Forbush decreases and $<$ 2-day GCR flux non-recurrent variations studied with LISA Pathfinder

Abstract

Non-recurrent short term variations of the galactic cosmic-ray (GCR) flux above 70 MeV n${}^{-1}$ were observed between 2016 February 18 and 2017 July 3 aboard the European Space Agency LISA Pathfinder (LPF) mission orbiting around the Lagrange point L1 at 1.5$\times$10${}^6$ km from Earth. The energy dependence of three Forbush decreases (FDs) is studied and reported here. A comparison of these observations with others carried out in space down to the energy of a few tens of MeV n${}^{-1}$ shows that the same GCR flux parameterization applies to events of different intensity during the main phase. FD observations in L1 with LPF and geomagnetic storm occurrence is also presented. Finally, the characteristics of GCR flux non-recurrent variations (peaks and depressions) of duration $<$ 2 days and their association with interplanetary structures are investigated. It is found that, most likely, plasma compression regions between subsequent corotating high-speed streams cause peaks, while heliospheric current sheet crossing cause the majority of the depressions.

References in corpus (3)

• Measurements of 0.2 to 20 GeV/n cosmic-ray proton and helium spectra from 1997 through 2002 with the BESS spectrometer
• Heliospheric modulation of cosmic rays during the neutron monitor era: Calibration using PAMELA data for 2006--2010
• The LISA PathFinder DMU and Radiation Monitor

Cited by in corpus (6)

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• Cosmic-ray flux predictions and observations for and with Metis on board Solar Orbiter
• LISA test-mass charging. Particle flux modeling, Monte Carlo simulations and induced effects on the sensitivity of the observatory
• Diverse properties of electron Forbush decreases revealed by the Dark Matter Particle Explorer