Nanoparticles-loaded plastic scintillators for fast/thermal neutrons/gamma discrimination: Simulation and results

摘要

We report herein the application of a new series of plastic scintillators loaded with lithium tetraborate nanoparticles (Li2B4O7) designed for the simultaneous detection of fast neutrons, thermal neutrons and gammarays. First, MCNP simulations are performed to highlight the potential benefit of Li2B4O7 loading. Then, a nanoparticle-loaded scintillator is prepared and evaluated towards the detection of a partially thermalized neutron/gamma 252-californium source. Several scenarios of radiation/matter interactions are evaluated against the observed results. A detection chamber composed of boron-containing chipboard wood has been specifically designed and a subtraction method was set up to afford the best discrimination pattern. For the first time, a triple discrimination is presented with a nanoparticles-loaded plastic scintillator, where both Li-6(n, alpha) and B-10(n, alpha) signatures are observed. A Figure of Merit of 1.40 was calculated between fast neutrons and gamma rays around 480 keVee. The Figure of Merit between fast + thermal neutrons and gamma rays is slightly worse as it is 1.16 at 380 keVee.