Developments at JAEA AVF cyclotron facility for heavy-ion microbeam

Kurashima, Satoshi; Okumura, Susumu; Miyawaki, Nobumasa; Ishibori, Ikuo; Yoshida, Kenichi; Sato, Takahiro; Kashiwagi, Hirotsugu; Yuri, Yosuke; Agematsu, Takashi; Nara, Takayuki; et al.

Proceedings of 18th International Conference on Cyclotrons and Their Applications (CYCLOTRONS 2007), p.131 - 133, 2007/00

We have been improving the beam quality of the JAEA (Japan Atomic Energy Agency) AVF cyclotron to form a several-hundred-MeV heavy-ion microbeam by a magnetic focusing lens. An energy spread of the order of 10, obtained by ordinary acceleration using a fundamental dee voltage, makes it difficult to focus an ion beam to a spot size of 1 m in diameter with focusing lens because of the chromatic aberration. A flat-top acceleration system using the fifth-harmonic frequency of the acceleration frequency was installed in the cyclotron in order to reduce to the order of 10. In addition, developments of a new center region, an energy spread measurement system using an analyzing magnet and a high performance beam buncher are in progress. The energy spread of the 260 MeV Ne beam has been reduced to 0.05% by the flat-top acceleration, and the microbeam with a spot size of approximately 1 m has been successfully formed.