Constraints on the flux of primary cosmic-ray photons at energies E > 10^18 eV from Yakutsk muon data

A. V. Glushkov, I. T. Makarov, M. I. Pravdin +4

Comparing the signals measured by the surface and underground scintillator detectors of the Yakutsk Extensive Air Shower Array, we place upper limits on the integral flux and the f…