Interactions of Charged, Accelerated Particles in the Solar Atmosphere, and the Generation of Secondary Energetic Particles and Radiation: Pioneer Results

Abstract

In this chapter, we describe only the very first, pioneering results, those obtained before the famous discovery of solar gamma rays (which occurred during the events of August 1972) and the discovery of solar neutrons (which occurred on the 21 June 1980 and on the 3 June 1982). At those times, scientists concerned themselves mostly with problems involving the production of high energy neutrons and gamma ray lines, and did not much consider the problem of gamma ray generation as caused by the decay of neutral pions (generated by the interactions of accelerated protons of higher energy than 270 MeV with protons in the solar atmosphere). The first significant \( {\pi^{\rm{0}}} \)-decay peak at 70 MeV was observed by the Gamma Ray Spectrometer (GRS) on the Solar Maximum Mission (SMM) satellite, during the solar neuron/gamma ray event of March 6 1989 (see Section 4.5; more detail about π0-decay-driven gamma radiation is given in Sections 11.8 and 11.9). Let us note that the problem of energetic particle interactions in the solar atmosphere producing secondary radiation (both particulate and photon) is a specific case of the more general problem of cosmic ray interaction, propagation and acceleration in space plasmas, which is considered in detail in the Dorman (M2006) manuscript of similar title.