WHITE MOUNTAIN COSMIC RAY NEUTRON MULTIPLICITY MONITOR

The multiplicity, i.e. the number of neutrons produced by a single nucleon incident upon a neutron monitor, increases, on the average, with increasing nucleon.energy. This article describes a new type neutron monitor which was especially designed to study the cosmic radiation by taking maximum advantage of this multiplicity effect. The neutron multiplicity monitor has a Bi target of increased thickness and a graphite moderator, instead of the customary Pb target and paraffin (or polyethylene) moderator of other monitors. A transistorized data-handling system records multiplicities from 1 to 399 and provides hourly readouts of the data onto magnetic tape. The procedure used to correct the data for the accidental overlapping of multiplicities is described together with the monitor's neutron background, detection efficiency, mean life time and counting statistics. A description of the White Mountain cosmic ray neutron multiplicity monitor station is included. © 1969.