title: Observations of energetic particles with EPAC on Ulysses in polar latitudes of the heliosphere.
abstract: Measurements with the Energetic Particle Composition instrument (EPAC) aboard Ulysses show particles from near the ecliptic that were apparently accelerated by shocks associated with a corotating interaction region. The particles were detected together with the shocks and even when shocks no longer arrived at Ulysses up to -65 degrees of heliographic latitude but not beyond. Particles could have reached these latitudes along magnetic fields; such connections to the outer lower latitude heliosphere evidently do not exist above that latitude. The accelerated streams have composition similar to solar wind abundances, no dispersion, and a net inward anisotropy. The underlying composition between the recurrent stream is similar to the anomalous component of cosmic rays. The channel sensitive to high-energy protons (> 230 megaelectron volts) shows a 26-day variation of the flux superimposed on the heliospheric modulation of galactic ions.
authors.affiliation: Max-Planck-Institut für Aeronomie, Katlenburg-Lindau, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Keppler
authors.forename: M
authors.initials: M
authors.lastname: Fränz
authors.forename: A
authors.initials: A
authors.lastname: Korth
authors.forename: M K
authors.initials: MK
authors.lastname: Reuss
authors.forename: J B
authors.initials: JB
authors.lastname: Blake
authors.forename: R
authors.initials: R
authors.lastname: Seidel
authors.forename: J J
authors.initials: JJ
authors.lastname: Quenby
authors.forename: M
authors.initials: M
authors.lastname: Witte
mesh_terms: D000054:Acceleration; D005118:Extraterrestrial Environment; D007477:Ions; D012399:Rotation; D016082:Solar System; D018531:Spacecraft
chemical_list: D007477:Ions