Searching for EAS Features in the Detection of Delayed Particles and Muons at the MSU EAS Array

The time distributions of particles in extensive air showers (EASs) have been studied using the EAS array at Moscow State University [1, 2]. More than 105 particles are produced in an EAS during the interaction of cosmic rays with energies above 1014 eV with the atmosphere. Delayed particles are detected in 3.5% of EASs with an unshielded detector located at the Earth’s surface. Muons are detected in 60% of EASs using a shielded detector located under a soil ground layer equivalent to a 20 m of water column. The detector signals are recorded using a two-beam analog storage oscilloscope. It has been found that the detection probability increases when observing muons for EASs containing from $${{10}^{5}}$$ to $${{10}^{6}}$$ particles, and when observing delayed particles for EASs containing from $${{10}^{6}}$$ to $${{10}^{7}}$$ particles. The distribution over distances to the EAS axis when observing delayed particles is wider than for muons and the age distributions do not differ within errors. The features of EASs with delayed particles and the hypothesis that the height of the appearance of delayed particles can be higher than the height at which EAS electrons and muons are produced are considered.