Solar Modulation effects on Cosmic Rays - Modelization with Force Field approximation, 1D and 2D numerical approaches and characterization with AMS-02 proton fluxes

07/30/2012

The magnetic field of the Sun is the source of the biggest of the Solar System magnetospheres, the heliosphere, and of the observed modulation of the galactic cosmic rays. Solar modulation is dominant on low energy particles (below 10 GeV), and affects not only the galactic cosmic ray intensities, but even their spectral shape. For each cosmic ray species, the particle fluxes measured at Earth are deformed with respect to the local interstellar ones, depending on the Solar activity. The propagation of cosmic rays in the heliosphere is described by the so called Parker Equation, formulated in the sixties. The equation takes into account several phenomena happening inside the Heliosphere, such as diffusion, convection, adiabatic energy changes and drifts. Since there is no full analytical solution to the Parker Equation, several different approaches have been tried, from numerical solutions to analytical approximations. In the first part of this work, the different ways of solving the transport equation are studied and numerical methods (1D and 2D) are outlined. The second part is the characterization of the modulation, using the AMS-02 proton fluxes. The AMS detector was installed last year in the ISS and is expected to gather data from cosmic ray fluxes up to 1 TeV, continously between 10 to 18 years. The rates of events reaching the detector - 40 million events per day - have never been achieved before, and represent an unique opportunity to systematically study the Solar modulation in a daily basis.

Authors in the community:

• 

  L

  Luís Miguel Mina Lopes Batalha

  ist163448

Supervisors of this institution:

• 

  F

  Fernando José De Carvalho Barão

  ist13092

physical-sciences - Physical sciences

eng - English

Instituto Superior Técnico