Boron loaded plastic scintillator could detect both fast neutrons (thanks to hydrogen) and slow neutrons (thanks to 10B). The large cross sections of both reactions lead to high detection efficiency of incident neutrons. However, gamma rays must be rejected first as the scintillator is also sensitive to them. In the present research zero crossing method was used to test neutron-gamma discrimination performance of BC454 boron loaded plastic scintillator. Three contrast experiments were carried out and different thermalization degrees lead to different time spectra in the MCA. Further analysis proved that three Gaussian curves could be used to fit the spectra; they corresponded to gamma rays, fast neutrons and slow neutrons respectively. The slow neutron curve could be clearly separated from the gamma curve. Discrimination performance for fast neutrons became poor, but their peaks could also be separated.
Monte Carlo simulations and measurements for efficiency determination of lead shielded plastic scintillator detectors
