Studying the effects of thermally diffusing Ce into the surface of YAlO3 for associated particle imaging.

Active radiation environments and high-rate backgrounds pose a significant challenge towards improving the detection and characterization of Special Nuclear Material (SNM) using Associated Particle Imaging (API). Ongoing research seeks to reduce the sensitivity of a charged particle, or associated particle, detector to x-ray backgrounds through the creation and characterization of an alpha-sensitive, Ce-doped surface region of Yttrium Aluminium Perovskite (YAP). A wet-chemical layer of trivalent cerium (III) acetylacetonate hydrate was thermally diffused with a reducing atmosphere into single YAP crystals for a temperature range of 800 °C to 1500 °C. The diffusion concentration profile of the cerium compound was assayed with Rutherford Backscattering Spectrometry (RBS), where the Ce diffusion activation energy and the pre-exponential factor within YAP were found to be 1.02 ± 0.10 eV and 9.7 ± 2.0 × 10 - 15 m 2 s - 1 , respectively. Resulting transient polycrystalline structural features at the surface of the YAP crystals were investigated with X-Ray Diffraction (XRD). YAP, Yttrium Aluminium Garnet (YAG), and Yttrium Aluminium Monoclinic (YAM) phases were identified, as well as contributions from Y 2 O 3 , CeO 2 , Ce 2 O 3 , and the metastable hexagonal polymorph of YAlO 3 (YAH). The luminescent responses of the complex surface layers to x-ray and α excitement were examined as functions of annealing temperature. Radioluminescence emissions typical of the Ce3+ 4f → 5d transition occupying both the Y3+ and Al3+ sites in YAP and YAG were observed. The brightness of the samples under alpha radiation increased as a function of diffused Ce concentration until the point of optical darkening. [ABSTRACT FROM AUTHOR]