Integral Neutron Multiplicity Measurements from Cosmic Ray Interactions in Lead

Sixty element $^{3}$He neutron multiplicity detector systems were designed, constructed and tested for use in cosmic ray experiments with a 30-cm cube lead target (306 kg). A series of measurements were performed for the cosmic ray configuration at ground level (3 meters water equivalent, mwe), in the St. Petersburg metro tunnel (185 mwe), and in the Pyh\"{a}salmi mine in Finland (583 and 1185 mwe). Anomalous coincidence events with charged cosmic ray particles at sea level produced events with 100-120 neutrons due possibly to the total disintegration of the Pb nucleus. These events were also detected at 185 mwe, but the particles causing such disintegration are currently unidentified. A two layer 4$\pi $charged particle coincidence/anticoincidence system has been built and integrated into the system to help identify the charge of the originating particle events. Designs for a modular 100-cm cube lead target (11.35 mt) will be presented as well as examples of preliminary data from the various measurements and a discuss of future plans for underground experiments including possible searches for Weakly Interacting Massive Particles (WIMP, dark matter).