Development of position sensitive detector module using scintillator and Si photomultiplier for hard x-ray imaging and spectroscopy

We explore the use of scintillation detectors coupled with silicon photomultipliers (SiPMs) as position sensitive hard x-ray spectroscopic detectors for potential applications in the field of high-energy astrophysics. X-ray photons on interaction with scintillation crystals generate optical photons and the distribution of these scintillation light photons is captured with the array of SiPM pixels, providing the spectral and spatial information of the incident x-ray photons. As the position is estimated by fitting the distribution of optical photons, it should be possible to achieve spatial resolution lesser than the pixel size. Development of two detector modules with CsI (Tl) and CeBr3 scintillators coupled with different sets of array of SiPM pixels is presented here. Spectral and spatial resolutions of both detector modules are characterized with experiments using x-ray lines from laboratory radioactive sources. It is shown that a faster scintillator with an array of low-noise SiPM pixels provides better spectral and spatial resolution and it is possible to achieve subpixel spatial resolution with such a detector module.