[P-EM13] 内部磁気圏

[PEM13-P27] Inter-channel calibration of the high-energy electron experiments (HEP) instrument onboard the Arase satellite

*堀 智昭¹、三谷 烈史²、高島 健²、Park Inchun¹、栗田 怜¹、寺本 万里子¹、東尾 奈々³、笠原 慧⁴、横田 勝一郎⁵、三好 由純¹、篠原 育² (1.名古屋大学宇宙地球環境研究所、2.宇宙航空研究開発機構宇宙科学研究所、3.宇宙航空研究開発機構、4.東京大学大学院理学系研究科、5.大阪大学大学院理学研究科)

キーワード：あらせ衛星、粒子観測器、キャリブレーション

An inter-channel comparison of electron fluxes measured by the HEP instrument onboard the Arase satellite is conducted with a focus on the apparent non-uniformity in detection efficiency and relative offset of the background flux level between the channels, which was partly reported previously. We extend the data set to cover the entire two-year period since the start of the regular observations. The flux ratio of different channels is sorted by the electron flux level of much higher energies that was simultaneously measured by the extremely high-energy electron experiment (XEP) instrument onboard Arase. The result shows that the HEP flux of all azimuthal channels is more or less affected by MeV electrons which are most likely to have penetrated into the instrument box and directly hit the detectors. However, it is also revealed that the non-uniform count distribution over the channels still remains even when the penetrating electrons are absent. We conduct a set of Geant-4 simulations to trace electrons with various energies and incident angles to the detector plane in order to give a quantitative interpretation for the resultant count distributions, in terms of the effects of penetrating electrons and obliquely-colliding incident electrons.