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.
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.
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.
Baikal-GVD has recently published its first measurement of the diffuse astrophysical neutrino flux, performed using high-energy cascade-like events. We further explore the Baikal-GVD cascade dataset ...collected in 2018-2022, with the aim to identify possible associations between the Baikal-GVD neutrinos and known astrophysical sources. We leverage the relatively high angular resolution of the Baikal-GVD neutrino telescope (2-3 deg.), made possible by the use of liquid water as the detection medium, enabling the study of astrophysical point sources even with cascade events. We estimate the telescope's sensitivity in the cascade channel for high-energy astrophysical sources and refine our analysis prescriptions using Monte-Carlo simulations. We primarily focus on cascades with energies exceeding 100 TeV, which we employ to search for correlation with radio-bright blazars. Although the currently limited neutrino sample size provides no statistically significant effects, our analysis suggests a number of possible associations with both extragalactic and Galactic sources. Specifically, we present an analysis of an observed triplet of neutrino candidate events in the Galactic plane, focusing on its potential connection with certain Galactic sources, and discuss the coincidence of cascades with several bright and flaring blazars.
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.
The effect of lipophilic
N
-(3,5-di-
tert
-butyl-4-hydroxybenzyl)-
N
,
N
-di(2-pyridylmethyl)-amine and its water-soluble hydrochloride on the oxidative status of tissues of Wistar rats
in vivo
was ...studied. The change in the xanthine oxidase activity, the level of free radical processes in blood, and the antioxidant activities of blood serum were determined by spectrophometry. The contents of TBA-dependent products (TBA is thiobarbituric acid) in animal tissues were measured by biochemiluminescence under induced oxidative stress conditions. The effect of
N
-(3,5-di-
tert
-butyl-4-hydroxybenzyl)-
N
,
N
-di-(2-pyridylmethyl)amine on organism
in vivo
is multi-factorial and is more pronounced for the water-soluble hydrochloride.
The possibilities of producing large batches of magnetic nanoparticles (MNPs) using electrical explocion of the wire (EEW), laser target evaporation, and spark discharge are considered. MNP ...bioapplications require production of magnetic materials in the form of as stabilized aqueous suspensions or hydrogels with magnetic fillers; therefore, some details of synthesis of these materials and their certification are discussed. The problems of the interaction of MNPs with biological systems, biocompatibility, the applicability of ferrogel substrata to cellular technology and regenerative medicine, and as biomimetics in the development of magnetic biosensors are considered. The results of analysis of some biological experiments with various suspensions prepared based on the same MNP batch are presented. An analysis of the examples of magnetic biodetection and existing theoretical approaches will allow estimation of prospects of this scientific direction to develop highly sensitive film sensors based on the giant magnetic impedance effect for biomedical applications.
