Study of the impact of out-of-target fragmentation in cross section measurements with the FOOT experiment

Hadrontherapy is an innovative cancer treatment technique that utilizes beams of charged particles, specifically protons and heavier ions, to target tumors deep within the body. These particles have a unique depth-dose distribution in tissue, with low doses at the entry point and a sharp peak of maximum dose (Bragg peak) near the end of their path. This makes them effective at targeting tumors while minimizing damage to surrounding healthy tissues. Carbon and oxygen ions, in particular, have been found to have an enhanced biological effect, making them useful for treating tumors. However, it is important to consider nuclear interactions in these treatments. As beam particles travel through the body, they can fragment and release dose beyond the Bragg peak. Additionally, fragments of nuclei present in the human body can modify the dose released in healthy tissues. The lack of comprehensive data on cross sections makes it difficult to predict the effects of these interactions. To fill these gaps in experimental data, the FOOT experiment has been designed to detect, track and identify charged fragments produced in ion collisions with different targets. Its final goal is to measure double differential cross sections both in angle and kinetic energy with an uncertainty lower than 5%. However, cross section measurements can be spoiled by out-of-target fragmentations that could occur anywhere along the experimental apparatus, such as in the detectors’ planes or in the air surrounding them. In this thesis, a straightforward algorithm for event classification, based on the zone of fragmentation, is presented and studied. First, the accuracy of the classification is analyzed to ensure the proper functioning of the algorithm. Then, the effectiveness of a selection on events, based on the classification algorithm, is evaluated through the study of reconstructed tracks. To do so, a sample of simulated data of oxygen at 400 MeV/n impinging on a target of graphite is employed.