В настоящее время сотрудничеством “Байкал” ведутся работы по созданию глубоководного нейтринного телескопа НТ1000 с эффективным объемом 2 км3 на оз. Байкал. Телескоп будет состоять из функционально независимых установок – кластеров гирлянд оптических модулей на основе фотоэлектронных умножителей (по 8 гирлянд в каждом кластере). Начиная с 2011 г. на оз. Байкал ведутся натурные испытания базовых элементов и систем будущего телескопа в составе автономных измерительных комплексов – прототипов кластера НТ1000. В статье описаны базовые элементы и принципиальная схема функционирования одного из рассматриваемых в настоящее время вариантов акустической системы позиционирования телескопа НТ1000 и приводятся результаты испытаний прототипа этой системы в составе экспериментального кластера 2012 года.

В настоящее время сотрудничеством “Байкал” ведутся работы по созданию глубоководного нейтринного телескопа НТ1000 с эффективным объемом 2 км3 на оз. Байкал. Телескоп будет состоять из функционально независимых установок – кластеров гирлянд оптических модулей на основе фотоэлектронных умножителей (по 8 гирлянд в каждом кластере). Начиная с 2011 г. на оз. Байкал ведутся натурные испытания базовых элементов и систем будущего телескопа в составе автономных измерительных комплексов – прототипов кластера НТ1000. В статье описаны базовые элементы и принципиальная схема функционирования одного из рассматриваемых в настоящее время вариантов акустической системы позиционирования телескопа НТ1000 и приводятся результаты испытаний прототипа этой системы в составе экспериментального кластера 2012 года.

The NT1000 deep-water neutrino telescope with an effective volume of ∼2 km 3 is currently being developed at Lake Baikal by the BAIKAL collaboration. The telescope will be composed of functionally independent setups—clusters of strings of optical modules based on photomultiplier tubes (with eight strings in each cluster). Since 2011, field tests of the basic elements and systems of the future telescope included in autonomous measuring complexes—prototypes of the NT1000 cluster—have been performed at Lake Baikal. The basic elements and the layout of one of the currently considered versions of the acoustic positioning system for the NT1000 telescope are described, and results of tests of the system prototype included as a component in the experimental cluster of the year 2012 are presented.

We present the results of our search for neutrino events coinciding in time and direction with gamma-ray bursts (GRBs) with the Baikal underwater neutrino telescope NT200. No events confirming a neutrino accompaniment of GRBs have been detected. Model-independent limits (Greens function) on the neutrino flux from GRBs have been obtained. For the Waxman-Bahcall neutrino spectrum, the limit on the neutrino flux from a GRB has been found to be E ν 2 Φ ν ⩽ 1.1 × 10 −6 GeV cm −2 s −1 sr −1 .

A project of the NT1000 deep-water neutrino telescope with an effective volume of ∼1 km3 is currently being developed by the BAIKAL collaboration. The telescope will be located in Lake Baikal in close vicinity of the NT200+ detector, which is currently in operation. The telescope will be composed of 12 clusters with 8 similar strings of optical modules in each (each string has two sections of the NT1000 optical modules). The section of the NT1000 optical modules has been developed using higher-efficiency photomultiplier tubes and state-of-the-art electronics. The field tests of the experimental string consisting of two sections with six optical modules in each have been performed. The results of these investigations are used in the project of the NT1000 neutrino telescope and in the hydrological study of Lake Baikal.

A new analysis of the data from the NT200 neutrino telescope based on the reconstruction of parameters for high-energy showers generated in neutrino interactions has yielded new upper limits on the diffuse neutrino fluxes predicted by a number of theoreticalmodels. The upper limit on the all-flavor neutrino flux with an energy spectrum E −2 is E 2Φ ν < 2.9 × 10−7 GeV cm−2 s−1 sr−1.

The main physical results obtained with the Baikal neutrino telescope NT200 during the period 1998–2003 are reviewed: the limits for the diffuse flux of high-energy neutrinos, high-energy muons, and magnetic monopoles and the results of search for neutrinos from the center of the Earth due to annihilation of weakly interacting massive particles and from local neutrino sources. In April, 2005, the neutrino telescope NT200 was extended by introduction of three new strings, located at a distance of 100 m from the NT200 center. The new deep-water complex NT200+ has an effective volume for detecting cascades from high-energy neutrinos larger than that of NT200 by a factor of 4. At a cascade energy of 10 PeV, the effective volume of the new complex is 107 m3. Further development of the Baikal neutrino experiment is related to the design and fabrication of a detector with a volume of about 1 km3.

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+.

High-frequency noise of Lake Baikal is investigated using a submersible self-contained instrument to determine the noise background for the acoustic detection of superhigh-energy neutrinos. It is found that, under stationary and uniform meteorological conditions, the integral noise power in the frequency band 1–50 kHz is virtually independent of depth and is 10–200 mPa or more, depending on the specific conditions. The noise itself contains multiple short pulses of different amplitudes and shapes.

One of the possible ways to study high energy neutrino is to detect acoustic pulses from showers in water. First results of the study of high frequency acoustic noise in Lake Baikal are presented. Many short pulses with different amplitudes and shapes were observed, they should be considered as a background for acoustic neutrino detection. However, most of the short excesses are explained as a result of noise sound waves interference and can be eliminated by a correlation analysis. An algorithm for separation of acoustic signals with definite shape, which probably were produced by quasi local sources, is presented. The efficiency of the method was tested on real data, obtained with a 2-channels acoustic module. This algorithm is now used for online data filtering in the 4-channels acoustic device, which was designed and will be installed close to the Baikal Neutrino telescope NT-200+.

The hydroacoustic coordinate-measuring system of the NT-200 Baikal neutrino telescope is described. It is a ranging long-base hydroacoustic system constantly operating in an automated or interactive mode and capable of measuring the coordinates of the detecting modules of the NT-200 to within 20 cm. Special attention is given to the justification of the estimate of the coordinate measurement errors. As an illustration, some results of measuring the coordinates of the elements of the NT-200 and the hydrophysical characteristics of lake Baikal are presented.