Abstract
Galactic sites of acceleration of cosmic rays to energies of order 10
15
eV and higher, dubbed PeVatrons, reveal themselves by recently discovered gamma radiation of energies above 100 TeV. ...However, joint gamma-ray and neutrino production, which marks unambiguously cosmic-ray interactions with ambient matter and radiation, was not observed until now. In 2020 November, the IceCube neutrino observatory reported an ∼150 TeV neutrino event from the direction of one of the most promising Galactic PeVatrons, the Cygnus Cocoon. Here we report on the observation of a 3.1
σ
(post-trial) excess of atmospheric air showers from the same direction, observed by the Carpet–2 experiment and consistent with a few months flare in photons above 300 TeV, in temporal coincidence with the neutrino event. The fluence of the gamma-ray flare is of the same order as that expected from the neutrino observation, assuming the standard mechanism of neutrino production. This is the first evidence for the joint production of high-energy neutrinos and gamma-rays in a Galactic source.
We analyzed characteristics of diffusion and its kurtosis obtained using diffusion-kurtosis MRI in the hemisphere contralateral to the one affected by acute cerebrovascular accident. Diffusion ...characteristics in the white and gray matter were compared using analysis of covariance (ANCOVA) in healthy subjects and stroke patients with consideration for the age and sex factors. Significant differences between the groups were revealed for apparent diffusion coefficient and mean kurtosis in the white matter. Age dependence was studied using regression analysis and, according to the results of ANCOVA, this factor was found to be significant for apparent diffusion coefficient and diffusion kurtosis in the white matter. Metrics are proposed that can be used to determine the risk of stroke.
We report on the search of astrophysical gamma rays with energies in the 100 TeV to several PeV range arriving in directional and temporal coincidence with public alerts from HAWC (TeV gamma rays) ...and IceCube (neutrinos above ∼ 100TeV). The observations have been performed with the Carpet-2 air-shower detector at the Baksan Neutrino Observatory, working in the “photon-friendly” mode since 2018. Photon candidate showers are selected by their low muon content. No significant excess of the photon candidates have been observed, and upper limits on gamma-ray fluences associated with the alerts are obtained. For events with good viewing conditions, the Carpet-2 effective area for photons is of the order of the IceCube effective area for neutrinos of the same energy, so the constraints start to probe the production of neutrinos in fast flares of Galactic sources.
Isotropic diffuse gamma-ray flux in the PeV energy band is an important tool for multimessenger tests of models of the origin of high-energy astrophysical neutrinos and for new-physics searches. So ...far, this flux has not yet been observed. Carpet-2 is an air-shower experiment capable of detecting astrophysical gamma rays with energies above 0.1 PeV. Here we report the upper limits on the isotropic gamma-ray flux from Carpet-2 data obtained in 1999–2011 and 2018–2022. These results, obtained with the new statistical method based on the shape of the muon-number distribution, summarize Carpet-2 observations as the upgraded installation, Carpet-3, starts its operation.
The evolution of bubble cavitation behind the front of a converging cylindrical rarefaction wave in distilled water containing micro inhomogeneities is investigated numerically within the framework ...IKvanW mathematical model. The dynamics of the cavitation zone state is considered in a one-dimensional formulation with cylindrical symmetry. A thin liquid layer bounded by the free surface is loaded by a shock wave generated by a piston coaxial the axis of symmetry. As a result of shock wave reflection from free surface, a rarefaction wave converging toward the axis of symmetry is formed. The influence of the initial size of microbubbles, gas phase concentration, and parameters of shock wave loading on the dynamics offormation of the cavitation zone and its growth in the course of rarefaction wave focusing is analyzed.
The results of studies of a conformal broadband applicator antenna for microwave radiothermometry based on a flexible substrate and textile technologies are presented. Grounds are given for the ...design and selection of structural materials for implementation of the antenna. Results obtained from calculation of the standing wave ratio (SWR), the measurement depth of the antenna, and the distribution of radiation power through the volume of the biological tissue are presented. The working frequency band of the textile antenna was 1400 MHz and the measurement depth for breast tissues was 40 mm.
The article considers stochastic mathematical models for thermolysis kinetics of complex oil-like hydrocarbon systems using mathematical statistics and the theory of random processes. Mathematical ...modeling shows that the thermolysis process is collective, nonergodic, and nonstationary. The criteria for which hydrocarbon systems obey the first order and Avrami kinetic laws are established. Using the example of thermolysis of high-viscosity Al’shacha oil, it is shown that the kinetics of the release of gaseous products of thermolysis are better described by models of stationary kinetics, and the yield of residues and distillates is better described by models of nonstationary kinetics. The established regularities can be used in modeling thermal and thermocanalytic processes of petrochemistry and oil refining.
In the present work we report on the observation of an excess of gamma-ray candidate events in temporal and spatial coincidence with the IceCube high-energy neutrino alert consistent with the origin ...in the Cygnus Cocoon region. The observations have been performed with Carpet-2, a surface air-shower detector equipped with a large-area muon detector at the Baksan Neutrino Observatory in the Northern Caucasus. As well as we report about the current state of the Carpet-3 facility, which includes a muon detector with an increased area and an expanded surface array. The main aim of the Carpet-3 facility is the registration of cosmic gamma-rays with energy larger than 100 TeV. Moreover, it gives a possibility to carry out research on the composition of primary cosmic rays around the knee. It is planned that the Carpet-3 EAS array will be operation by the end of 2021.
A new method of focusing the rarefaction wave in a one-dimensional axisymmetric formulation is proposed. The method is based on shock wave generation initiated by motion of a piston coaxial with the ...axis of symmetry with a prescribed pulse profile for the maximum velocities of 20 to 100 m/s and the exponent decay constant up to 10 μs. It is found that reflection of the shock wave from the free boundary generates a rarefaction wave propagating toward the axis of symmetry with increasing amplitude, and a cavitation zone is formed and developed behind the wave front.
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