  A Monte-Carlo study to reconstruct energy and mass of cosmic rays with
energies above 300 TeV using ground based measurements of the electromagnetic
part of showers initiated in the atmosphere is presented. The shower properties
determined with two detector arrays measuring the air Cherenkov light and the
particle densities as realized at the HEGRA experiment are processed to
determine the energy of the primary particle without the need of any hypothesis
concerning its mass. The mass of the primary particle is reconstructed coarsely
from the same observables in parallel to the energy determination.
