Evolution of the galactic cosmic ray electron to proton ratio: Ulysses COSPIN/KET observations
Abstract
The on-going Ulysses mission provides a unique opportunity to study the propagation and modulation of galactic cosmic rays (GCRs) in the inner heliosphere. The time history of electrons and protons is a suitable tool to investigate the importance of drifts in heliospheric modulation. Around the 2000 solar maximum, when the Sun switched from an A>0 to an A<0 solar magnetic epoch, the electron to proton ratio was approximately the same as in the 1990 solar maximum, when the solar magnetic field reversed from an A<0 to an A>0-solar magnetic epoch. Thus drifts are only of minor importance at solar maximum. From 2000 on, the intensity of electrons and protons increased by a factor of 0.85 and 0.4. The larger increase in the electron intensities can be reproduced by particle transport models when assumming that drifts are becoming increasingly important again. We will discuss the Ulysses observations and compare them with results of numerical simulations.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35.3460H