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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Сергей Александрович
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- 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 метаданныеRevisited Reference Solar Proton Event of 23 February 1956: Assessment of the Cosmogenic-Isotope Method Sensitivity to Extreme Solar Events(2020) Usoskin, I. G.; Kovaltsov, G. A.; Rozanov, E. V.; Sukhodolov, T. V.; Koldobskiy, S. A.; Колдобский, Сергей Александрович©2020. The Authors.Our direct knowledge of solar eruptive events is limited to several decades and does not include extreme events, which can only be studied by the indirect proxy method over millennia, or by a large number of Sun-like stars. There is a gap, spanning 1–2 orders of magnitude, in the strength of events between directly observed and reconstructed ones. Here, we study the proxy method sensitivity to identify extreme solar particle events (SPEs). First, the strongest directly observed SPE (23 February 1956), used as a reference for proxy-based reconstructions, was revisited using the newly developed method. Next, sensitivity of the cosmogenic-isotope method to detect a reference SPE was assessed against the precision and number of individual isotopic records, showing that it is too weak by a factor ≈30 to be reliably identified in a single record. Uncertainties of 10Be and 14C data are shown to be dominated by local/regional patterns and measurement errors, respectively. By combining several proxy records, a SPE 4–5 times stronger than the reference one can be potentially detected, increasing the present-day sensitivity by an order of magnitude. This will allow filling the observational gap in SPE strength distribution, thus enriching statistics of extreme events from 3–4 presently known ones to several tens. This will provide a solid basis for research in the field of extreme events, both for fundamental science, namely solar and stellar physics, and practical applications, such as the risk assessments of severe space-based hazards for modern technological society.
- ПубликацияТолько метаданныеThe 3D numerical modeling of the solar modulation of galactic protons and helium nuclei related to observations by PAMELA between 2006 and 2009(2020) Ngobeni, M. D.; Aslam, O. P. M.; Bisschoff, D.; Potgieter, M. S.; Mikhailov, V. V.; Koldobskiy, S. A.; Михайлов, Владимир Владимирович; Колдобский, Сергей Александрович© 2020, Springer Nature B.V.The global features of the modulation of galactic cosmic ray protons and helium nuclei in a very quiet heliosphere are studied with a comprehensive, three-dimensional, drift model and compared to proton and helium observations measured by PAMELA from 2006 to 2009. Combined with accurate very local interstellar spectra (VLIS) for protons and helium nuclei, this provides the opportunity to study in detail how differently cosmic ray species with dissimilar mass-to-charge ratio (A/ Z) are modulated down to a few GV. The effects at Earth of the difference in their VLIS’s and those caused by the main modulation mechanisms are illustrated. We find that both the PAMELA proton and helium spectra are reproduced well with the numerical model, assuming the same set of modulation parameters and diffusion coefficients. A comparative study of 3He2 (He-3) and 4He2 (He-4) modulated spectra reveals that they do not undergo identical spectral changes below 3 GV mainly due to differences in their VLIS’s. This result is important to uncover and investigate the effects on the proton to total helium ratio (p/He) caused by the difference in their VLIS’s and those by A/ Z. The computed p/He displays three modulation regimes, reflecting the complex interplay of modulation processes in the heliosphere. At rigidities above ∼3 GV, the p/He ratio at the Earth is found to deviate modestly from a value of ∼5.5, largely independent of the assumed modulation conditions. This result indicates that the PAMELA measurement of p/He reveals at these rigidities the shapes of their VLIS’s. Below ∼0.6 GV, p/He increases with decreasing rigidity from 2006 to 2009 and significant variations are predicted depending on the assumed solar modulation conditions. This result indicates that as modulation levels decreased from 2006 to 2009, the contribution of adiabatic energy changes dissipated faster for protons than for helium nuclei at the same rigidity mainly due to different slopes of their VLIS’s. The differences between modulation effects for protons and helium are found to be the consequence of how the combined interplaying modulation mechanisms in the heliosphere affect the modulated spectra based on their A/ Z and particularly on their VLIS’s.
