Distribution of Arrival Times of Air Shower Particles

We have studied the instantaneous distribution of particles in extensive air showers at sea level by measuring the relative delays between particles with three liquid scintillation counters. The delays measured were in the range from 5 to 300 mμsec. The sizes of the showers were in the range from ${10}^5$ to ${10}^6$ particles. Using statistical methods of analysis we have found that at a given instant most electrons with energies of ∼20 Mev lie in a flat disk of thickness between 1 and 2 meters. The particles which can penetrate at least 20 cm of lead lie in a disk of thickness between 2 and 3 meters. The disk of penetrating particles follows behind the disk of electrons by less then 3 meters.