The Baikal-GVD neutrino detector is a deep-underwater neutrino telescope under construction and recently after the winter 2023 deployment it consists of 3456 optical modules attached on 96 vertical ...strings. This 3-dimensional array of photo-sensors allows to observe ambient light in the vicinity of the Baikal-GVD telescope that is associated mostly with water luminescence. Results on time and space variations of the luminescent activity are reviewed based on data collected in 2018-2022.
We present the results of the two-year (2021-2022) monitoring of absorption and scattering lengths of light with wavelength 400-620 nm within the effective volume of the deep underwater neutrino ...telescope Baikal-GVD, which were measured by a device Baikal-5D No.2. The Baikal-5D No.2. was installed during the 2021 winter expedition at a depth of 1180 m. The absorption and scattering lengths were measured every week in 9 spectral points. The device Baikal-5D No.2 also has the ability to measure detailed scattering and absorption spectra. The data obtained make it possible to estimate the range of changes in the absorption and scattering lengths over a sufficiently long period of time and to investigate the relationship between the processes of changes in absorption and scattering. An analysis was made of changes in absorption and scattering spectra for the period 2021-2022.
The Baikal-GVD is a deep-underwater neutrino telescope being constructed in Lake Baikal. After the winter 2023 deployment campaign the detector consists of 3456 optical modules installed on 96 ...vertical strings. The status of the detector and progress in data analysis are discussed in present report. The Baikal-GVD data collected in 2018-2022 indicate the presence of cosmic neutrino flux in high-energy cascade events consistent with observations by the IceCube neutrino telescope. Analysis of track-like events results in identification of first high-energy muon neutrino candidates. These and other results from 2018-2022 data samples are reviewed in this report.
We present a new procedure for time calibration of the Baikal-GVD neutrino telescope. The track reconstruction quality depends on accurate measurements of arrival times of Cherenkov photons. ...Therefore, it is crucial to achieve a high precision in time calibration. For that purpose, in addition to other calibration methods, we employ a new procedure using atmospheric muons reconstructed in a single-cluster mode. The method is based on iterative determination of effective time offsets for each optical module. This paper focuses on the results of the iterative reconstruction procedure with time offsets from the previous iteration and the verification of the method developed. The theoretical muon calibration precision is estimated to be around 1.5-1.6ns.
PoS(ICRC2023)1458 The Baikal-GVD alert system was launched at the beginning of 2021. There are
alerts for muon neutrinos (long upward-going track-like events) and all-flavour
neutrinos (high-energy ...cascades). The system is able to get a preliminary
response to external alerts with a temporal delay of about 3-10 minutes. The
Baikal-GVD data processing and the results of the follow-up procedure are
described. We report on the analysis of the coincidence in time and direction
between the Baikal-GVD cascade GVD20211208CA with an estimated energy of 43 TeV
and the announced alert IceCube211208A possibly associated with a flaring state
of the blazar PKS 0735+178.
We report on the observation of a rare neutrino event detected by Baikal-GVD
in April 2021. The event GVD210418CA is the highest-energy cascade observed by
Baikal-GVD so far from the direction below ...the horizon. The estimated cascade
energy is $224\pm75$~TeV. The evaluated signalness parameter of GVD210418CA is
97.1\% using an assumption of the E$^{-2.46}$ spectrum of astrophysical
neutrinos. The arrival direction of GVD210418CA is near the position of the
well-known radio blazar TXS~0506+056, with the angular distance being within a
90\% directional uncertainty region of the Baikal-GVD measurement. The event
was followed by a radio flare observed by the RATAN-600 radio telescope,
further strengthening the case for the neutrino-blazar association.
The Baikal-GVD deep underwater neutrino experiment participates in the international multi-messenger program to detect the astrophysical sources of high- and ultrahigh-energy cosmic-ray particles, ...being at the stage of array deployment and a step-by-step increase of the telescope’s effective volume to the scale of a cubic kilometer. At present, the telescope consists of seven clusters containing 2016 photodetectors. The effective volume of the detector has reached 0.35 km
for the selection of shower events from neutrino interactions in Baikal water. The experimental data have been accumulated in a continuous exposure mode since 2015, allowing a prompt data analysis and a celestial-sphere monitoring program to be implemented in real time. We discuss the structure of the data acquisition system, describe the physical event reconstruction procedure in the mode of fast response to alerts, and present the results of our analysis of nine alerts from the polar IceCube telescope from early September to late October 2020.
The deployment of the Baikal-GVD deep underwater neutrino telescope is continuing in Lake Baikal. By April 2022, ten clusters of the telescope were put into operation, with 2880 optical modules in ...total. One of the relevant tasks in this context is to study the possibilities of increasing the efficiency of the detector based on the experience of its operation and the results obtained at other neutrino telescopes in recent years. In this paper, a variant of optimizing the configuration of the telescope is considered, based on the installation of additional strings of optical modules between the clusters (external strings). An experimental version of the external string was installed in Lake Baikal in April 2022. This paper presents a first estimate of the impact of adding external strings on the neutrino detection efficiency, as well as the technical implementation of the detection and data acquisition systems of the external string and first results of its in-situ tests.
We report on the first observation of the diffuse cosmic neutrino flux with the Baikal-GVD neutrino telescope. Using cascade-like events collected by Baikal-GVD in 2018--2021, a significant excess of ...events over the expected atmospheric background is observed. This excess is consistent with the high-energy diffuse cosmic neutrino flux observed by IceCube. The null cosmic flux assumption is rejected with a significance of 3.05\(\sigma\). Assuming a single power law model of the astrophysical neutrino flux with identical contribution from each neutrino flavor, the following best-fit parameter values are found: the spectral index \(\gamma_{astro}\) = \(2.58^{+0.27}_{-0.33}\) and the flux normalization \(\phi_{astro}\) = 3.04\(^{+1.52}_{-1.21}\) per one flavor at 100 TeV.
Baikal-GVD Experiment Avrorin, A. V.; Avrorin, A. D.; Aynutdinov, V. M. ...
Physics of atomic nuclei,
11/2020, Letnik:
83, Številka:
6
Journal Article
Recenzirano
Baikal-GVD is a deep-underwater neutrino detector of cubic-kilometer scale. It is designed to detect astrophysical neutrinos up to multi-PeV energies and beyond. The deployment of this facility began ...in spring 2015. Since April 2020, the detector includes seven clusters, each consisting of eight strings carrying in total 288 optical modules located at depths of 750 to 1275 m. By the end of the first phase of construction of the detector in 2024, it is planned to deploy 15 clusters, whereby an effective volume of 0.75 km
for detecting high-energy cascades would be reached. The design and status of the Baikal-GVD detector are described in the present article along with selected results of data analysis.
