Electrical & Computer Engineering, Department of
First Advisor
Dr. Sina Balkir
Second Advisor
Dr. Michael Hoffman
Date of this Version
Spring 2022
Abstract
A time-of-flight (TOF) detection system for a silicon photomultiplier (SiPM) is designed for the purpose of improving on existing technology for applications in positron emission tomography, with an emphasis on low power and low timing jitter. A reconstruction algorithm is implemented in Matlab to demonstrate the effect of TOF on the image quality per number of source events, as compared to systems restricted to line-of-response (LOR) data only. A case study is performed on SiPM functionality, behavioral modeling, and contemporary front-end amplification designs for a SiPM detector. A charge sensitive amplifier (CSA) circuit is modified for simultaneous collection of timing and energy information, implementing a novel hybrid current-division scheme by capacitively coupling the SiPM to the CSA so that the SiPM's fast leading edge behavior and linear energy-charge correlation is preserved, while conserving power and minimizing jitter. Simulations provide the proof of concept for this design, operating at under 600 μW of power, and injecting less than 60 ps of jitter into the timing output signal. Preliminary testing is conducted using a specialized integrated circuit with analog input CSA channels to verify operation. An energy resolution of 11.7 % was achieved for the 511 keV peak of a Na-22 source, and 10.9 % for the 662 keV peak of a Cs-137 source, using an ON Semiconductor 3mm SiPM and a LYSO scintillator.
Advisors: Sina Balkir and Michael Hoffman
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfilment of Requirements For the Degree of Master of Science, Major: Electrical Engineering, Under the Supervision of Professors Sina Balkir and Michael Hoffman. Lincoln, Nebraska: May, 2022
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