A study on the path of energetic protons in the MESEP event of September 12, 2000

Authors

  • A.Al-Sawad,∗ , D. Al- Feadh , F. Al-Hamadani

Abstract

On 2000 September 12-14 the Energetic and Relativistic Nuclei and Electron (ERNE)
instrument on the Solar and Heliospheric Observatory (SOHO) observed a gradual solar energetic
particle (SEP) event associated with Halo CME and M class solar flare from the South West
hemisphere. Production of 20-90 MeV protons lasted for 160-137 hr respectively. The analysis of the
intensity-time profile, 4 He/p - Fe/O ratios and anisotropy flux suggested that this event is combined
with a second eruption associated with a Halo CME from the North East hemisphere and that the shock
wave of the first CME was an efficient accelerator for? 20 MeV protons during only the first 8 hr after
the launch. According to our calculation of the angle ? Bn between the shock normal and the direction
of the upstream magnetic field, shock parameters such as speed, compression ratio and Mach number,
this shock seems to be gradually slowed down, weakened, and became transparent for the protons
produced by the second eruption behind the previous CME or the protons of the second CME may
have access to field lines that curve around the first CME structure.

Published

2020-10-16

Issue

Section

Articles