TUOPA03 　合同セッション　 10月18日 会議室A 10:40-11:10

J-PARC 3GeVシンクロトロンにおける大強度ビーム損失低減の達成

Achievement of low beam loss at high-intensity operation of J-PARC 3 GeV RCS

○サハ プラナブ，岡部 晃大，仲野谷 孝充，吉本 政弘，菖蒲田 義博，原田 寛之，田村 文彦，沖田 英史，畠山 衆一郎，守屋 克洋，山本 風海（原子力機構, J-PARC センター），發知 英明（KEK/J-PARC）

○Pranab Saha, Kota Okabe, Takamitsu Nakanoya, Masahiro Yoshimoto, Yoshihiro Shobuda, Hiroyuki Harada, Fumihiko Tamura, Hidefumi Okita, Shuichiro Hatakeyama, Katsuhiro Moriya, Kazami Yamamoto (JAEA, J-PARC), Hideaki Hotchi (KEK/J-PARC)

In the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC, the beam power is increased to 800 kW for operation to the MLF (Material and Life Science Experimental Facility). The total beam loss up to the designed 1 MW has already been well controlled, but for further minimizing the beam loss, especially the uncontrolled ones caused by the foil scattering of the circulating beam during multi-turn charge-exchange injection, recently we have implemented a new approach by minimizing the injection beam size and using a smaller size stripper foil. A smaller foil reduces foil hitting of the circulating beam so does the foil scattering uncontrolled beam loss mainly at the injection area. In addition, an optimized transverse painting area matching with a smaller injection beam also gives a smaller circulating beam emittance to reduce beam loss at the collimator section and the downstream. The corresponding residual radiation at 700 kW was measured to be significantly reduced as compared to that with an original bigger injection beam size and a larger foil. An optimized injection beam size with a smaller foil have been successfully implemented for the RCS operation.