| Journal Title /掲載ジャーナル名 |
Physical Review Letters |
| Publication Year and Month /掲載年月 |
August, 2022 |
| Paper Title /論文タイトル |
Observation of Spectral Structures in the Flux of Cosmic-Ray Protons from 50 GeV to 60 TeV with CALET on the ISS |
| DOI /論文DOI |
10.1103/PhysRevLett.129.101102 |
| Author of Waseda University /本学の著者 |
KOBAYASHI, Kazuyoshi(Researcher(Associate Professor), Faculty of Science and Engineering, Waseda Research Institute for Science and Engineering):Corresponding Author |
| Related Websites /関連Web |
– |
| Abstract /抄録 |
A precise measurement of the cosmic-ray proton spectrum with the Calorimetric Electron Telescope (CALET) is presented in the energy interval from 50 GeV to 60 TeV, and the observation of a softening of the spectrum above 10 TeV is reported. The analysis is based on the data collected during ∼6.2 years of smooth operations aboard the International Space Station and covers a broader energy range with respect to the previous proton flux measurement by CALET, with an increase of the available statistics by a factor of ∼2.2. Above a few hundred GeV we confirm our previous observation of a progressive spectral hardening with a higher significance (more than 20 sigma). In the multi-TeV region we observe a second spectral feature with a softening around 10 TeV and a spectral index change from −2.6 to −2.9 consistently, within the errors, with the shape of the spectrum reported by DAMPE. We apply a simultaneous fit of the proton differential spectrum which well reproduces the gradual change of the spectral index encompassing the lower energy power-law regime and the two spectral features observed at higher energies. |
