Spectroscopy and imaging that involve gamma rays have application in many Fields of science, from astronomy to medicine and health or radiation detection for safety. The Silicon Photomultipliers (SiPMs) aim to replace the Photomultiplier Tubes (PMTs) as the new standard for photodetectors in indirect conversion systems based on scintillators thanks to its insensitivity to magnetic fields and more compact design. Lanthanum bromide represents the state of the art in scintillators due to its high light yield, fast scintillation emission, and high intrinsic resolution. However, in some applications there is a lack of appropriate electronic circuitry capable of high dynamic range (DR) readout of SiPM, while maintaining a resolution comparable with PMT state of the art. In fact, despite several ASICs for SiPM have been realized, mostly for PET (Position Emission Tomography), a readout ASIC able to cope with large dynamic range (10^4) seems not to be available. This thesis has been made in the framework of the Gamma project, in collaboration with Istituto Nazionale di Fisica Nucleare (INFN) and Fondazione Bruno Kessler (FBK), whose aim is to develop a SiPM-based detection module for spectroscopy (100 keV-20 MeV) with state of the art energy resolution (i.e. better than 4% at 662 keV). Then, after some considerations about the scintillator, SiPMs, and today state of the art electronics for their readout, a new high-dynamic range ASIC that provides 84dB DR and resolution at 662 keV below 4% will be presented. All the stages of the circuit will be analyzed together with simulations of their functionality. A First prototype has been realized and the experimental results are reported, concluding with a look towards future developments.
La spettroscopia e imaging che coinvolgono raggi gamma hanno applicazione in diversi campi scienti ci, dall’astronomia alla medicina e la salute pubblica o rivelazione di radiazione per la pubblica sicurezza. I fotomoltiplicatori in silicio (SiPMs) mirano a rimpiazzare i tubi fotomoltiplicatori (PMTs) come nuovo standard per fotorivelatori nei sistemi a conversione indiretta basati su scintillatori grazie alla loro insensibilità ai campi magnetici e la maggior compattezza. Il bromuro di lantanio rappresenta lo stato dell’arte grazie alla sua elevata resa luminosa, ai veloci eventi di scintillazione, e alla alta risoluzione intrinseca. Tuttavia, in alcune applicazioni c’è una mancanza di circuiteria appropriata capace di lettura ad elevata dinamica (DR) per SiPM mantenendo al contempo una risoluzione comparabile con lo stato dell’arte a PMT (ovvero al di sotto del 4% a 662 keV). Infatti, nonostante diversi ASICs per SiPM sono stati realizzati, prevalentemente per PET (Position Emission Tomography), un ASIC di lettura in grado di raggiungere un’elevata dinamica (10^4) non sembra essere disponibile. Questa tesi è stata realizzata nell’ambito del progetto Gamma, in collaborazione con l’Istituto Nazionale di Fisica Nucleare (INFN) e Fondazione Bruno Kessler (FBK), il cui scopo è lo sviluppo di un modulo di rivelazione basato su SiPM per spettroscopia (100keV-20MeV) con risoluzione energetica allo stato dell’arte. Dopo alcune considerazioni riguardo allo scintillatore, ai SiPM, e all’attuale stato dell’arte della loro elettronica di lettura, verrà presentato un nuovo ASIC con una dinamica di lettura di 84dB e risoluzione energetica a 662 keV sotto al 4%. Verranno analizzati tutti gli stadi del circuito, accompagnati da simulazioni della loro funzionalità. Un primo prototipo è stato realizzato e i risultati sperimentali saranno qui riportati, concludendo con uno sguardo agli sviluppi futuri del progetto.
Design of a high dynamic range ASIC for SiPM-based readout of large scintillator crystals
SANCANDI, FLAVIO
2016/2017
Abstract
Spectroscopy and imaging that involve gamma rays have application in many Fields of science, from astronomy to medicine and health or radiation detection for safety. The Silicon Photomultipliers (SiPMs) aim to replace the Photomultiplier Tubes (PMTs) as the new standard for photodetectors in indirect conversion systems based on scintillators thanks to its insensitivity to magnetic fields and more compact design. Lanthanum bromide represents the state of the art in scintillators due to its high light yield, fast scintillation emission, and high intrinsic resolution. However, in some applications there is a lack of appropriate electronic circuitry capable of high dynamic range (DR) readout of SiPM, while maintaining a resolution comparable with PMT state of the art. In fact, despite several ASICs for SiPM have been realized, mostly for PET (Position Emission Tomography), a readout ASIC able to cope with large dynamic range (10^4) seems not to be available. This thesis has been made in the framework of the Gamma project, in collaboration with Istituto Nazionale di Fisica Nucleare (INFN) and Fondazione Bruno Kessler (FBK), whose aim is to develop a SiPM-based detection module for spectroscopy (100 keV-20 MeV) with state of the art energy resolution (i.e. better than 4% at 662 keV). Then, after some considerations about the scintillator, SiPMs, and today state of the art electronics for their readout, a new high-dynamic range ASIC that provides 84dB DR and resolution at 662 keV below 4% will be presented. All the stages of the circuit will be analyzed together with simulations of their functionality. A First prototype has been realized and the experimental results are reported, concluding with a look towards future developments.| File | Dimensione | Formato | |
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2017_12_Sancandi.pdf
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https://hdl.handle.net/10589/137380