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The CMS experiment at the CERN LHC View the table of contents for this issue, or go to the journal homepage for more 2008 JINST 3 S08004 (http://iopscience.iop.org/1748-0221/3/08/S08004) Home Search Collections Journals About Contact us My IOPscience iopscience.iop.org/page/terms http://iopscience.iop.org/1748-0221/3/08 http://iopscience.iop.org/1748-0221 http://iopscience.iop.org/ http://iopscience.iop.org/search http://iopscience.iop.org/collections http://iopscience.iop.org/journals http://iopscience.iop.org/page/aboutioppublishing http://iopscience.iop.org/contact http://iopscience.iop.org/myiopscience 2 0 0 8 J I N S T 3 S 0 8 0 0 4 PUBLISHED BY INSTITUTE OF PHYSICS PUBLISHING AND SISSA RECEIVED: January 9, 2008 ACCEPTED: May 18, 2008 PUBLISHED: August 14, 2008 THE CERN LARGE HADRON COLLIDER: ACCELERATOR AND EXPERIMENTS The CMS experiment at the CERN LHC CMS Collaboration ABSTRACT: The Compact Muon Solenoid (CMS) detector is described. The detector operates at the Large Hadron Collider (LHC) at CERN. It was conceived to study proton-proton (and lead- lead) collisions at a centre-of-mass energy of 14 TeV (5.5 TeV nucleon-nucleon) and at luminosi- ties up to 1034 cm−2s−1 (1027 cm−2s−1). At the core of the CMS detector sits a high-magnetic- field and large-bore superconducting solenoid surrounding an all-silicon pixel and strip tracker, a lead-tungstate scintillating-crystals electromagnetic calorimeter, and a brass-scintillator sampling hadron calorimeter. The iron yoke of the flux-return is instrumented with four stations of muon detectors covering most of the 4π solid angle. Forward sampling calorimeters extend the pseudo- rapidity coverage to high values (|η | ≤ 5) assuring very good hermeticity. The overall dimensions of the CMS detector are a length of 21.6 m, a diameter of 14.6 m and a total weight of 12500 t. KEYWORDS: Instrumentation for particle accelerators and storage rings - high energy; Gaseous detectors; Scintillators, scintillation and light emission processes; Solid state detectors; Calorimeters; Gamma detectors; Large detector systems for particle and astroparticle physics; Particle identification methods; Particle tracking detectors; Spectrometers; Analogue electronic circuits; Control and monitor systems online; Data acquisition circuits; Data acquisition concepts; Detector control systems; Digital electronic circuits; Digital signal processing; Electronic detector readout concepts; Front-end electronics for detector readout; Modular electronics; Online farms and online filtering; Optical detector readout concepts; Trigger concepts and systems; VLSI circuits; Analysis and statistical methods; Computing; Data processing methods; Data reduction methods; Pattern recognition, cluster finding, calibration and fitting methods; Software architectures; Detector alignment and calibration methods; Detector cooling and thermo-stabilization; Detector design and construction technologies and materials; Detector grounding; Manufacturing; Overall mechanics design; Special cables; Voltage distributions. © 2008 IOP Publishing Ltd and SISSA http://www.iop.org/EJ/jinst/ http://www.iop.org/EJ/jinst/ 2 0 0 8 J I N S T 3 S 0 8 0 0 4 CMS Collaboration Yerevan Physics Institute, Yerevan, Armenia S. Chatrchyan, G. Hmayakyan, V. Khachatryan, A.M. Sirunyan Institut für Hochenergiephysik der OeAW, Wien, Austria W. Adam, T. Bauer, T. Bergauer, H. Bergauer, M. Dragicevic, J. Erö, M. Friedl, R. Frühwirth, V.M. Ghete, P. Glaser, C. Hartl, N. Hoermann, J. Hrubec, S. Hänsel, M. Jeitler, K. Kast- ner, M. Krammer, I. Magrans de Abril, M. Markytan, I. Mikulec, B. Neuherz, T. Nöbauer, M. Oberegger, M. Padrta, M. Pernicka, P. Porth, H. Rohringer, S. Schmid, T. Schreiner, R. Stark, H. Steininger, J. Strauss, A. Taurok, D. Uhl, W. Waltenberger, G. Walzel, E. Widl, C.-E. Wulz Byelorussian State University, Minsk, Belarus V. Petrov, V. Prosolovich National Centre for Particle and High Energy Physics, Minsk, Belarus V. Chekhovsky, O. Dvornikov, I. Emeliantchik, A. Litomin, V. Makarenko, I. Marfin, V. Mossolov, N. Shumeiko, A. Solin, R. Stefanovitch, J. Suarez Gonzalez, A. Tikhonov Research Institute for Nuclear Problems, Minsk, Belarus A. Fedorov, M. Korzhik, O. Missevitch, R. Zuyeuski Universiteit Antwerpen, Antwerpen, Belgium W. Beaumont, M. Cardaci, E. De Langhe, E.A. De Wolf, E. Delmeire, S. Ochesanu, M. Tasevsky, P. Van Mechelen Vrije Universiteit Brussel, Brussel, Belgium J. D’Hondt, S. De Weirdt, O. Devroede, R. Goorens, S. Hannaert, J. Heyninck, J. Maes, M.U. Mozer, S. Tavernier, W. Van Doninck,1 L. Van Lancker, P. Van Mulders, I. Villella, C. Wastiels, C. Yu Université Libre de Bruxelles, Bruxelles, Belgium O. Bouhali, O. Charaf, B. Clerbaux, P. De Harenne, G. De Lentdecker, J.P. Dewulf, S. Elgammal, R. Gindroz, G.H. Hammad, T. Mahmoud, L. Neukermans, M. Pins, R. Pins, S. Rugovac, J. Stefanescu, V. Sundararajan, C. Vander Velde, P. Vanlaer, J. Wickens – ii – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Ghent University, Ghent, Belgium M. Tytgat Université Catholique de Louvain, Louvain-la-Neuve, Belgium S. Assouak, J.L. Bonnet, G. Bruno, J. Caudron, B. De Callatay, J. De Favereau De Jeneret, S. De Visscher, P. Demin, D. Favart, C. Felix, B. Florins, E. Forton, A. Giammanco, G. Grégoire, M. Jonckman, D. Kcira, T. Keutgen, V. Lemaitre, D. Michotte, O. Militaru, S. Ovyn, T. Pierzchala, K. Piotrzkowski, V. Roberfroid, X. Rouby, N. Schul, O. Van der Aa Université de Mons-Hainaut, Mons, Belgium N. Beliy, E. Daubie, P. Herquet Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil G. Alves, M.E. Pol, M.H.G. Souza Instituto de Fisica - Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil M. Vaz Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil D. De Jesus Damiao, V. Oguri, A. Santoro, A. Sznajder Instituto de Fisica Teorica-Universidade Estadual Paulista, Sao Paulo, Brazil E. De Moraes Gregores,2 R.L. Iope, S.F. Novaes, T. Tomei Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria T. Anguelov, G. Antchev, I. Atanasov, J. Damgov, N. Darmenov,1 L. Dimitrov, V. Genchev,1 P. Iaydjiev, A. Marinov, S. Piperov, S. Stoykova, G. Sultanov, R. Trayanov, I. Vankov University of Sofia, Sofia, Bulgaria C. Cheshkov, A. Dimitrov, M. Dyulendarova, I. Glushkov, V. Kozhuharov, L. Litov, M. Makariev, E. Marinova, S. Markov, M. Mateev, I. Nasteva, B. Pavlov, P. Petev, P. Petkov, V. Spassov, Z. Toteva,1 V. Velev, V. Verguilov Institute of High Energy Physics, Beijing, China J.G. Bian, G.M. Chen, H.S. Chen, M. Chen, C.H. Jiang, B. Liu, X.Y. Shen, H.S. Sun, J. Tao, J. Wang, M. Yang, Z. Zhang, W.R. Zhao, H.L. Zhuang Peking University, Beijing, China Y. Ban, J. Cai, Y.C. Ge, S. Liu, H.T. Liu, L. Liu, S.J. Qian, Q. Wang, Z.H. Xue, Z.C. Yang, Y.L. Ye, J. Ying – iii – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Shanghai