Персона: Колдобский, Сергей Александрович
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Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
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- ПубликацияТолько метаданныеHelium Fluxes Measured by the PAMELA Experiment from the Minimum to the Maximum Solar Activity for Solar Cycle 24(2022) Marcelli, N.; Boezio, M.; Lenni, A.; Menn, W.; Galper, A. M.; Koldashov, S. V.; Koldobskiy, S.; Leonov, A. A.; Malakhov, V. V.; Mayorov, A. G.; Mikhailov, V. V.; Spillantini, P.; Voronov, S. A.; Yurkin, Y. T.; Колдобский, Сергей Александрович; Леонов, Алексей Анатольевич; Малахов, Виталий Валерьевич; Майоров, Андрей Георгиевич; Михайлов, Владимир Владимирович; Воронов, Сергей Александрович; Юркин, Юрий Тихонович© 2022. The Author(s). Published by the American Astronomical Society..Time-dependent energy spectra of galactic cosmic rays (GCRs) carry fundamental information regarding their origin and propagation. When observed at the Earth, these spectra are significantly affected by the solar wind and the embedded solar magnetic field that permeates the heliosphere, changing significantly over an 11 yr solar cycle. Energy spectra of GCRs measured during different epochs of solar activity provide crucial information for a thorough understanding of solar and heliospheric phenomena. The PAMELA experiment collected data for almost 10 years (2006 June 15-2016 January 23), including the minimum phase of solar cycle 23 and the maximum phase of solar cycle 24. In this paper, we present new spectra for helium nuclei measured by the PAMELA instrument from 2010 January to 2014 September over a three-Carrington-rotation time basis. These data are compared to the PAMELA spectra measured during the previous solar minimum, providing a picture of the time dependence of the helium-nuclei fluxes over a nearly full solar cycle. Time and rigidity dependencies are observed in the proton-to-helium flux ratios. The force-field approximation of the solar modulation was used to relate these dependencies to the shapes of the local interstellar proton and helium-nuclei spectra.
- ПубликацияТолько метаданныеUpdated Neutron-Monitor Yield Function: Bridging Between In Situ and Ground-Based Cosmic Ray Measurements(2020) Mishev, A. L.; Koldobskiy, S. A.; Kovaltsov, G. A.; Gil, A.; Колдобский, Сергей АлександровичAn updated yield function for a standard NM64 neutron monitor (NM) is computed and extended to different atmospheric depths from sea level to 500 g/cm(2) (similar to 5.7 km altitude) and is presented as lookup tables and a full parametrization. The yield function was validated using the cosmic ray spectra directly measured in space by the AMS-02 experiment during the period May 2011 through May 2017 and confronted with count rates of all NM64-type NMs being in operation during this period. Using this approach, stability of all the selected NMs was analyzed for the period 2011-2017. Most of NMs appear very stable and suitable for studies of long-term solar modulation of cosmic rays. However, some NMs suffer from instabilities like trends, apparent jumps, or strong seasonal waves in the count rates.
- ПубликацияТолько метаданныеSearch for Albedo Tritium with PAMELA Experiment(2019) Koldobskiy, S. A.; Voronov, S. A.; Колдобский, Сергей Александрович; Воронов, Сергей Александрович© 2019, Pleiades Publishing, Ltd.Particles of albedo radiation are the particles born in interactions of primary cosmic rays penetrating inside Earth’s atmosphere and magnetosphere and the atmosphere nuclei. These interactions result in so-called particle showers and the detection of these showers is the essence of work for ground-based cosmic-ray detectors such as neutron monitors, muon hodoscopes and EAS arrays. Some products of these interactions undergoing by scattering and having the curve paths in geomagnetic field propagate upwards to the boundary of Earth’s magnetosphere. These particles are called albedo particles. The principle of their identification is simple. They are registered in geomagnetic zones where the penetration of low-energy galactic or solar cosmic rays is restricted due to Earth’s magnetic field. The results of measurements of albedo protons, deuterons, electrons and positrons has been already published by PAMELA collaboration. In this work the first approach to search for the albedo tritium nuclei with energies above 100 MeV/nucleon is described.
