Investigtion of Inner Belt Flux Anisotropies

We investigate pitch angle distributions in the inner radiation belt for L-shells between 2-2.5 REarth and in the equatorial regions with B/B0 of <1.05. The data from the INTEGRAL Radiation Monitor (IREM) onboard ESA’s INTEGRAL satellite is analysed for the years from 2010-2014 and 2019-2020 during its descent into the proton belt during two solar minima. The Proton Telescope (PROTEL) onboard the CRRES mission (NASA, U.S. Department of Defense; 1990-1991) is used for comparison of the data in the same regions, divided into a pre-storm, storm and post-storm period. The channels used for this study are most susceptible to protons and least affected by electron contamination. The pitch angles of the instruments to the magnetic field is retrieved and their countrate dependence is investigated. The peak countrates are observed at around 90°for all investigated channels. For IREM, the fitted anisotropy factor (n) is larger (n=8-9) for the lower energy channel (>12 MeV) for the L-shell 2 - 2.25 RE and lower (n=2-4) for the higher energy channels (>43 MeV). For L-shell= 2.25-2.5 RE the anisotropy factors for the lower energy channel are also large (n=6-7) and for the higher energy channels low (n=2-6). Similar behaviour is found for the PROTEL data. In the low energy channel (>11 MeV) the highest anisotropy (n=5.5) is found. During the storm the anistropy increases to about 20 in the higher energy channels (>44 MeV) and stays elevated in the post-storm period.