Time dependence of the e^- flux measured by PAMELA during the July 2006 - December 2009 solar minimum

TL;DR

This paper presents detailed measurements of cosmic ray electrons by PAMELA during a solar minimum, revealing how solar activity influences electron fluxes and validating a sophisticated solar modulation model.

Contribution

It provides the first detailed, time-resolved electron spectra during a solar minimum and compares them with an advanced 3D solar modulation model.

Findings

Electron fluxes vary with solar activity over the studied period.

The 3D model accurately reproduces observed electron spectra.

Results improve understanding of cosmic ray modulation in the heliosphere.

Abstract

Precision measurements of the electron component in the cosmic radiation provide important information about the origin and propagation of cosmic rays in the Galaxy not accessible from the study of the cosmic-ray nuclear components due to their differing diffusion and energy-loss processes. However, when measured near Earth, the effects of propagation and modulation of galactic cosmic rays in the heliosphere, particularly significant for energies up to at least 30 GeV, must be properly taken into account. In this paper the electron (e^-) spectra measured by PAMELA down to 70 MeV from July 2006 to December 2009 over six-months time intervals are presented. Fluxes are compared with a state-of-the-art three-dimensional model of solar modulation that reproduces the observations remarkably well.