- ПубликацияТолько метаданныеEast-West Proton Flux Anisotropy Observed with the PAMELA Mission(2021) Bruno, A.; Martucci, M.; Cafagna, F. S.; Sparvoli, R.; Galper, A. M.; Koldashov, S. V.; Koldobskiy, S.; Leonov, A. A.; Malakhov, V. V.; Mayorov, A. G.; Mikhailov, V. V.; Spillantini, P.; Voronov, S. A.; Yurkin, Y. T.; Колдобский, Сергей Александрович; Леонов, Алексей Анатольевич; Малахов, Виталий Валерьевич; Майоров, Андрей Георгиевич; Михайлов, Владимир Владимирович; Воронов, Сергей Александрович; Юркин, Юрий Тихонович© 2021. The American Astronomical Society. All rights reserved..We present a study of the east-west anisotropy of trapped-proton fluxes in low-Earth orbit based on the measurements of the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) experiment. The differential intensities of eastward- and westward-traveling protons detected in the South Atlantic Anomaly region were estimated as a function of equatorial pitch angle and drift shell, for six energy bins between 80 MeV and 2 GeV. We found that, as a consequence of the strong atmospheric gradient coupled with the large gyroradius in this energy range, the intensities of eastward fluxes exceed those of westward fluxes by a factor of ∼10-20. However, the reported directional asymmetry also depends on the sign of the local flux gradient, resulting in more intense westward fluxes beyond the radial distances where the inner belt peaks. PAMELA observations can be used to improve the description of the near-Earth radiation environment at lowest altitudes and highest trapping energies, where current theoretical and empirical models are affected by the largest uncertainties.
- ПубликацияТолько метаданныеApplication of verified neutron monitor yield function for GLE analysis(2022) Mishev, A.; Usoskin, I.; Koldobskiy, S.; Kovaltsov, G.; Kocharov, L.; Колдобский, Сергей АлександровичSystematic study of solar energetic particles provides an important basis to understand their acceleration and propagation in the interplanetary space. After solar eruptive processes, such as solar flares and/or coronal mass ejections, solar ions are accelerated to high energy. In the majority of cases, the maximum energy of the accelerated solar ions is several tens of MeV/nucleon, but in some cases, it exceeds 100 MeV/nucleon or even reaches the GeV/nucleon range. In this case, the energy is high enough, so that solar ions generate an atmospheric cascade in the Earth’s atmosphere, whose secondary particles reach the ground, being eventually registered by ground-based detectors, specifically neutron monitors. This particular class of events is known as ground-level enhancements (GLEs). Several methods for analysis of GLEs, using neutron monitor data were developed over the years. Here, we present a method for assessment of the spectral and angular characteristics of the GLEs using data from the world-wide NM network, namely by modeling the global neutron monitor network response with a new verified yield function. The method is based on consecutive steps, specifically detailed computation of asymptotic cones and rigidity cut-off of each station used in the analysis and optimization of the global neutron monitor response over experimental and modeled count rate increases. The method is compared with other methods, including in-situ measurements. A very good agreement between our method and space-borne measurements with PAMELA space probe, specifically the derived fluence of solar protons during GLE 71 was achieved, therefore verification of the method is performed. © Copyright owned by the author(s).
- ПубликацияТолько метаданныеA major update of the International GLE Database: Correction for the variable GCR background(2022) Usoskin, I.; Koldobskiy, S.; Kovaltsov, G.; Gil, A.; Usoskina, I.; Willamo, T.; Ibragimov, A.; Колдобский, Сергей АлександровичThe main detector to provide data to study highly energetic (above ≈400 MeV) solar particles is the network of ground-based neutron monitors (NMs). Solar events recorded on the ground are called ground-level enhancements (GLEs). All GLE-related data from the NM network are collected in the International GLE Database (IGLED, https://gle.oulu.fi), which provides formal NM count-rate increases above the constant pre-increase level which is due to galactic cosmic rays (GCR). However, the basic formal assumption that the GCR background level remains constant throughout a GLE event is often violated. We have carefully revised the IGLED and provided a new data set of de-trended NM count-rate increases that accounts for the variable GCR background. This had led to a significant revision of the corresponding integral omnidirectional fluences of solar particles reconstructed from the GLE data. The database of the de-trended NM count rate is revised for most GLE events since 1956. Integral omnidirectional fluences were re-assessed for 58 GLE events and parameterized for 52 reasonably strong events by applying the modified Ellison-Ramaty spectral shape. This forms a basis for more precise studies of parameters of solar energetic particle events and thus for solar and space physics. © Copyright owned by the author(s).
