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E. A. Osipova

Publications and source records attributed to E. A. Osipova.

12 recordsLinked to original sources
arXiv2024

Four years of wide-field search for nanosecond optical transients with the TAIGA-HiSCORE Cherenkov array

It has been previously demonstrated [Panov et al. Physics of Atomic Nuclei 84(2021)1037] that the TAIGA-HiSCORE Cherenkov array, originally built for cosmic ray physics and ultrahigh-energy gamma-ray astronomy studies using the extensive air shower method, can be used in conventional optical astronomy for wide-field searches for rare nanosecond optical transients of astrophysical origin. The FOV of the facility is on the scale of 1~ster, and it is capable of detecting very rare transients in the visible light range with fluxes greater than approximately 3000~quanta/m$^2$/10~ns (10~ns is the apparatus integration time) and pulse durations of 10\,ns. Among the potential sources of distant nanosecond optical transients are the evaporation of primary black holes, magnetic reconnection in the accretion disks of black holes, and signals from distant lasers of extraterrestrial civilizations. The paper describes the methods and results of the search for optical transients using the TAIGA-HiSCORE Cherenkov array from 2018 to 2022 (four winter seasons of data collection). No reliable astrophysical candidates for optical transients were found. We set an upper bound on the flux of the searched events as $\sim 1\times10^{-3}$\,events/ster/h.

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arXiv2021

Search for Astrophysical Nanosecond Optical Transients with TAIGA-HiSCORE Array

A wide-angle Cerenkov array TAIGA-HiSCORE (FOV $\sim$0.6 sr), was originally created as a part of TAIGA installation for high-energy gamma-ray astronomy and cosmic ray physics. Array now consist on nearly 100 optical stations on the area of 1 km$^2$. Due to high accuracy and stability ($\sim$1 ns) of time synchronization of the optical stations the accuracy of EAS arrival direction reconstruction is reached 0.1$^\mathrm{o}$. It was proven that the array can also be used to search for nanosecond events of the optical range. The report discusses the method of searching for optical transients using the HiSCORE array and demonstrates its performance on a real example of detecting signals from an artificial Earth satellite. The search for this short flares in the HiSCORE data of the winter season 2018--2019 is carried out. One candidate for double repeater has been detected, but the estimated probability of random simulation of such a transient by background EAS events is not less than 10%, which does not allow us to say that the detected candidate corresponds to a real astrophysical transient. An upper bound on the frequency of optical spikes with flux density of more than $10^{-4} \mathrm{erg/s/cm}^2$ and a duration of more than 5\,ns is established as $\sim 2 \times 10^{-3}$ events/sr/hour.

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arXiv2021

The primary cosmic-ray energy spectrum measured with the Tunka-133 array

The EAS Cherenkov light array Tunka-133, with $\sim$ 3 km$^2$ geometric area, is taking data since 2009.The array permits a detailed study of energy spectrum and mass composition of cosmic rays in the energy range from $6\cdot 10^{15}$ to $10^{18}$ eV. We describe the methods of time and amplitude calibration of the array and the methods of EAS parameters reconstruction. We present the all-particle energy spectrum, based on 7 seasons of operation.

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arXiv2017

Towards a cosmic-ray mass-composition study at Tunka Radio Extension (ARENA 2016)

The Tunka Radio Extension (Tunka-Rex) is a radio detector at the TAIGA facility located in Siberia nearby the southern tip of Lake Baikal. Tunka-Rex measures air-showers induced by high-energy cosmic rays, in particular, the lateral distribution of the radio pulses. The depth of the air-shower maximum, which statistically depends on the mass of the primary particle, is determined from the slope of the lateral distribution function (LDF). Using a model-independent approach, we have studied possible features of the one-dimensional slope method and tried to find improvements for the reconstruction of primary mass. To study the systematic uncertainties given by different primary particles, we have performed simulations using the CONEX and CoREAS software packages of the recently released CORSIKA v7.5 including the modern high-energy hadronic models QGSJet-II.04 and EPOS-LHC. The simulations have shown that the largest systematic uncertainty in the energy deposit is due to the unknown primary particle. Finally, we studied the relation between the polarization and the asymmetry of the LDF.

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arXiv2017

Imporoving reconstrucion methods for radio measurements with Tunka-Rex

Tunka-Rex is detector for radio emission produced by cosmic-ray air-showers located in Siberia, triggered by Tunka-133, a co-located air-Cherenkov detector during night, and by a scintillator array Tunka-Grande during day. Tunka-Rex demonstrates that the radio technique can provide a cost-effective extension of existing air-shower arrays. Operating in the frequency range of 30-80 MHz, Tunka-Rex is limited by the galactic background, and suffers from the local radio interferences. We investigate the possibilities of the improving of measured data using different approaches, particularly, the multivariate background suppression is considered, as well as improved likelihood fit of the lateral distribution of amplitudes.

