• M. Tejima, D.A. Arakawa, Y. Hashimoto
  KEK, Ibaraki
• K. Hanamura
  MELCO SC, Tsukuba
• N. Hayashi
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• K. Satou, T. Toyama, N. Yamamoto
  J-PARC, KEK & JAEA, Ibaraki-ken

To main­tain the beam orbit of beam trans­port line from RCS to MR in J-PARC (3-50BT), 14 beam po­si­tion mon­i­tors (BPMs) were in­stalled. Their sig­nals gath­ered in the local con­trol build­ing (D01) have been mea­sured by using 14 dig­i­tiz­ing os­cil­lo­scopes. The data ac­qui­si­tion sys­tem have a per­for­mance of shot-by-shot mea­sure­ment.

• N. Hayashi, H. Harada, H. Hotchi
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• M. Tejima
  KEK, Ibaraki
• T. Toyama
  J-PARC, KEK & JAEA, Ibaraki-ken

The J-PARC RCS is an M-Watt class rapid cy­cling syn­chrotron and it has de­liv­ered an in­ten­sive beam to the neu­tron tar­get and the MR. In order to over­come large space charge ef­fect, its phys­i­cal aper­ture is de­signed to be more than 250mm in di­am­e­ter. Even though its cham­ber size is very large, the BPM sys­tem gives pre­cise data to de­ter­mine beam op­tics pa­ram­e­ters of the ring. For this pur­pose, only rel­a­tive po­si­tions and res­o­lu­tions are im­por­tant. How­ev­er, for much high­er in­ten­si­ty, the ab­so­lute beam po­si­tion and ac­cu­rate COD cor­rec­tion are in­dis­pens­able. We have care­ful­ly in­stalled the BPM and mea­sured the po­si­tion with re­spect to the quadrupole mag­net (QM) near­by. But it is also nec­es­sary to es­ti­mate its ab­so­lute po­si­tion by using beam. If each QM could be con­trolled in­de­pen­dent­ly, the sim­ple beam based align­ment tech­nique can be uti­lized, but it is not the case for RCS. There are seven fam­i­lies of QM, and only each fam­i­ly can be con­trolled at one time. We de­vel­oped a new tech­nique by ex­pand­ing the sim­ple method for the case of mul­ti­ple QM fo­cus­ing changed si­mul­ta­ne­ous­ly, and ap­plied to the J-PARC RCS. The paper de­scribes this method and dis­cussed about ex­per­i­men­tal re­sults.

• K. Ohmi, T. Ieiri, Y. Ohnishi, Y. Seimiya, M. Tejima, M. Tobiyama, D.M. Zhou
  KEK, Ibaraki

Op­tics pa­ram­e­ters at the in­ter­ac­tion point, beta, x-y cou­pling, dis­per­sion and their chro­mat­ic aber­ra­tions, se­ri­ous­ly af­fect the beam-beam per­for­mance as is shown in ex­per­i­ments and sim­u­la­tions. The con­trol of the op­tics pa­ram­e­ters is es­sen­tial to main­tain the high lu­mi­nos­i­ty in KEKB. They drift day by day, or be­fore and after the beam abort. They were often mon­i­tored at in­ter­vals of the op­er­a­tion with tak­ing the study time. They are re­cent­ly mea­sured dur­ing the physics run using a pilot bunch with­out col­li­sion. We show the mea­sured the op­tics pa­ram­e­ters and their vari­a­tions and dis­cuss the re­la­tion to the lu­mi­nos­i­ty.

• S. Hatakeyama, N. Hayashi
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• D.A. Arakawa, Y. Hashimoto, S. Hiramatsu, J.-I. Odagiri, M. Tejima, M. Tobiyama, T. Toyama, N. Yamamoto
  KEK, Ibaraki
• K. Hanamura
  MELCO SC, Tsukuba
• K. Satou
  J-PARC, KEK & JAEA, Ibaraki-ken

The Data Ac­qui­si­tion Sys­tem of Beam Po­si­tion Mon­i­tors(BPMs) in J-PARC Main Ring are con­sist of 186 Lin­ux-based Data Pro­cess­ing Cirquits(BPMCs) and 12 EPICS IOCs. They are im­por­tant tool to see the COD and turn-by-turn beam po­si­tions. This re­port de­scribes the pro­cess of the data re­con­struc­tion which in­clude how the var­i­ous cal­i­bra­tion con­stants are ap­plied.

• M. Tobiyama, Y.H. Chin, Y. Kurimoto, T. Obina, M. Tejima, T. Toyama
  KEK, Ibaraki
• Y. Shobuda
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

Trans­verse bunch by bunch feed­back sys­tems for J-PARC MR ac­cel­er­a­tor has been de­signed and test­ed. Bunch po­si­tions are de­tect­ed by Log-ra­tio po­si­tion de­tec­tion sys­tems with cen­ter fre­quen­cy of 12 MHz. The dig­i­tal fil­ter which con­sists of two LLRF4 boards sam­ples the po­si­tion sig­nal with 64 times of RF fre­quen­cy. Up to four sets of 16 tap FIR fil­ter with one-turn delay and dig­i­tal shift gain can be used. Pre­lim­i­nary re­sults of beam test of the sys­tem are also shown.

• T. Toyama, D.A. Arakawa, S. Hiramatsu, S. Igarashi, S. Lee, H. Matsumoto, J.-I. Odagiri, M. Okada, M. Tejima, M. Tobiyama
  KEK, Ibaraki
• K. Hanamura, S. Hatakeyama
  MELCO SC, Tsukuba
• Y. Hashimoto, K. Satou, J. Takano
  J-PARC, KEK & JAEA, Ibaraki-ken
• N. Hayashi
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

Ex­pe­ri­ences of op­er­at­ing BPM's dur­ing beam com­mis­sion­ing at the J-PARC MR are re­port­ed. The sub­jects are: (1) bug re­port, statis­tics and es­pe­cial­ly the ef­fect of a beam duct step, (2) po­si­tion res­o­lu­tion es­ti­ma­tion (<30 mi­crom­e­ters with 1 sec av­er­ag­ing), (3) beam based align­ment.

• Y. Funakoshi, T. Abe, K. Akai, Y. Cai, K. Ebihara, K. Egawa, A. Enomoto, J.W. Flanagan, H. Fukuma, K. Furukawa, T. Furuya, J. Haba, T. Ieiri, N. Iida, H. Ikeda, T. Ishibashi, M. Iwasaki, T. Kageyama, S. Kamada, T. Kamitani, S. Kato, M. Kikuchi, E. Kikutani, H. Koiso, M. Masuzawa, T. Mimashi, T. Miura, A. Morita, T.T. Nakamura, K. Nakanishi, M. Nishiwaki, Y. Ogawa, K. Ohmi, Y. Ohnishi, N. Ohuchi, K. Oide, T. Oki, M. Ono, M. Satoh, Y. Seimiya, K. Shibata, M. Suetake, Y. Suetsugu, T. Sugimura, Y. Susaki, T. Suwada, M. Tawada, M. Tejima, M. Tobiyama, N. Tokuda, S. Uehara, S. Uno, Y. Yamamoto, Y. Yano, K. Yokoyama, M. Yoshida, S.I. Yoshimoto, D.M. Zhou, Z.G. Zong
  KEK, Ibaraki

KEKB is an e-/e⁺ col­lid­er for the study of B physics and is also used for ma­chine stud­ies for fu­ture ma­chines. The peak lu­mi­nos­i­ty of KEKB, which is the world-high­est value, has been still in­creas­ing. This re­port sum­ma­rizes re­cent progress at KEKB.

Slides