- ПубликацияТолько метаданныеThe Cross Section of the Inelastic Interaction of Protons with the Tungsten Obtained with the PAMELA Space Experiment(2019) Golub, O. A.; Mayorov, A. G.; Koldobskiy, S.; Malakhov, V.; Yulbarisov, R. F.; Голуб, Ольга Александровна; Майоров, Андрей Георгиевич; Колдобский, Сергей Александрович; Малахов, Виталий Валерьевич; Юлбарисов, Рустам Фаритович© 2019, Pleiades Publishing, Ltd.We present the energy dependence of the cross section for the inelastic interaction of protons with tungsten in the energy range from an order of 1 to hundred GeV using the data of the PAMELA space experiment. It was intended for the precision measurements of the cosmic ray fluxes of different nature and include a set of detectors for the reliable determination of the particle characteristics. We present the comparison of the obtained results with the measurements at accelerators and with existing theoretical models. The results of the work can be demanded for the development of numerical models describing particles’ interactions.
- ПубликацияТолько метаданныеTime Lag Between Cosmic-Ray and Solar Variability: Sunspot Numbers and Open Solar Magnetic Flux(2022) Kahkonen, R.; Hofer, B.; Krivova, N. A.; Usoskin, I. G.; Koldobskiy, S. A.; Kovaltsov, G. A.; Колдобский, Сергей Александрович© 2022, The Author(s).Solar magnetic activity drives the dominant 11-year cyclic variability of different space environmental indices, but they can be delayed with respect to the original variations due to the different physical processes involved. Here, we analyzed the pairwise time lags between three global solar and heliospheric indices: sunspot numbers (SSN), representing the solar surface magnetic activity, the open solar flux (OSF), representing the heliospheric magnetic variability, and the galactic cosmic-ray (GCR) intensity near Earth, using the standard cross-correlation and the more detailed wavelet-coherence methods. All the three indices appear highly coherent at a timescale longer than a few years with persistent high coherence at the timescale of the 11-year solar cycle. The GCR variability is delayed with respect to the inverted SSN by about eight 27-day Bartels rotations on average, but the delay varies greatly with the 22-year cycle, being shorter or longer around positive A+ or negative A− solar polarity epochs, respectively. The 22-year cyclicity of the time lag is determined by the global heliospheric drift effects, in agreement with theoretical models. The OSF lags by about one year behind SSN, and is likely determined by a combination of the short lifetime of active regions and a longer (≈3 years) transport time of the surface magnetic field to the poles. GCRs covary nearly in antiphase with the OSF, also depicting a strong 22-year cycle in the delay, confirming that the OSF is a good index of the heliospheric modulation of GCRs. This provides an important observational constraint for solar and heliospheric physics.
- ПубликацияТолько метаданныеCosmic ray electron and positron spectrum with the PAMELA experiment(2019) Adriani, O.; Barbarino, G.; Bazilevskaya, G. A.; Bellotti, R.; Mikhailov, V. V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S. A.; Leonov, A. A.; Malakhov, V. V.; Mayorov, A. G.; Spillantini, P.; Voronov, S. A.; Yurkin, Yu. T.; Михайлов, Владимир Владимирович; Колдобский, Сергей Александрович; Леонов, Алексей Анатольевич; Малахов, Виталий Валерьевич; Майоров, Андрей Георгиевич; Воронов, Сергей Александрович; Юркин, Юрий Тихонович© Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).The PAMELA magnetic spectrometer, located on board the Resurs-DK1 satellite on Earth polar orbit with altitude of 350-600 km, measured the fluxes of cosmic ray particles and antiparticles in a wide energy range from 50 MeV to several TeVs. In this paper new results on the "all-electron" (sum electrons and positrons) spectrum are presented. New improved analysis on the full data set from 2006 to 2016 allows a significant increase in statistic compared to previously published results and an extension of energy interval up to 1 TeV.
- ПубликацияТолько метаданныеRole of heavier-than-proton nuclei in neutron monitor response(2022) Koldobskiy, S. A.; Kovaltsov, G.; Usoskin, I.; Колдобский, Сергей АлександровичHeavier-than-proton nuclei in cosmic rays are responsible for up to 45% of neutron monitor (NM) response depending on the level of solar modulation as well as the geomagnetic rigidity cutoff and altitude of a given NM location. Therefore, careful consideration of these heavy species is important for an accurate analysis of NM data, including a reconstruction of the solar modulation potential using the worldwide NM network data. Recently, the AMS-02 experiment allowed us to directly verify the NM response to heavy particles. In this work, we evaluate the expected contribution of heavy nuclei into the NM response considering different models of the local interstellar spectrum and also for different levels of solar activity. © Copyright owned by the author(s) under the terms of the Creative Commons.