Energy spectra and elemental composition of primary nuclei in the knee region: Recent results from the GAMMA experiment

On the basis of the extensive air shower (EAS) data obtained by the GAMMA experiment, the energy spectra and elemental composition of the primary cosmic rays are derived in the 1 - 100 PeV energy range. The reconstruction of the primary energy spectra is carried out using an EAS inverse approach with the hypothesis of power-law primary energy spectra with rigidity-dependent knees. The rigidity- dependent knee feature of the primary energy spectra is displayed at the rigidities ER similar or equal to 2.5 +/- 0.2 PeV/Z and ER similar or equal to 3.1 - 4.2 PeV/Z for the SIBYLL and QGSJET interaction models respectively.;Using the event-by-event method of the primary energy evaluation from the measured N-ch, N-mu and shower age (s) parameters, the all-particle energy spectrum is also obtained