Neutron cross-talk characterization of liquid organic scintillators

Correlated neutrons from a Cf-252 spontaneous fission source were measured with a coincidence detection system. The system consisted of three EJ-309 cylindrical liquid scintillators (length and diameter of 7.62 cm) configured to quantify the effects of neutron cross-talk on the total observed correlated counts. Because scatter-based detectors are susceptible to neutron cross-talk, the discrimination between true correlated counts and cross-talk is significant for neutron coincidence measurements. This measurement aimed to mitigate the neutron cross-talk between detectors with adequate polyethylene shielding, and was compared to simulations. The fractional influence of cross-talk on the total observed correlated counts was 30% for neutrons above ~0.65 MeV at a detector-source-detector angle of 30°. Furthermore, the fractional influence of neutron cross-talk increases for decreasing detector-source-detector angles at a constant detector standoff. The angular distribution of the scattered neutron was also simulated, and shows an anisotropic distribution in the scatter detector frame of reference primarily dependent on kinematics of the neutron-hydrogen scatter and the detector volume.