Interplanetary propagation of relativistic solar protons

✍ Scribed by M. Lumme; M. Nieminen; J. J. Torsti; E. Vainikka; J. Peltonen; E. Valtonen; H. Arvela

• Publisher: Springer
• Year: 1986
• Tongue: English
• Weight: 618 KB
• Volume: 107
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00155352

✦ Synopsis

Particle fluxes and pitch aL~;le ;:istributions of relativistic solar protons at Earth's orbit have been determined by Monte Carlo calculations. The analysis covers two hours after the release of the particles from the Sun and total of 8 x 106 particle trajectories were simulated. The pitch angle scattering was assumed to be isotropic and the scattering mean free path was varied from 0A to 4 AU.

The intensity-time profiles after a delta-like injection from the Sun show that the interplanetary propagation is clearly non-diffusive at scattering mean-free paths above 0.5 AU. All pitch angle distributions have a steady minimum at 90 ~ , and they become similar about 20 rain after the arrival of first particles.

As an application, the solar injection profile and the interplanetary scattering mean-free path of particles that gave rise to the GLE on 7 May, 1978 were determined. In contrast to the values of 3-5 AU published by other authors, the average scattering mean-free path was found to be about 1 AU.