Measurements and interpretation of registration of large number of neutrons generated in lead: the role of particle cascades

We register events with large number of neutrons at the ground level as well as in the underground laboratory. These neutrons are produced in secondary cosmic ray inter- actions with matter surrounding the neutron detectors. We used the set of helium-3 filled gas proportional counters and plastic scintillators. We performed a series of measurements in different experimental setups to determine a role of par- ticle cascades in generation of large neutron multiplicities. With GEANT4 simulation of experimental setup we esti- mated number of neutrons produced in a single event which is required to explain our measurements.