Exploiting Cherenkov Radiation With BGO-Based Metascintillators

• Published in: IEEE transactions on radiation and plasma medical sciences Vol. 7; no. 8; pp. 810 - 818
• Main Authors: Latella, Riccardo, Gonzalez, Antonio J., Bonifacio, Daniel A. B., Kovylina, Miroslavna, Griol, Amadeu, Benlloch, Jose M., Lecoq, Paul, Konstantinou, Georgios
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.11.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: BGO (crystal); Bismuth compounds; Bismuth Germanate (BGO); Blending effects; Cerenkov radiation; cherenkov; coincidence time resolution (CTR); Couplings; Crystals; Detectors; EJ232; Grease; LYSO; metapixel; metascintillator; near-ultraviolet (NUV); Optical coupling; Photomultiplier tubes; Photons; Photopeak; Positron emission; Positron emission tomography; Scintillators; Sensors; silicon photomultiplier (SiPM); Silicon photonics; time-of-flight positron emission tomography (TOF-PET); Timing; vacuum-ultraviolet (VUV)
• ISSN: 2469-7311; 2469-7303
• DOI: 10.1109/TRPMS.2023.3310581

In time-of-flight positron emission tomography (TOF-PET), the timing capabilities of the scintillation-based detector play an important role. An approach for fast timing is using the so-called metascintillators, which combine two materials leading to the synergistic blending of their favorable characteristics. An added effect for BGO-based metascintillators is taking advantage of better transportation of Cherenkov photons through UV-transparent materials such as plastic (type EJ232). To prove this, we use an optimized Coincidence Time Resolution (CTR) setup based on electronic boards with two output signals (timing and energy) and near-ultraviolet (NUV) and vacuum-ultraviolet (VUV) silicon photomultipliers (SiPMs) from Fondazione Bruno Kessler (FBK), along with different coupling materials. As a reference detector, we employed a <inline-formula> <tex-math notation="LaTeX">3\times 3\times 5 </tex-math></inline-formula>-mm3 LYSO:Ce,Ca crystal pixel coupled with optical grease to an NUV-HD SiPM. The evaluation is based on low-threshold rise time, energy and time of arrival of event datasets. Timing results of a BGO/EJ<inline-formula> <tex-math notation="LaTeX">232\,\,3\times 3\times 15 </tex-math></inline-formula>-mm3 metapixel show detector time resolutions (DTRs) of 159 ps for the full photopeak. We demonstrate the possibility of event discrimination using subsets with different DTR from the rise time distributions (RTDs). Finally, we present the synergistic capability of metascintillators to enhance Cherenkov photons detection when used along with VUV-sensitive SiPMs.