Dottorato in ENERGIA E AMBIENTE

Titolo della tesi: APPLICATION OF A PROTON LINEAR ACCELERATOR FOR CANCER THERAPY TO RADIATION RESISTANCE QUALIFICATION OF SPACE COMPONENTS AND SYSTEMS

The thesis focuses mainly on demonstrating the possibility to successfully employ a full-LINAC proton accelerator designed for particle therapy to perform irradiations of electronic components for space applications fulfilling the European Space Components Coordination standard prescriptions on beam qualification. The research activity is carried out at the TOP-IMPLART proton accelerator: it is a prototype of a pulsed fully linear machine aimed at active intensity modulated proton therapy under development at ENEA Frascati Research Centre in collaboration with the Italian Institute of Health (ISS) and the Oncological Hospital Regina Elena-IFO. Design beam properties of this accelerator, such as extraction energy, energy spread, transverse spot size and average current, are the same as conventional cyclotron-based facilities for proton therapy, whereas the instantaneous beam current is orders of magnitude higher as the beam is delivered in 3 µs long pulses with a maximum repetition rate of 200 Hz. In the first part of the research activity, we describe the methods and specific beam detectors developed for the characterization in air of the proton beam of the TOP-IMPLART linac and discuss how the clinical-oriented methods can be employed Radiation Hardness Assurance purposes. In particular, we want to demonstrate the capability of our delivery system to provide a continuous monitoring of the proton flux and fluence with an accuracy of at least ± 10%. This, coupled with a characterization of the beam parameters (energy, energy spectrum, transverse uniformity) at the target position with the same accuracy, shall fulfil the typical prescription of standard procedures for electronic components irradiation Beam energy and spectrum, transverse homogeneity, fluence and flux are assessed both experimentally and by numerical calculations. We than presents three irradiation campaigns carried out at a beam energy of 35 MeV: they were selected as exemplary of the different radiation hardness tests that can be performed with protons: displacement damage effects, single event effects and system level qualification where cumulative and stochastic effects are probed simultaneously. The outcomes of the irradiation campaigns are discussed in terms of lesson learned aiming constantly improving the methodology to better comply with the international standards. Lastly, we present the upgrade in the beam monitoring system carried out together with the energy upgrade to 55.5 MeV. Development of a new current monitor and new online control system for two existing devices are reported. They significantly improve fluence and flux monitoring precision, benefiting future RHA activities.