Institute of Ceramics, Shanghai, China (Associated Institute) P.J. Li, J. Liao, Z.L. Xue, D.S. Yan, H. Yuan Universidad de Los Andes, Bogota, Colombia C.A. Carrillo Montoya, J.C. Sanabria Technical University of Split, Split, Croatia N. Godinovic, I. Puljak, I. Soric University of Split, Split, Croatia Z. Antunovic, M. Dzelalija, K. Marasovic Institute Rudjer Boskovic, Zagreb, Croatia V. Brigljevic, K. Kadija, S. Morovic University of Cyprus, Nicosia, Cyprus R. Fereos, C. Nicolaou, A. Papadakis, F. Ptochos, P.A. Razis, D. Tsiakkouri, Z. Zinonos National Institute of Chemical Physics and Biophysics, Tallinn, Estonia A. Hektor, M. Kadastik, K. Kannike, E. Lippmaa, M. Müntel, M. Raidal, L. Rebane Laboratory of Advanced Energy Systems, Helsinki University of Technology, Espoo, Finland P.A. Aarnio Helsinki Institute of Physics, Helsinki, Finland E. Anttila, K. Banzuzi, P. Bulteau, S. Czellar, N. Eiden, C. Eklund, P. Engstrom,1 A. Heikkinen, A. Honkanen, J. Härkönen, V. Karimäki, H.M. Katajisto, R. Kinnunen, J. Klem, J. Kortesmaa,1 M. Kotamäki, A. Kuronen,1 T. Lampén, K. Lassila-Perini, V. Lefébure, S. Lehti, T. Lindén, P.R. Luukka, S. Michal,1 F. Moura Brigido, T. Mäenpää, T. Nyman, J. Nystén, E. Pietarinen, K. Skog, K. Tammi, E. Tuominen, J. Tuominiemi, D. Ungaro, T.P. Vanhala, L. Wendland, C. Williams Lappeenranta University of Technology, Lappeenranta, Finland M. Iskanius, A. Korpela, G. Polese,1 T. Tuuva Laboratoire d’Annecy-le-Vieux de Physique des Particules, IN2P3-CNRS, Annecy-le-Vieux, France G. Bassompierre, A. Bazan, P.Y. David, J. Ditta, G. Drobychev, N. Fouque, J.P. Guillaud, V. Her- mel, A. Karneyeu, T. Le Flour, S. Lieunard, M. Maire, P. Mendiburu, P. Nedelec, J.P. Peigneux, M. Schneegans, D. Sillou, J.P. Vialle – iv – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 DSM/DAPNIA, CEA/Saclay, Gif-sur-Yvette, France M. Anfreville, J.P. Bard, P. Besson,∗ E. Bougamont, M. Boyer, P. Bredy, R. Chipaux, M. De- jardin, D. Denegri, J. Descamps, B. Fabbro, J.L. Faure, S. Ganjour, F.X. Gentit, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, C. Jeanney, F. Kircher, M.C. Lemaire, Y. Lemoigne, B. Levesy,1 E. Locci, J.P. Lottin, I. Mandjavidze, M. Mur, J.P. Pansart, A. Payn, J. Rander, J.M. Reymond, J. Rolquin, F. Rondeaux, A. Rosowsky, J.Y.A. Rousse, Z.H. Sun, J. Tartas, A. Van Lysebetten, P. Venault, P. Verrecchia Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France M. Anduze, J. Badier, S. Baffioni, M. Bercher, C. Bernet, U. Berthon, J. Bourotte, A. Busata, P. Busson, M. Cerutti, D. Chamont, C. Charlot, C. Collard,3 A. Debraine, D. Decotigny, L. Do- brzynski, O. Ferreira, Y. Geerebaert, J. Gilly, C. Gregory,∗ L. Guevara Riveros, M. Haguenauer, A. Karar, B. Koblitz, D. Lecouturier, A. Mathieu, G. Milleret, P. Miné, P. Paganini, P. Poilleux, N. Pukhaeva, N. Regnault, T. Romanteau, I. Semeniouk, Y. Sirois, C. Thiebaux, J.C. Vanel, A. Zabi4 Institut Pluridisciplinaire Hubert Curien, IN2P3-CNRS, Université Louis Pasteur Strasbourg, France, and Université de Haute Alsace Mulhouse, Strasbourg, France J.L. Agram,5 A. Albert,5 L. Anckenmann, J. Andrea, F. Anstotz,6 A.M. Bergdolt, J.D. Berst, R. Blaes,5 D. Bloch, J.M. Brom, J. Cailleret, F. Charles,∗ E. Christophel, G. Claus, J. Cof- fin, C. Colledani, J. Croix, E. Dangelser, N. Dick, F. Didierjean, F. 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Wlochal RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany F. Adamczyk, A. Adolf, G. Altenhöfer, S. Bechstein, S. Bethke, P. Biallass, O. Biebel, M. Bonte- nackels, K. Bosseler, A. Böhm, M. Erdmann, H. Faissner,∗ B. Fehr, H. Fesefeldt, G. Fetchenhauer,1 J. Frangenheim, J.H. Frohn, J. Grooten, T. Hebbeker, S. Hermann, E. Hermens, G. Hilgers, K. Hoepfner, C. Hof, E. Jacobi, S. Kappler, M. Kirsch, P. Kreuzer, R. Kupper, H.R. Lampe, D. Lanske,∗ R. Mameghani, A. Meyer, S. Meyer, T. Moers, E. Müller, R. Pahlke, B. Philipps, D. Rein, H. Reithler, W. Reuter, P. Rütten, S. Schulz, H. Schwarthoff, W. Sobek, M. Sowa, T. Stapelberg, H. Szczesny, H. Teykal, D. Teyssier, H. Tomme, W. Tomme, M. Tonutti, O. Tsigenov, J. Tutas,∗ J. Vandenhirtz, H. Wagner, M. Wegner, C. Zeidler RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany F. Beissel, M. Davids, M. Duda, G. Flügge, M. Giffels, T. Hermanns, D. Heydhausen, S. Kalinin, S. Kasselmann, G. Kaussen, T. Kress, A. 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Vest, T. Weiler, C. Weiser, S. Weseler,∗ V. Zhukov7 Institute of Nuclear Physics "Demokritos", Aghia Paraskevi, Greece M. Barone, G. Daskalakis, N. Dimitriou, G. Fanourakis, C. Filippidis, T. Geralis, C. Kalfas, K. Karafasoulis, A. Koimas, A. Kyriakis, S. Kyriazopoulou, D. Loukas, A. Markou, C. Markou, – vi – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 N. Mastroyiannopoulos, C. Mavrommatis, J. Mousa, I. Papadakis, E. Petrakou, I. Siotis, K. The- ofilatos, S. Tzamarias, A. Vayaki, G. Vermisoglou, A. Zachariadou University of Athens, Athens, Greece L. Gouskos, G. Karapostoli, P. Katsas, A. Panagiotou, C. Papadimitropoulos University of Ioánnina, Ioánnina, Greece X. Aslanoglou, I. Evangelou, P. Kokkas, N. Manthos, I. Papadopoulos, F.A. Triantis KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary G. Bencze,1 L. Boldizsar, G. Debreczeni, C. Hajdu,1 P. Hidas, D. Horvath,8 P. Kovesarki, A. Laszlo, G. Odor, G. Patay, F. Sikler, G. Veres, G. Vesztergombi, P. 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Silvestris,1 P. Tem- pesta, R. Trentadue, S. Tupputi, G. Zito Università di Bologna e Sezione dell’ INFN, Bologna, Italy G. Abbiendi, W. Bacchi, C. Battilana, A.C. Benvenuti, M. Boldini, D. Bonacorsi, S. Braibant- Giacomelli, V.D. Cafaro, P. Capiluppi, A. Castro, F.R. Cavallo, C. Ciocca, G. Codispoti, M. Cuf- fiani, I. D’Antone, G.M. Dallavalle, F. Fabbri, A. Fanfani, S. Finelli, P. Giacomelli,12 V. Gior- dano, M. Giunta, C. Grandi, M. Guerzoni, L. Guiducci, S. Marcellini, G. Masetti, A. Montanari, F.L. Navarria, F. Odorici, A. Paolucci, G. Pellegrini, A. Perrotta, A.M. Rossi, T. Rovelli, G.P. Siroli, G. Torromeo, R. Travaglini, G.P. Veronese Università di Catania e Sezione dell’ INFN, Catania, Italy S. Albergo, M. Chiorboli, S. Costa, M. Galanti, G. Gatto Rotondo, N. Giudice, N. Guardone, F. Noto, R. Potenza, M.A. Saizu,48 G. Salemi, C. Sutera, A. Tricomi, C. Tuve Università di Firenze e Sezione dell’ INFN, Firenze, Italy L. Bellucci, M. Brianzi, G. Broccolo, E. Catacchini, V. Ciulli, C. Civinini, R. D’Alessandro, E. Fo- cardi, S. Frosali, C. Genta, G. Landi, P. Lenzi, A. Macchiolo, F. Maletta, F. Manolescu, C. Marchet- tini, L. Masetti,1 S. Mersi, M. Meschini, C. Minelli, S. Paoletti, G. Parrini, E. Scarlini, G. Sguazzoni Laboratori Nazionali di Frascati dell’ INFN, Frascati, Italy L. Benussi, M. Bertani, S. Bianco, M. Caponero, D. Colonna,1 L. Daniello, F. Fabbri, F. Felli, M. Giardoni, A. La