• M. Jonker, E.B. Holzer, S. Mallows, D. Manglunki, G. Morpurgo, Th. Otto, M. Sapinski, F. Tecker, J.A. Uythoven
  CERN, Geneva

The pro­posed Com­pact Lin­ear Col­lid­er (CLIC) is based on a two-beam ac­cel­er­a­tion scheme. The en­er­gy of high in­ten­si­ty, low en­er­gy drive beams is ex­tract­ed and trans­ferred to low in­ten­si­ty, high en­er­gy main beams. Di­rect ion­iza­tion loss by the beam par­ti­cles is the prin­ci­pal dam­age mech­a­nism. The total charge gives a sin­gle drive beam-train a dam­age po­ten­tial that is two or­ders of mag­ni­tude above the level caus­ing struc­tural dam­age in cop­per. For the main beam, it is the ex­treme charge den­si­ty due to the mi­cro­scop­ic beam size that gives it a dam­age po­ten­tial of four or­ders of mag­ni­tude above the safe level. The ma­chine pro­tec­tion sys­tem has to cope with a wide va­ri­ety of fail­ures, from real time fail­ures (RF break­downs, kick­ers mis­fir­ing), to slow equip­ment fail­ures, to beam in­sta­bil­i­ties (caused by e.g. tem­per­a­ture drifts, slow ground mo­tions). This paper dis­cuss­es the base­line for the CLIC ma­chine pro­tec­tion sys­tem which is based on pas­sive, ac­tive and per­mit based pro­tec­tion. As the per­mit based pro­tec­tion de­pends on the mea­sured per­for­mance of the pre­vi­ous pulse, the boot­strap pro­ce­dure with safe beams and step­wise in­crease in beam in­ten­si­ties, is also dis­cussed.

• M. Sapinski, B. Dehning, E.B. Holzer, M. Jonker, S. Mallows, Th. Otto
  CERN, Geneva
• C.P. Welsch
  Cockcroft Institute, Warrington, Cheshire

The Com­pact Lin­ear Col­lid­er (CLIC) is a pro­posed mul­ti-TeV lin­ear elec­tron-positron col­lid­er being de­signed by a world-wide col­lab­o­ra­tion. It is based on a novel two-beam ac­cel­er­a­tion scheme in which two beams (drive and main beam) are placed in par­al­lel to each other and en­er­gy is trans­ferred from the drive beam to the main one. Beam loss­es on ei­ther of them can have catas­troph­ic con­se­quences for the ma­chine be­cause of high in­ten­si­ty (drive beam) or high en­er­gy and small emit­tance (main beam). In the frame­work of ma­chine pro­tec­tion, a Beam Loss Mon­i­tor­ing sys­tem has to be put in place. This paper dis­cuss­es the re­quire­ments for the beam loss sys­tem in terms of de­tec­tor sen­si­tiv­i­ty, res­o­lu­tion, dy­nam­ic range and abil­i­ty to dis­tin­guish loss­es orig­i­nat­ing from var­i­ous sources. A par­tic­u­lar at­ten­tion is given to the two-beam mod­ule where the pro­tec­tion from beam loss­es is par­tic­u­lar­ly chal­leng­ing and im­por­tant.

• 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