Radiation damage in PVT (Polyvinyltoluene) induced by energetic ions

Abstract

Polyvinyltoluene (PVT) is an organic polymer employed as base material for many plastic scintillators useful to detect charged particles. Radiation damage in PVT is investigated irradiating the polymer in vacuum with different ion beams (H⁺, He⁺, N⁺ and Ar⁺) as a function of their ion stopping power. The structural modifications indced in the polymer are deduced by monitoring in situ, during the ion irradiation, the molecular desorption from the polymer by a highly sensitive mass-quadrupole spectrometer. The desorbed molecules are detected in the mass range 1–100 amu and the chemical yields are measured with respect to the calibrated gas leaks. Main emitted species are H₂, C₂H₂ and C₃H₅, the yields of which strongly depend on the ion stopping power. As will be discussed, the investigation of radiation damage in PVT permits to extend the results to the damage undergone by plastic scintillators during the detection of charged particles at high energy, such as protons of 10–100 MeV, an energy range useful in nuclear physics and in proton-therapy.