PCR nuclear composition at 1-30 PeV according to lateral distributions of electrons in EAS accompanied by high energy particles in emulsion chambers

New data on the primary cosmic ray nuclear composition were derived from the electron lateral distributions of EAS at Tien-Shan. The dependence on EAS electron size is presented from Ne = 5·105 to 3·107. Data were obtained for all EAS as well as for EAS accompanied by high energy gamma-rays and hadrons in X-ray emulsion chambers. According to model simulations the latter events are generated predominantly by primary protons. Results showed that the fraction of protons and light nuclei does not decrease above the 'knee' from Ne = 106 up to 107 (∼10 - 20 PeV primary energy)