Selection of showers with given energies at the GAMMA experiment (Armenia)

Some years ago, we defined the possibility to select showers generated by primaries with different masses but with the same primary energy at mountain altitude. The new GAMMA experiment (Armenia, 3200 m. a.s.l.) gives us the possibility to check our method using a EAS selection parameter specially adapted for this experiment. We show that experimental data are in particularly good agreement with the corresponding values obtained by simulation using the CORSIKA code. This possibility to pick up showers fixed energies will be used to determine the primary mass composition around the knee and to select gamma-showers 6 with energies in the range of 10 GeV.