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Scholarly Works (2 results)

Thesis
Peer Reviewed

Synthesis and Analysis of Novel Materials for Plastic Scintillators

Kishpaugh, David
Advisor(s): Pei, Qibing

UCLA Electronic Theses and Dissertations (2017)

This work seeks improve gamma scintillation light yield of organic plastic scintillators in pursuit of an improved detection technology for radiological and nuclear material. The detection and tracking of such material in transit, especially across borders, is a critical concern to the national security community. Novel polymer systems and additives have been developed, synthesized, and characterized which achieve this end while maintaining the robust nature and ease of fabrication which are the hallmarks of plastic scintillators. The results have shown significant improvement in extrapolated light yield over commercial standards when characterized with photomultiplier tubes. Further analysis has also demonstrated the utility of these materials with solid state silicon photomultiplier type detectors. In pursuit of further gains in performance, a new energy harvesting material making use of developments in the field of thermally activated delayed fluorescent compounds has been designed, synthesized, and characterized. The results from this work show promise and point to opportunities to make major increases in plastic light yield through further tailoring matrix and dopant materials.

Cover page: Synthesis and Analysis of Novel Materials for Plastic Scintillators

Article
Peer Reviewed

Transparent Ultra-High-Loading Quantum Dot/Polymer Nanocomposite Monolith for Gamma Scintillation

UCLA Previously Published Works (2017)

Spectroscopic gamma-photon detection has widespread applications for research, defense, and medical purposes. However, current commercial detectors are either prohibitively expensive for wide deployment or incapable of producing the characteristic gamma photopeak. Here we report the synthesis of transparent, ultra-high-loading (up to 60 wt %) Cd_xZn_1-xS/ZnS core/shell quantum dot/polymer nanocomposite monoliths for gamma scintillation by in situ copolymerization of the partially methacrylate-functionalized quantum dots in a monomer solution. The efficient Förster resonance energy transfer of the high-atomic-number quantum dots to lower-band-gap organic dyes enables the extraction of quantum-dot-borne excitons for photon production, resolving the problem of severe light yield deterioration found in previous nanoparticle-loaded scintillators. As a result, the nanocomposite scintillator exhibited simultaneous improvements in both light yield (visible photons produced per MeV of gamma-photon energy) and gamma attenuation. With these enhancements, a 662 keV Cs-137 gamma photopeak with 9.8% resolution has been detected using a 60 wt % quantum-dot nanocomposite scintillator, demonstrating the potential of such a nanocomposite system in the development of high-performance low-cost spectroscopic gamma detectors.