Electron and Positron solar modulation and prediction for AMS-02

TL;DR

This paper develops a Monte Carlo simulation to analyze and predict how solar modulation differently affects electrons and positrons, aiding interpretation of cosmic ray data from AMS-02.

Contribution

It introduces a detailed stochastic model that accounts for charge-dependent solar modulation effects on electrons and positrons in the heliosphere.

Findings

Simulated positron fraction matches AMS-01 and PAMELA data

Model predicts positron behavior for AMS-02

Charge sign dependence in solar modulation is quantified

Abstract

The solar modulation, a combination of diffusion, convection, magnetic drift and energy loss inside the heliosphere is usually seen as a depletion in the Galactic cosmic ray (CR) flux at low energy (less than 10 GeV/nuc). Antiparticles such as antiprotons or positrons undergo the same processes of respective particles but with a different magnitude depending on the Solar magnetic field polarity. For electrons and positrons, due to the small mass, energy loss mechanisms as inverse compton, synchrotron, bremsstrahlung and ionization have to be taken into account, together with the typical adiabatic losses considered in the heliosphere. We developed a Monte Carlo stochastic simulation with the aim to compare the solar modulation of particles and antiparticles in the same observation period. We are able to estimate the different behaviours associated to the charge sign dependent processes of the heliospheric modulation. We compared the simulated positron fraction with measurements performed by AMS-01 and PAMELA. We also present the prediction for the AMS-02 experiment.