We carried out electron observations with balloons to investigate acceleration and propagation of electrons in the universe. We developed BETS (Balloon-borne Electron Telescope with Scintillation fibers) for electron observations in Sanriku. We obtained electron energy spectrum from 10 GeV to 100 GeV with it. At higher energies, the energy spectrum of electron might show some structure caused by nearby sources like the Vela supernova remnant. In order to observe the energy spectrum above 100 GeV, we needed a thicker calorimeter and a longer observation time. We developed PPB-BETS (Polar Patrol Balloon-BETS) by improving BETS to carry out a long duration ballooning in Antarctica. Energy spectrum of electrons from 100 GeV to 1000 GeV was obtained by a successful fight for 13 days. The arrival direction of electrons seems to be consistent with isotropic distribution for the data taken with PPB-BETS, although we need better statistics to make it clear. We have a future plan to make an observation of electrons and gamma-rays with a scale model of CALET (CALorimetric Electron Telescope) by long duration ballooning in the southern hemisphere for 2 weeks. We proposed CALET for the cosmic-ray observations on the International Space Station (ISS), and it has been selected as one of mission candidates for the second utilization plan on the Exposure Facility of the Japanese Experiment Module (JEM-EF). We are developing a scale model of 1/16 of CALET.
|ジャーナル||journal of the physical society of japan|
|出版ステータス||Published - 2009|
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