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This work presents a systematic study of the properties (Light Output Non-Uniformity (LONU) and energy resolution) of two CsI(Tl) scintillation units over a span of almost three years, under adverse conditions of humidity and temperature. These two crystals are part of the CALIFA detector, a highly segmented calorimeter and spectrometer for γ rays and light-charged particles, that is placed surrounding the reaction target at Cave C, the experimental cave of the R 3 B (Reactions with Radioactive Relativistic Beams) collaboration at the GSI-FAIR facilities in Darmstadt, Germany. The findings obtained after the experiment indicate that there was no significant impact on the performance in terms of resolution and LONU. This suggests that the employed wrapping for light collection effectively serves as an excellent barrier against humidity. As a result, the crystal is preserved in a far better condition than initially anticipated. [ABSTRACT FROM AUTHOR]

The goal of the present work is to develop a time-of-flight positron emission tomography (TOF-PET) detector system with 100 picosecond (ps) coincidence time resolution (CTR) using arrays of 20 mm length scintillator crystal elements. If successful, this would yield a 1.5-fold better reconstructed image signal to noise ratio (SNR) compared to state-of-the-art clinical TOF-PET systems. The proposed detector configuration comprises LGSO scintillation crystal elements optically coupled to silicon photomultipliers (SiPMs) which are read out by a fast, high precision, multi-channel amplifier/comparator integrated circuit (IC). Results obtained with that IC were compared with those achieved using a high-frequency (HF) readout, comprising discrete element readout for each detector channel. CTR values of 89.6 ± 0.8 ps and 105.1 ± 0.9 ps FWHM were achieved with the HF readout for 3 × 3 × 3 mm3 and 3 × 3 × 10 mm3 LGSO crystals, respectively, and 92.8 ± 0.9 ps and 114.1 ± 1.1 ps FWHM were achieved using the IC board for the same crystal elements. These results demonstrate the capabilities of a scalable IC readout solution for a 100 ps CTR TOF-PET design. [ABSTRACT FROM AUTHOR]