The All-Particle Spectrum of Primary Cosmic Rays in the Wide Energy Range from 10{sup 14} to 10{sup 17} eV Observed with the Tibet-III Air-Shower Array
- Department of Physics, Hirosaki University, Hirosaki 036-8561 (Japan)
- Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)
- Faculty of Engineering, Yokohama National University, Yokohama 240-8501 (Japan)
- Department of Physics, Hebei Normal University, Shijiazhuang 050016 (China)
- Department of Mathematics and Physics, Tibet University, Lhasa 850000 (China)
- Department of Physics, Shandong University, Jinan 250100 (China)
- Institute of Modern Physics, Southwest Jiaotong University, Chengdu 610031 (China)
- Department of Physics, Yunnan University, Kunming 650091 (China)
- Faculty of Engineering, Kanagawa University, Yokohama 221-8686 (Japan)
- Faculty of Education, Utsunomiya University, Utsunomiya 321-8505 (Japan)
We present an updated all-particle energy spectrum of primary cosmic rays in a wide range from 10{sup 14} to 10{sup 17} eV using 5.5 x 10{sup 7} events collected from 2000 November through 2004 October by the Tibet-III air-shower array located 4300 m above sea level (an atmospheric depth of 606 g cm{sup -2}). The size spectrum exhibits a sharp knee at a corresponding primary energy around 4 PeV. This work uses increased statistics and new simulation calculations for the analysis. We discuss our extensive Monte Carlo calculations and the model dependencies involved in the final result, assuming interaction models QGSJET01c and SIBYLL2.1, and heavy dominant (HD) and proton dominant (PD) primary composition models. Pure proton and pure iron primary models are also examined as extreme cases. A detector simulation was also performed to improve our accuracy in determining the size of the air showers and the energy of the primary particle. We confirmed that the all-particle energy spectra obtained under various plausible model parameters are not significantly different from each other, which was the expected result given the characteristics of the experiment at high altitude, where the air showers of the primary energy around the knee reach near-maximum development, with their features dominated by electromagnetic components, leading to a weak dependence on the interaction model or the primary mass. This is the highest statistical and the best systematics-controlled measurement covering the widest energy range around the knee energy region.
- OSTI ID:
- 21255756
- Journal Information:
- Astrophysical Journal, Vol. 678, Issue 2; Other Information: DOI: 10.1086/529514; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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