Measurement of anomalous cosmic ray oxygen at heliolatitudes ∼25° to ∼64°
Simnett, G. M.; Pick, M.; Anderson, K. A.; Krimigis, S. M.; Lanzerotti, L. J.; Armstrong, T. P.; Gold, R. E.; Lin, R. P.; Roelof, E. C.; Sarris, E. T.; Maclennan, C. G.
United States, United Kingdom
Abstract
We report measurements of the oxygen component (0.5 - 22 MeV/nucl) of the interplanetary cosmic ray flux as a function of heliolatitude. The measurements reported here were made with the Wart telescope of the HI-SCALE low energy particle instrument on the Ulysses spacecraft as the spacecraft climbed from ∼24° to ∼64° south solar heliolatitude during 1993 and early 1994. As a function of heliolatitude, the O abundance at 2-2.8 MeV/nucl drops sharply at latitudes above the heliospheric current sheet. The oxygen spectrum obtained above the current sheet has a broad peak centered at an energy of ∼2.5 MeV/nucl that is the anomalous O component at these latitudes. There is little evidence for a latitude dependence in the anomalous O fluxes as measured above the current sheet. Within the heliospheric current sheet, the O measurements are composed of both solar and anomalous origin particles.