• H. Hotchi, H. Harada, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• Y. Irie
  KEK, Ibaraki

We have re­cent­ly demon­strat­ed 300-kW out­put in the J-PARC 3-GeV RCS. In this paper we will dis­cuss beam dy­nam­ics is­sues in such a high in­ten­si­ty beam op­er­a­tion to­geth­er with the cor­re­spond­ing beam sim­u­la­tion re­sults.

• K. Satou, T. Toyama
  J-PARC, KEK & JAEA, Ibaraki-ken
• H. Harada, K. Yamamoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

A sin­gle-wire pro­por­tion­al counter which has the max­i­mum gain of 6·10⁴ is used as a beam loss mon­i­tor (p-BLM), thus low-lev­el beam loss can be mon­i­tored. How­ev­er, it in­volves gain re­duc­tion prob­lem by the space charge ef­fect. It is es­sen­tial to es­ti­mate the space charge ef­fect to uti­lize a pro­por­tion­al counter for beam loss mon­i­tor­ing. The cal­i­bra­tion pro­ce­dure is dis­cussed for the p-BLMs for 3-50BT and MR. Mea­sure­ments of resid­u­al dose were made and some nu­clei were iden­ti­fied. Ra­di­a­tion from the short-life nu­cle­us, Fe53 (T1/2=8.51m), may be a good index to pre­dict a resid­u­al dose after a long term beam op­er­a­tion.

• K. Yamamoto, H. Harada, S. Hatakeyama, N. Hayashi, H. Hotchi, P.K. Saha, M. Yoshimoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• R. Saeki
  KEK/JAEA, Ibaraki-Ken

A 3GeV Rapid-Cy­cling Syn­chrotron (RCS) in Japan Pro­ton Ac­cel­er­a­tor Re­search Com­plex (J-PARC) has con­tin­u­ous­ly pro­vid­ed more than 100kW pro­ton beam to the Neu­tron tar­get since Oc­to­ber 2009. And we also suc­cess­ful­ly ac­cel­er­at­ed 300kW beam for one hour on De­cem­ber 10th by way of trial. We found some prob­lems through these ex­pe­ri­ences. We re­port those prob­lems and the resid­u­al dose in such high in­ten­si­ty op­er­a­tion.

• P.K. Saha, H. Harada, H. Hotchi, K. Yamamoto, Y. Yamazaki, M. Yoshimoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• I. Sugai
  KEK, Ibaraki

The beam loss caused by the nu­cle­ar scat­ter­ing to­geth­er with the mul­ti­ple Coulomb scat­ter­ing at the strip­ping foil is one of the key issue in RCS (Rapid Cy­cling Syn­chrotron) of the J-PARC (Japan Pro­ton Ac­cel­er­a­tor Re­search Ac­cel­er­a­tor). In order to have a very re­al­is­tic un­der­stand­ing, a sys­tem­at­ic study with both ex­per­i­ment and sim­u­la­tion has been car­ried out re­cent­ly. A total of seven tar­gets with dif­fer­ent thick­ness were used and the mea­sured beam loss­es were found to be good in agree­ment with that in the sim­u­la­tion. A de­tail and re­al­is­tic un­der­stand­ing from such a study will be very use­ful not only to op­ti­mize the foil sys­tem in­clud­ing the thick­ness and size at pre­sent with the in­jec­tion beam en­er­gy of 181 MeV but also for the near fu­ture up­grade with 400 MeV and in ad­di­tion can be a good ex­am­ple for sim­i­lar ex­ist­ing and propos­ing pro­jects.

• M. Yoshimoto, H. Harada, N. Hayashi, H. Hotchi, Y. Irie, M. Kawase, M. Kinsho, R. Saeki, P.K. Saha, K. Yamamoto, Y. Yamazaki
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• T. Ishiyama
  KEK/JAEA, Ibaraki-Ken
• I. Sugai
  KEK, Ibaraki

The hy­brid type thick boron-doped car­bon (HBC) strip­ping foils are in­stalled and used for the beam in­jec­tion at the 3GeV RCS (Rapid Cy­cling Syn­chrotron) in J-PARC (Japan Pro­ton Ac­cel­er­a­tor Re­search Com­plex). The HBC foils are de­vel­oped by Sugai group in KEK, which im­proved the life­time dras­ti­cal­ly. Up to now, the per­for­mance de­te­ri­o­ra­tion of the strip­ping foils can not be seen after the long beam ir­ra­di­a­tion for the 120kW user op­er­a­tion and 300kW high power beam demon­stra­tion at the RCS. In order to ex­am­ine the char­ac­ter­is­tic of the HBC foils, var­i­ous beam stud­ies were car­ried out. The beam-ir­ra­di­at­ed spot at the foil was mea­sured by scan­ning the foil set­ting po­si­tion, the charge ex­change ef­fi­cien­cy was eval­u­at­ed with var­i­ous thick­ness foils, and the ef­fect of the SiC fibers sup­port­ing the foil mount­ing was checked with dif­fer­ent mount­ing foils. Beam study re­sults ob­tained with using the HBC foils will be pre­sent­ed. In ad­di­tion, the trends of out­gas from the strip­ping foils and the de­for­ma­tions of the foils dur­ing the beam ir­ra­di­a­tion will be re­port­ed.