Positron‐Emitter Production in Solar Flares from³He Reactions

Abstract

We treat in detail positron production from the decay of radioactive nuclei produced in nuclear reactions of accelerated 3 He. Because of their large cross sections and low threshold energies, these reactions can significantly contribute to positron production in solar flares with accelerated-particle compositions enriched in 3 He. The addition of these 3 He reactions extends earlier calculations of positron production by accelerated protons and -particles. 3 He reactions not only add significantly to the total positron yield in flares, but can also yield a positron depth distribution that peaks higher in the solar atmosphere. We discuss the impact these reactions have on the analysis of the annihilation line observed with RHESSI from the 2002 July 23 flare. A significant contribution from 3 He reactions expands the utility of the annihilation line as a sensitive tool for investigating the structure of the flaring solar atmosphere.

Gamma Radiation From Flare-Accelerated Particles Impacting the Sun

“…Kozlovsky, Murphy, and Share (2004) set a I a lower limit of 0.35 to the alp ratio in the 2002 July 23 flare observed by RHESSI, consistent with the SMM observations. Plotted in Figure 8 is the spectrum between 350 and 650 keV accumulated from II :06-11 : 1 0 UT during the 2003 October 28 flare after subtracting bremsstrahlung and nuclear contributions.…”

Nonlinear oscillations and waves in multi-species cold plasmas

“…These plasmas exist naturally in various astrophysical environments [22][23][24][25][26] and are also produced in laboratory by laser matter interaction [27]. An enormous amount of effort has been put in understanding nonlinear wave phenomena in such plasmas in various physical regimes [28][29][30][31][32][33][34][35][36][37].…”

Coupled ion acoustic and drift waves in magnetized superthermal electron-positron-ion plasmas

“…29 Importantly, these three component plasmas have also been produced in the laboratory, [30][31][32] and the existence of positrons in other laboratory plasmas has been confirmed. [33][34][35] The process of pair production (electron-positron) can occur during the interaction of a strong laser pulse with plasmas, [36][37][38][39] as well as by the interaction of superthermal electrons with high-Z material.…”