Characterization of the VATA241 front-end ASIC for the BrainPET scanner

The BrainPET scanner is a magnetically-compatible human PET insert based on APDs and LYSO:Ce monolithic scintillators, which is currently under development at CIEMAT, intended for the operation inside magnetic resonance imaging (MRI) equipment. An ASIC called VATA241 was specifically designed for the BrainPET project. This ASIC includes a constant fraction discriminator (CFD) in its architecture and presents a better robustness and reliability with respect to the first leading-edge-based ASIC [1], which was successfully utilized in our first BrainPET demonstrator for validating the principle of operation of our detector blocks [2]. In this work we have characterized the VATA241 in terms of noise, time walk, jitter, linearity and operation with detector blocks. Moreover, we have carried out its optimization performance by adjusting the corresponding different bias currents. Based on the characterization carried out by CIEMAT, manufacturer Gamma Medica-Ideas (GM-I) has performed the tuning of the simulation model of this ASIC as well as the optimization of the timing performance for the fabrication of the final VATA241.2 ASIC, which will be used in our full-ring PET scanner.