Monaca, B. Ortenzi, M. Pallotta, A. Paolozzi, C. Paris, L. Passamonti, D. Pier- luigi, B. Ponzio, C. Pucci, A. Russo, G. Saviano Università di Genova e Sezione dell’ INFN, Genova, Italy P. Fabbricatore, S. Farinon, M. Greco, R. Musenich Laboratori Nazionali di Legnaro dell’ INFN, Legnaro, Italy (Associated Institute) S. Badoer, L. Berti, M. Biasotto, S. Fantinel, E. Frizziero, U. Gastaldi, M. Gulmini,1 F. Lelli, G. Maron, S. Squizzato, N. Toniolo, S. Traldi – viii – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 INFN e Universita Degli Studi Milano-Bicocca, Milano, Italy S. Banfi, R. Bertoni, M. Bonesini, L. Carbone, G.B. Cerati, F. Chignoli, P. D’Angelo, A. De Min, P. Dini, F.M. Farina,1 F. Ferri, P. Govoni, S. Magni, M. Malberti, S. Malvezzi, R. Mazza, D. Menasce, V. Miccio, L. Moroni, P. Negri, M. Paganoni, D. Pedrini, A. Pullia, S. Ragazzi, N. Redaelli, M. Rovere, L. Sala, S. Sala, R. Salerno, T. Tabarelli de Fatis, V. Tancini, S. Taroni Istituto Nazionale di Fisica Nucleare de Napoli (INFN), Napoli, Italy A. Boiano, F. Cassese, C. Cassese, A. Cimmino, B. D’Aquino, L. Lista, D. Lomidze, P. Noli, P. Paolucci, G. Passeggio, D. Piccolo, L. Roscilli, C. Sciacca, A. Vanzanella Università di Padova e Sezione dell’ INFN, Padova, Italy P. Azzi, N. Bacchetta,1 L. Barcellan, M. Bellato, M. Benettoni, D. Bisello, E. Borsato, A. Can- delori, R. Carlin, L. Castellani, P. Checchia, L. Ciano, A. Colombo, E. Conti, M. Da Rold, F. Dal Corso, M. De Giorgi, M. De Mattia, T. Dorigo, U. Dosselli, C. Fanin, G. Galet, F. Gas- parini, U. Gasparini, A. Giraldo, P. Giubilato, F. Gonella, A. Gresele, A. Griggio, P. Guaita, A. Kaminskiy, S. Karaevskii, V. Khomenkov, D. Kostylev, S. Lacaprara, I. Lazzizzera, I. Lippi, M. Loreti, M. Margoni, R. Martinelli, S. Mattiazzo, M. Mazzucato, A.T. Meneguzzo, L. Modenese, F. Montecassiano,1 A. Neviani, M. Nigro, A. Paccagnella, D. Pantano, A. Parenti, M. Passaseo,1 R. Pedrotta, M. Pegoraro, G. Rampazzo, S. Reznikov, P. Ronchese, A. Sancho Daponte, P. Sartori, I. Stavitskiy, M. Tessaro, E. Torassa, A. Triossi, S. Vanini, S. Ventura, L. Ventura, M. Verlato, M. Zago, F. Zatti, P. Zotto, G. Zumerle Università di Pavia e Sezione dell’ INFN, Pavia, Italy P. Baesso, G. Belli, U. Berzano, S. Bricola, A. Grelli, G. Musitelli, R. Nardò, M.M. Necchi, D. Pagano, S.P. Ratti, C. Riccardi, P. Torre, A. Vicini, P. Vitulo, C. Viviani Università di Perugia e Sezione dell’ INFN, Perugia, Italy D. Aisa, S. Aisa, F. Ambroglini, M.M. Angarano, E. Babucci, D. Benedetti, M. Biasini, G.M. Bilei,1 S. Bizzaglia, M.T. Brunetti, B. Caponeri, B. Checcucci, R. Covarelli, N. Dinu, L. Fanò, L. Farnesini, M. Giorgi, P. Lariccia, G. Mantovani, F. Moscatelli, D. Passeri, A. Piluso, P. Placidi, V. Postolache, R. Santinelli, A. Santocchia, L. Servoli, D. Spiga1 Università di Pisa, Scuola Normale Superiore e Sezione dell’ INFN, Pisa, Italy P. Azzurri, G. Bagliesi,1 G. Balestri, A. Basti, R. Bellazzini, L. Benucci, J. Bernardini, L. Berretta, S. Bianucci, T. Boccali, A. Bocci, L. Borrello, F. Bosi, F. Bracci, A. Brez, F. Calzolari, R. Castaldi, U. Cazzola, M. Ceccanti, R. Cecchi, C. Cerri, A.S. Cucoanes, R. Dell’Orso, D. Dobur, S. Dutta, F. Fiori, L. Foà, A. Gaggelli, S. Gennai,13 A. Giassi, S. Giusti, D. Kartashov, A. Kraan, L. Latronico, F. Ligabue, S. Linari, T. Lomtadze, G.A. Lungu,48 G. Magazzu, P. Mammini, F. Mariani, G. Martinelli, M. Massa, A. Messineo, A. Moggi, F. Palla, F. Palmonari, G. Petragnani, G. Petrucciani, A. Profeti, F. Raffaelli, D. Rizzi, G. Sanguinetti, S. Sarkar, G. Segneri, D. Sentenac, A.T. Serban, A. Slav, P. Spagnolo, G. Spandre, R. Tenchini, S. Tolaini, G. Tonelli,1 A. Venturi, P.G. Verdini, M. Vos, L. Zaccarelli – ix – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Università di Roma I e Sezione dell’ INFN, Roma, Italy S. Baccaro,14 L. Barone, A. Bartoloni, B. Borgia, G. Capradossi, F. Cavallari, A. Cecilia,14 D. D’Angelo, I. Dafinei, D. Del Re, E. Di Marco, M. Diemoz, G. Ferrara,14 C. Gargiulo, S. Guerra, M. Iannone, E. Longo, M. Montecchi,14 M. Nuccetelli, G. Organtini, A. Palma, R. Paramatti, F. Pellegrino, S. Rahatlou, C. Rovelli, F. Safai Tehrani, A. Zullo Università di Torino e Sezione dell’ INFN, Torino, Italy G. Alampi, N. Amapane, R. Arcidiacono, S. Argiro, M. Arneodo,15 R. Bellan, F. Benotto, C. Bi- ino, S. Bolognesi, M.A. Borgia, C. Botta, A. Brasolin, N. Cartiglia, R. Castello, G. Cerminara, R. Cirio, M. Cordero, M. Costa, D. Dattola, F. Daudo, G. Dellacasa, N. Demaria, G. Dughera, F. Dumitrache, R. Farano, G. Ferrero, E. Filoni, G. Kostyleva, H.E. Larsen, C. Mariotti, M. Marone, S. Maselli, E. Menichetti, P. Mereu, E. Migliore, G. Mila, V. Monaco, M. Musich, M. Nervo, M.M. Obertino,15 R. Panero, A. Parussa, N. Pastrone, C. Peroni, G. Petrillo, A. Romero, M. Ruspa,15 R. Sacchi, M. Scalise, A. Solano, A. Staiano, P.P. Trapani,1 D. Trocino, V. Vaniev, A. Vilela Pereira, A. Zampieri Università di Trieste e Sezione dell’ INFN, Trieste, Italy S. Belforte, F. Cossutti, G. Della Ricca, B. Gobbo, C. Kavka, A. Penzo Chungbuk National University, Chongju, Korea Y.E. Kim Kangwon National University, Chunchon, Korea S.K. Nam Kyungpook National University, Daegu, Korea D.H. Kim, G.N. Kim, J.C. Kim, D.J. Kong, S.R. Ro, D.C. Son Wonkwang University, Iksan, Korea S.Y. Park Cheju National University, Jeju, Korea Y.J. Kim Chonnam National University, Kwangju, Korea J.Y. Kim, I.T. Lim Dongshin University, Naju, Korea M.Y. Pac Seonam University, Namwon, Korea S.J. Lee – x – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Konkuk University, Seoul, Korea S.Y. Jung, J.T. Rhee Korea University, Seoul, Korea S.H. Ahn, B.S. Hong, Y.K. Jeng, M.H. Kang, H.C. Kim, J.H. Kim, T.J. Kim, K.S. Lee, J.K. Lim, D.H. Moon, I.C. Park, S.K. Park, M.S. Ryu, K.-S. Sim, K.J. Son Seoul National University, Seoul, Korea S.J. Hong Sungkyunkwan University, Suwon, Korea Y.I. Choi Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico H. Castilla Valdez, A. Sanchez Hernandez Universidad Iberoamericana, Mexico City, Mexico S. Carrillo Moreno Universidad Autonoma de San Luis Potosi, San Luis Potosi, Mexico A. Morelos Pineda Technische Universiteit Eindhoven, Eindhoven, Netherlands (Associated Institute) A. Aerts, P. Van der Stok, H. Weffers University of Auckland, Auckland, New Zealand P. Allfrey, R.N.C. Gray, M. Hashimoto, D. Krofcheck University of Canterbury, Christchurch, New Zealand A.J. Bell, N. Bernardino Rodrigues, P.H. Butler, S. Churchwell, R. Knegjens, S. Whitehead, J.C. Williams National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan Z. Aftab, U. Ahmad, I. Ahmed, W. Ahmed, M.I. Asghar, S. Asghar, G. Dad, M. Hafeez, H.R. Hoorani, I. Hussain, N. Hussain, M. Iftikhar, M.S. Khan, K. Mehmood, A. Osman, H. Shahzad, A.R. Zafar National University of Sciences And Technology, Rawalpindi Cantt, Pakistan (Associated