Irradiation damage induced on polyethylene terephtalate by 1.6 MeV deuteron ions

The irradiation damage caused on polyethylene terephtalate (Mylar, PET) samples by 1.6 MeV deuteron ions has been measured using simultaneously the nuclear reaction analysis (NRA) and the transmission energy loss (TEL) techniques. The irradiation was carried out at normal incidence relative to the target surface with the irradiation beam being used as the analysis beam. The evolution of the overall damage during irradiation was evaluated by measuring the variation of the energy loss of the deuteron beam passing through the target. For this purpose, a solid state Si detector placed at a forward angle of 30 deg. relative to the incident beam direction was used. The NRA spectra recorded by a second Si detector located backward at 150 deg. allowed the evaluation of the carbon and the oxygen depletion. The beam spot size was circular in shape and 1 mm in diameter and the beam current was set at 5 nA. The ion fluence was increased up to the value of 2.5 x 1016 deuterons/cm2. It was observed that the target energy loss decreased steadily as the fluence increased and levelled off at high fluence. The 16O(d,p0)17O, 16O(d,p1)17O* and 12C(d,p0)13C reactions were used for monitoring the evolution of the oxygen and carbon content as a function of the deuteron fluence. A monotonic decrease of the oxygen content with the increase of ion fluence was observed. At the highest fluence the oxygen depletion reached a value of about 75%. For carbon, a weak depletion was observed at fluence ranging from 2.5 x 1015 d/cm2 to 1.0 x 1016 d/cm2 followed by a levelling-off with a total loss around 20%