Activation of Polymethyl-Methacrylate by Proton Beam

Activation has been used for many kinds of useful applications, such as use of the radioisotopes for diagnosis and treatment of cancer, and wear (or corrosion) investigation for using thin layer activation (TLA) technique, etc. But activation also has severe problems for the post-processing of the samples; such as time-loss, inconvenience of sample handling, personal radiation safety, etc. For in-vitro experiments, we observed death of tumor cells by proton irradiation. The use of large activated container material can cause erroneous results in this case. To solve these problems, we studied why the samples were activated and how the level of the activation could be reduced. In proton beam irradiation experiments, the target materials could be defined as the container and sample itself. We could easily reduce activation of container material comparing to activation of sample itself. Therefore, we tried to find less activated container material by irradiating proton beam in PS (polystyrene), PMP (polymethypenten), PMMA (poly methacrylate), PVC (polyvinyl chloride), and PP (polypropylene), which are the base materials of the bottles and Petri dishes, frequently used in laboratories. We used 45 MeV proton beams (MC-50 Cyclotron, KIRAMS) with 10 nA. In this study, we presented characteristics of proton beam irradiated PMMA