大気チェレンコフ光による超高エネルギー宇宙線の原子核種の判別法

石川 弘


Abstract


   A simulation study for Cherenkov light images of extensive air showers was performed to develop a method to distinguish the nuclide of ultra-high energy cosmicrays. Cherenkov telescope of 3m diameter was assumed to be installed in the Tibet highland of 4300m.
   As a result of the simulation, Vertical length (LENGTH) , fatness (FATNESS) and the rising altitude of air showers (X20) of Cherenkov images were examined variously. Showers with LENGTH of 2.0° or more are found to be originated by protons, and showers with FATNESS greater than 0.9° are known to be originated from very heavy nucleus as iron. It was found that air showers with X20 less than 0.9° are originated form Fe nuclei, and for showers with X20 greater than 1.5° the primary cosmic rays are limited to proton. Incident energies of air showers are estimated with an error of 20% for protons and 14% for irons.