Cristina Consolandi
University of Hawaii at Manoa
Solar Modulation of Galactic Cosmic Rays and Solar Energetic Particles measured by the Alpha Magnetic Spectrometer on the International Space Station
The Alpha Magnetic Spectrometer (AMS) is a state of the art particle detector measuring charged particle in the energy range of 120 MeV to a few TeV on the International Space Station (ISS) since May 2011. As a space-borne experiment, AMS detects charged particles before their interaction with the atmosphere, enabling direct measurements of their spectra and chemical composition. During its 13 years of operations, AMS collected over 240 billion events. Galactic Cosmic Rays (GCRs) entering the heliosphere are subject to diffusion, convection, adiabatic energy losses, and magnetic drift due to their interaction with the solar wind together with the embedded solar magnetic field. These processes lead to the modulation of the GCR intensity at Earth's orbit around the Sun, which is especially visible below 100 GeV. This modulation is time dependent and correlates with the solar activity, following the 11- and 22-year solar cycles. GCR spectra may also have temporary reductions that can last from days to months, due to their interactions with strong disturbances in the solar magnetic field created by eruptions from the Sun, such as Coronal Mass Ejections (CMEs) and Co-rotating Interaction Regions (CIRs). The large acceptance and high precision of AMS allow us to perform accurate measurements of the fluxes as functions of time and energy. This provides unique information to probe the dynamics of solar modulation. In addition, AMS has detected several Solar Energetic Particle (SEP) events produced during strong solar eruptions of M- and X- class flares and fast CMEs. AMS studied these SEPs at energies up to a few GeV with unprecedented accuracy. The unique features of the solar modulation of GCRs, SEPs observed by AMS and the physics behind these will be presented.