Evaluation of Arrays of Silicon Photomultipliers for Beta Imaging

Silicon photomultipliers (SiPMs) have shown great promise as photodetectors in detecting scintillation light from gamma and beta rays, and are currently being investigated for use in imaging. Most studies have been done with single sensors for gamma detection. We have built linear and two dimensional arrays of SiPMs and evaluated them for suitability in beta imaging. Both arrays employ I mm x I mm Multi Pixel Photon Counters (MPPCs). The first array is a I x 4 array with 2.5 mm pixel pitch. The second is a 5 x 5 array with 3 mm pitch. For both arrays we acquired energy spectra for annihilation photons with LYSO scintillators, and for positrons from F-18 and T1-204 with blue plastic scintillator. We imaged collimated F-18 beta sources, and measured the spatial resolution and sensitivity. For the linear array, the spatial resolution is 2.6 mm at the center of the array, and the sensitivity is 0.27 cps/Bq. For the 5 x 5 array, the spatial resolution is 2.1 mm at the center of the array, and the sensitivity is 0.36 cps/Bq.