A.V. Trubitsyn

Nuclear composition of primary cosmic rays in the `knee' region according MSU EAS array data

Experimental data on the EAS muon number fluctuations obtained with the Moscow State University EAS array are analysed to derive the primary mass composition at energies before and after the knee. The mass composition before the knee ( eV) corresponds to that measured by direct methods, while the mass composition after the knee ( eV) is enriched by heavy nuclei.

Primary cosmic ray mass composition at energies 1015–1017 eV as measured by the MSU EAS array

Abstract Experimental muon number distributions in Extensive Air Showers obtained at Moscow State University with enlarged statistics and improved procedure for muon number determination are analysed in the framework of an updated quark-gluon string model. The primary mass composition at energies before and after the kink in the primary energy spectrum is estimated. Mass composition before the kink is close to a normal one, and after the kink experimental data agree with the assumption that normal composition becomes enriched slowly by heavy nuclei according to the Peters-Zatsepin model.

The primary cosmic ray mass composition around the knee of the energy spectrum

Experimental muon number distributions in EAS obtained at Moscow State University are analysed to estimate the primary mass composition at energies before and after knee. The mass composition before the knee corresponds to the normal one (as at E 0 ∼10 12 eV), while experimental data after the knee are in agreement with the assumption that normal composition becomes enriched slowly by heavy nuclei, as also supported by contemporary diffusion models.

Observations of pointlike sources of ultrahigh energy with the MSU EAS array

Observations of extensive air showers (EASs) in Cygnus and Hercules made using the Moscow State University (MSU) EAS array during four seasons starting in the fall of 1984 are briefly reviewed. The operation time of the array and the numbers of showers recorded during each of the seasons are presented for Cyg X-1, Cyg X-2, Cyg X-3, and Her X-1 along with the expected numbers of showers. An analysis is also made of the 10-GeV and higher muon contents from the Cyg X-1 bin observed in 1985-86, when the highest excess over the background occurred. 21 refs.