The energy spectrum of all-particle cosmic rays around the knee region observed with the Tibet-III air-shower array

Abstract

We have already reported the first result on the all-particle spectrum around the knee region based on data from 2000 November to 2001 October observed by the Tibet-III air-shower array. In this paper, we present an updated result using data set collected in the period from 2000 November through 2004 October in a wide range over 3 decades between \(10^{14}\) eV and \(10^{17}\) eV, in which the position of the knee is clearly seen at around 4 PeV. The spectral index is -2.68 \(\pm\) 0.02(stat.) below 1PeV, while it is -3.12 \(\pm\) 0.01(stat.) above 4 PeV in the case of QGSJET+HD model, and various systematic errors are under study now.