Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Detection of Solar Neutrons and Solar Neutron Decay Protons

Yasushi Muraki
* ORCID logo ,
Tatsumi Koi
,
Yutaka Matsubara
,
Satoshi Masuda
,
Pedro Miranda
,
Shoko Miyake
ORCID logo ,
Tsuguya Naito
,
Ernesto Ortiz Fragoso
,
Akitoshi Oshima
,
Takashi Sako
,
Shoichi Shibata
,
Hisanori Takamaru
,
Munetoshi Tokumaru
ORCID logo ,
Jose Franco Valdes-Galicia
,
Kyoko Watanabe
Version 1 : Received: 7 November 2023 / Approved: 8 November 2023 / Online: 8 November 2023 (06:44:03 CET)

A peer-reviewed article of this Preprint also exists.

Muraki, Y.; Koi, T.; Masuda, S.; Matsubara, Y.; Miranda, P.; Miyake, S.; Naito, T.; Ortiz, E.; Oshima, A.; Sako, T.; Shibata, S.; Takamaru, H.; Tokumaru, M.; Valdés-Galicia, J.F.; Watanabe, K. Detection of Solar Neutrons and Solar Neutron Decay Protons. Universe 2024, 10, 16. Muraki, Y.; Koi, T.; Masuda, S.; Matsubara, Y.; Miranda, P.; Miyake, S.; Naito, T.; Ortiz, E.; Oshima, A.; Sako, T.; Shibata, S.; Takamaru, H.; Tokumaru, M.; Valdés-Galicia, J.F.; Watanabe, K. Detection of Solar Neutrons and Solar Neutron Decay Protons. Universe 2024, 10, 16.

Abstract

Solar flares are broadly classified as impulsive or gradual. Ions accelerated in a gradual flare are thought to be accelerated through a shock acceleration mechanism, but the particle acceleration process in an impulsive flare is still largely unexplored. To understand the acceleration process, it is necessary to measure the high-energy gamma-rays and neutrons produced by the impulsive flare. Under such circumstances, on November 7, 2004, a huge X2.0 flare occurred on the solar surface, where ions were accelerated to energies greater than 10 GeV. The accelerated primary protons collided with the solar atmosphere and produced line gamma-rays and neutrons. These particles were received as neutrons and line gamma-rays, respectively. Neutrons of a few GeV, on the other hand, decay to produce secondary protons while traveling 0.06 au in the solar-terrestrial space. These secondary protons arrived at the magnetopause. Although the flux of secondary protons is very low, the effect of collecting secondary protons arriving in a wide region of the magnetosphere (the Funnel or Horn effect) has resulted in significant signals being received by the solar neutron telescope at Mt. Sierra Negra (4,600 m). This information suggests that ions on the solar surface are accelerated to over 10 GeV with an impulsive flare.

Keywords

solar flare; impulsive flare; gradual flare; solar comic-rays; solar energetic particles; particle acceleration; solar neutrons

Subject

Physical Sciences, Astronomy and Astrophysics

Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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