The Carpet facility of the Baksan Neutrino Observatory (Institute for Nuclear Research of the Russian Academy of Sciences) was put into operation in 1974. However, it has been modernized more than ...once and extended and continues to function according to several research programs. In this paper a review is given of the main results in the field of UHE gamma ray astronomy that were obtained with the Carpet array over the entire time of its operation. The current status of the array and a new stage in its development are also discussed.
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.
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► The surface activity of SDS is increased due to presence of bivalent ions. ► In presence of bivalent ions double chain surfactants like Ca(DS)2 can be formed. ► The hydrolysis of ...SDS is enhanced in NaCl solutions, producing dodecanol. ► Bivalent ions further enhance the SDS hydrolysis in solution. ► SDS in hard water represents a multicomponent surfactant solution.
The complementary drop and bubble profile analysis and maximum bubble pressure tensiometry are used to measure the dynamic surface tension of aqueous SDS solutions in the presence of hardness salts (CaCl2 and MgCl2 in the ratio of 2:1 at concentrations of 6 and 40FH). The presence of hardness salts results in an essential increase of the SDS adsorption activity, which indicates the formation of Ca(DS)2 and Mg(DS)2 in the SDS solutions. The surface tension isotherms of SDS in presence of Ca(DS)2 and Mg(DS)2 are described using the generalised Frumkin model.
The presence of hardness salts accelerates the ageing of SDS solutions as compared with the addition of 0.01M NaCl due to a faster hydrolysis and hence formation of dodecanol. These results are used to estimate the possible concentration of dodecanol in the studied SDS solutions.
The buoyant bubble profile method with harmonic surface oscillations is used to measure the dilational rheology of SDS solutions in presence of hardness salts in the frequency range between 0.005Hz and 0.2Hz. The visco-elasticity modulus in the presence of hardness salts is higher as compared with its values in the presence of 0.01M NaCl additions. The ageing of SDS solutions leads to an essential increase of the visco-elastic modulus.
Neutrino Burst Monitoring in Our Galaxy Novoseltsev, Yu. F.; Dzaparova, I. M.; Kochkarov, M. M. ...
Journal of experimental and theoretical physics,
04/2022, Volume:
134, Issue:
4
Journal Article
Peer reviewed
Baksan underground scintillation telescope (BUST) operates under the program of neutrino burst search since the middle of 1980. We report the current status of the experiment and the results ...associated with analysis of background events and facility operation stability. We demonstrate the BUST potentialities in detecting neutrino bursts from close supernovae. Over the period from 30.06.1980 to 30.06.2021, the observation time is 35.5 years. During this time, not a single candidate for a neutrino burst has been registered. This leads to an upper bound of the mean frequency of gravitational collapses of stars in our Galaxy of 0.065 year
–1
at the 90% confidence level.
We present the earliest astronomical observation of a high-energy neutrino error box of which the variability was discovered after high-energy-neutrino detection. The one robotic telescope of the ...MASTER global international networks automatically imaged the error box of the very high-energy-neutrino event IceCube-170922A. Observations were carried out in minutes after the IceCube-170922A neutrino event was detected by the IceCube observatory at the South Pole. MASTER found the blazar TXS 0506+056 to be in the off-state after one minute and then switched to the on-state no later than two hours after the event. The effect is observed at a 50 significance level. We also present own a unique 16 yr light curve of blazar TXS 0506+056 (518 data set).
The adsorption kinetics, adsorption isotherm and the dilational surface rheology at low oscillation frequencies of sodium dodecyl sulphate (SDS) were studied by drop and bubble profile, and bubble ...pressure tensiometry. The effect of the inevitably present dodecanol in any SDS solution is taken into account by interpreting the experimental data with theoretical models valid for mixed surfactant solutions. In particular the dilational rheology method appears to be very suitable for demonstrating the continuously on-going hydrolysis reaction in a SDS solution, as the resulting dilational elasticities and viscosities change from a frequency dependencies characteristic to SDS to those expected for dodecanol adsorption layers. For surfactants as active as dodecanol, it turns out that all adsorption and rheological quantities depend significantly on the use of drop or bubble profile tensiometry, i.e. the small reservoir of available surface active molecules in a single droplet has to be considered quantitatively to obtain reliable data.
A current status of the project of a large volume scintillation telescope at the Baksan neutrino observatory is presented. The main research activities of the BLVST are low- energy neutrino physics, ...astrophysics and geophysics. To detect geoneutrinos, large-scale new- generation scintillator detectors located at large depths in the regions with a low background level from nuclear reactors are required. The Baksan Neutrino Observatory is geographically located in one of these places. Recently resumed R&D activities are aimed at the creation of new-generation telescope with a target mass of 10 kt at a depth of 4800 m.w.e. A small scale prototype is already under construction.
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.
The article reports on the current status of the Baksan Large Neutrino Telescope project and describes some selective results of the first stage of the project, a detector prototype with a liquid ...scintillator mass of 0.5 tons. The results of the second stage of the project, a prototype with liquid scintillator mass of 5 tons, and project prospects also presented.
Abstract
The LIGO/Virgo collaborations have reported the results of their searches for gravitational-waves from the first half of their third observing run. 39 events were combined into the second ...Gravitational-Wave Transient Catalog (GWTC-2), reaching the total number of 50. In addition to these, two neutron star - black hole merger events were also confirmed. The search for neutrino counterparts of LIGO/Virgo gravitational-wave events was performed on the Baksan Underground Scintillation Telescope. The processing algorithm and the results of the counterpart search are described.
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