Experimental studies of the decoding performances of a semi-monolithic scintillator detector

A detector module based on a semi-monolithic scintillator crystal array and a SiPMs array was designed, fabricated and tested. The scintillator detector consisted of 18 polished LYSO slices measuring 1 × 10 × 20 mm
³
. The slices were assembled together with BaSO
₄
material in between and outside. The bottom surface if the array was air-coupled with the 6 × 6 SiPMs array. The readout electronics read all 36 channels of SiPM signals simultaneously. The X and Y positions of the gamma interactions were calculated from the recorded SiPM signals using the method of the center of the gravity (COG). The experimental results show: (1) Scintillating photons can pass through BaSO
₄
to allow accurate slice decoding with the COG method. (2) All slices were able to be resolved clearly when coupling three slices of crystals 1 mm in thickness with one 3 mm SiPM. (3) The detector wrapped with ESR has a better flood map than that wrapped with Teflon. (4) The light guides helped in improving the uniformity of the lines (crystal slices) in the flood maps. (5) The light guide may decrease the PTVR when it is too thick. (6) Flood map of detector with ESR package and 1.75 mm-thick light guide shows the best quality.