Injection onsets of 2 GeV protons, 1 MeV electrons, and 100 keV electrons in solar cosmic ray flares

Abstract

view Abstract Citations (127) References (47) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Injection onsets of 2 GeV protons, 1 MeV electrons, and 100 keV electrons in solar cosmic ray flares Cliver, E. W. ; Kahler, S. W. ; Shea, M. A. ; Smart, D. F. Abstract The data for all 32 ground-level cosmic-ray events (GLEs) observed from 1942 through 1978 are reviewed, and injection onset times for the 2 GeV protons, 1 MeV electrons, and 100 keV electrons are inferred. Contrary to previous investigations, no compelling evidence is found for a systematic delay in GLE onset times. The most likely time of GeV proton injection onset in these large flares appears to be near the maximum of the first significant microwave peak. GLEs with long delays to onset tend to be small in size. In addition, the data indicate a systematic phase relationship among the injection onsets of the three particle species considered, with the low-energy electron onset times preceding those of the relativistic protons by not more than 5 min, and the relativistic electrons following the GeV protons by not less than 5 min. This phase relationship holds even when the inferred injection times of all three species follow the flare flash phase by more than 20 min. To account for these observations, a picture is suggested in which the earliest observed particles are injected when an outward moving acceleration region at a shock front intersects the open field lines connecting to earth. Publication: The Astrophysical Journal Pub Date: September 1982 DOI: 10.1086/160261 Bibcode: 1982ApJ...260..362C Keywords: Particle Acceleration; Solar Cosmic Rays; Solar Flares; Solar Protons; Astronomical Models; Relativistic Particles; Shock Fronts; Solar Corona; Solar Electrons; Time Response; Solar Physics full text sources ADS |