Low Energy (0.5-5.0 MeV/nuc) Anomalous Cosmic Rays at High Heliolatitudes and in the Ecliptic Plane

Abstract

In 1997 to early 1998, anomalous cosmic ray (ACR) oxygen (O) was measured by the HI-SCALE instrument on the Ulysses spacecraft at 5 AU in the ecliptic plane for the energy range 0.5-5.0 MeV/nuc. At 1 AU in the ecliptic at this time (measured by the EPAM instrument on the ACE spacecraft) ACR O was only seen in the energy range 2-5 MeV/nuc. The radial gradient for 2-5 MeV/nuc ACR O was large, ∼40%/AU, for days 242-305, 1997. By mid-1998, no ACR O could be measured in the entire energy range.