Particle Detector (PD) Experiment of the Korea Space Environment Monitor (KSEM) Aboard Geostationary Satellite GK2A

The Particle Detector (PD) experiment aboard the geostationary satellite GEO-KOMPSAT-2A (GK2A) measures populations of electrons and positive ions in the Earth’s geostationary orbit at a geographic longitude of 128.2^∘ , inclination of 0^∘ and a mean orbital radius of 6.6 Earth radii ( R_E ). The PD experiment consists of three sensors with different viewing angles relative to the spacecraft. Each sensor consists of two telescopes that are mechanically configured back-to-back with a field-of-view of 20^∘× 20^∘ and measures electrons and ions, using silicon detectors equipped with foils and magnets for the separation of ions and electrons. The energy ranges of the sensor for electrons and ions are 100–3800 keV and 148–22500 keV, respectively. A particular emphasis on electron measurement is given by allocating 48 energy bins in the measured energy range, whereas 22 energy bins are allocated for ion measurements. This unprecedented energy resolution of Δ E/E in the range 5–25