Enhanced columnar structure in CsI layer by substrate patterning

An approach to the fabrication of a scintillation layer by forming a sequence of columns of regular, controlled size perpendicular to the substrate, which provides a high light collimation property, thereby improving the resolution of the radiation detection is reported. The preparation and morphology of CsI on these patterned substrates are described. The optical properties of evaporated CsI(TI) layers, such as line spread function, transmission and modulation transfer function, are discussed. The results obtained with 200- mu m-thick CsI layers coupled to a linear photodiode array with 20 dots/mm resolution showed that the spatial resolution of CsI(TI) evaporated on patterned substrates was about 75 mu m (FWHM, whereas that of CsI(TI) on flat substrates was about 220 mu m FWHM. Micrographs taken by scanning electron microscopy revealed that these layers retained the well-defined columnar structure originating from substrate patterns. Adhesion and light transmission of CsI(TI) were also improved by patterning the substrate.<
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