Measurements from The Heavy-Ion Telescope at The ISS Kibo Exposed Facility

Abstract

Space radiation such as solar energetic particles, galactic cosmic rays (GCR), and trapped particles affect space activities. Heavy ions, in particular, have high linear energy transfer (LET) that exacerbates the risk of radiation exposure for astronauts and affects the electrical circuits of satellites. The Japan Aerospace Exploration Agency (JAXA) has operated the Space Environment Data Acquisition Equipment - Attached Payload (SEDA-AP) at the International Space Station (ISS) Japanese Experiment Module (Kibo) - Exposed Facility, since 2009. The heavy-ion telescope (HIT) is one of the SEDA-AP instruments, which comprises two position-sensitive silicon detectors and 16 silicon detectors. Based on the ΔE × E particle-identification method, HIT measures fluxes of energetic ions from Li to Fe and calculates the loss of energies at each sensor. The HIT results are consistent with the general GCR model and other ISS experiments in terms of elemental abundances and LET distributions. In addition, HIT might have detected heavy ions from a X5.4 solar flare. Moreover, there is the possibility of detecting the anomalous cosmic rays (ACR) from the ADEOS satellite observations; however, ACR was not observed because the pitch angle was not in the field of view of HIT or no distribution of ACR exists at 400 km altitude.