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At the Department of Physics of the University of Pisa, Italy, a new and fully engineered version of the YAP-(S)PET small animal scanner has been recently installed. The new YAP-(S)PET is able to perform both PET and SPECT studies on small animals. The scanner is made up of four heads: each one is composed of a 4 × 4 cm² YAIO3:Ce (or YAP:Ce) matrix of 20 × 20 elements, 2 × 2 × 25 mm³ each, coupled to a Position Sensitive Photomultiplier (PS-PMT) (Hamamatsu R2486). The four modules are positioned on a rotating gantry. The switching to the SPECT modality is easily made by mounting a high resolution parallel hole (0.6 mm ⊘, 0.15 mm septum) lead collimator in front of each crystal. This paper reports the performance of the system in terms of absolute sensitivity and spatial resolution for both PET and SPECT modalities. The scatter fraction and noise-equivalent count rate (NEC) for a mouse phantom for different energy windows have been measured in PET modality. Images of phantoms and animals are also presented. [ABSTRACT FROM AUTHOR]

A high performance detector head with matrices of silicon photomultipliers (SiPMs) as photodetectors is under development at the University of Pisa and INFN Pisa. The silicon photomultipliers fabricated at FBK-irst (Trento, Italy) are being evaluated for this purpose. Single SiPM detectors of 1 mm × 1 mm size and the first SiPM test matrices composed of four (2 × 2) pixel elements in a common substrate have been tested with LYSO crystals. The energy and timing resolution of single SiPMs have been evaluated, obtaining an energy resolution of 20% FWHM at 511 keV, and a coincidence timing resolution of 1.4 ns FWHM. In addition, the first tests performed with the SiPM matrices prove the feasibility of such devices. [ABSTRACT FROM AUTHOR]