Development of a miniaturised particle radiation monitor for Earth orbit

Geometry and algorithm design for a novel highly miniaturised radiation monitor (HMRM) for spacecraft in medium Earth orbit are presented. The HMRM device comprises a telescopic configuration of application-specific active pixel sensors enclosed in a titanium shield, with an estimated total mass of 52 g and volume of 15 cm3. The monitor is intended to provide real-time dosimetry and identification of energetic charged particles in fluxes of up to 108 cm-2 s-1 (omnidirectional). Achieving this capability with such a small instrument could open new prospects for radiation detection in space. The methodology followed for the design and optimisation of the particle detector geometry is explained and analysis algorithms - for real-time use within the monitor and for post-processing reconstruction of spectra - are presented. Simulations with the Geant4 toolkit are used to predict operational results in various Earth orbits. Early test results of a prototype monitor, including calibration of the pixel sensors, are also reported.