Minimizing disturbance in ion beam profiling with PEPITES monitor

In the field of beam diagnostics for radiotherapy, accurate dose delivery relies on ultra-thin, linear and radioresistant monitors to minimize beam scattering and achieve precise profiling. The first PEPITES prototype monitor features two segmented cathodes, each paired with a high-voltage-biased anode. This latter effectively captures secondary electrons generated by the cathodes when they interact with the beam, enabling the detection of a measurable signal. The Water Equivalent Thickness (WET) of this design is approximately 10 μm*. To achieve efficient profiling of the charged particle beam when the monitor is positioned several meters upstream of the patient, we developed a thinner design. This configuration features two anodes positioned outside the beam path, reducing by half the amount of material that interacts with the beam, thereby minimizing beam disturbances. Both, the previous and the updated PEPITES monitor designs were recently tested at CNAO,Italy. Measurements were successfully conducted using a 115 MeV carbon ion beam at varying high-voltage power. These results will be presented and compared to demonstrate the enhanced efficiency of the upgraded PEPITES version.