Characterization of a silicon detector and front-end electronics prototype for single ion discrimination in hadrontherapy

The Move-IT research project of the National Institute for Nuclear Physics aims at the study of models for biologically optimized treatment planning systems in particle therapy and the development of dedicated devices for plan verification. On behalf of this collaboration, the Turin medical physics group is working for the development of a new prototype of silicon strips detector. This device, based on 50 μm thin silicon sensors with internal gain, aims to detect the single beam particle and count their number up to 10 9 cm 2 /s fluxes, with a precision ≥ 99%. The prototype detector will cover a 3×3 cm 2 area, segmented in strips. The classic orthogonal strip positioning is used for beam profile measures. At the moment, two types of sensor geometry with different silicon design features have been characterized with laser, radioactive sources and with a clinical proton beam. For what concerns the front-end electronics, the challenging tasks are represented by the charge and dynamic range which are respectively the 3-150 fC and the hundreds of MHz instantaneous rate (at least 100 MHz, 250 MHz ideally). On this purpose, our group is exploring different solutions with the design of two prototypes of custom front-end electronics: one based on a resistive feedback differential transimpedance amplifier and a second one based on a charge sensitive amplifier with gain boost and a discrimination-activated reset of the feedback capacitance. Preliminary results on the ASIC characterization are presented in the following sections.