- ПубликацияТолько метаданныеRevised GLE database: Fluences of solar energetic particles as measured by the neutron-monitor network since 1956(2020) Usoskin, I.; Koldobskiy, S.; Kovaltsov, G. A.; Gil, A.; Колдобский, Сергей АлександровичAims. Continuous measurements of ground-based neutron monitors (NMs) form the main data source for studying high-energy high-intensity solar energetic particle (SEP) events that are called ground-level enhancements (GLEs). All available data are collected in the International GLE Database (IGLED), which provides formal NM count-rate increases above the constant pre-increase level which is due to galactic cosmic rays (GCR). This data set is used to reconstruct the energy spectra of GLE events. However, the assumption of a constant GCR background level throughout GLE events is often invalid. Here we thoroughly revise the IGLED and provide a data set of detrended NM count-rate increases that accounts for the variable GCR background. Methods. The formal GLE count-rate increases were corrected for the variable GCR background, which may vary significantly during GLE events. The corresponding integral omnidirectional fluences of SEPs were reconstructed for all GLEs with sufficient strength from the detrended data using the effective rigidity method. Results. The database of the detrended NM count rate is revised for GLE events since 1956. Integral omnidirectional fluences were estimated for 58 GLE events and parametrised for 52 sufficiently strong events using the modified Ellison-Ramaty spectral shape. Conclusions. The IGLED was revised to account for the variable GCR background. Integral omnidirectional fluences reconstructed for most of GLE events were added to IGLED. This forms the basis for more precise studies of parameters of SEP events and thus for solar and space physics.
- ПубликацияТолько метаданныеNew Method of Assessment of the Integral Fluence of Solar Energetic (> 1 GV Rigidity) Particles from Neutron Monitor Data(2019) Kovaltsov, G. A.; Mishev, A. L.; Usoskin, I. G.; Koldobskiy, S. A.; Колдобский, Сергей Александрович© 2019, The Author(s).A new method to reconstruct the high-rigidity part (≥ 1 GV) of the spectral fluence of solar energetic particles (SEP) for GLE events, based on the world-wide neutron monitor (NM) network data, is presented. The method is based on the effective rigidity Reff and scaling factor Keff. In contrast to many other methods based on derivation of the best-fit parameters of a prescribed spectral shape, it provides a true non-parametric (viz. free of a priori assumptions on the exact spectrum) estimate of fluence. We reconstructed the SEP fluences for two recent GLE events, #69 (20 Jan. 2005) and #71 (17 May 2012), using four NM yield functions: (CD00 – Clem and Dorman in Space Sci. Rev.93, 335, 2000), (CM12 – Caballero-Lopez and Moraal in J. Geophys. Res.117, A12103, 2012), (Mi13 – Mishev, Usoskin, and Kovaltsov in J. Geophys. Res.118, 2783, 2013), and (Ma16 – Mangeard et al. in J. Geophys. Res.121, 7435, 2016b). The results were compared with full reconstructions and direct measurements by the PAMELA instrument. While reconstructions based on Mi13 and CM12 yield functions are consistent with the measurements, those based on CD00 and Ma16 ones underestimate the fluence by a factor of 2 – 3. It is also shown that the often used power-law approximation of the high-energy tail of SEP spectrum does not properly describe the GLE spectrum in the NM-energy range. Therefore, the earlier estimates of GLE integral fluences need to be revised.
- ПубликацияТолько метаданныеGalactic Cosmic Ray Electrons and Positrons over a Decade of Observations in the PAMELA Experiment(2019) Adriani, O.; Bazilevskaya, G. A.; Barbarino, G. C.; Bellotti, R.; Mikhailov, V. V.; Voronov, S. A.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S. A.; Leonov, A. А.; Mayorov, A. G.; Malakhov, V. V.; Runtso, M. F.; Spillantini, P.; Yurkin, Y. T.; Михайлов, Владимир Владимирович; Воронов, Сергей Александрович; Колдобский, Сергей Александрович; Леонов, Алексей Анатольевич; Майоров, Андрей Георгиевич; Малахов, Виталий Валерьевич; Юркин, Юрий Тихонович© 2019, Allerton Press, Inc.Abstract: The PAMELA magnetic spectrometer was launched onboard the Resurs-DK1 satellite into a near-polar Earth orbit with an altitude of 350–600 km, in order to study fluxes of cosmic ray particles and antiparticles in the wide energy range of ~80 MeV to hundreds of GeV. The results from observations of electron and positron fluxes in 2006–2016 are presented.
