• K. Hasegawa, T. Kobayashi, Y. Kondo, T. Morishita, H. Oguri
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• Y. Hori, C. Kubota, H. Matsumoto, F. Naito, M. Yoshioka
  KEK, Ibaraki

The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) ac­cel­er­ates a beam from the ion source to the DTL. The beam test of the linac was start­ed in Novem­ber 2006 and 181 MeV beam was suc­cess­ful­ly ac­cel­er­at­ed in Jan­uary 2007. Since then, the linac has been de­liv­ered beams for com­mis­sion­ing of the linac it­self, down­stream ac­cel­er­a­tors and fa­cil­i­ties. Trip rates of the RFQ, how­ev­er, un­ex­pect­ed­ly in­creased in Au­tumn 2008, and we have been suf­fer­ing from this issue for user run op­er­a­tion since then. We tried to re­cov­er by ten­der con­di­tion­ing, mod­i­fi­ca­tion of RF con­trol, im­prove­ment of vac­u­um prop­er­ties and so on. By tak­ing these mea­sures, we man­age to have 2 to 3 days con­tin­u­ous beam op­er­a­tion. In this re­port, we de­scribe the sta­tus of the RFQ.