FOOT: a new experiment to measure nuclear fragmentation at intermediate energies

Abstract

Abstract Particle therapy uses proton or 12 C beams to treat deep-seated solid tumors. Due to the advantageous characteristics of charged particles energy deposition in matter, the maximum of the dose is released to the tumor at the end of the beam range, in the Bragg peak region. However, the beam nuclear interactions with the patient tissues induces fragmentation both of projectile and target nuclei and needs to be carefully taken into account. In proton treatments, the target fragmentation produces low energy, short range fragments along all the beam range, that may deposit a non negligible dose in the entry channel. In 12 C treatments the main concern is represented by long range fragments due to projectile fragmentation that release their dose in the healthy tissues surrounding the tumor. The FOOT experiment (FragmentatiOn Of Target) of INFN is designed to study these processes, in order to improve the nuclear interactions description in next generation Treatment Planning Systems software, and hence the treatment plans quality. Target ( 16 O and 12 C nuclei) fragmentation induced by 150-250 MeV proton beams will be studied via an inverse kinematic approach, where 16 O and 12 C therapeutic beams collide on graphite and hydrocarbon targets to provide the nuclear fragmentation cross section on hydrogen. The projectile fragmentation of these beams will be explored as well. The FOOT detector includes a magnetic spectrometer for the fragments momentum measurement, a thin plastic scintillator for ΔE and time of flight measurements and a scintillating crystal calorimeter to measure the fragments kinetic energy. These measurements will be combined in order to make an accurate fragment charge and isotopic identification.