@article{oai:repo.qst.go.jp:00048805,
 author = {Nakao, Masao and Hojo, Satoru and Katagiri, Ken and Miyahara, Nobuyuki and Noda, Akira and Sugiura, Akinori and Wakui, Takashi and V.Smirnov(JINR） and S.Vorozhtsov(JINR) and A.Goto(RIKEN） and 中尾 政夫 and 北條 悟 and 片桐 健 and 宮原 信幸 and 野田 章 and 杉浦 彰則 and 涌井 崇志},
 issue = {A},
 journal = {Nuclear Instruments and Methods in Physics Research Section B},
 month = {Nov},
 note = {To increase the beam intensity of cyclotrons used for producing radionuclides, beam loss during extraction must be reduced. Extraction efficiency is limited by the beam parameters in front of the deflector, especially angular distribution. Computer simulation of the second harmonic mode for 18 MeV protons, which is frequently used, has been carried out to understand beam behavior in a cyclotron. The extraction efficiency is determined by the width of the angular distribution of particles in the phase space plot at the deflector. An effective method to reduce the width is to shorten the bunch at injection. The simulation shows that the bunch phase length at injection must be ⩽30° to realize a 30 μA extraction beam current and satisfy the deflector heat limit of 200 W.},
 pages = {214--217},
 title = {Approach to increase beam intensity extracted from a cyclotron},
 volume = {406},
 year = {2016}
}