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

Experimental Investigation of the Nature of the Knee in the Primary Cosmic Ray Energy Spectrum with the GAMMA experiment

“…It is probable that the registered excess explains the trend to a heavier PCR mass composition at energies above the knee (see [14,15]) as well as the decline of the parameter S with rising energy in the region below the knee with its further constancy and, probably, a subsequent increase [16,8]. Such a decline of the S parameter is more rapid than could be expected from the shift of the EAS maximum down with increasing energy.…”