Calorimeter prototyping for the iMPACT project pCT scanner

The iMPACT project aims at building a novel pCT scanner for protons of medical energies in the range between 200 and 300 MeV, a proton tracking system that provides accurate information to create a map of the tissue density of human organs. Such information is crucial for an accurate aiming of proton-therapy beams and is currently provided by X-rays CT scans, with an accuracy lower than the one which could be achieved by using protons. One of its core elements is a high-granularity scintillator-based range calorimeter, designed to measure the proton residual energy after it travels the patient's body. Here we review the design features of the iMPACT calorimeter, together with an all-around qualification of prototypes of its core components through test-bench measurements and proton beam data. We focus, in particular, on the qualification of the calorimeter elements towards a large-scale prototype, and a calibration study which will eventually allow to operate such a high granularity calorimeter with a fully digital readout at the target proton rate.