Precise measurements of the cosmic ray proton energy spectrum in the “knee” region
We report the high-purity identification of cosmic-ray (CR) protons and a precise measurement of their energy spectrum from 0.15 to 12 PeV using the Large High Altitude Air Shower Observatory (LHAASO). Abundant event statistics, combined with the simultaneous detection of electrons/photons, muons, and Cherenkov light in air showers, enable spectroscopic measurements with statistical and systematic precision comparable to satellite data at lower energies. The proton spectrum shows significant hardening relative to low-energy extrapolations, culminating at 3 PeV, followed by sharp softening. This distinct spectral structure closely aligned with the knee in the all-particle spectrum points to the emergence of a new CR component at PeV energies that might be linked to the dozens of PeVatrons recently discovered by LHAASO, and offers crucial clues to the origin of Galactic cosmic rays.
Authors
- Jian Guo (ORCID: https://orcid.org/0000-0002-1667-1701)
- Su-Ming Weng (ORCID: https://orcid.org/0000-0001-7746-9462)
- Xuzhe Zhao (ORCID: https://orcid.org/0000-0002-8924-0777)
- B.T. Zhang
- Zhijie Jiang (ORCID: https://orcid.org/0000-0002-7076-4239)
- Dong Xiao (ORCID: https://orcid.org/0000-0001-9055-598X)
- R. Wang (ORCID: https://orcid.org/0000-0002-5059-8456)
- L.Y. Wang
- Ruizhi Yang
- Wenhan Zeng (ORCID: https://orcid.org/0000-0002-8615-1293)
- H. C. Li
- Yu Luo (ORCID: https://orcid.org/0000-0003-2319-1172)
- Chang Cai (ORCID: https://orcid.org/0000-0001-6624-8998)
- J.L. Zhang
- Jiangbiao He (ORCID: https://orcid.org/0000-0001-5456-5320)
- C. Feng (ORCID: https://orcid.org/0000-0001-9138-3200)
- M.L. Chen (ORCID: https://orcid.org/0009-0000-5295-5624)
- Y. W. Bao (ORCID: https://orcid.org/0000-0001-8918-5248)
- Chengyan Ren (ORCID: https://orcid.org/0000-0003-4352-1888)
- K. J. Zhu (ORCID: https://orcid.org/0000-0003-1872-435X)
- Rongpu Zhou (ORCID: https://orcid.org/0000-0001-5381-4372)
- D. Yan (ORCID: https://orcid.org/0000-0002-3868-9654)
- Xiangdong Ji (ORCID: https://orcid.org/0000-0002-8246-2502)
- Yi-Zhong Fan (ORCID: https://orcid.org/0000-0002-8966-6911)
- Qing Gao (ORCID: https://orcid.org/0000-0001-8000-7736)
- S. P. Zhao (ORCID: https://orcid.org/0000-0003-2120-8356)
- Jun Qun Fang (ORCID: https://orcid.org/0000-0001-9532-8444)
- R.Y. Liu
- Yaodong Cheng (ORCID: https://orcid.org/0000-0003-3891-9461)
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- H. K. Lv (ORCID: https://orcid.org/0000-0002-7779-3630)
- M. Zha
- Zhonghai Zhao (ORCID: https://orcid.org/0000-0003-2051-1740)
- H. B. Jiang (ORCID: https://orcid.org/0000-0003-1415-6332)
- Hongbing Tan (ORCID: https://orcid.org/0000-0003-4906-6345)
- L.P Wang
- X.P. Zhang
- P. Pattarakijwanich (ORCID: https://orcid.org/0000-0001-8451-5316)
- P. Lipari (ORCID: https://orcid.org/0000-0001-6832-6443)
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- Kenny C. Y. Ng (ORCID: https://orcid.org/0000-0001-8016-2170)
- Fenghe Li (ORCID: https://orcid.org/0009-0001-1293-5132)
- Jiang‐Ning Zhou (ORCID: https://orcid.org/0000-0003-1225-2873)
- Xiaoyang He (ORCID: https://orcid.org/0000-0002-8651-0145)
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Publication Details
- Journal
- Science Bulletin
- Published
- 2025-11-15
- DOI
- https://doi.org/10.1016/j.scib.2025.10.048
- Citations
- 7
- Primary Topic
- Astrophysics and Cosmic Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 13.09