WP 1620

Long term GCR variations

Galactic cosmic rays (GCRs) entering the heliosphere interact with the solar wind and its embedded heliospheric magnetic field such that their energy spectra undergo important global and temporal changes with respect to their corresponding local interstellar spectra (LIS). Such a process is known as solar modulation of GCRs. In particular, the observed GCRs fluxes, below a few tens of GeV, show a significant quasi-periodical temporal variation, in anti-correlation with the 11-year solar activity cycle (22-year magnetic polarity cycle).

An improved comprehension of the processes at the basis of the solar modulation has important implications on GCRs studies, as well as connection with solar physics and space weather. In fact, the significance of GCRs studies in identifying CRs sources or in searching for dark matter annihilation signals relies heavily on a thorough understanding of the background and related uncertainties, that is limited by solar modulation effects in a time-, charge-, energy- and particle type-dependent way. With a different perspective, thanks to GCRs responsiveness to solar activity, we can use them as a proxy of solar activity to better understanding the solar environment, solar and plasma astrophysics, and improving on predicting the varying CR flux in the interplanetary space, that provides a significant challenge for space missions and air travellers.

Based on different sets of data,  different models describing the transport of GCR radiation inside the heliosphere will be tested, validated, and exploited to calculate GCRs differential fluxes in different epochs and locations in the heliosphere