Academic Lecture: Silicon Photomultiplier Technologies Developed at Fondazione Bruno Kessler


Title:Silicon Photomultiplier Technologies Developed at Fondazione Bruno Kessler 
Speaker:Alberto Gola(Fondazione Bruno Kessler) 
Chair:Prof. Wen Liangjian 
Time:10:00 AM, 17th October, 2019 
Location:B326, main building 

Since 2005, Fondazione Bruno Kessler (FBK, Trento) has continuously developed and improved its SiPM technology for a wide variety of applications, ranging from medical imaging to big science experiments and industrial applications. Current-generation Near Ultra Violet, High Density (NUV-HD) SiPM technology features a peak photon-detection efficiency (PDE) higher than 60% at 410 nm, low primary and correlated noise and is very well suited for medical imaging applications, such as time-of-flight positron emission tomography (TOF-PET). Indeed, using an advanced high-frequency readout, a research group at CERN demonstrated state-of-the-art coincidence resolving time of 58 ps FWHM, employing 4x4 mm2 NUV-HD SiPMs coupled to small LSO:Ce:Ca crystals. With a similar, optimized setup, a single-photon time resolution (SPTR) of 90 ps FWHM was also demonstrated, which is even more important when faint Cherenkov emission is used to improve timing performance in relatively slow scintillators such as BGO. 
On the other hand, different applications require specific optimizations of SiPM parameters, especially in the field of big science experiments. To this end, several improvements of the NUV-HD technology are ongoing, including reduction of optical crosstalk probability, optimization of SiPM performance for operation at cryogenic temperatures, for the readout of very large areas and for direct detection of vacuum ultra-violet (VUV) light, below 200 nm. Moreover, recent interest in using SiPMs in harsh radiation environment, such as in space missions or in accelerator experiments, poses additional challenges in detector optimization and partially redefines the typical design trade-offs. 
At the lower-energy end of the sensitivity spectrum, we observe a growing interest from industry in using SiPMs for detection of near infrared light. Among different applications, the most important one is LIDAR, especially for advanced driver-assistance systems in the automotive field. NIR-sensitive SiPMs (NIR-HD) fabricated at FBK use a thicker epitaxial layer to enhance detection efficiency at longer wavelengths, achieving high PDE of 12 % 905nm, without micro lenses. Ongoing research is aimed at further improving this result by careful engineering of the SPAD structure. 

About the speaker: 
Alberto Gola received the 5-years degree in Electronic Engineering in 2003 and the Ph.D. in Information Tecnology Engineering in 2007, both from the Politecnico of Milano. Between 2007 and 2009 he has been working at the Department of Electronic Engineering of the Politecnico di Milano in a PostDoc position. In Milano, his research interests were focused on Silicon Drift Detectors, SDD-based Gamma Cameras, multi-channel ASIC design, DAQ systems, optimal filtering and signal processing. Since 2010, he is with Fondazione Bruno Kessler, where his research activity is focused on development of Silicon Photomultipliers. He designed a large portion of the SiPM fabricated at FBK, including next generation detectors such as ultra-high-density SiPMs. More recently, he has been L3 manager for photonics and local INFN coordinator in the DarkSide 20k project, carried out in collaboration with INFN, directing activities for development of cryogenic SiPMs. Since 2017, he becomes custom tech team leader and coordinates all the activities related to design, development and characterization of SiPM detectors.