@article{oai:repo.qst.go.jp:00049142,
 author = {野田, 耕司 and noda and 古川, 卓司 and furukawa and 渋谷, 真二 and shibuya and 村松, 正幸 and muramatsu and 上杉, 智教 and uesugi and 金澤, 光隆 and kanazawa and 取越, 正己 and torikoshi and 高田, 栄一 and takada and 山田, 聰 and Noda, Koji and Furukawa, Takuji and Shibuya, Shinnji and Muramatsu, Masayuki and Uesugi, Tomonori and Kanazawa, Mitsutaka and Torikoshi, Masami and Takada, Eiichi and Yamada, Satoru},
 journal = {Nuclear Instruments and Methods in Physics Research A},
 month = {Oct},
 note = {The RF-knockout (RF-KO) slow-extraction method with frequency modulation (FM) and amplitude modulation (AM) has brought high-accuracy irradiation to the treatment ofa cancer tumor moving with respiration, because of a quick response to beam start/stop. However, a beam spill extracted from a synchrotron ring through RF-KO slowextraction has a huge ripple with a frequency of around 1 kHz related to the FM. The spill ripple will disturb the lateral dose distribution in the beam scanning methods. Thus, the source ofthe spill ripple has been investigated through experiments and simulations. There are two tune regions for the extraction process through the RF-KO method: the
extraction region and the diffusion region. The particles in the extraction region can be extracted due to amplitude growth through the transverse RF field, only when its frequency matches with the tune in the extraction region. For a large chromaticity, however, the particles in the extraction region can be extracted through the synchrotron oscillation, even when the frequency does not match with the tune in the extraction region. Thus, the spill structure during one
period ofthe FM strongly depends on the horizontal chromaticity. They are repeated with the repetition frequency of the FM, which is the very source ofthe spill ripple in the RF-KO method.},
 pages = {241--252},
 title = {Source of spill ripple in the RF-KO slow-extraction method with FM and AM},
 volume = {492},
 year = {2002}
}