High‐Z Sensitized Plastic Scintillators: A Review

Abstract

The need for affordable and reliable radiation detectors has prompted significant investment in new radiation detector materials, due to concerns about national security and nuclear nonproliferation. Plastic scintillators provide an affordable approach to large volume detectors, yet their performance for high-energy gamma radiation is severely limited by the small radiation stopping power inherent to their low atomic number. Although some sensitization attempts with organometallics were made in the 1950s to 1960s, the concomitant decrease in light yield has limited the usefulness of these sensitized detectors. Recently, with new knowledge gained during the rapid development of organic optoelectronics and nanotechnology, there has been a revived interest in the field of heavy element sensitized plastic scintillators. Here, the recent efforts on sensitized plastic scintillators are summarized. Basic scintillator physics is first reviewed. The discussion then focuses on two major thrusts in the field: sensitization with: (1) organometallics and (2) oxide and fluoride nanoparticles. The design rationales and major results are examined in detail, with existing limitations and possible future pathways discussed. Special attention is paid to the underlying energy deposition and transfer processes, as these determine the key performance metrics such as light yield and radioluminescence decay lifetime.

The Bright X‐Ray Stimulated Luminescence of HfO2 Nanocrystals Activated by Ti Ions

“…Luminescent NPs—metals, semiconductors, or insulators—have come to the forefront in modern solid state physics, lighting, next generation electronics, and sensing, in the environmental and life science, as well as in medical and biological fields . In particular, extensive theoretical and spectroscopic studies of the optical response of inorganic luminescent NPs have been proving the suitability of these systems in the field of phosphors and scintillators for lighting and radiation detection applications . For instance, defect‐engineering strategies can be applied in wide bandgap nanomaterials.…”

Real‐Time Optical Response of Polysiloxane/Quantum Dot Nanocomposites under 2 MeV Proton Irradiation: Luminescence Enhancement of Polysiloxane Emission through Quantum Dot Sensitization

“…More specifically, the samples embedding QD at the concentrations of 0.003 and 0.015 wt% show a light yield increase of 8% and 3% in comparison with the undoped PSS sample, respectively. As the optical contribution of the QDs to the total emission can be considered from Figure a–g as negligible, the increasing light yield is correlated with the high‐Z sensitization offered by the nanocrystals . In fact, for γ‐irradiation, it has been already demonstrated that the presence of inorganic nanocrystals within an organic polymer favors the conversion of γ‐photons into photoelectrons, although the excitation events subsequently occur within the organic material .…”

“…As the optical contribution of the QDs to the total emission can be considered from Figure 4a-g as negligible, the increasing light yield is correlated with the high-Z sensitization offered by the nanocrystals. [29] In fact, for γ-irradiation, it has been already demonstrated that the presence of inorganic nanocrystals within an organic polymer favors the conversion of γ-photons into photoelectrons, although the excitation events subsequently occur within the organic material. [29] Similarly, in our case, the presence of nanocrystals increases the specific energy loss experienced by protons, although the ionization and excitation events mainly occur within the polymer, giving rise to the enhanced luminescence in comparison with the pure PSS (Figure 5a).…”

“…[29] In fact, for γ-irradiation, it has been already demonstrated that the presence of inorganic nanocrystals within an organic polymer favors the conversion of γ-photons into photoelectrons, although the excitation events subsequently occur within the organic material. [29] Similarly, in our case, the presence of nanocrystals increases the specific energy loss experienced by protons, although the ionization and excitation events mainly occur within the polymer, giving rise to the enhanced luminescence in comparison with the pure PSS (Figure 5a). Indeed, at these low QD concentrations, it can be assumed that the proton interactions mainly occur within the polymer matrix, without the involvement of a QD.…”

Gleaming Uranium: An Emerging Emitter for Building X‐ray Scintillators

“…Owing to the low density of the chemical composition, organic scintillators still display several drawbacks in detecting high‐energy photons . Organic chromophores are precluded in this article, interested readers can find review articles from Hamel and Pei and co‐workers, in which the status of organic scintillators is comprehensively summarized . Metal ion‐based emitters are substantially utilized to build inorganic scintillators owing to their high energy conversion efficiency and energy resolution .…”