UCLA

Fast scintillators with a spectroscopic gamma response are essential in nuclear security and medical imaging. However, few individual scintillation materials exhibit both fast scintillation decay and high photopeak energy resolution. We report a nanocomposite scintillator comprising 40 wt % of hafnium oxide nanoparticles uniformly dispersed in a luminescent plastic matrix. The nanoparticles have an average diameter of 4.2 nm and are covalently attached to the polymer matrix to prevent agglomeration and thus achieve high optical transparency across nanocomposite monoliths up to 8.5 mm thick. The measured transmittance is around 80% across the emission range. Gamma pulse scintillation has a fast decay time constant of 2.5 ns and high light output of 8000-9000 photons/MeV. The gamma scintillation shows energy proportionality from 32 to 1275 keV. A 1.93 cm3 nanocomposite produces photopeaks at 32 and 662 keV for 137Cs and at 511 and 1275 keV for 22Na. The photopeak energy resolution at 662 keV is 7.2-9.1%.