Radiation environment measurements and single event upset observations in sun-synchronous orbit

Analysis of data from the Cosmic Radiation Environment and Dosimetry experiment (CREDO) carried in sun-synchronous polar orbit on UoSat-3 shows the influence of cosmic rays, trapped protons, and solar particles and allows comparison with device behavior. For the quiet-time cosmic ray environment, a comparison has been made between CREDO count rates as a function of LET and the predicted count rate (for several values of rigidity) using the Adams model and applying a full treatment to the isotropic pathlength distribution in the 1 cm² by 300 μm diodes. Two periods of very intense solar activity have been observed from the data set to date; an analysis of the count rate LET spectra during this event reveals that in the 2-3 GV rigidity range, counts are enhanced up to 10³ MeV/(g-cm^-2) and that solar flare effects are observed for rigidity values up to 6-7 GV. A CREDO count rate contour map of the South Atlantic Anomaly at 800 km altitude has been constructed from frequent UoSat-3 traversals of this region