Higher-order statistics from NMIS to measure neutron and gamma ray cross talk in plastic scintillators

Cross talk occurs when a particle that is detected in a detector is subsequently detected in a neighboring detector. In this paper, a method is proposed to infer the degree and type of neutron and gamma ray cross talk between detectors that are placed side by side. To this end, a set of measurements was performed using the Nuclear Materials Identification System to acquire the time-dependent bicovariance functions of the pulses registered by an instrumented 252Cf source and two fast plastic scintillators. The acquired signatures were then analyzed to infer the degree and type of coincidences due to cross talk in relation to “true” coincidences given by the spontaneous fission process.