Stability Analysis of the TOP-IMPLART 35 MeV Proton Beam

The TOP-IMPLART (Intensity Modulated Proton Linear Accelerator for RadioTherapy) is the demonstrator of a 150 MeV proton linear accelerator devoted to cancer treatment application under development at ENEA-Frascati. It is a full linear machine composed by a 425 MHz 7 MeV injector and a high frequency linac operating at 2997.92 MHz. The first accelerating section, installed and in operation, consists of 4 SCDTL structures and delivers a 35 MeV beam in 3 microseconds pulses at a maximum repetition frequency of 50 Hz. The principal advantage of a linear accelerator, in a therapeutic application, is the quick setting possibility (up to pulse-to-pulse, in principle) of the physical properties of the proton beam, offering larger flexibility (compared to traditional circular designs) and improved precision on dose delivery to the patient., The short and long range stability of the machine have been analyzed measuring on a pulse by pulse basis both the output beam characteristics and other machine parameters in order to identify those that mainly affect the beam stability. This work describes the methodology used in this study, the main results achieved and the future developments.