Deep-Water Neutrino Telescope in Lake Baikal Allakhverdyan, V. A.; Avrorin, A. D.; Avrorin, A. V. ...
Physics of atomic nuclei,
12/2021, Letnik:
84, Številka:
9
Journal Article
Recenzirano
The Baikal-GVD deep-water neutrino telescope of the cubic kilometer scale, focused on research in the field of astrophysics and particle physics, is being built in Lake Baikal. As of 2021, the ...effective volume of the detector reaches 0.4 km
3
for cascades generated by high-energy astrophysical neutrinos. The paper describes the design and basic characteristics of the telescope data acquisition system, discusses some aspects of deep-water engineering related to the deployment of the detector, and presents selected results obtained with the partially complete detector.
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Deployment of the deep-sea neutrino telescope Baikal-GVD continues in Lake Baikal. By April 2022, ten telescope clusters, which include 2880 optical modules, were put into operation. One of the ...urgent tasks of the Baikal project is to study the possibility of increasing the detection efficiency of the detector based on the experience of its operation and the results obtained with other neutrino telescopes in recent years. In this paper, the authors consider a variant of optimizing the telescope configuration by installing an additional string of optical modules between the detector clusters (external string). An experimental version of the external garland was installed in Lake Baikal in April 2022. The paper presents the results from calculations of the efficiency of registration of neutrino events for a new setup configuration, the technical implementation of the system for recording and collecting data from the external garland, and the first results of its full-scale tests in Lake Baikal.
The status of the Baikal-GVD neutrino telescope under construction and its main scientific results are presented. The detector consists of 2916 optical sensors located at 81 vertical strings deep ...below the surface of Lake Baikal. Its geometric configuration is optimized for detecting neutrinos with energies above 100 TeV. Events from muon neutrinos were identified, the flux of which is consistent with the expectation for the flux of atmospheric neutrinos. The data obtained during the alerts of the ANTARES and IceCube telescopes were analyzed. Candidate events for high-energy neutrinos of astrophysical origin have been obtained.
In this paper we perform a theoretical analysis of the direct passage of neutrons in the atmosphere from an altitude of about 5 km up to several hundred kilometers. We consider that these neutrons ...are generated during thunderstorms in what favor there is some experimental evidence. Two main mechanisms of the neutrons generation in thunderstorms appeared in the literature: the nuclear synthesis directly in the lightning channel and the photonuclear synthesis owing to production of gamma‐rays by the runaway electrons. Both of them are discussed in the present work. For the qualitative analysis we considered the process of neutrons propagation in the atmosphere as consisting of three stages: initial neutron deceleration to thermal energies, then diffusion, and further free propagation. Absorption of neutrons was neglected. Also, in modeling the atmospheric matter only nitrogen and oxygen were considered as the main atmospheric components. With these conditions and taking into account the predicted parameters of the neutron generation source, it is shown that the estimated flux well corresponds to the known experimental results. On this basis the preferred mechanism of the neutron generation is indicated. For a more rigorous picture of the neutrons propagation, capable for description of the slowing down, thermalization, and diffusion processes, one has to perform a numerical calculation and for this we propose a computer simulation scheme based on the cellular automation method. The corresponding plain analysis of the neutrons passage confirms the estimation mentioned above. The proposed scheme can be used for modeling the real neutron source. On the basis of our results we discuss some characteristic features of the observed neutron fluxes. The obtained results are to be tested by the “Radioskaf” experiment based on the scientific device called “RAZREZ.” One of the experiment objectives is detection of neutrons with different energies at altitudes of 200–400 km aiming to reveal the nature and characteristics of the neutron radiation source.
We study logical limit laws for uniform attachment random graphs. In this random graph model, vertices and edges are introduced recursively: at time n+1, the vertex n+1 is introduced together with m ...edges joining the new vertex with m different vertices chosen uniformly at random from 1,…,n. We prove that this random graph obeys convergence law for first-order sentences with at most m−2 variables.
MSO 0-1 law for recursive random trees Malyshkin, Y.A.; Zhukovskii, M.E.
Statistics & probability letters,
June 2021, 2021-06-00, Letnik:
173
Journal Article
Recenzirano
We prove the monadic second-order 0-1 law for two recursive tree models: uniform attachment tree and preferential attachment tree. We also show that the first order 0-1 law does not hold for non-tree ...uniform attachment models.
Proton-conducting electrolytes (PCEs) are extensively researched materials utilized in solid oxide electrochemical cells with various operating principles. The high ionic (protonic) transport of PCEs ...offers superior performance of such cells at reduced temperatures (400–600 °C). However, chemical-related deformations (strains) caused by the materials' hydration/dehydration pose serious technological challenges for fabricating multilayered (cer-cer, cer-met, and cer-glass) assemblies. Therefore, studying both thermal and chemical expansions of PCEs is crucial. This work presents in-depth high-temperature characterization of Sc-doped BaSnO3 compounds (BaSn1−xScxO3−δ) in terms of their thermochemical expansion behavior. This characterization includes high-temperature X-ray diffraction and dilatometry analyses under various measuring conditions. On one hand, the collected data can serve as technological characteristics for the selection of appropriate functional materials. On the other hand, the thermochemical expansion data can be used to evaluate the thermodynamic parameters (enthalpy and entropy of hydration) and transport parameters (water chemical diffusion coefficient and chemical surface exchange constant) of PCEs. The latter was shown in the present work for the first time. This paves a new way to reveal the relationships between the composition, structure, thermochemical response, and transport properties of complex oxides capable of reversible water uptake.
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.
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