Observation of time evolution of cosmic ray electron and positron flux with Dark Matter Particle Explorer

Abstract

In this analysis, we measure the time-dependence of the primary cosmic ray electron and positron (CRE) fluxes using over 3 years of data from the Dark Matter Particle Explorer (DAMPE). The monthly CRE fluxes show clear variabilities due to the solar modulation effect. We also investigate the short-term structures of the CRE fluxes in September, 2017 when an X level solar flare event occurred. Energy-dependent Forbush descreases have been observed. The Forbush decrease amplitude and recovery time of the CRE fluxes depend on energies, which may have interesting implication in understanding the disturbances of interplanetary environment due to solar activities. All these results indicate that the DAMPE has a great potential to probe the interplay between particles and the heliosphere environment.

Progresses of the Dark Matter Particle Explorer experiment

“…After reaching the minima, the CRE fluxes recover to the normal values for a time scale of about one week, similar with that found by PAMELA [64]. Both the amplitudes and recovery time decrease with energy (see [67] for more details). Such behaviors are consistent with one class of solar disturbances causing the Forbush decrease, which is probably associated with a complicated shock-associated interplanetary coronal mass ejection disturbance with a large radial extent [70].…”

“…We measure the monthly CRE fluxes from April, 2016 to June, 2019, from 2 GeV to 20 GeV [67]. The flux ratios relative to that of April, 2016, for a few energy bins are shown in Figure 9.…”