Document Type

Article

Publication Date

4-2024

Abstract

Organic plastic scintillators are widely used in a variety of homeland security applications, most commonly as detectors for radiation portal monitors due to their relative low cost, physical robustness, and fast-timing properties. However, plastic scintillators also typically provide lower light yields and photon sensitivity compared to other detector material alternatives, so many studies over the past two decades have sought ways to overcome these shortfalls. Research recently conducted at the Air Force Institute of Technology and Oak Ridge National Laboratory demonstrated that photocuring novel plastics offered a viable method for producing fast-curing plastic scintillators (FCPSs). These formulations included an acrylic polymer base and utilize diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO) as the photo-initiator for polymerization; however, that research also indicated that higher concentrations of TPO might adversely affect scintillator light output. The present research refined the optimal TPO concentrations that fully cure these acrylic-base scintillators and maximize light production to 0.04-0.05 percent by weight. Additionally, this research examined whether the use of high-Z loading to improve photon sensitivity impairs the pulse-shape discrimination (PSD) of the FCPSs and confirmed that high-Z loadings of up to 10 percent by weight of triphenyl bismuth (BiPh3) improved photon sensitivity by approximately 10 percent and preserved PSD with figures of merit of > 1.0. Finally, alternative wave shifters were also evaluated for feasibility in future FCPS formulations; however, Exalite-416 was determined as the optimal wave shifter for future use.

Comments

Distribution A: Approved for public release; distribution unlimited.

Source Publication

Journal of Radiation Effects Research and Engineering

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