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 10 3 −10 5 TeV energy range. The reconstruction of the primary energy spectra is carried out using an EAS inverse approach in the framework of the SIBYLL2.1 and QGSJET01 interaction models and the hypothesis of powerlaw primary energy spectra with rigidity-dependent knees. The energy spectra of primary H, He, O-like and F e-like nuclei obtained with the SIBYLL interaction model agree with corresponding extrapolations of the balloon and satellite data to ∼ 10 3 TeV energies. The energy spectra obtained from the QGSJET model show a predominantly proton composition in the knee region. The rigidity-dependent knee feature of the primary energy spectra for each interaction model is displayed at the following rigidities: E R ≃ 2500 ± 200 TV (SIBYLL) and E R ≃ 3100 − 4200 TV (QGSJET).All the results presented are derived taking into account the detector response, the reconstruction uncertainties of the EAS parameters, and fluctuations in the EAS development.

We present all-particle primary cosmic-ray energy spectrum in the 3 · 10 6 − 2 · 10 8 GeV energy range obtained by a multi-parametric event-by-event evaluation of the primary energy. The results are obtained on the basis of an expanded EAS data set detected at mountain level (700 g/cm 2 ) by the GAMMA experiment. The energy evaluation method has been developed using the EAS simulation with the SIBYLL interaction model taking into account the response of GAMMA detectors and reconstruction uncertainties of EAS parameters. Nearly unbiased (< 5%) energy estimations regardless of a primary nuclear mass with an accuracy of about 15−10% in the 3 · 10 6 − 2 · 10 8 GeV energy range respectively are attained.An irregularity ('bump') in the spectrum is observed at primary energies of ∼ 7.4 · 10 7 GeV. This bump exceeds a smooth power-law fit to the data by about 4 standard deviations. Not rejecting stochastic nature of the bump completely, we examined the systematic uncertainties of our methods and conclude that they cannot be responsible for the observed feature.

The Aragats Space Environment Center in Armenia provides real-time monitoring of cosmic particle fluxes. Neutron monitors operating at altitudes of 2000 m and 3200 m on Mt Aragats continuously gather data to detect possible abrupt enhancement of the count rates. Additional high precision detectors, measuring muon and electron fluxes, along with directional information have been put in operation on Mt Aragats in the summer of 2002. We plan to use this information to establish an early warning system against extreme solar energetic particle (SEP) events which pose danger to the satellite electronics and the space station crew. Solar ion and proton fluxes as measured by space-borne sensors on ACE and GOES satellites are used to derive expected arrival times of highest energy ions at 1 AU. The peaks in the time series detected by Aragats neutron monitors, coincided with these times, demonstrate the possibility of early detection of SEP events using the ground-based detectors.

The phenomenological characteristics of the electron and muon components of extensive air showers with the range 105⩽Ne⩽107 are obtained from the GAMMA installation of the ANI experiment at Mt Aragats in Armenia at an observation level of 700 g cm-2. The experimental results are compared with other experiments and with the simulation carried out using the CORSIKA code and ARES package.

Experimental data on EAS characteristics with Ne > 105 are used to calculate the so-called αe-parameter which is directly connected with the energy of the primary cosmic ray radiation. It is shown that the distribution of showers selected by a constant value of this parameter is isotropic, and the measurement of the αe-spectrum is a direct way to obtain the primary energy spectrum. Using the αe-parameter, the primary all-particle energy spectrum of the cosmic radiation in the knee region is obtained. The energy spectrum is compared with the corresponding data of other experiments.