A scalable $64\times 64$ pixels monolithic HV-CMOS sensor for hadron therapy with 1ns time stamping capability and in-pixel ADC

In this paper we present an array of 64x64 pixels, designed for proton beam source characterization. The configurable pixel allows to measure the energy or the arrival time of detected particles in a short time window, or it can count events for a pre-defined observation time. The adopted solution uses a signal gating followed by a sample and hold and in-pixel single slope ADC to avoid pile-up effect when the flux of protons is high. In order to guarantee a fine time resolution (1ns) across the entire array, a scalable architecture has been conceived for possible extending the resolution of the sensor with no major modifications. The chip has been electrically characterized and tested with optical stimulus and using a beta source.