Performance comparison of two SiPM arrays with matrix or row/column output electrodes for PET and radiation detector applications

We evaluated the performance of two latest 8×8 arrays of 2×2 mm² MPPCs (SiPM array made by Hamamatsu Photonics, K.K.) for PET applications. One MPPC array has a common cathode and 64 individual anode outputs in an 8×8 matrix format, while the other has internally connected 8 rows of anodes and 8 columns of cathodes to provide position-sensitive output with significantly reduced number of readout channels but increased dark counts and longer signal rise time. We measured the dark currents, energy spectra and energy resolutions, signal rise times, and detector coincidence timing resolutions from the two MPPC arrays coupled with scintillator detectors. The dark current measured from one row of anode signals is about √8 times higher than the one from one single anode signal, and the signal rise time is about twice longer. The 511 KeV energy resolutions measured from the detector based on using different MPPC arrays are about the same. The critical coincidence timing resolution does show significant difference. The coincidence timing resolutions (FWHM), measured between two single-channel detectors that consist of a MPPC array and a fast single-channel PMT each optically coupled to an 1x1x20 mm³ LFS scintillator crystal, are ~0.9 ns and ~1.8 ns for one anode and one row of anodes, respectively. In summary, the MPPC array with row/column readout has increased dark count noise and deteriorated timing performance. Nevertheless, it is still applicable for non time-of-flight PET detector and imaging applications.