Polyvinylcarbazole polymer scintillators with high loading of a bismuth organometallic exhibit good light yields, and are found to be capable of gamma-ray spectroscopy. When activated by a standard fluor, diphenylanthracene, a bismuth-loaded polymer produces ∼12000 photons/MeV, exhibits an emission maximum at 420 nm, a ∼15 ns decay, and energy resolution of 9% at 662 keV is measured. The same bismuth-loaded polymer doped with an iridium complex fluor has an emission maximum of 500 nm, a decay time of 1.2 µs, a light yield of ∼30000 photons/MeV, and energy resolution better than 7% FWHM at 662 keV.

Abstract-We are developing new scintillator materials that offer potential for high resolution gamma ray spectroscopy at low cost. Single crystal SrI 2 (Eu) offers ~3% resolution at 662 keV, in sizes of ~1 in 3 . We have developed ceramics processing technology allowing us to achieve cubic inch scale transparent ceramic scintillators offering gamma spectroscopy performance superior to NaI(Tl).We fabricated a bismuth-loaded plastic scintillator that demonstrates energy resolution of ~8% at 662 keV in small sizes.

Recently discovered scintillators for gamma ray spectroscopy, single crystal SrI 2 (Eu), GYGAG(Ce) transparent ceramic and Bismuth-loaded plastics, offer resolution and fabrication advantages compared to commercial scintillators, such as NaI(Tl) and standard PVT plastic. Energy resolution at 662 keV of 2.7% is obtained with SrI 2 (Eu), while 4.5% is obtained with GYGAG(Ce). A new transparent ceramic scintillator for radiographic imaging systems, GLO(Eu) offers high light yield of 70,000 Photons/MeV, high stopping, and low radiation damage. Implementation of single crystal SrI 2 (Eu), Gd-based transparent ceramics, and Biloaded plastic scintillators can advance the state-of-the art in ionizing radiation detection systems.

We synthesize a series of polyvinylcarbazole monoliths containing varying loadings of triphenyl bismuth as a high-Z dopant and varying fluors, either organic or organometallic, in order to study their use as scintillators capable of gamma ray spectroscopy. A trend of increasing bismuth loading resulting in a better-resolved photopeak is observed. For PVK parts with no fluor or a standard organic fluor, diphenylanthracene, increasing bismuth loading results in decreasing light yield while with samples 1 or 3 % by weight of the spin-orbit coupling organometallic fluor FIrpic, which emits light from both singlet and triple excitons, show increasing light yield with increasing bismuth loading. Our best performing PVK/ BiPh 3 /FIrpic scintillator with 40 wt % BiPh 3 and 3 wt % FIrpic has an emission maximum of 500 nm, a light yield of ~30,000 photons/MeV, and energy resolution better than 7% FWHM at 662 keV. Replacing the Ir complex with an equal weight of diphenylanthracene produces a sample with a light yield of ~6,000 photons/MeV, with an emission maximum at 420 nm and energy resolution of 9% at 662 keV. Transmission electron microscopy studies show that the BiPh 3 forms small clusters of approximately 5 nm diameter.