Bonn 2010 – wissenschaftliches Programm
EP 6.3: Vortrag
Dienstag, 16. März 2010, 14:30–14:45, AKM
Spatial gradients of galactic cosmic rays in the inner heliosphere at the end of solar cycle 23 — •Jan Gieseler1, Bernd Heber1, Nico De Simone2, and Valeria Di Felice2 — 1IEAP, Christian-Albrechts-Universität zu Kiel, 24118 Kiel, Germany — 2INFN, Structure of Rome Tor Vergata and Physics Department of University of Rome Tor Vergata, 00133 Rome, Italy
Ulysses was launched in October 1990 in the maximum phase of solar cycle 22, reached its final, highly inclined (80.2°) Keplerian orbit around the Sun in February 1992, and was finally switched off in June 2009. During its 18 years of measurements, the spacecraft performed three so-called fast latitude scans, in 1994-1995, 2000-2001, and 2007-2008, traveling from highest southern to northern latitudes within one year. This provides the opportunity to study the propagation of galactic cosmic rays over a wide range of heliographic latitudes during different levels of solar activity and different polarities in the inner heliosphere. Because the Ulysses measurements reflect not only the spatial but also the temporal variation of the energetic particle intensities, it is essential to know the intensity variations for a stationary observer in the heliosphere. This was accomplished in the past with the IMP 8 spacecraft until it was lost in 2006. Fortunately, the satellite-borne experiment PAMELA was launched in June 2006 and can be used as a reliable 1 AU baseline for measurements of the Kiel Electron Telescope aboard Ulysses. Thus, we have the opportunity to determine spatial gradients for protons and electrons from below 1 GV to above 4 GV with an accuracy never been achieved before.