Fast single-ion hit system for heavy-ion mirobeam at TIARA cyclotron, 2

Yokota, Wataru; Sato, Takahiro; Okumura, Susumu; Kurashima, Satoshi; Miyawaki, Nobumasa; Kashiwagi, Hirotsugu; Yoshida, Kenichi; Kamiya, Tomihiro

The fast single-ion hit system is being developed using the focusing microbeam system at the TIARA cyclotron of the Takasaki Advanced Radiation Research Institute, JAEA. The highest hit rate of 25/s, 2.5 times as high as the goal value, was achieved using a microbeam of 260 MeV-Ne beam last fiscal year. However, a couple of subjects to be solved for practical single-ion irradiation were found. One was multiple hits at the same targeted point, which appeared at several percent of the total hit number. The percentage has been lowered to less than 1% by improving the time response of the detection system of the single-ion hit. The other is a miss hit around a targeted point, which appears at more than ten percents of the total hit number. The measured phenomena relating to the miss hit suggest that it may concern scattering of ions by the micro slit of the focusing system.