Visualization of focused proton beam dose distribution by atomic force microscopy using blended polymer films based on polyacrylic acid

Omichi, Masaaki*; Takano, Katsuyoshi*; Sato, Takahiro; Kamiya, Tomihiro; Ishii, Yasuyuki; Okubo, Takeru; Koka, Masashi; Kada, Wataru; Sugimoto, Masaki; Nishikawa, Hiroyuki*; Seki, Shu*

A new visualization method for dose distribution of a focused proton beam in sub-micrometer scale was developed using a formation of a bulky cross-linked structure of polyacrylic acid -, '-methylence bisacrylamide, blend film. The areas irradiated by the focused proton beam were swelled on the film. The height of the swelling was significantly increased according to the beam fluence and the increase of containing ratio of the methylence bisacrylamide. The height was saturated at the fluence of 510 ions/m. The proton beam-sensitive polymer film was used for the analysis of dose distribution on its surface. The irradiated surface was observed by employing an atomic force microscope. This observation result showed that the method could be used to confirm the writing patterns and the beam-spot shape. Nanostructures with a crescent shape are visualized clearly at a misaligned beam-spot shape in the set up of the beam-optics.