Fabrication of X-ray/Gamma-ray Detector by Growth of Microcolumnar CSI:Tl onto Silicon Photomultipliers

AbstractWe present a technique to fabricate high spatial resolution and cost-effective X-ray/gamma-ray detectors using silicon photomultipliers (SiPMs) and microcolumnar structured CsI:Tl scintillator. SiPMs were placed inside a vacuum chamber and physical vapor deposition was used to directly deposit CsI:Tl onto the active surface of SiPMs. This approach leads to improved light transport from the scintillation material to the photodetector due to minimal light loss and light spread. Devices made by this technique may be used for gamma- and X-ray photon counting and imaging. Scanning electron micrographs show highly oriented microcolumnar CsI:Tl structure orthogonal to the SiPMs’ surface. These microcolumnar structures are excellent for channeling scintillation light to the SiPM and provide sub-macro-pixel resolution. We report the performance characteristics of the resultant detector in terms of position sensitivity, optical crosstalk, and signal-to-noise ratio. The performance of the detector fabricated in this manner is evaluated against other methods of coupling CsI:Tl scintillators to SiPMs