Radiation damage in PVT (polyvinyltoluene) induced by energetic ions

Polyvinyltoluene (PVT) is an organic polymer employed as base material for many plastic scintillators useful to detect charged particles. Radiation da mage in PVT is investigated irradiating the polymer in vacuum with differen t ion beams (H+, He+, N+ and Ar+) as a function of their ion stopping power . The structural modifications induced in the polymer are deduced by monito ring in situ, during the ion irradiation, the molecular desorption from the polymer by a highly sensitive mass-quadrupole spectrometer. The desorbed m olecules are detected in the mass range 1-100 amu and the chemical yields a re measured with respect to the calibrated gas leaks. Main emitted species are H-2, C2H2 and C3H5, the yields of which strongly depend on the ion stop ping power. As will be discussed, the investigation of radiation damage in PVT permits to extend the results to the damage undergone by plastic scintillators duri ng 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.