NUCLEAR FRAGMENTATION CROSS SECTIONS MEASUREMENTS FOR HADRONTHERAPY: IMPLEMENTATION AND OPTIMIZATION OF A BEAM MONITORING SYSTEM

The FOOT project is a nuclear physics experiment that aims to measure the differential cross sections (d2σ/dΩ·dE) of the nuclear interactions involved in particle therapy and space radioprotection. The final experimental data will be adopted as benchmark for the MC simulation tools, to improve the current particle therapy treatment planning systems and to develop a new shielding design suitable for the future space missions. The FOOT project consists of two different experimental setups and in both of them a drift chamber is adopted as Beam Monitor to measure the projectile direction and position, to count the total number of delivered particles and to reject the pre-target fragmentation events. In this Ph. D. project, which has contributed to the construction and start of the FOOT experiment, the drift chamber has been finalized, tested, calibrated and operated in the experiment. A multi-track reconstruction algorithm has been developed taking advantages of the Legendre transformation properties combined with a χ2 minimization algorithm. The software has been tested and optimized both on experimental and on MC simulated data and it has been included within the FOOT global reconstruction code. The detector has been used in different tests and data takings. In particular, an extensive calibration and performance assessment has been conducted with protons at 228 and 80 MeV. In this occasion, the overall Beam Monitor efficiency, spatial resolution and active area have been measured. In addition, the space-time relations of the drift chamber have been measured and the results have been adopted as benchmark for a self calibration method developed to estimate the space-time relations using only the Beam Monitor hits and tracks. The detector has been successfully operated in the FOOT data takings performed with both the experimental setups. In particular, in the framework of the emulsion spectrometer measurements, the Beam Monitor has been employed to measure the profile of the irradiation pattern and to count the total number of delivered particles. Then, during the test performed with the electronic spectrometer, the drift chamber has been used with the FOOT general DAQ system to measure the incoming beam direction and position. In addition, the Beam Monitor has performed a characterization of the GSI 700 MeV/u carbon ion beam, measuring the transverse spot size, the rate and the angular spread of the incoming beam. The final part of the project has been devoted to a detailed study of the performances of the detector in view of the work for the data analysis of the FOOT experiment. In particular, different selection criteria have been studied to identify and reject the pre-target fragmentation events and the impact of the drift chamber spatial resolution on the cross section accuracy has been estimated by means of MC simulations.