Cosmic ray spectrum in the energy range 1.0E15-1.0E18 eV and the second knee according to the small Cherenkov setup at the Yakutsk EAS array

• Main Authors: Knurenko, S. P., Petrov, Z. E., Sidorov, R., Sleptsov, I. Ye., Starostin, S. K., Struchkov, G. G.
• Format: Report
• Language: unknown
• Published: arXiv 2013
• Subjects: High Energy Astrophysical Phenomena astro-ph.HE; FOS Physical sciences; Yakutsk
• Online Access: https://dx.doi.org/10.48550/arxiv.1310.1978; https://arxiv.org/abs/1310.1978

From the data on Cherenkov light from EASs collected over the period of more than 15 years, the spectrum of cosmic rays was obtained in the energy range 1.0E15-1.0E18 eV. This spectrum has two features: at ~3.0E15 eV (first knee) and at ~1.0E17 eV (second knee). The first knee is characterized by the indexes γ_1=2.7+/-0.03 and γ_2 = 3.12+/-0.03 and the second knee - by γ_1 = 2.92+/-0.03 and γ_2=3.24+/-0.04. In the second case the difference amounts to Δγ_23=0.32{\pm}0.03{\pm}0.05 which is less than the case of the first knee Δγ_12=0.42+/-0.03+/-0.05 (here dual errors represent statistics and systematics correspondingly). The lesser difference Δγ_23 can be explained with the influx of cosmic rays from Meta-galaxy and, hence, with some increase of the cosmic rays intensity in the energy range 5.0E16-1.0E18 eV, which compensates the escape of heavier nuclei from the Galaxy. The presence of the second knee could be confirmed by abrupt change in mass composition from from lnA~3 at ~1.0E17 eV to lnA~1.5 at 1.0E18eV found from the analysis of longitudinal development of EAS. : 8 pages, 3 figures in Proc. of 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 2013