Fluorescent 1,8-naphthalimides-containing polymers as plastic scintillators. An attempt for neutron-gamma discrimination

This paper deals with the scintillation of fluorescent polymeric materials and their utilization in nuclear detection. Despite the importance of its applications, discrimination between fast neutrons and gamma rays in plastic scintillators remains very difficult due to the extreme sensitivity of these detectors to gamma. We have investigated the relevance of different 4-substituted 1,8-naphthalimides as fluorophores, either dispersed in a polymer matrix or copolymerized with styrene or methyl methacrylate to prepare new scintillating materials. Thus, various polymer pellets (Ø 18 mm, length 10-15 mm) incorporating from 0.05% to 1% of naphthalimide were prepared. The charge comparison method commonly used as discrimination technique in nuclear physics experiments was chosen. This technique lies in identifying neutrons from gamma rays by the shape of the light pulse delivered in the scintillator. Preliminary results indicate that the developed scintillators did not satisfy the discrimination criterion.