Characteristics and energy dependence of recurrent galactic cosmic-ray flux depressions and of a Forbush decrease with LISA Pathfinder

TL;DR

This study analyzes galactic cosmic-ray flux depressions and a Forbush decrease using data from LISA Pathfinder's particle detector, highlighting the potential of interplanetary missions to monitor solar and interplanetary phenomena affecting cosmic rays.

Contribution

It presents the first detailed characterization of GCR flux depressions and a Forbush decrease using data from a high-rate particle detector on LISA Pathfinder, demonstrating the detector's utility for space weather monitoring.

Findings

GCR flux depressions show energy-dependent characteristics.

The Forbush decrease was successfully observed and characterized.

Interplanetary missions can effectively monitor ICMEs using onboard particle detectors.

Abstract

Galactic cosmic-ray (GCR) energy spectra observed in the inner heliosphere are modulated by the solar activity, the solar polarity and structures of solar and interplanetary origin. A high counting rate particle detector (PD) aboard LISA Pathfinder (LPF), meant for subsystems diagnostics, was devoted to the measurement of galactic cosmic-ray and solar energetic particle integral fluxes above 70 MeV n$^{-1}$ up to 6500 counts s$^{-1}$. PD data were gathered with a sampling time of 15 s. Characteristics and energy-dependence of GCR flux recurrent depressions and of a Forbush decrease dated August 2, 2016 are reported here. The capability of interplanetary missions, carrying PDs for instrument performance purposes, in monitoring the passage of interplanetary coronal mass ejections (ICMEs) is also discussed.