been obtained for the direction toward the LMC in the channel of annihilation into a pair of neutrinos.

The status and perspectives of the feasibility study to detect high energy cosmic neutrinos acoustically in Lake Baikal is presented. The concept of on acoustic array as a part of the Baikal Gigaton Volume Neutrino Telescope GVD based on results of simulation and background measurements is described.

We present the status of the Gigaton Volume Detector in Lake Baikal (Baikal-GVD) designed for the detection of high energy neutrinos of astrophysical origin. The telescope consists of functionally independent clusters, sub-arrays of optical modules (OMs), which are connected to shore by individual electro-optical cables. During 2015 the GVD demonstration cluster, comprising 192 OMs, has been successfully operated in Lake Baikal. In 2016 this array was upgraded to baseline configuration of GVD cluster with 288 OMs arranged on eight vertical strings. Thus the instrumented water volume has been increased up to about 5.9 Mtons. The array was commissioned in early April 2016 and takes data since then. We describe the configuration and design of the 2016 array. Preliminary results obtained with data recorded in 2015 are also discussed.

We reanalyze the dataset collected during the years 1998-2003 by the deep underwater neutrino telescope NT200 in the lake Baikal with the low energy threshold (10 GeV) in searches for neutrino signal from dark matter annihilations near the center of the Milky Way. Two different approaches are used in the present analysis: counting events in the cones around the direction towards the Galactic Center and the maximum likelihood method. We assume that the dark matter particles annihilate dominantly over one of the annihilation channels b (b) over bar, W+W-, tau(+)tau(-), mu(+)mu(-) or nu(nu) over bar. No significant excess of events towards the Galactic Center over expected neutrino background of atmospheric origin is found and we derive 90% CL upper limits on the annihilation cross section of dark matter. (C) 2016 Elsevier B.V. All rights reserved.

The future next-generation neutrino telescope Baikal-GVD will be a km3-scale array aimed at the detection of astrophysical neutrino fluxes. It will have modular structure and consist of functionally independent sub-arrays - clusters of strings of optical modules. The prototyping phase of the project has been concluded in 2015 with the deployment of the first cluster of Baikal-GVD in Lake Baikal. We discuss the current status and perspectives of the Baikal-GVD project.

Baikal-GVD will be a neutrino telescope at the cubic-kilometer scale in Lake Baikal. The first out of 10-12 clusters of the first phase of GVD has been deployed and commissioned in April 2015. This paper describes design and implementation of the dataacquisition system of GVD.

In April 2015 the demonstration cluster "Dubna" was deployed and started to take data in Lake Baikal.This array is the first cluster of the cubic kilometer scale Gigaton Volume Detector (Baikal-GVD), which is constructed in Lake Baikal.In this contribution we will review the design and status of the array.

In April 2015, the first cluster of Baikal-GVD was deployed in Lake Baikal and put into operation. It comprises eight strings. Each string consists of 24 optical modules. An optical module is a detection element of Baikal-GVD; it includes a Hamamatsu R7081-100 photomultiplier tube with a high quantum sensitivity. We describe the design of the optical module, the front-end electronics, and the laboratory characterization and calibration.

The objective of the Baikal-GVD project is the construction of a km(3)-scale neutrino telescope in Lake Baikal. The Gigaton Volume Detector consists of a large three-dimensional array of photo-multiplier tubes. The first GVD-cluster has been deployed and commissioned in April 2015. The data acquisition system (DAQ) of the detector takes care of the digitization of the photo-multiplier tube signals, data transmission, filtering and storage. The design and the implementation of the data acquisition system are described.

The first stage of the GVD-cluster composed of five strings was deployed in April 2014. Each string consists of two sections with 12 optical modules per section. A section is the basic detection unit of the Baikal neutrino telescope. We will describe the section design, review its basic elements – optical modules, FADC readout units, slow control and calibration systems, and present selected results for section in-situ tests in Lake Baikal.

We discuss neutrinos originating from dark matter in the Galactic Center and present sensitivity of Baikal Gigaton Volume Detector to this signal.

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.

We analyze sensitivity of the gigaton volume telescope Baikal-GVD for detection of neutrino signal from dark matter annihilations or decays in the Galactic Center. Expected bounds on dark matter annihilation cross section and its lifetime are found for several annihilation/decay channels.

The Prototyping phase of the BAIKAL-GVD project has been started in April 2011 with the deployment of first autonomous engineering array which comprises all basic elements and systems of the Gigaton Volume Detector (GVD) in Lake Baikal. The prototyping phase will be concluded with deployment of the GVD demonstration cluster “DUBNA” in 2015, which will comprise 192 light sensors arranged at 8 strings. The first stage of the GVD demonstration cluster which consists of three strings was deployed in April 2013 and successfully operated up to February 2014. We review the prototyping phase of the BAIKAL-GVD project and describe the configuration and design of the 2013 engineering array.

A.D. Avrorin a, A.V. Avrorin a, V.M. Aynutdinov a, R. Bannash g, I.A. Belolaptikov b, D.Yu. Bogorodsky c, V.B. Brudanin b, N.M. Budnev c, I.A. Danilchenko a, S.V. Demidov a, Domogatsky a, A.A. Doroshenko a, A.N. Dyachok c, Zh.-A.M. Dzhilkibaev a, S.V. Fialkovsky e, A.R. Gafarov c, O.N. Gaponenko a, K.V. Golubkov a, T.I. Gress c, Z. Honzb, K.G. Kebkal g, O.G. Kebkal g, K.V. Konischev b, A.V. Korobchenko b, A.P. Koshechkin a, F.K. Koshel a, A.V. Kozhin d, V.F. Kulepov e, D.A. Kuleshov a, V.I. Ljashuk a, M.B. Milenin e, R.A. Mirgazov c, E.R. Osipova d, A.I. Panfilov a, L.V. Pan’kov c, E.N. Pliskovsky b, M.I. Rozanov f , E.V. Rjabov c, B.A. Shaybonov b, A.A. Sheifler a, M.D. Shelepov a, A.V. Skurihin d, A.A. Smagina b, O.V. Suvorova ∗a, V.A. Tabolenko c, B.A. Tarashansky c, S.A. Yakovlev g, A.V. Zagorodnikov c, V.A. Zhukov a, and V.L. Zurbanov c aInstitute for Nuclear Research, Moscow, 117312 Russia bJoint Institute for Nuclear Research, Dubna, 141980 Russia cIrkutsk State University, Irkutsk, 664003 Russia dInstitute of Nuclear Physics, Moscow State University, Mos cow, 119991 Russia eNizhni Novgorod State Technical University, Nizhni Novgor od, 603950 Russia f St. Petersburg State Marine Technical University, St. Pete rsburg, 190008 Russia gEvoLogics, Germany

В апреле 2013 года в оз. Байкал была установлена и включена в режиме постоянной экспозиции первая очередь экспериментального кластера глубоководного нейтринного телескопа НТ1000, состоящая из трех гирлянд, оснащенных 24 оптическими модулями каждая. В статье описана система регистрации и сбора данных созданной установки.