Simulating the background noise in the LEGRI CZT detectors

A Monte-Carlo model of the MINISAT 01 satellite has been built. This model, based on the GEANT software suite, is used to study the background noise i nduced in the cadmium zinc telluride (CZT) in the LEGRI detector. We find t hat the background noise count rate at the poles is similar to 50% higher t han at the equator. This increase is due to the effects of geomagnetic rigi dity cut-off. We also simulate the effects of passages through the South At lantic Anomaly (SAA) with simulations showing an increase of similar to 0.5 counts cm(-2) sec(-1) after the SAA, in good agreement with observational data.