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Description
The High-Voltage Monolithic Active Pixel Sensors (HV-MAPS) extend the monolithic design concept by embedding the readout electronics in a deep n-well, enabling high voltage operation and fast charge collection via drift. The MuPix11 is an HV-MAPS chip with a pixel size of 80 x 80 $\mu$m that can be thinned to 50 $\mu$m, offering low material budget and precise spatial and time resolution.
The analogue pixel signal is digitised in the periphery, producing leading- and trailing-edge timing information from which the Time-over-Threshold (ToT) is computed. Since charged particles deposit different amounts of energy depending on their type and momentum, the ToT provides a useful proxy for measuring energy deposition and distinguishing different particles.
This work presents first results from testbeam campaigns conducted at the Paul Scherrer Institute with the goal of systematically investigating the dependence of the ToT response on particle type and momenta. The measurements were performed with a setup consisting of four layers of quad modules, each composed of four MuPix11 sensors mounted on a single printed circuit board. Two datasets are used, one containing pions, muons, and electrons with momenta from 100 to 350 MeV/c, and another with surface muons of 28 MeV/c. By reconstructing particle trajectories across the sensor planes, hits are associated with individual particles, enabling a track-based analysis of the ToT response.