Proton Monitor Las Dos Torres: First Intercomparison of In-Orbit Results

A new proton monitor on board NANOSAT-1B—Las Dos Torres (translated: The Two Towers)—and its preliminary results after two years in orbit and its intercomparison to a RadFET and to trapped proton models are presented. This satellite was fully developed by INTA (National Institute of Aerospace Technology, Spain) and was launched on July 29, 2009. The instrument includes two stacks of radiation-sensing elements: the “dark” and “light” towers. The displacement damage was measured, both through the increase of a photodiode dark current (“dark tower”) and the decrease of the photocurrent signal in a photodiode optically linked to light emitting diodes (“light tower”). The instrument was also designed to monitor the ionization current of the photodiodes and the variations in the proton flux in the South Atlantic Anomaly.