Synthesis and processing of lithium-loaded plastic scintillators on the kilogram scale

Abstract

Plastic scintillators that can discriminate between gamma rays, fast neutrons, and thermal neutrons were synthesized and characterized while considering the balance between processing and performance at the kilogram scale. These trade-offs were necessitated by the inclusion of 0.1 wt. % lithium-6 to enable detection of thermal neutrons. The synthesis and processing of these plastic scintillators on the kilogram scale required consideration of many factors. First, a comonomer (methacrylic acid) was used to solubilize salts of lithium-6, which allow for a thermal-neutron capture reaction that produces scintillation light following energy transfer. Second, scintillation performance and processability were considered because the increasing content of the comonomer resulted in a sharp decrease in the light output. The use of small amounts of comonomer (less than or equal to 3 wt. %) resulted in better performance but required high processing temperatures. At large scales, these high temperatures could initiate an exothermic polymerization that results in premature curing and/or defects. The deleterious effects of the comonomer may be mitigated by using m-terphenyl as a primary dye rather than 2,5-diphenyloxazole (PPO), which has been traditionally used in organic scintillators. Finally, the curing environment was controlled to avoid defects like cracking and discoloration while maintaining solubility of dopants during curing. For scintillators that were produced from kilogram-scale batches of precursors, the effective attenuation of scintillation light was characterized.

References in corpus (7)

• Online Monitoring of the Osiris Reactor with the Nucifer Neutrino Detector
• Neutrino Detectors as Tools for Nuclear Security
• Experimental Results from an Antineutrino Detector for Cooperative Monitoring of Nuclear Reactors
• The PROSPECT Physics Program
• Measurement of the Antineutrino Spectrum from ${}^{235}$U Fission at HFIR with PROSPECT
• A mobile antineutrino detector with plastic scintillators
• A prototype for SANDD: A highly-segmented pulse-shape-sensitive plastic scintillator detector incorporating silicon photomultiplier arrays

Cited by in corpus (3)

• ${}^6$Li-loaded liquid scintillators produced by direct dissolution of compounds in diisopropylnaphthalene (DIPN)
• Performance of large-scale 6Li-doped pulse-shape discriminating plastic scintillators
• A prototype reactor-antineutrino detector based on ${}^6$Li-doped pulse-shaping-discriminating plastic scintillator