Search for variations in the frequency of registration of delayed particles at the MSU extensive air showers array

At the MSU EAS array the temporal distributions of particles in extensive air showers (EAS) with energies greater than 10 eV were studied. Delayed particles were registered in 3.5% of EAS. The flash in the frequency rate of registration of delayed particles from 1986 to 1990 with a maximum of the registration frequency in 1987 and the fine structure of which at the decline of the flash, consisted of a series of bursts of quasi-periodic fading oscillations with an oscillation period of approximately 4 days and a burst duration of about 32 days, is discussed. At the same time, the EAS frequency registration rate in limits of statistical errors was unchanged.