The cosmic-ray energy spectrum between 1014.5 and 1016.3 eV covering the "knee" region

M. Amenomori*, Z. Cao, B. Z. Dai, L. K. Ding, Y. X. Feng, Z. Y. Feng, K. Hibino, N. Hotta, Q. Huang, A. X. Huo, H. Y. Jia, G. Z. Jiang, S. Q. Jiao, F. Kajino, K. Kasahara, Labaciren, S. M. Liu, D. M. Mei, L. Meng, X. R. MengMimaciren, K. Mizutanin, J. Mu, H. Nanjo, M. Nlshizawa, M. Ohnishi, I. Ohta, T. Ouchi, J. R. Ren, T. U. Saito, M. Sakata, Z. Z. Shi, M. Shibata, A. Shiomi, T. Shirai, H. Sugimoto, X. X. Sun, K. Taira, Y. H. Tan, N. Tateyama, Shoji Torii, H. Wang, C. Z. Wen, Y. Yamamoto, G. C. Yu, P. Yuan, T. Yuda, C. S. Zhang, H. M. Zhang, L. Zhang, Zhasang, Zhaxiciren, W. D. Zhou

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

81 Citations (Scopus)


The Tibet array is the first air shower detector to search for 10 TeV gamma-ray point sources. This array also has a high sensitivity to air showers initiated by cosmic rays around the "knee" of the all-particle spectrum at 1015-1016 eV, with quite small ambiguity for the energy estimation, since the development of air showers in this high energy region is close to maximum at Yangbajing altitude (4300 m above sea level). Using the data set taken with the Tibet array in the period from 1990 October through 1993 July, we obtained the differential energy spectrum of primary cosmic rays between 3 × 1014 and 2 × 1016 eV covering the knee region. The overall spectrum obtained does not resemble a single power law and shows a gradual steepening of the slope at energies around 1015.25 eV. The spectrum is expressed as J(E0) = 1.5 × 10-20(E0/1014.75 eV)-2.60±0.04(m-2 s-1 sr-1 eV-1) at E0 < 1014.75 eV and J(E0) = 1.2 × 10-23(E0/1015.85 eV)-3.00±0.05(m-2 s-1 sr-1 eV-1) at E0 > 1015.85 eV, where this changes gradually between 1014.75 and 1015.85 eV and takes the value J(E0) = 6.7 × 10-22 (m-2 s-1 sr-1 eV-1) at E0 = 1015.25 eV.

Original languageEnglish
Pages (from-to)408-414
Number of pages7
JournalAstrophysical Journal
Issue number1 PART I
Publication statusPublished - 1996
Externally publishedYes


  • Cosmic rays

ASJC Scopus subject areas

  • Space and Planetary Science


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