• D. Wollmann, O. Aberle, G. Arnau-Izquierdo, R.W. Assmann, J.-P. Bacher, V. Baglin, G. Bellodi, A. Bertarelli, A.P. Bouzoud, C. Bracco, R. Bruce, M. Brugger, S. Calatroni, F. Caspers, F. Cerutti, R. Chamizo, A. Cherif, E. Chiaveri, P. Chiggiato, A. Dallocchio, R. De Morais Amaral, B. Dehning, M. Donze, A. Ferrari, R. Folch, P. Francon, P. Gander, J.-M. Geisser, A. Grudiev, E.B. Holzer, D. Jacquet, J.B. Jeanneret, J.M. Jimenez, M. Jonker, J.M. Jowett, Y. Kadi, K. Kershaw, L. Lari, J. Lendaro, F. Loprete, R. Losito, M. Magistris, M. Malabaila, A. Marsili, A. Masi, S.J. Mathot, M. Mayer, C.C. Mitifiot, N. Mounet, E. Métral, A. Nordt, R. Perret, S. Perrollaz, C. Rathjen, S. Redaelli, G. Robert-Demolaize, S. Roesler, A. Rossi, B. Salvant, M. Santana-Leitner, I. Sexton, P. Sievers, T. Tardy, M.A. Timmins, E. Tsoulou, E. Veyrunes, H. Vincke, V. Vlachoudis, V. Vuillemin, Th. Weiler, F. Zimmermann
  CERN, Geneva
• I. Baishev, I.A. Kurochkin
  IHEP Protvino, Protvino, Moscow Region
• D. Kaltchev
  TRIUMF, Vancouver

The LHC has two ded­i­cat­ed clean­ing in­ser­tions: IR3 for mo­men­tum clean­ing and IR7 for be­ta­tron clean­ing. The col­li­ma­tion sys­tem has been spec­i­fied and built with tight me­chan­i­cal tol­er­ances (e.g. jaw flat­ness ~ 40 μm) and is de­signed to achieve a high ac­cu­ra­cy and re­pro­ducibil­i­ty of the jaw po­si­tions. The prac­ti­cal­ly achiev­able clean­ing ef­fi­cien­cy of the pre­sent Phase-I sys­tem de­pends on the pre­ci­sion of the jaw cen­ter­ing around the beam, the ac­cu­ra­cy of the gap size and the jaw par­al­lelism against the beam. The re­pro­ducibil­i­ty and sta­bil­i­ty of the sys­tem is im­por­tant to avoid the fre­quent rep­e­ti­tion of beam based align­ment which is cur­rent­ly a lengthy pro­ce­dure. With­in this paper we de­scribe the method used for the beam based align­ment of the LHC col­li­ma­tion sys­tem, its achieved ac­cu­ra­cy and sta­bil­i­ty and its per­for­mance at 450GeV.

Slides

• W. Bartmann, R.W. Assmann, C. Bracco, B. Dehning, B. Goddard, E.B. Holzer, V. Kain, M. Meddahi, A. Nordt, S. Redaelli, A. Rossi, M. Sapinski, D. Wollmann
  CERN, Geneva

The mov­able LHC in­jec­tion pro­tec­tion de­vices in the SPS to LHC trans­fer lines and down­stream of the in­jec­tion kick­er in the LHC were com­mis­sioned with low-in­ten­si­ty beam. The dif­fer­ent beam-based align­ment mea­sure­ments used to de­ter­mine the beam cen­tre and size are de­scribed, to­geth­er with the re­sults of mea­sure­ments of the trans­verse beam dis­tri­bu­tion at large am­pli­tude. The sys­tem was set up with beam to its nom­i­nal set­tings and the pro­tec­tion level against var­i­ous fail­ures was de­ter­mined by mea­sur­ing the trans­mis­sion and trans­verse dis­tri­bu­tion into the LHC as a func­tion of os­cil­la­tion am­pli­tude. Beam loss­es lev­els for reg­u­lar op­er­a­tion were also ex­trap­o­lat­ed. The re­sults are com­pared with the ex­pect­ed de­vice set­tings and pro­tec­tion level, and the im­pli­ca­tions for LHC op­er­a­tion dis­cussed.

• P. Peiffer, A. Bernhard, F. Burkart, S. Ehlers
  KIT, Karlsruhe
• T. Baumbach, S. Gerstl, A.W. Grau, R. Rossmanith
  Karlsruhe Institute of Technology (KIT), Karlsruhe
• D. Schoerling, D. Wollmann
  CERN, Geneva

The monochro­matic­i­ty and in­ten­si­ty of syn­chrotron light emit­ted by un­du­la­tors strong­ly de­pend on the un­du­la­tor field qual­i­ty. For the par­tic­u­lar case of su­per­con­duc­tive un­du­la­tors it was shown re­cent­ly that their field qual­i­ty can be sig­nif­i­cant­ly im­proved by an array of cou­pled high tem­per­a­ture su­per­con­duc­tor loops at­tached to the sur­face of the su­per­con­duc­tive un­du­la­tor. Local field er­rors in­duce cur­rents in the cou­pled closed su­per­con­duct­ing loops and, as a re­sult, the here­by gen­er­at­ed mag­net­ic field min­i­mizes the field er­rors. In pre­vi­ous pa­pers the con­cept was de­scribed the­o­ret­i­cal­ly and a proof-of-prin­ci­ple ex­per­i­ment was re­port­ed. This paper re­ports re­sults of the first quan­ti­ta­tive mea­sure­ment of the phase error re­duc­tion in a 12-pe­ri­od short model un­du­la­tor equipped with a full-scale in­duc­tion shim­ming sys­tem.