Search Publications
Determination of 7-30 MeV electron intensities: ULYSSES COSPIN/KET Results
Sierks, H.; Kunow, H.; Muller-Mellin, R. +6 more
The COsmic and Solar Particle INvestigation Kiel Electron Telescope was designed to measure electrons from a few MeV up to a few GeV using particle energy loss and particle velocity measurement techniques. Unfortunately the KET channel measuring electrons in the energy range from 7-170 MeV is contaminated by a γ-ray background (Ferrando et al., 19…
A Path Integral Solution to the Stochastic Differential Equation of the Markov Process for Cosmic Ray Transport
Zhang, Ming
Cosmic ray transport in interplanetary or interstellar magnetic fields can be viewed as a Markov stochastic process and the transport equation has therefore recently been reformulated with a set of stochastic differential equations that describe the guiding center and the momentum of individual charged particles. The Fokker-Planck diffusion equati…
The heliospheric Modulation od Cosmic ray Electrons: Rigidity Dependence of the perpendicular Diffusion Coefficient
Ferreira, S. E. S.; Potgieter, M. S.; Heber, B.
The modulation of cosmic ray electrons in the heliosphere provides a useful tool in understanding and estimating the diffusion tensor applicable to heliospheric modulation. Using a comprehensive modulation model including all major mechanisms to study electron modulation, especially at energies below 500 MeV, we found that perpendicular diffusion …
Observation of a ~ 7 MeV Electron Super-flux at 5 AU by Ulysses
Kunow, H.; Muller-Mellin, R.; Bothmer, V. +4 more
From the Ulysses launch up to the end of 1995, the 4-10 MeV energy electron count rate of the COSPIN/KET instrument has been consistent with simple expectations from Jovian electrons propagation. From the beginning of 1996 to the end of 1998, Ulysses was below ~ 30 degrees of heliographic latitude and between 4.5 and 5.4 AUs from the Sun, making i…
Charge sign dependent modulation: Ulysses COSPIN/KET results
Sierks, H.; Kunow, H.; Bothmer, V. +8 more
According to drift dominated modulation models galactic cosmic ray protons and electrons respond differently to the latitudinal extension of the heliospheric current sheet. In an A 0 solar magnetic cycle intensities of ¥ positively charged particles should vary only weakly with the latitudinal extension, whereas electrons should show a much strong…
Effects of anisotropic perpendicular diffusion on the energy and spatial dependence of galactic electron modulation in the heliosphere
Potgieter, M. S.; Ferreira, Stefan
Perpendicular diffusion enhanced in the polar directions of the heliosphere seems required in numerical models based on Parker's transport equation for cosmic rays, especially in explaining the small latitudinal gradients observed for protons by the Ulysses spacecraft during its fast latitude scan. This modulation topic is further studied using el…
Rigidity Dependence of Near-Earth Latitudinal Proton Density Gradients
Potgieter, M. S.; Heber, B.; Burger, R. A.
The rigidity dependence of the latitudinal gradient of cosmic-ray protons observed by Ulysses poses a challenge to modulation models: it increases as function of rigidity up to about 1.4 GV and then decreases. Although models could reproduce the observed small positive gradient for an A > 0 solar polarity cycle, its maximum was at a rigidity we…
Propagation of the Onset of Modulation in Cycle 23 from 1 to 72 AU
Krimigis, S. M.; Simpson, J. A.; Zhang, M. +3 more
In late 1997, the modulation of galactic cosmic rays at 1 AU began to increase in response to increasing solar activity. We report observations of the onset of modulation from spacecraft ranging from IMP-8 and U l y s s e s near the ecliptic at 1 AU and 5 AU respectively out to Voyager 1 and 2 , in the northern and southern solar hemispheres at ra…
Variations of anomalous and galactic cosmic ray fluxes in the northern hemisphere:ULYSSES EPAC and KET observations
Kunow, H.; Fraenz, M.; Heber, Bernd +1 more
From beginning of 1995 to the end of 1997 the Ulysses spacecraft scanned a heliographic latitude range of 80 degrees in the northern hemisphere. In this paper we will discuss Ulysses Energetic Particle Composition Experiment (EPAC) and Ulysses COsmic and Solar Particle INvestigation Kiel Electron Telescope (KET) observations of different anomalous…
Implications of Increased Perpendicular Diffusion on the Tilt Angle Depedence of Electron Modulation in the Heliosphere
Ferreira, S. E. S.; Potgieter, M. S.; Burger, R. A.
For numerical solutions of Parker's cosmic ray transport equation to be compatible with the small latitudinal gradients observed for protons by Ulysses, enhanced perpendicular diffusion seems needed in the polar regions of the heliosphere. The role of enhanced perpendicular diffusion was further investigated by examining electron modulation as a f…