This article reports the method and the results of a study on the impact of the detected light intensity on gamma-neutron discrimination. In particular, the minimum number of photons required to achieve a statistically significant separation was measured and shown to be stable against a variation of the photon detection efficiency (PDE) of the system under study. The method, developed using an EJ-276 scintillator bar coupled to a silicon photomultiplier (SiPM), is of general interest. For this specific system, the minimum statistic was measured to be 317 +/- 16 photons, corresponding to different values of the deposited energy, as the PDE was changed.
