Analyses and the effect of impurities contained in charge stripper foils for the 3-GeV RCS of J-PARC

J-PARC、3GeV RCSの荷電変換フォイルの不純物の分析とその影響

山崎 良雄; 吉本 政弘  ; Saha, P. K.   ; 金正 倫計  ; 田口 富嗣; 山本 春也; 菅井 勲*

Yamazaki, Yoshio; Yoshimoto, Masahiro; Saha, P. K.; Kinsho, Michikazu; Taguchi, Tomitsugu; Yamamoto, Shunya; Sugai, Isao*

For a charge stripper foil in the RCS, we applied the Hybrid type thick Boron-doped Carbon foil which is developed with the arc-discharge method. In the research, we found that impurities content such as Fe, Cu, Na, Al differed from each foil. Such metals contribute a large-angle scattering and neutrons-generation by nuclear reaction against the injecting beam, as a result residual radioactivity was increased around the foil. On the other hand, we have a big problem with residual radioactivity of foil itself. By nuclear reaction with the proton beam, long half-life radioactive isotopes such as Na and Be mainly were detected from the irradiated foils. Be is generated from Boron including as the basic in HBC. Na is generated from impurities such as Na and Al contained in charge stripper foils. Especially Na has year-order long half-life and workers must be exposed to radiation while treating the irradiated foils. We will report about improvement of production control not to contain impurities into foils.