- 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 метаданныеPion decay model of the Tibet-AS gamma PeV gamma-ray signal(2021) Koldobskiy, S.; Neronov, A.; Semikoz, D.; Колдобский, Сергей АлександровичThe Tibet-AS gamma Collaboration has recently reported a measurement of diffuse gamma-ray flux from the outer Galactic disk in the energy range reaching PeV. We complement this measurement with the Fermi/LAT measurement of the diffuse flux from the same sky region and study the pion decay model of the combined Fermi/LAT + Tibet-AS gamma spectrum. We find that within such a model the average cosmic-ray spectrum in the outer Galactic disk has the same characteristic features as the local cosmic-ray spectrum. In particular, it experiences a hardening at several hundred GV rigidity and a knee feature in the PV rigidity range. The slope of the average cosmic-ray spectrum above the break is close to the locally observed slope of the helium spectrum gamma similar or equal to 2.5, but is harder than the slope of the local proton spectrum in the same rigidity range. Although the combination of Fenni/LAT and Tibet-AS gamma data points to the presence of the knee in the average cosmic-ray spectrum, the quality of the data is not yet sufficient for the study of knee shape and cosmic-ray composition.
- ПубликацияТолько метаданныеApplication of the verified neutron monitor yield function for an extended analysis of the GLE # 71 on 17 May 2012(2021) Mishev, A. L.; Usoskin, I. G.; Kocharov, L. G.; Kovaltsov, G. A.; Koldobskiy, S. A.; Колдобский, Сергей Александрович© 2020. The Authors.Intense solar activity was observed in May 2012. A notable ground level enhancement (GLE) was registered on 17 May 2012 by several space-borne instruments as well as on ground by neutron monitors (NMs). This event is known as GLE # 71. Here, we derived the spectral and angular characteristics, and apparent source position of the solar protons during the GLE # 71, employing verified newly computed NM yield function and sophisticated unfolding procedure. We considerably improved the previously derived information about the spectra and angular distribution, namely, the precision, time span, and time resolution of the derived characteristics, specifically during the event onset and late phase. A comparison with direct measurements, with the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) experiment, of the particle fluence was performed, and good agreement between NM and direct space-borne data analysis was achieved. Subsequently, we computed the effective dose rates in the polar region at several altitudes during the event using the derived rigidity spectra of the solar protons as a reliable input for the corresponding radiation model. The contribution of the galactic cosmic rays and solar protons to the exposure is explicitly considered. We computed the integrated exposure during the event and discussed the exposure of crew members/passengers to radiation at several altitudes.
- ПубликацияТолько метаданныеNew reconstruction of event-integrated spectra (spectral fluences) for major solar energetic particle events(2021) Raukunen, O.; Vainio, R.; Kovaltsov, G. A.; Koldobskiy, S.; Usoskin, I.; Колдобский, Сергей Александрович© ESO 2021.Aims. Fluences of solar energetic particles (SEPs) are not easy to evaluate, especially for high-energy events (i.e. ground-level enhancements, GLEs). Earlier estimates of event-integrated SEP fluences for GLEs were based on partly outdated assumptions and data, and they required revisions. Here, we present the results of a full revision of the spectral fluences for most major SEP events (GLEs) for the period from 1956 to 2017 using updated low-energy flux estimates along with greatly revisited high-energy flux data and applying the newly invented reconstruction method including an improved neutron-monitor yield function. Methods. Low- and high-energy parts of the SEP fluence were estimated using a revised space-borne/ionospheric data and ground-based neutron monitors, respectively. The measured data were fitted by the modified Band function spectral shape. The best-fit parameters and their uncertainties were assessed using a direct Monte Carlo method. Results. A full reconstruction of the event-integrated spectral fluences was performed in the energy range above 30 MeV, parametrised and tabulated for easy use along with estimates of the 68% confidence intervals. Conclusions. This forms a solid basis for more precise studies of the physics of solar eruptive events and the transport of energetic particles in the interplanetary medium, as well as the related applications.