Federico Moretti

Neutrinos offer a unique window into the world, and here we propose a new water-based scintillator with intentionally slow scintillation enabling clear Cherenkov–scintillation discrimination for improved neutrino detection.

Eu-doped CsBr films (CsBr:Eu) exhibit excellent sensitivity for X-rays and are superior storage phosphors for high energy (MeV) photon radiography applications when coupled with thick copper or tungsten substrates. We report on the growth of micro-columnar CsBr:Eu films on copper substrates for megavolt (MV) X-ray imaging application. Our films exhibit dense uniformly distributed micro-columns with an average diameter of ~ 10 μm and a sharp, needle-like top. The advantage of this micro-columnar structured film is that the light can be channeled through the narrow columns to improve both light transmission and spatial resolution. We also determined the optimal Eu concentration in CsBr for the best storage phosphor performance. Growth of uniformly thick, micro-columnar structured films up to 2 mm was achieved on 2"×2" metallic substrates, which were then characterized by optically-stimulated luminescence coupled with X-ray excitation. Furthermore, 5 mm thick film growth demonstrates the potential to scale up to even thicker films.

Zinc tungstate is a semiconductor known for its favorable photocatalytic, photoluminescence, and scintillation properties, coupled with its relatively low cost, reduced toxicity, and high stability in biological and catalytic environments. In particular, zinc tungstate evinces scintillation properties, namely the ability to emit visible light upon absorption of energetic radiation such as x rays, which has led to applications not only as radiation detectors but also for biomedical applications involving the delivery of optical light to deep tissue, such as photodynamic therapy and optogenetics. Here, we report on the synthesis of zinc tungstate nanorods generated via an optimized but facile method, which allows for synthetic control over the aspect ratio of the as-synthesized anisotropic motifs via rational variation of the solution pH. We investigate the effect of aspect ratio on their resulting photoluminescent and radioluminescent properties. We further demonstrate the potential of these zinc tungstate nanorods for biomedical applications, such as photodynamic therapy for cancer treatment, by analyzing their toxicological profile within cell lines and neurons.

Scintillators based on Tl salts that provide high densities and high effective atomic numbers are currently being investigated for their possible use in radioisotope identification applications. Ce-doped Tl₂LaCl₅, in particular, has been the leading compound of those studied, showing good light output and energy resolution. The analogous Tl₂CeCl₅ has received much less attention, and the information known about it is rather incomplete. This paper focuses on the scintillation and optical properties of Tl₂CeCl₅ single crystals and compares them to those of Tl₂LaCl₅:Ce to better evaluate the effect of full substitution of La with Ce.

The removal of vacancy-related defects by addition of AuBr3 to the melt during crystal growth impacts the performance of BaBr2:Eu and Cs2LiLaBr6:Ce very differently.

Nanoscale scintillators represent an important class of materials underlying the functioning of high resolution, high ‘light yield’ radiation detection equipment, applicable for medicine in addition to security and environmental monitoring. This current study has focused on the controlled synthesis of Cs₂ZnX₄ (X = Cl, Br) not only due to its very fast and promising radioluminescence decay time but also because no reliable synthesis protocols have been reported for producing nanoscale motifs of this material, to date. Solution-based methods can be used to synthesize products, possessing different, discrete morphologies with the ability to dictate particle size and shape. Specifically, we have demonstrated that a hot injection technique can be used to fabricate nanoscale rods and plates. Using this method, we systematically studied the effect of varying reaction variables, such as (i) reaction temperature, (ii) surfactants, and (iii) reaction time. As synthesized nanorods of Cs₂ZnCl₄ possessed lengths of 101.3 ± 24.4 nm with widths of 17.3 ± 4.5 nm, whereas Cs₂ZnBr₄, created under identical conditions, were characterized by lengths of 206 ± 50 nm and widths of 26.7 ± 12.6 nm. Ligand-assisted re-precipitation (LARP) was used to produce the corresponding micron-sized particles. Under these conditions, we successfully synthesized spindles and spherical particles of Cs₂ZnCl₄ with sizes of 1.58 ± 0.16 μm and 1.03 ± 0.34 μm, respectively, whereas plates of Cs₂ZnBr₄ were prepared with average sizes of 0.76 ± 0.21 μm. High resolution synchrotron mapping, using the hard X-ray nanoprobe at NSLS II, was used to confirm the expected spatial distribution of Cs, Zn, and Cl within the as-produced crystals. Nanorods of Cs₂ZnCl₄ and Cs₂ZnBr₄ were subsequently tested for scintillation light yield and decay times. Preliminary results showed that Cs₂ZnCl₄ maintained a light yield of 100–300 photons per MeV with a fast decay component of 2.6 ns. The Cs₂ZnBr₄ analogue did not give rise to any perceptible scintillation emission.