Institute) A. Ali, A. Bashir, A.M. Jan, A. Kamal, F. Khan, M. Saeed, S. Tanwir, M.A. Zafar Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland J. Blocki, A. Cyz, E. Gladysz-Dziadus, S. Mikocki, M. Rybczynski, J. Turnau, Z. Wlodarczyk, P. Zychowski – xi – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Institute of Experimental Physics, Warsaw, Poland K. Bunkowski, M. Cwiok, H. Czyrkowski, R. Dabrowski, W. Dominik, K. Doroba, A. Kali- nowski, K. Kierzkowski, M. Konecki, J. Krolikowski, I.M. Kudla, M. Pietrusinski, K. Pozniak,16 W. Zabolotny,16 P. Zych Soltan Institute for Nuclear Studies, Warsaw, Poland R. Gokieli, L. Goscilo, M. Górski, K. Nawrocki, P. Traczyk, G. Wrochna, P. Zalewski Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland (Associated Institute) K.T. Pozniak, R. Romaniuk, W.M. Zabolotny Laboratório de Instrumentação e Física Experimental de Partículas, Lisboa, Portugal R. Alemany-Fernandez, C. Almeida, N. Almeida, A.S. Araujo Vila Verde, T. Barata Monteiro, M. Bluj, S. Da Mota Silva, A. David Tinoco Mendes, M. Freitas Ferreira, M. Gallinaro, M. Huse- jko, A. Jain, M. Kazana, P. Musella, R. Nobrega, J. Rasteiro Da Silva, P.Q. Ribeiro, M. Santos, P. Silva, S. Silva, I. Teixeira, J.P. Teixeira, J. Varela,1 G. Varner, N. Vaz Cardoso Joint Institute for Nuclear Research, Dubna, Russia I. Altsybeev, K. Babich, A. Belkov,∗ I. Belotelov, P. Bunin, S. Chesnevskaya, V. Elsha, Y. Er- shov, I. Filozova, M. Finger, M. Finger Jr., A. Golunov, I. Golutvin, N. Gorbounov, I. Gramenitski, V. Kalagin, A. Kamenev, V. Karjavin, S. Khabarov, V. Khabarov, Y. Kiryushin, V. Konoplyanikov, V. Korenkov, G. Kozlov, A. Kurenkov, A. Lanev, V. Lysiakov, A. Malakhov, I. Melnitchenko, V.V. Mitsyn, K. Moisenz, P. Moisenz, S. Movchan, E. Nikonov, D. Oleynik, V. Palichik, V. Pere- lygin, A. Petrosyan, E. Rogalev, V. Samsonov, M. Savina, R. Semenov, S. Sergeev,17 S. Shmatov, S. Shulha, V. Smirnov, D. Smolin, A. Tcheremoukhine, O. Teryaev, E. Tikhonenko, A. Urkinbaev, S. Vasil’ev, A. Vishnevskiy, A. Volodko, N. Zamiatin, A. Zarubin, P. Zarubin, E. Zubarev Petersburg Nuclear Physics Institute, Gatchina (St Petersburg), Russia N. Bondar, Y. Gavrikov, V. Golovtsov, Y. Ivanov, V. Kim, V. Kozlov, V. Lebedev, G. Makarenkov, F. Moroz, P. Neustroev, G. Obrant, E. Orishchin, A. Petrunin, Y. Shcheglov, A. Shchetkovskiy, V. Sknar, V. Skorobogatov, I. Smirnov, V. Sulimov, V. Tarakanov, L. Uvarov, S. Vavilov, G. Velichko, S. Volkov, A. Vorobyev High Temperature Technology Center of Research & Development Institute of Power Engi- neering, (HTTC RDIPE), Moscow, Russia (Associated Institute) D. Chmelev, D. Druzhkin,1 A. Ivanov, V. Kudinov, O. Logatchev, S. Onishchenko, A. Orlov, V. Sakharov, V. Smetannikov, A. Tikhomirov, S. Zavodthikov – xii – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Institute for Nuclear Research, Moscow, Russia Yu. Andreev, A. Anisimov, V. Duk, S. Gninenko, N. Golubev, D. Gorbunov, M. Kirsanov, N. Krasnikov, V. Matveev, A. Pashenkov, A. Pastsyak, V.E. Postoev, A. Sadovski, A. Skassyrskaia, Alexander Solovey, Anatoly Solovey, D. Soloviev, A. Toropin, S. Troitsky Institute for Theoretical and Experimental Physics, Moscow, Russia A. Alekhin, A. Baldov, V. Epshteyn, V. Gavrilov, N. Ilina, V. Kaftanov,∗ V. Karpishin, I. Kiselevich, V. Kolosov, M. Kossov,1 A. Krokhotin, S. Kuleshov, A. Oulianov, A. Pozdnyakov, G. Safronov, S. Semenov, N. Stepanov, V. Stolin, E. Vlasov,1 V. Zaytsev Moscow State University, Moscow, Russia E. Boos, M. Dubinin,18 L. Dudko, A. Ershov, G. Eyyubova, A. Gribushin, V. Ilyin, V. Klyukhin, O. Kodolova, N.A. Kruglov, A. Kryukov, I. Lokhtin, L. Malinina, V. Mikhaylin, S. Petrushanko, L. Sarycheva, V. Savrin, L. Shamardin, A. Sherstnev, A. Snigirev, K. Teplov, I. Vardanyan P.N. Lebedev Physical Institute, Moscow, Russia A.M. Fomenko, N. Konovalova, V. Kozlov, A.I. Lebedev, N. Lvova, S.V. Rusakov, A. Terkulov State Research Center of Russian Federation - Institute for High Energy Physics, Protvino, Russia V. Abramov, S. Akimenko, A. Artamonov, A. Ashimova, I. Azhgirey, S. Bitioukov, O. Chikilev, K. Datsko, A. Filine, A. Godizov, P. Goncharov, V. Grishin,1 A. Inyakin,19 V. Kachanov, A. Kalinin, A. Khmelnikov, D. Konstantinov, A. Korablev, V. Krychkine, A. Krinitsyn, A. Levine, I. Lobov, V. Lukanin, Y. Mel’nik, V. Molchanov, V. Petrov, V. Petukhov, V. Pikalov, A. Ryazanov, R. Ryutin, V. Shelikhov, V. Skvortsov, S. Slabospitsky, A. Sobol, A. Sytine, V. Talov, L. Tourtchanovitch, S. Troshin, N. Tyurin, A. Uzunian, A. Volkov, S. Zelepoukine20 Electron National Research Institute, St Petersburg, Russia (Associated Institute) V. Lukyanov, G. Mamaeva, Z. Prilutskaya, I. Rumyantsev, S. Sokha, S. Tataurschikov, I. Vasilyev Vinca Institute of Nuclear Sciences, Belgrade, Serbia P. Adzic, I. Anicin,21 M. Djordjevic, D. Jovanovic,21 D. Maletic, J. Puzovic,21 N. Smiljkovic1 Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid, Spain E. Aguayo Navarrete, M. Aguilar-Benitez, J. Ahijado Munoz, J.M. Alarcon Vega, J. Alberdi, J. Alcaraz Maestre, M. Aldaya Martin, P. Arce,1 J.M. Barcala, J. Berdugo, C.L. Blanco Ramos, C. Burgos Lazaro, J. Caballero Bejar, E. Calvo, M. Cerrada, M. Chamizo Llatas, J.J. Cher- coles Catalán, N. Colino, M. Daniel, B. De La Cruz, A. Delgado Peris, C. Fernandez Bedoya, A. Ferrando, M.C. Fouz, D. Francia Ferrero, J. Garcia Romero, P. Garcia-Abia, O. Gonza- lez Lopez, J.M. Hernandez, M.I. Josa, J. Marin, G. Merino, A. Molinero, J.J. Navarrete, J.C. Oller, J. Puerta Pelayo, J.C. Puras Sanchez, J. Ramirez, L. Romero, C. Villanueva Munoz, C. Willmott, C. Yuste – xiii – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Universidad Autónoma de Madrid, Madrid, Spain C. Albajar, J.F. de Trocóniz, I. Jimenez, R. Macias, R.F. Teixeira Universidad de Oviedo, Oviedo, Spain J. Cuevas, J. Fernández Menéndez, I. Gonzalez Caballero,22 J. Lopez-Garcia, H. Naves Sordo, J.M. Vizan Garcia Instituto de Física de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain I.J. Cabrillo, A. Calderon, D. Cano Fernandez, I. Diaz Merino, J. Duarte Campderros, M. Fernan- dez, J. Fernandez Menendez,23 C. Figueroa, L.A. Garcia Moral, G. Gomez, F. Gomez Casade- munt, J. Gonzalez Sanchez, R. Gonzalez Suarez, C. Jorda, P. Lobelle Pardo, A. Lopez Garcia, A. Lopez Virto, J. Marco, R. Marco, C. Martinez Rivero, P. Martinez Ruiz del Arbol, F. Matorras, P. Orviz Fernandez, A. Patino Revuelta,1 T. Rodrigo, D. Rodriguez Gonzalez, A. Ruiz Jimeno, L. Scodellaro, M. Sobron Sanudo, I. Vila, R. Vilar Cortabitarte Universität Basel, Basel, Switzerland M. Barbero, D. Goldin, B. Henrich, L. Tauscher, S. Vlachos, M. Wadhwa CERN, European Organization for Nuclear Research, Geneva, Switzerland D. Abbaneo, S.M. Abbas,24 I. Ahmed,24 S. Akhtar, M.I. Akhtar,24 E. Albert, M. Alidra, S. Ashby, P. Aspell, E. Auffray, P. Baillon, A. Ball, S.L. Bally, N. Bangert, R. Barillère, D. Barney, S. Beauceron, F. Beaudette,25 