Variation in nuclear composition of primary cosmic rays in the energy range 1017-1019 eV
D'yakonov M. N. , Egorova V. P., Ivanov A. A., Knurenko S. P. , Kolosov V. A., Nikol'skii S. I. , Pavlov V. N. , Sleptsov I. E.
Distributions of the height of maximum development of extensive air showers constructed from measurements of Cerenkov light at the Yakutsk extensive-air-shower installation have been analyzed. The relative numbers of protons and nuclei among the primary particles with energies of 1017— 1019 eV are estimated.