Use of EAS muon production depth distribution for the study of primary cosmic rays and high energy interactions

The reconstruction of EAS longitudinal development by means of TTC-approach, applied to muons detected by large tracking and timing telescopes allows a new and powerful tool for the study of primary mass composition in the knee energy region. It permits to extend the methodology first applied by Fly's Eye in EeV energy region to PeV energies. In particular possible measurements of inelastic cross section and inelasticity of proton-air interactions are discussed