| The Earth's magnetosphere is composed of energetic electrons and protons. It is important to verify average populations and energy distributions of these particles and quantify the effects of geomagnetic events on their populations and energy distributions. Abrupt changes have been observed in the energy and distribution of protons during magnetic storms creating a large population of very energetic (> 1 MeV) protons in the slot region of the Earth's Van Allen belts. A few attempts have been made in the past to investigate the sources and loss mechanism of these energetic particles. We have carried out detailed modelling of a High Energy Proton Telescope (HEPT) proposed as a scientific instrument for the proposed Canadian Outer Radiation Belt Injection, Transport, and Loss Satellite (ORBITALS) mission. HEPT is capable of measuring the energetic proton and electron distributions in the energy range of 3-120 MeV for protons and 3-20 MeV for electrons. The detector consists of two heads, one to cover the range of 3 to 26 MeV protons and the second to cover the range of 26 to 120 MeV protons with total view angles of 18° and 36°, respectively. The detector efficiency and geometric factors were calculated numerically using the GEANT4 high energy physics modelling code. In addition, model calculations were carried out to compare the model instrument performance with experimental measurements carried out at the TRIUMF accelerator facility giving good agreement. The results obtained indicate that the detector design would be suitable for a satellite mission to study energetic particle distributions during energetic solar particle events. |