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arXiv2017

Tunka-Rex: energy reconstruction with a single antenna station (ARENA 2016)

The Tunka-Radio extension (Tunka-Rex) is a radio detector for air showers in Siberia. From 2012 to 2014, Tunka-Rex operated exclusively together with its host experiment, the air-Cherenkov array Tunka-133, which provided trigger, data acquisition, and an independent air-shower reconstruction. It was shown that the air-shower energy can be reconstructed by Tunka-Rex with a precision of 15\% for events with signal in at least 3 antennas, using the radio amplitude at a distance of 120\,m from the shower axis as an energy estimator. Using the reconstruction from the host experiment Tunka-133 for the air-shower geometry (shower core and direction), the energy estimator can in principle already be obtained with measurements from a single antenna, close to the reference distance. We present a method for event selection and energy reconstruction, requiring only one antenna, and achieving a precision of about 20\%. This method increases the effective detector area and lowers thresholds for zenith angle and energy, resulting in three times more events than in the standard reconstruction.

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arXiv2017

Tunka-Rex: Status, Plans, and Recent Results (ARENA 2016)

Tunka-Rex, the Tunka Radio extension at the TAIGA facility (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy) in Siberia, has recently been expanded to a total number 63 SALLA antennas, most of them distributed on an area of one square kilometer. In the first years of operation, Tunka-Rex was solely triggered by the co-located air-Cherenkov array Tunka-133. The correlation of the measurements by both detectors has provided direct experimental proof that radio arrays can measure the position of the shower maximum. The precision achieved so far is 40 g/cm^2, and several methodical improvements are under study. Moreover, the cross-comparison of Tunka-Rex and Tunka-133 shows that the energy reconstruction of Tunka-Rex is precise to 15 %, with a total accuracy of 20 % including the absolute energy scale. By using exactly the same calibration source for Tunka-Rex and LOPES, the energy scale of their host experiments, Tunka-133 and KASCADE-Grande, respectively, can be compared even more accurately with a remaining uncertainty of about 10 %. The main goal of Tunka-Rex for the next years is a study of the cosmic-ray mass composition in the energy range above 100 PeV: For this purpose, Tunka-Rex now is triggered also during daytime by the particle detector array Tunka-Grande featuring surface and underground scintillators for electron and muon detection.

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arXiv2017

Latest results of the Tunka Radio Extension (ISVHECRI2016)

The Tunka Radio Extension (Tunka-Rex) is an antenna array consisting of 63 antennas at the location of the TAIGA facility (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy) in Eastern Siberia, nearby Lake Baikal. Tunka-Rex is triggered by the air-Cherenkov array Tunka-133 during clear and moonless winter nights and by the scintillator array Tunka-Grande during the remaining time. Tunka-Rex measures the radio emission from the same air-showers as Tunka-133 and Tunka-Grande, but with a higher threshold of about 100 PeV. During the first stages of its operation, Tunka-Rex has proven, that sparse radio arrays can measure air-showers with an energy resolution of better than 15\% and the depth of the shower maximum with a resolution of better than 40 g/cm\textsuperscript{2}. To improve and interpret our measurements as well as to study systematic uncertainties due to interaction models, we perform radio simulations with CORSIKA and CoREAS. In this overview we present the setup of Tunka-Rex, discuss the achieved results and the prospects of mass-composition studies with radio arrays.

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arXiv2016

A comparison of the cosmic-ray energy scales of Tunka-133 and KASCADE-Grande via their radio extensions Tunka-Rex and LOPES

The radio technique is a promising method for detection of cosmic-ray air showers of energies around $100\,$PeV and higher with an array of radio antennas. Since the amplitude of the radio signal can be measured absolutely and increases with the shower energy, radio measurements can be used to determine the air-shower energy on an absolute scale. We show that calibrated measurements of radio detectors operated in coincidence with host experiments measuring air showers based on other techniques can be used for comparing the energy scales of these host experiments. Using two approaches, first via direct amplitude measurements, and second via comparison of measurements with air shower simulations, we compare the energy scales of the air-shower experiments Tunka-133 and KASCADE-Grande, using their radio extensions, Tunka-Rex and LOPES, respectively. Due to the consistent amplitude calibration for Tunka-Rex and LOPES achieved by using the same reference source, this comparison reaches an accuracy of approximately $10\,\%$ - limited by some shortcomings of LOPES, which was a prototype experiment for the digital radio technique for air showers. In particular we show that the energy scales of cosmic-ray measurements by the independently calibrated experiments KASCADE-Grande and Tunka-133 are consistent with each other on this level.

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arXiv2014

Search for neutrino emission from relic dark matter in the Sun with the Baikal NT200 detector

We have analyzed a data set taken over 2.76 years live time with the Baikal neutrino telescope NT200. The goal of the analysis is to search for neutrinos from dark matter annihilation in the center of the Sun. Apart from the conventional annihilation channels $b\bar{b}$, $W^+W^-$ and $τ^+τ^-$ we consider also the annihilation of dark matter particles into monochromatic neutrinos. From the absence of any excess of events from the direction of the Sun over the expected background, we derive 90% upper limits on the fluxes of muons and muon neutrinos from the Sun, as well as on the elastic cross sections of dark matter scattering on protons.

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arXiv2013

The prototyping/early construction phase of the BAIKAL-GVD project

The Prototyping phase of the BAIKAL-GVD project has been started in April 2011 with the deployment of a three string engineering array which comprises all basic elements and systems of the Gigaton Volume Detector (GVD) in Lake Baikal. In April 2012 the version of engineering array which comprises the first full-scale string of the GVD demonstration cluster has been deployed and operated during 2012. The first stage of the GVD demonstration cluster which consists of three strings is deployed in April 2013. We review the Prototyping phase of the BAIKAL-GVD project and describe the configuration and design of the 2013 engineering array.

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