Kj. Trattner et al., ULYSSES COSPIN LET - LATITUDINAL GRADIENTS OF ANOMALOUS COSMIC-RAY O,N AND NE/, Astronomy and astrophysics, 316(2), 1996, pp. 519-527
A key goal of the Ulysses mission is the measurement of the latitudina
l gradient of the Anomalous Cosmic Ray (ACR) component. Earlier studie
s using data from the COSPIN/LET experiment on board Ulysses together
with in-ecliptic data from the HILT instrument on SAMPEX have shown a
small (similar to 2% per degree) positive latitudinal gradient for ano
malous oxygen in the energy range 8 to 16 MeV/n. This result is consis
tent with the effects of curvature and gradient drifts in the heliosph
eric magnetic field for the current polarity configuration: positively
charged particles are expected to flow down to the heliographic equat
or from the polar regions. In this paper we extend our previous work a
nd include two additional ACR species, nitrogen (4 to 20 MeV/n) and ne
on (4 to 30 MeV/n). We also present our latest results on the ACR oxyg
en latitudinal gradient over an extended energy range (4 to 20 MeV/n).
The period covered for all three species include the Ulysses south po
lar pass, the rapid transit from the south pole to the ecliptic and a
significant portion of the climb to high northern latitudes. For all s
pecies and energy ranges the latitudinal gradients are between 1% and
2%, consistent with earlier studies, and show a slight tendency to lar
ger gradients for higher magnetic rigidity.