G. Benelli, R. Benetta, J.L. Benichou, W. Bialas, A. Bjorkebo, D. Blechschmidt, C. Bloch, P. Bloch, S. Bonacini, J. Bos, M. Bosteels, V. Boyer, A. Bran- son, H. Breuker, R. Bruneliere, O. Buchmuller, D. Campi, T. Camporesi, A. Caner, E. Cano, E. Carrone, A. Cattai, J.P. Chatelain, M. Chauvey, T. Christiansen, M. Ciganek, S. Cittolin, J. Cogan, A. Conde Garcia, H. Cornet, E. Corrin, M. Corvo, S. Cucciarelli, B. Curé, D. D’Enterria, A. De Roeck, T. de Visser, C. Delaere, M. Delattre, C. Deldicque, D. Delikaris, D. Deyrail, S. Di Vincenzo,26 A. Domeniconi, S. Dos Santos, G. Duthion, L.M. Edera, A. Elliott-Peisert, M. Eppard, F. Fanzago, M. Favre, H. Foeth, R. Folch, N. Frank, S. Fratianni, M.A. Freire, A. Frey, A. Fucci, W. Funk, A. Gaddi, F. Gagliardi, M. Gastal, M. Gateau, J.C. Gayde, H. Ger- wig, A. Ghezzi, D. Gigi, K. Gill, A.S. Giolo-Nicollerat, J.P. Girod, F. Glege, W. Glessing, R. Gomez-Reino Garrido, R. Goudard, R. Grabit, J.P. Grillet, P. Gutierrez Llamas, E. Gutier- rez Mlot, J. Gutleber, R. Hall-wilton, R. Hammarstrom, M. Hansen, J. Harvey, A. Hervé, J. Hill, H.F. Hoffmann, A. Holzner, A. Honma, D. Hufnagel, M. Huhtinen, S.D. Ilie, V. Innocente, W. Jank, P. Janot, P. Jarron, M. Jeanrenaud, P. Jouvel, R. Kerkach, K. Kloukinas, L.J. Kottelat, J.C. Labbé, D. Lacroix, X. Lagrue,∗ C. Lasseur, E. Laure, J.F. Laurens, P. Lazeyras, J.M. Le Goff, M. Lebeau,28 P. Lecoq, F. Lemeilleur, M. Lenzi, N. Leonardo, C. Leonidopoulos, M. Letheren, M. Liendl, F. Limia-Conde, L. Linssen, C. Ljuslin, B. Lofstedt, R. Loos, J.A. Lopez Perez, C. Lourenco, A. Lyonnet, A. Machard, R. Mackenzie, N. Magini, G. Maire, L. Malgeri, R. Ma- lina, M. Mannelli, A. Marchioro, J. Martin, F. Meijers, P. Meridiani, E. Meschi, T. Meyer, A. Meynet Cordonnier, J.F. Michaud, L. Mirabito, R. Moser, F. Mossiere, J. Muffat-Joly, M. Mul- ders, J. Mulon, E. Murer, P. Mättig, A. Oh, A. Onnela, M. Oriunno, L. Orsini, J.A. Osborne, – xiv – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 C. Paillard, I. Pal, G. Papotti, G. Passardi, A. Patino-Revuelta, V. Patras, B. Perea Solano, E. Perez, G. Perinic, J.F. Pernot, P. Petagna, P. Petiot, P. Petit, A. Petrilli, A. Pfeiffer, C. Piccut, M. Pimiä, R. Pintus, M. Pioppi, A. Placci, L. Pollet, H. Postema, M.J. Price, R. Principe, A. Racz, E. Radermacher, R. Ranieri, G. Raymond, P. Rebecchi, J. Rehn, S. Reynaud, H. Rezvani Naraghi, D. Ricci, M. Ridel, M. Risoldi, P. Rodrigues Simoes Moreira, A. Rohlev, G. Roiron, G. Rolandi,27 P. Rumerio, O. Runolfsson, V. Ryjov, H. Sakulin, D. Samyn, L.C. Santos Amaral, H. Sauce, E. Sbrissa, P. Scharff-Hansen, P. Schieferdecker, W.D. Schlatter, B. Schmitt, H.G. Schmuecker, M. Schröder, C. Schwick, C. Schäfer, I. Segoni, P. Sempere Roldán, S. Sgobba, A. Sharma, P. Siegrist, C. Sigaud, N. Sinanis, T. Sobrier, P. Sphicas,28 M. Spiropulu, G. Stefanini, A. Strandlie, F. Szoncsó, B.G. Taylor, O. Teller, A. Thea, E. Tournefier, D. Treille, P. Tropea, J. Troska, E. Tsesmelis, A. Tsirou, J. Valls, I. Van Vulpen, M. Vander Donckt, F. Vasey, M. Vazquez Acosta, L. Veillet, P. Vichoudis, G. Waurick, J.P. Wellisch, P. Wertelaers, M. Wilhelmsson, I.M. Willers, M. Winkler, M. Zanetti Paul Scherrer Institut, Villigen, Switzerland W. Bertl, K. Deiters, P. Dick, W. Erdmann, D. Feichtinger, K. Gabathuler, Z. Hochman, R. Ho- risberger, Q. Ingram, H.C. Kaestli, D. Kotlinski, S. König, P. Poerschke, D. Renker, T. Rohe, T. Sakhelashvili,29 A. Starodumov30 Institute for Particle Physics, ETH Zurich, Zurich, Switzerland V. Aleksandrov,31 F. Behner, I. Beniozef,31 B. Betev, B. Blau, A.M. Brett, L. Caminada,32 Z. Chen, N. Chivarov,31 D. Da Silva Di Calafiori, S. Dambach,32 G. Davatz, V. Delachenal,1 R. Della Marina, H. Dimov,31 G. Dissertori, M. Dittmar, L. Djambazov, M. Dröge, C. Eggel,32 J. Ehlers, R. Eichler, M. Elmiger, G. Faber, K. Freudenreich, J.F. Fuchs,1 G.M. Georgiev,31 C. Grab, C. Haller, J. Herrmann, M. Hilgers, W. Hintz, Hans Hofer, Heinz Hofer, U. Horis- berger, I. Horvath, A. Hristov,31 C. Humbertclaude, B. Iliev,31 W. Kastli, A. Kruse, J. Kuipers,∗ U. Langenegger, P. Lecomte, E. Lejeune, G. Leshev, C. Lesmond, B. List, P.D. Luckey, W. Lus- termann, J.D. Maillefaud, C. Marchica,32 A. Maurisset,1 B. Meier, P. Milenovic,33 M. Milesi, F. Moortgat, I. Nanov,31 A. Nardulli, F. Nessi-Tedaldi, B. Panev,34 L. Pape, F. Pauss, E. Petrov,31 G. Petrov,31 M.M. Peynekov,31 D. Pitzl, T. Punz, P. Riboni, J. Riedlberger, A. Rizzi, F.J. Ronga, P.A. Roykov,31 U. Röser, D. Schinzel, A. Schöning, A. Sourkov,35 K. Stanishev,31 S. Stoenchev,31 F. Stöckli, H. Suter, P. Trüb,32 S. Udriot, D.G. Uzunova,31 I. Veltchev,31 G. Viertel, H.P. von Gun- ten, S. Waldmeier-Wicki, R. Weber, M. Weber, J. Weng, M. Wensveen,1 F. Wittgenstein, K. Zagoursky31 Universität Zürich, Zürich, Switzerland E. Alagoz, C. Amsler, V. Chiochia, C. Hoermann, C. Regenfus, P. Robmann, T. Rommerskirchen, A. Schmidt, S. Steiner, D. Tsirigkas, L. Wilke National Central University, Chung-Li, Taiwan S. Blyth, Y.H. Chang, E.A. Chen, A. Go, C.C. Hung, C.M. Kuo, S.W. Li, W. Lin – xv – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 National Taiwan University (NTU), Taipei, Taiwan P. Chang, Y. Chao, K.F. Chen, Z. Gao,1 G.W.S. Hou, Y.B. Hsiung, Y.J. Lei, S.W. Lin, R.S. Lu, J.G. Shiu, Y.M. Tzeng, K. Ueno, Y. Velikzhanin, C.C. Wang, M.-Z. Wang Cukurova University, Adana, Turkey S. Aydin, A. Azman, M.N. Bakirci, S. Basegmez, S. Cerci, I. Dumanoglu, S. Erturk,36 E. Eskut, A. Kayis Topaksu, H. Kisoglu, P. Kurt, K. Ozdemir, N. Ozdes Koca, H. Ozkurt, S. Ozturk, A. Polatöz, K. Sogut,37 H. Topakli, M. Vergili, G. Önengüt Middle East Technical University, Physics Department, Ankara, Turkey H. Gamsizkan, S. Sekmen, M. Serin-Zeyrek, R. Sever, M. Zeyrek Bogaziçi University, Department of Physics, Istanbul, Turkey M. Deliomeroglu, E. Gülmez, E. Isiksal,38 M. Kaya,39 O. Kaya,39 S. Ozkorucuklu,40 N. Sonmez41 Institute of Single Crystals of National Academy of Science, Kharkov, Ukraine B. Grinev, V. Lyubynskiy, V. Senchyshyn National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, UKRAINE L. Levchuk, S. Lukyanenko, D. Soroka, P. Sorokin, S. Zub Centre for Complex Cooperative Systems, University of the West of England, Bristol, United Kingdom (Associated Institute) A. Anjum, N. Baker, T. Hauer, R. McClatchey, M. Odeh, D. Rogulin, A. Solomonides University of Bristol, Bristol, United Kingdom J.J. Brooke, R. Croft, D. Cussans, D. Evans, R. Frazier, N. Grant, M. Hansen, R.D. Head, G.P. Heath, H.F. Heath, C. Hill, B. Huckvale, J. Jackson,42 C. Lynch, C.K. Mackay, S. Metson, S.J. Nash, D.M. Newbold,42 A.D. Presland, M.G. Probert, E.C. Reid, V.J. Smith, R.J. Tapper, R. Walton Rutherford Appleton Laboratory, Didcot, United Kingdom E. Bateman, K.W. Bell, R.M. Brown, B. Camanzi, I.T. Church, D.J.A. Cockerill, J.E. Cole, J.F. Connolly,∗ J.A. Coughlan, P.S. Flower, P. Ford, V.B. Francis, M.J. French, S.B. Galagedera, W. Gannon, A.P.R. Gay, N.I. Geddes, R.J.S. Greenhalgh, R.N.J. Halsall, W.J. Haynes, J.A. Hill, F.R. Jacob, P.W. Jeffreys, L.L. Jones, B.W. Kennedy, A.L. Lintern, A.B. Lodge, A.J. Maddox, Q.R. Morrissey, P. Murray, G.N. Patrick, C.A.X. Pattison, M.R. Pearson, S.P.H. Quinton, G.J. Rogers, J.G. Salisbury, A.A. Shah, C.H. Shepherd-Themistocleous, B.J. Smith, M. Sproston, R. Stephenson, S. Taghavi, I.R. Tomalin, M.J. Torbet, J.H. Williams, W.J. Womersley, S.D. Worm, F. Xing – xvi – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Imperial College, University of London, London, United Kingdom M. Apollonio, F. Arteche, R. Bainbridge, G. Barber, P. Barrillon, J. Batten, R. Beuselinck, P.M. Brambilla Hall, D. Britton, W. Cameron, D.E. Clark, I.W. Clark, D. Colling, N. Cripps, G. Davies, M. Della Negra, G. Dewhirst, S. Dris, C. Foudas, J. Fulcher, D. Futyan, D.J. Graham, S. Greder, S. Greenwood, G. Hall, J.F. Hassard, J. Hays, G. Iles, V. Kasey, M. Khaleeq, J. Leaver, P. Lewis, B.C. MacEvoy, O. Maroney, E.M. McLeod, D.G. Miller, J. Nash, A. Nikitenko,30 E. Noah Messomo, M. Noy, A. Papageorgiou, M. Pesaresi, K. Petridis, D.R. Price, X. Qu, D.M. Raymond, A. Rose, S. Rutherford, M.J. Ryan, F. Sciacca, C. Seez, P. Sharp,1 G. Sidiropoulos,1 M. Stettler,1 M. Stoye, J. Striebig, M. Takahashi, H. Tallini, A. Tapper, C. Timlin, L. Toudup, T. Virdee,1 S. Wakefield, P. Walsham, D. Wardrope, M. Wingham, Y. Zhang, O. Zorba Brunel University, Uxbridge, United Kingdom C. Da Via, I. Goitom, P.R. Hobson, D.C. Imrie, I. Reid, C. Selby, O. Sharif, L. Teodorescu, S.J. Watts, I. Yaselli Boston University, Boston, Massachusetts, U.S.A. E. Hazen, A. Heering, A. Heister, C. Lawlor, D. Lazic, E. Machado, J. Rohlf, L. Sulak, F. Varela Rodriguez, S. X. Wu Brown University, Providence, Rhode Island, U.S.A. A. Avetisyan, T. Bose, L. Christofek, D. Cutts, S. Esen, R. Hooper, G. Landsberg, M. Narain, D. Nguyen, T. Speer, K.V. Tsang University of California, Davis, Davis, California, U.S.A. R. Breedon, M. Case, M. Chertok, J. Conway, P.T. Cox, J. Dolen, R. Erbacher, Y. Fisyak, E. Friis, G. Grim, B. Holbrook, W. Ko, A. Kopecky, R. Lander, F.C. Lin, A. Lister, S. Maruyama, D. Pellett, J. Rowe, M. Searle, J. Smith, A. Soha, M. Squires, M. Tripathi, R. Vasquez Sierra, C. Veelken University of California, Los Angeles, Los Angeles, California, U.S.A. V. Andreev, K. Arisaka, Y. Bonushkin, S. Chandramouly, D. Cline, R. Cousins, S. Erhan,1 J. Hauser, M. Ignatenko, C. Jarvis, B. Lisowski,∗ C. Matthey, B. Mohr, J. Mumford, S. Otwinowski, Y. Pischalnikov, G. Rakness, P. Schlein,∗ Y. Shi, B. Tannenbaum, J. Tucker, V. Valuev, R. Wallny, H.G. Wang, X. Yang, Y. Zheng University of California, Riverside, Riverside, California, U.S.A. J. Andreeva, J. Babb, S. Campana, D. Chrisman, R. Clare, J. Ellison, D. Fortin, J.W. Gary, W. Gorn, G. Hanson, G.Y. Jeng, S.C. Kao, J.G. Layter, F. Liu, H. Liu, A. Luthra, G. Pasztor,43 H. Rick, A. Satpathy, B.C. Shen,∗ R. Stringer, V. Sytnik, P. Tran, S. Villa, R. Wilken, S. Wimpenny, D. Zer-Zion University of California, San Diego, La Jolla, California, U.S.A. J.G. Branson, J.A. Coarasa Perez, E. Dusinberre, R. Kelley, M. Lebourgeois, J. Letts, E. Lipeles, – xvii – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 B. Mangano, T. Martin, M. Mojaver, J. Muelmenstaedt, M. Norman, H.P. Paar, A. Petrucci, H. Pi, M. Pieri, A. Rana, M. Sani, V. Sharma, S. Simon, A. White, F. Würthwein, A. Yagil University of California, Santa Barbara, Santa Barbara, California, U.S.A. A. Affolder, A. Allen, C. Campagnari, M. D’Alfonso, A. Dierlamm,23 J. Garberson, D. Hale, J. Incandela, P. Kalavase, S.A. Koay, D. Kovalskyi, V. Krutelyov, S. Kyre, J. Lamb, S. Lowette, M. Nikolic, V. Pavlunin, F. Rebassoo, J. Ribnik, J. Richman, R. Rossin, Y.S. Shah, D. Stuart, S. Swain, J.R. Vlimant, D. White, M. Witherell California Institute of Technology, Pasadena, California, U.S.A. A. Bornheim, J. Bunn, J. Chen, G. Denis, P. Galvez, M. Gataullin, I. Legrand, V. Litvine, Y. Ma, R. Mao, D. Nae, I. Narsky, H.B. Newman, T. Orimoto, C. Rogan, S. Shevchenko, C. Steenberg, X. Su, M. Thomas, V. Timciuc, F. van Lingen, J. Veverka, B.R. Voicu,1 A. Weinstein, R. Wilkin- son, Y. Xia, Y. Yang, L.Y. Zhang, K. Zhu, R.Y. Zhu Carnegie Mellon University, Pittsburgh, Pennsylvania, U.S.A. T. Ferguson, D.W. Jang, S.Y. Jun, M. Paulini, J. Russ, N. Terentyev, H. Vogel, I. Vorobiev University of Colorado at Boulder, Boulder, Colorado, U.S.A. M. Bunce, J.P. Cumalat, M.E. Dinardo, B.R. Drell, W.T. Ford, K. Givens, B. Heyburn, D. Johnson, U. Nauenberg, K. Stenson, S.R. Wagner Cornell University, Ithaca, New York, U.S.A. L. Agostino, J. Alexander, F. Blekman, D. Cassel, S. Das, J.E. Duboscq, L.K. Gibbons, B. Helt- sley, C.D. Jones, V. Kuznetsov, J.R. Patterson, D. Riley, A. Ryd, S. Stroiney, W. Sun, J. Thom, J. Vaughan, P. Wittich Fairfield University, Fairfield, Connecticut, U.S.A. C.P. Beetz, G. Cirino, V. Podrasky, C. Sanzeni, D. Winn Fermi National Accelerator Laboratory, Batavia, Illinois, U.S.A. S. Abdullin,1 M.A. Afaq,1 M. Albrow, J. Amundson, G. Apollinari, M. Atac, W. Badgett, J.A. Bakken, B. Baldin, K. Banicz, L.A.T. Bauerdick, A. Baumbaugh, J. Berryhill, P.C. Bhat, M. Binkley, I. Bloch, F. Borcherding, A. Boubekeur, M. Bowden, K. Burkett, J.N. Butler, H.W.K. Cheung, G. Chevenier,1 F. Chlebana, I. Churin, S. Cihangir, W. Dagenhart, M. De- marteau, D. Dykstra, D.P. Eartly, J.E. Elias, V.D. Elvira, D. Evans, I. Fisk, J. Freeman, I. Gaines, P. Gartung, F.J.M. Geurts, L. Giacchetti, D.A. Glenzinski, E. Gottschalk, T. Grassi, D. Green, C. Grimm, Y. Guo, O. Gutsche, A. Hahn, J. Hanlon, R.M. Harris, T. Hesselroth, S. Holm, B. Holzman, E. James, H. Jensen, M. Johnson, U. Joshi, B. Klima, S. Kossiakov, K. Kousouris, J. Kowalkowski, T. Kramer, S. Kwan, C.M. Lei, M. Leininger, S. Los, L. Lueking, G. Lukhanin, S. Lusin,1 K. Maeshima, J.M. Marraffino, D. Mason, P. McBride, T. Miao, S. Moccia, N. Mokhov, S. Mrenna, S.J. Murray, C. Newman-Holmes, C. Noeding, V. O’Dell, M. Paterno, D. Petravick, R. Pordes, O. Prokofyev, N. Ratnikova, A. Ronzhin, V. Sekhri, E. Sexton-Kennedy, I. Sfiligoi, – xviii – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 T.M. Shaw, E. Skup, R.P. Smith,∗ W.J. Spalding, L. Spiegel, M. Stavrianakou, G. Stiehr, A.L. Stone, I. Suzuki, P. Tan, W. Tanenbaum, L.E. Temple, S. Tkaczyk,1 L. Uplegger, E.W. Vaan- dering, R. Vidal, R. Wands, H. Wenzel, J. Whitmore, E. Wicklund, W.M. Wu, Y. Wu, J. Yarba, V. Yarba, F. Yumiceva, J.C. Yun, T. Zimmerman University of Florida, Gainesville, Florida, U.S.A. D. Acosta, P. Avery, V. Barashko, P. Bartalini, D. Bourilkov, R. Cavanaugh, S. Dolinsky, A. Drozdetskiy, R.D. Field, Y. Fu, I.K. Furic, L. Gorn, D. Holmes, B.J. Kim, S. Klimenko, J. Konigsberg, A. Korytov, K. Kotov, P. Levchenko, A. Madorsky, K. Matchev, G. Mitselmakher, Y. Pakhotin, C. Prescott, L. Ramond, P. Ramond, M. Schmitt, B. Scurlock, J. Stasko, H. Stoeck, D. Wang, J. Yelton