Using cross-correlations of SEUs and AP8 as a diagnostic tool

This work demonstrates that spurious effects, such as SEUs, anomalies, and enhanced noise in shielded sensors, can be used as proxy data sets to evaluate AP8 at low altitude, to provide corrections to it, and to indicate the energy of the protons that are producing the background effect. The approach is to use a 2-D (longitude and latitude) cross-correlation between the background data set and the current-epoch AP8 predicted fluxes. The correlation is done as a function of proton energy and satellite altitude. The technique can be used to determine the energy of the particle that is producing a particular effect. This cross-correlation technique shows that using APS with a present-epoch magnetic field model accurately predicts the present location of the South Atlantic Anomaly proton flux enhancement at the TOPEX altitude (/spl sim/1300 km), and furthermore, lower altitude cross-correlations using COBE data show that a dual-peaked intensity structure above 100 MeV in AP8 is an artifact of the model and its interpolation routines; only a single peak is actually present in the particle distribution in space.