A position sensitive scintillation detector using a side-by-side GAGG-F/GAGG-T phoswich block

Position sensitive detectors are the key component of gamma-ray imaging systems such as coded-aperture cameras and emission computed tomography systems. Improving the intrinsic spatial resolution of detectors is critical to system performances. Recent advance of the GAGG scintillator production allows variable decay time with different Al/Ga ratios. In this paper, we developed a novel position sensitive scintillation detector using a side-by-side fast-GAGG/typical-GAGG (GAGG-F/GAGG-T) phoswich array, which consisting of 12x12 phoswich unit pairs assembled by the GAGG-F scintillator (decay time constant similar to 50 ns) and the GAGG-T scintillator (decay time constant similar to 90 ns) in a pixel size of 1.35x2.7x4mm(3) and coupled to a 8x8 SiPM (MicroFJ-30035-TSV) array. An experiment was conducted using the irradiation of a(57)Co source (122 keV). Experimental results demonstrate that events from the GAGG-F and GAGG-T scintillators can be discriminated with only 7% mis-assignment probability. The 12x12 of GAGG-F and GAGG-T scintillator arrays are both distinguishable in separated flood maps. The average energy resolutions of GAGG-F and GAGG-T scintillators at 122 keV are 27.58% and 23.51% respectively. The side-by-side GAGG-F/GAGG-T detector has the advantage of improved intrinsic spatial resolution, no intrinsic background radiation and uniform detection efficiency.