Florida International University, Miami, Florida, U.S.A. V. Gaultney, L. Kramer, L.M. Lebolo, S. Linn, P. Markowitz, G. Martinez, J.L. Rodriguez Florida State University, Tallahassee, Florida, U.S.A. T. Adams, A. Askew, O. Atramentov, M. Bertoldi, W.G.D. Dharmaratna,49 Y. Gershtein, S.V. Gleyzer, S. Hagopian, V. Hagopian, C.J. Jenkins, K.F. Johnson, H. Prosper, D. Simek, J. Thomaston Florida Institute of Technology, Melbourne, Florida, U.S.A. M. Baarmand, L. Baksay,44 S. Guragain, M. Hohlmann, H. Mermerkaya, R. Ralich, I. Vodopiyanov University of Illinois at Chicago (UIC), Chicago, Illinois, U.S.A. M.R. Adams, I. M. Anghel, L. Apanasevich, O. Barannikova, V.E. Bazterra, R.R. Betts, C. Dragoiu, E.J. Garcia-Solis, C.E. Gerber, D.J. Hofman, R. Hollis, A. Iordanova, S. Khalatian, C. Mironov, E. Shabalina, A. Smoron, N. Varelas The University of Iowa, Iowa City, Iowa, U.S.A. U. Akgun, E.A. Albayrak, A.S. Ayan, R. Briggs, K. Cankocak,45 W. Clarida, A. Cooper, P. Deb- bins, F. Duru, M. Fountain, E. McCliment, J.P. Merlo, A. Mestvirishvili, M.J. Miller, A. Moeller, C.R. Newsom, E. Norbeck, J. Olson, Y. Onel, L. Perera, I. Schmidt, S. Wang, T. Yetkin Iowa State University, Ames, Iowa, U.S.A. E.W. Anderson, H. Chakir, J.M. Hauptman, J. Lamsa Johns Hopkins University, Baltimore, Maryland, U.S.A. B.A. Barnett, B. Blumenfeld, C.Y. Chien, G. Giurgiu, A. Gritsan, D.W. Kim, C.K. Lae, P. Maksi- movic, M. Swartz, N. Tran The University of Kansas, Lawrence, Kansas, U.S.A. P. Baringer, A. Bean, J. Chen, D. Coppage, O. Grachov, M. Murray, V. Radicci, J.S. Wood, V. Zhukova – xix – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Kansas State University, Manhattan, Kansas, U.S.A. D. Bandurin, T. Bolton, K. Kaadze, W.E. Kahl, Y. Maravin, D. Onoprienko, R. Sidwell, Z. Wan Lawrence Livermore National Laboratory, Livermore, California, U.S.A. B. Dahmes, J. Gronberg, J. Hollar, D. Lange, D. Wright, C.R. Wuest University of Maryland, College Park, Maryland, U.S.A. D. Baden, R. Bard, S.C. Eno, D. Ferencek, N.J. Hadley, R.G. Kellogg, M. Kirn, S. Kunori, E. Lock- ner, F. Ratnikov, F. Santanastasio, A. Skuja, T. Toole, L. Wang, M. Wetstein Massachusetts Institute of Technology, Cambridge, Massachusetts, U.S.A. B. Alver, M. Ballintijn, G. Bauer, W. Busza, G. Gomez Ceballos, K.A. Hahn, P. Harris, M. Klute, I. Kravchenko, W. Li, C. Loizides, T. Ma, S. Nahn, C. Paus, S. Pavlon, J. Piedra Gomez, C. Roland, G. Roland, M. Rudolph, G. Stephans, K. Sumorok, S. Vaurynovich, E.A. Wenger, B. Wyslouch University of Minnesota, Minneapolis, Minnesota, U.S.A. D. Bailleux, S. Cooper, P. Cushman, A. De Benedetti, A. Dolgopolov, P.R. Dudero, R. Egeland, G. Franzoni, W.J. Gilbert, D. Gong, J. Grahl, J. Haupt, K. Klapoetke, I. Kronkvist, Y. Kubota, J. Mans, R. Rusack, S. Sengupta, B. Sherwood, A. Singovsky, P. Vikas, J. Zhang University of Mississippi, University, Mississippi, U.S.A. M. Booke, L.M. Cremaldi, R. Godang, R. Kroeger, M. Reep, J. Reidy, D.A. Sanders, P. Sonnek, D. Summers, S. Watkins University of Nebraska-Lincoln, Lincoln, Nebraska, U.S.A. K. Bloom, B. Bockelman, D.R. Claes, A. Dominguez, M. Eads, M. Furukawa, J. Keller, T. Kelly, C. Lundstedt, S. Malik, G.R. Snow, D. Swanson State University of New York at Buffalo, Buffalo, New York, U.S.A. K.M. Ecklund, I. Iashvili, A. Kharchilava, A. Kumar, M. Strang Northeastern University, Boston, Massachusetts, U.S.A. G. Alverson, E. Barberis, O. Boeriu, G. Eulisse, T. McCauley, Y. Musienko,46 S. Muzaffar, I. Osborne, S. Reucroft, J. Swain, L. Taylor, L. Tuura Northwestern University, Evanston, Illinois, U.S.A. B. Gobbi, M. Kubantsev, A. Kubik, R.A. Ofierzynski, M. Schmitt, E. Spencer, S. Stoynev, M. Szleper, M. Velasco, S. Won University of Notre Dame, Notre Dame, Indiana, U.S.A. K. Andert, B. Baumbaugh, B.A. Beiersdorf, L. Castle, J. Chorny, A. Goussiou, M. Hildreth, C. Jessop, D.J. Karmgard, T. Kolberg, J. Marchant, N. Marinelli, M. McKenna, R. Ruchti, M. Vigneault, M. Wayne, D. Wiand – xx – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 The Ohio State University, Columbus, Ohio, U.S.A. B. Bylsma, L.S. Durkin, J. Gilmore, J. Gu, P. Killewald, T.Y. Ling, C.J. Rush, V. Sehgal, G. Williams Princeton University, Princeton, New Jersey, U.S.A. N. Adam, S. Chidzik, P. Denes,47 P. Elmer, A. Garmash, D. Gerbaudo, V. Halyo, J. Jones, D. Marlow, J. Olsen, P. Piroué, D. Stickland, C. Tully, J.S. Werner, T. Wildish, S. Wynhoff,∗ Z. Xie University of Puerto Rico, Mayaguez, Puerto Rico, U.S.A. X.T. Huang, A. Lopez, H. Mendez, J.E. Ramirez Vargas, A. Zatserklyaniy Purdue University, West Lafayette, Indiana, U.S.A. A. Apresyan, K. Arndt, V.E. Barnes, G. Bolla, D. Bortoletto, A. Bujak, A. Everett, M. Fahling, A.F. Garfinkel, L. Gutay, N. Ippolito, Y. Kozhevnikov,1 A.T. Laasanen, C. Liu, V. Maroussov, S. Medved, P. Merkel, D.H. Miller, J. Miyamoto, N. Neumeister, A. Pompos, A. Roy, A. Sedov, I. Shipsey Purdue University Calumet, Hammond, Indiana, U.S.A. V. Cuplov, N. Parashar Rice University, Houston, Texas, U.S.A. P. Bargassa, S.J. Lee, J.H. Liu, D. Maronde, M. Matveev, T. Nussbaum, B.P. Padley, J. Roberts, A. Tumanov University of Rochester, Rochester, New York, U.S.A. A. Bodek, H. Budd, J. Cammin, Y.S. Chung, P. De Barbaro,1 R. Demina, G. Ginther, Y. Gotra, S. Korjenevski, D.C. Miner, W. Sakumoto, P. Slattery, M. Zielinski The Rockefeller University, New York, New York, U.S.A. A. Bhatti, L. Demortier, K. Goulianos, K. Hatakeyama, C. Mesropian Rutgers, the State University of New Jersey, Piscataway, New Jersey, U.S.A. E. Bartz, S.H. Chuang, J. Doroshenko, E. Halkiadakis, P.F. Jacques, D. Khits, A. Lath, A. Macpherson,1 R. Plano, K. Rose, S. Schnetzer, S. Somalwar, R. Stone, T.L. Watts University of Tennessee, Knoxville, Tennessee, U.S.A. G. Cerizza, M. Hollingsworth, J. Lazoflores, G. Ragghianti, S. Spanier, A. York Texas A&M University, College Station, Texas, U.S.A. A. Aurisano, A. Golyash, T. Kamon, C.N. Nguyen, J. Pivarski, A. Safonov, D. Toback, M. Wein- berger – xxi – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Texas Tech University, Lubbock, Texas, U.S.A. N. Akchurin, L. Berntzon, K.W. Carrell, K. Gumus, C. Jeong, H. Kim, S.W. Lee, B.G. Mc Gonag- ill, Y. Roh, A. Sill, M. Spezziga, R. Thomas, I. Volobouev, E. Washington, R. Wigmans, E. Yazgan Vanderbilt University, Nashville, Tennessee, U.S.A. T. Bapty, D. Engh, C. Florez, W. Johns, T. Keskinpala, E. Luiggi Lopez, S. Neema, S. Nordstrom, S. Pathak, P. Sheldon University of Virginia, Charlottesville, Virginia, U.S.A. D. Andelin, M.W. Arenton, M. Balazs, M. Buehler, S. Conetti, B. Cox, R. Hirosky, M. Humphrey, R. Imlay, A. Ledovskoy, D. Phillips II, H. Powell, M. Ronquest, R. Yohay University of