Detection of high-energy solar neutrons and protons by ground level detectors on April 15, 2001

作者：Muraki Y^*; Matsubara Y; Masuda S; Sakakibara S; Sako T; Watanabe K; Buetikofer R; Flueckiger E O; Chilingarian A; Hovsepyan G; Kakimoto F; Terasawa T; Tsunesada Y; Tokuno H; Velarde A; Evenson P; Poirier J; Sakai T

来源：Astroparticle Physics, 2008, 29(4): 229-242.

DOI：10.1016/j.astropartphys.2007.12.007

• solar neutron and proton
• neutron telescope
• neutron monitor
• easter event
• solar cosmic rays

In association with the large solar flare of April 15, 2001, the Chacaltaya neutron monitor observed a 3.6 sigma enhancement of the counting rate between 13:51 and 14:15 UT. Since the enhancement was observed beginning 11 min before the GLE, solar neutrons must be involved in this enhancement. The integral energy spectrum of solar neutrons can be expressed by a simple power law in energy with the index gamma = -3.0 +/- 1.0. On the other hand, an integral energy spectrum of solar protons has been obtained in the energy range between 650 MeV and 12 GeV. The spectrum can also be expressed by a power law with the power index gamma = -2.75 +/- 0.15. The flux of solar protons observed at Chacaltaya (at >= 12 GeV) was already one order less than the flux of the galactic cosmic rays. It may be the first simultaneous observation of the energy spectra of both high-energy protons and neutrons. Comparing the Yohkoh soft X-ray telescope images with the observed particle time profiles, an interesting picture of the particle acceleration mechanism has been deduced.

• 出版日期2008-5