Measurements of time resolution of the RD50-MPW2 DMAPS prototype using TCT and $^{90}\mathrm{Sr}$

Abstract: Results in this paper present an in-depth study of time resolution for active pixels of the RD50-MPW2 prototype CMOS particle detector. Measurement techniques employed include Backside- and Edge-TCT configurations, in addition to electrons from a $<sup>{90}\mathrm{Sr}$ source. A sample irradiated to $$5\cdot 10<sup>{14}\,\mathrm{n}_\mathrm{eq}/\mathrm{cm}<sup>2$$ was used to study the effect of radiation damage. Timing performance was evaluated for the entire pixel matrix and with positional sensitivity within individual pixels as a function of the deposited charge. Time resolution obtained with TCT is seen to be uniform throughout the pixel's central region with approx. $220\,\mathrm{ps}$ at $12\,\mathrm{ke}<sup>-$ of deposited charge, degrading at the edges and lower values of deposited charge. $<sup>{90}\mathrm{Sr}$ measurements show a slightly worse time resolution as a result of delayed events coming from the peripheral areas of the pixel.