Trapped positron flux formation in the innermost magnetosphere of the Earth
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The possible existence of a positron radiation belt in the inner magnetosphere of the Earth, its space location, flux, energy distribution and the ratio of e+/e− fluxes is considered. The source of the positrons/electrons is assumed to be the decay of charged pions (π - μ - e decay chain) produced, in the nuclear interactions between protons and the neutral constituents of the atmosphere. The production of excess positron fluxes over electron ones through this process is examined for two different proton populations and their atmospheric interactions in the altitude range of 80 to 1000 km. Monte Carlo simulations of intranuclear cascade process through SHIELD code was utilized to simulate these interactions. Considering the trapped proton fluxes in the inner magnetosphere as a source, the simulations for interactions in rarified atmosphere shows excess of positrons over electrons with ratios above 2 for proton energies below 2.5 GeV. Although, protons above this energy do not produce excess of positrons compared to electrons in atmospheric interactions, we assumed the primary cosmic rays with the energy greater than 8–10 GeV also as a source for these interactions, and utilizing the east-west asymmetry in the arrival directions of these primary cosmic rays combined with the exponential nature of the atmosphere density we also obtained an excess of positrons over electrons escaping from the atmosphere to the altitudes of satellite orbits. A comparison is attempted with the recent data of AMS experiment on board the space shuttle.
KeywordsRadiation Belt Arrival Direction Geomagnetic Equator Trap Positron Trap Proton
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