An event monitoring system has a plurality of detector units for detecting neutrons or other emissions from radioactive materials (i.e., events). At least one of the detector units has a detector for the events and an amplifier to amplify signals generated by the detector. A signal handler receives the amplified signals and an adder adds to the signals an indication of the detector unit from which the signals originated. A combiner combines the signals. A serial link conveys the combined signals from the signal handler to a signal processor which includes a signal receiver for the combined signals. A time stamper applies to the signal an indication of time of the generation of the signal by the detector unit, and a computer processes the signals, including the time and detector unit indications, using software to produce information on the signals or events they represent.