Abstract
We analyzed the high-energy gamma and neutron emissions observed by the SONG instrument onboard the CORONAS-F satellite during August 25, 2001, October 28, 2003, November 4, 2003, and January 20, 2005 solar flares. These flares produced neutrons and/or protons recorded near Earth. The SONG response was consistent with detection of the pion-decay gamma emission and neutrons in these events. We supposed that a time profile of the soft X-ray derivative was a good proxy of time behavior of the flare energy release. Then we showed that time intervals of the maximum both of energy release and pion-decay-emission coincided well. We determined the onset time of GLEs 65, 69 on the basis of neutron monitor data using the superposed epoch method. The time of high-energy proton onset on November 4, 2003 was found from the GOES data. The time delay between the high-energy gamma ray observation and the high-energy protons onset time was <5 minutes. This time lag corresponds to the least possible proton propagation time. So, we conclude that in these events both protons interacted in the solar atmosphere and the first protons which arrived to Earth, belonged to one and the same population of the accelerated particles.
Highlights
Solar energetic protons, as Solar Proton Events (SPE) or Ground Level Enhancement (GLE), are observed directly over long time, most probably since the events on February 28 and March 7 in 1942 were identified by Forbush [1] and named later as GLE 1 and 2, respectively
We studied the flare gamma-ray emission using the response function of the detector simulated with the help of the GEANT 3.21 program
CORONAS-F measurements extended this set essentially. 120 flares with hard X-ray emission were observed with CORONAS-F, and high-energy electron bremsstrahlung with photon energy >5 MeV was observed in 15 flares
Summary
As Solar Proton Events (SPE) or Ground Level Enhancement (GLE), are observed directly over long time, most probably since the events on February 28 and March 7 in 1942 were identified by Forbush [1] and named later as GLE 1 and 2, respectively. The pion-decay emission was detected by SMM/GRS [18, 19], GRANAT/Phebus [20,21,22], Compton Gamma-Ray Observatory (CGRO) with Energetic Gamma-Ray Experiment Telescope (EGRET) [23, 24], and GAMMA/GAMMA1 [25, 26] This emission was detected during the declining phase of the solar cycle 23 with the Solar Neutrons and Gamma-rays (SONG) spectrometer [27] on the Complex Orbital Observations of the Active Sun (CORONAS-F) space mission from four solar flares [28, 29]. After short description of the SONG instrument we discuss the observations of gamma-rays and neutrons during abovementioned events These observations indicated the presence of protons accelerated up to high energy in solar atmosphere. It has never been saturated during the events under consideration
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