Modulation of Galactic Cosmic Ray Particles observed on board the Ulysses Spacecraft

B. Heber, A. Raviart, C. Paizis, M. Bialk, W. Dröge, R. Ducros, P. Ferrando, H. Kunow, R. Müller-Mellin, C. Rastoin, K. Röhrs, and G. Wibberenz.
Modulation of Galactic Cosmic Rays Particles observed on board the Ulysses Spacecraft
Proceedings of the 23th International Cosmic Ray Conference 3. 1993

Contents

The variation of electron, proton and alpha-particle fluxes has been analysed using the data collected bey the Kiel Electron Telescope on board the Ulysses spacecraft from November 1990 to January 1993. During that time Ulysses traveled between 1 AU and 5.4 AU close to the ecliptic plane. The authors present fluxes, temporal variations, and radial gradients of galactic cosmic rays from > 30 MeV/n, using IMP-8 and Kiel neutron monitor They conclude, that the variation of nuclei > 1000 MV/c magnetic rigidity can be fitted with a model assuming exponential variations with time and radial distance. The annual variation for nuclei decreases with increasing mean magnetic rigidity, whereas the annual variation of electrons seems to be weaker. The radial gradient for nuclei in the GV rigidity range from the data analysed so far shows a slight decrease with rigidity. The averaged value of about 3.3 %/AU determined directly for relativistic particles is in good agreement with integral gradients from previous missions. 


Channel     T          P       gamma_3       gamma
          MeV/n        MV        %/a          %/a 

P116    125 -  320     680   107  +- 5.6
P190    320 - 2100    1620    91.2+- 9.7   77.0+-2.0
P4000    > 2100       6000    27.1+- 2.4   23.6+-1.0
A32      34 -  125     800   218  +-22
A116    125 -  320    1140   123  +-16.7 
A190    320 - 2100    3240    81.6+- 6.9   71.1+-4.1
A4000    > 2100      12000    16.6+- 4.3   14.1+-0.6
E12      60 -  500     120    12  +- 5
E300     >  150        800    61  +-20

KNM      > 1500      17100    14.9+- 3.5   10.4+-1.0
IMP-8    >  106       2000    76.5+- 5.0

Energy ranges T, weighted mean rigidity P and temporal rate of increase gamma for protons, alpha-particles and electrons of KET, IMP-8 and the Kiel neutron monitor (KNM)

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