University of Oulu

Usoskin, Ilya; Asvestari, Eleanna; Willamo, Teemu; Gil, Agnieszka; Kovaltsov, Gennady A.; Mikhailov, Vladimir V.; Mayorov, Andrey 2017 Analysis of Ground-Level Enhancements : strong events are hard. 35th international cosmic ray conference, ICRC2017, The astroparticle physics conference. 12-20 July 2017, Bexco, Busan, Korea, PoS(ICRC2017)126,

Analysis of Ground-Level Enhancements : strong events are hard

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Author: Usoskin, Ilya1; Asvestari, Eleanna2,3; Willamo, Teemu4;
Organizations: 1Space Climate Research Unit and Sodankylä Geophysical Observatory, University of Oulu, FIN-90014 Finland
2Space Climate Research Unit, University of Oulu, FIN-90014 Finland
3Department of Physics, University of Helsinki, FIN-00014, Finland
4University of Helsinki, FIN-00014 Helsinki, Finland
5Institute of Mathematics and Physics, Siedlce University, Stanislawa Konarskiego 2, 08-110 Siedlce, Poland
6Ioffe Physical-Technical Institute, Politechnicheskaya st. 26, 194021 St. Petersburg, Russia
7National research nuclear university (MEPhI), Kashirskoye sh. 31, 115409 Moscow, Russia
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.1 MB)
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Language: English
Published: Sissa, 2017
Publish Date: 2017-11-01


Ground Level Enhancements (GLEs) recorded by neutron monitor detectors are characterized by a variety of energy spectra of solar energetic particles (SEP), which vary between soft (as in August 1972) and hard (February 1956) ones. The aim of this work is to investigate the statistical relation between the hardness of the energy spectra and the event-integrated intensity. We calculated the event-integrated omnidirectional fluence of protons above 30 MeV (F₃₀) and above 200 MeV (F₂₀₀) using energy spectra reconstructed from both ground-based and space-borne data. The ratio of the F₃₀-to-F₂₀₀ fluences is considered as an index of the hardness of the events spectra. The main results of this study is that all strong events (with the event-integrated intensity greater than 100%*hr) are characterized by a hard or very hard spectrum, while weak and moderate events do not show any clear pattern between the hardness and the intensity of the event.

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Series: POS. Proceedings of science
ISSN: 1824-8039
ISSN-E: 1824-8039
ISSN-L: 1824-8039
Article number: 126
Host publication: 35th international cosmic ray conference, ICRC2017, The astroparticle physics conference. 12-20 July 2017, Bexco, Busan, Korea
Conference: International Cosmic Ray Conference
Type of Publication: B3 Article in conference proceedings
Field of Science: 115 Astronomy and space science
Funding: This work was partly supported by the Center of Excellence ReSoLVE (Academy of Finland project No. 272157). A.G. acknowledges the Polish National Science Centre, decision number DEC-2016/22/E/HS5/00406
Academy of Finland Grant Number: 272157
Detailed Information: 272157 (Academy of Finland Funding decision)
Copyright information: © 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).