Wisconsin, Madison, Wisconsin, U.S.A. M. Anderson, Y.W. Baek, J.N. Bellinger, D. Bradley, P. Cannarsa, D. Carlsmith, I. Crotty,1 S. Dasu, F. Feyzi, T. Gorski, L. Gray, K.S. Grogg, M. Grothe, M. Jaworski, P. Klabbers, J. Klukas, A. Lanaro, C. Lazaridis, J. Leonard, R. Loveless, M. Magrans de Abril, A. Mohapatra, G. Ott, W.H. Smith, M. Weinberg, D. Wenman Yale University, New Haven, Connecticut, U.S.A. G.S. Atoian, S. Dhawan, V. Issakov, H. Neal, A. Poblaguev, M.E. Zeller Institute of Nuclear Physics of the Uzbekistan Academy of Sciences, Ulugbek, Tashkent, Uzbekistan G. Abdullaeva, A. Avezov, M.I. Fazylov, E.M. Gasanov, A. Khugaev, Y.N. Koblik, M. Nishonov, K. Olimov, A. Umaraliev, B.S. Yuldashev 1Also at CERN, European Organization for Nuclear Research, Geneva, Switzerland 2Now at Universidade Federal do ABC, Santo Andre, Brazil 3Now at Laboratoire de l’Accélérateur Linéaire, Orsay, France 4Now at CERN, European Organization for Nuclear Research, Geneva, Switzerland 5Also at Université de Haute-Alsace, Mulhouse, France 6Also at Université Louis Pasteur, Strasbourg, France 7Also at Moscow State University, Moscow, Russia 8Also at Institute of Nuclear Research ATOMKI, Debrecen, Hungary 9Also at University of California, San Diego, La Jolla, U.S.A. 10Also at Tata Institute of Fundamental Research - HECR, Mumbai, India 11Also at University of Visva-Bharati, Santiniketan, India 12Also at University of California, Riverside, Riverside, U.S.A. 13Also at Centro Studi Enrico Fermi, Roma, Italy 14Also at ENEA - Casaccia Research Center, S. Maria di Galeria, Italy 15Now at Università del Piemonte Orientale, Novara, Italy – xxii – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 16Also at Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland 17Also at Fermi National Accelerator Laboratory, Batavia, U.S.A. 18Also at California Institute of Technology, Pasadena, U.S.A. 19Also at University of Minnesota, Minneapolis, U.S.A. 20Also at Institute for Particle Physics, ETH Zurich, Zurich, Switzerland 21Also at Faculty of Physics of University of Belgrade, Belgrade, Serbia 22Now at Instituto de Física de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain 23Also at Institut für Experimentelle Kernphysik, Karlsruhe, Germany 24Also at National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan 25Also at Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France 26Also at Alstom Contracting, Geneve, Switzerland 27Also at Scuola Normale Superiore and Sezione INFN, Pisa, Italy 28Also at University of Athens, Athens, Greece 29Also at Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi, Georgia 30Also at Institute for Theoretical and Experimental Physics, Moscow, Russia 31Also at Central Laboratory of Mechatronics and Instrumentation, Sofia, Bulgaria 32Also at Paul Scherrer Institut, Villigen, Switzerland 33Also at Vinca Institute of Nuclear Sciences, Belgrade, Serbia 34Also at Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria 35Also at State Research Center of Russian Federation - Institute for High Energy Physics, Protvino, Russia 36Also at Nigde University, Nigde, Turkey 37Also at Mersin University, Mersin, Turkey 38Also at Marmara University, Istanbul, Turkey 39Also at Kafkas University, Kars, Turkey 40Also at Suleyman Demirel University, Isparta, Turkey 41Also at Ege University, Izmir, Turkey 42Also at Rutherford Appleton Laboratory, Didcot, United Kingdom 43Also at KFKI Research Institute for Particle and Nuclear Physics, Budapest, Hungary 44Also at University of Debrecen, Debrecen, Hungary 45Also at Mugla University, Mugla, Turkey 46Also at Institute for Nuclear Research, Moscow, Russia 47Now at Lawrence Berkeley National Laboratory, Berkeley, U.S.A. 48Now at National Institute of Physics and Nuclear Engineering, Bucharest, Romania 49Also at University of Ruhuna, Matara, Sri Lanka ∗Deceased Corresponding author: Roberto Tenchini (Roberto.Tenchini@cern.ch) – xxiii – mailto:Roberto.Tenchini@cern.ch 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Contents CMS collaboration ii 1 Introduction 1 1.1 General concept 2 2 Superconducting magnet 6 2.1 Overview 6 2.2 Main features of the magnet components 6 2.2.1 Superconducting solenoid 6 2.2.2 Yoke 11 2.2.3 Electrical scheme 12 2.2.4 Vacuum system 13 2.2.5 Cryogenic plant 13 2.2.6 Other ancillaries 13 2.3 Operating test 14 2.3.1 Cool-down 15 2.3.2 Charge and discharge cycles 15 2.3.3 Cold mass misalignment 17 2.3.4 Electrical measurements 18 2.3.5 Yoke mechanical measurements 23 2.3.6 Coil stability characteristics 23 2.3.7 Coil warm-up 25 3 Inner tracking system 26 3.1 Introduction 26 3.1.1 Requirements and operating conditions 27 3.1.2 Overview of the tracker layout 29 3.1.3 Expected performance of the CMS tracker 30 3.1.4 Tracker system aspects 32 3.2 Pixel detector 33 3.2.1 Pixel system general 33 3.2.2 Sensor description 35 3.2.3 Pixel detector read-out 37 3.2.4 The pixel barrel system 43 3.2.5 The forward pixel detector 46 3.2.6 Power supply 53 3.2.7 Cooling 54 3.2.8 Slow controls 54 3.3 Silicon strip tracker 55 3.3.1 Silicon sensors 55 – xxiv – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 3.3.2 Read-out system 56 3.3.3 Silicon modules 62 3.3.4 Tracker Inner Barrel and Disks (TIB/TID) 64 3.3.5 Tracker Outer Barrel (TOB) 67 3.3.6 Tracker EndCaps (TEC) 73 3.3.7 Geometry and alignment 78 3.3.8 Detector control and safety system 81 3.3.9 Operating experience and test results 82 4 Electromagnetic calorimeter 90 4.1 Lead tungstate crystals 90 4.2 The ECAL layout and mechanics 92 4.3 Photodetectors 96 4.3.1 Barrel: avalanche photodiodes 96 4.3.2 Endcap: vacuum phototriodes 98 4.4 On-detector electronics 100 4.5 Off-detector electronics 103 4.5.1 Global architecture 103 4.5.2 The trigger and read-out paths 104 4.5.3 Algorithms performed by the trigger primitive generation 105 4.5.4 Classification performed by the selective read-out 105 4.6 Preshower detector 106 4.6.1 Geometry 106 4.6.2 Preshower electronics 107 4.7 ECAL detector control system 108 4.7.1 Safety system 109 4.7.2 Temperature 109 4.7.3 Dark current 109 4.7.4 HV and LV 110 4.8 Detector calibration 110 4.9 Laser monitor system 113 4.9.1 Laser-monitoring system overview 114 4.10 Energy resolution 116 5 Hadron calorimeter 122 5.1 Barrel design (HB) 122 5.2 Endcap design (HE) 131 5.3 Outer calorimeter design (HO) 138 5.4 Forward calorimeter design (HF) 145 5.5 Read-out electronics and slow control 149 5.6 HF luminosity monitor 154 6 Forward detectors 156 – xxv – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 6.1 CASTOR 156 6.2 Zero degree calorimeter (ZDC) 159 7 The muon system 162 7.1 Drift tube system 165 7.1.1 General description 165 7.1.2 Technical design 168 7.1.3 Electronics 174 7.1.4 Chamber assembly, dressing, and installation 180 7.1.5 Chamber performance 185 7.2 Cathode strip chambers 197 7.2.1 Chamber mechanical design 200 7.2.2 Electronics design 202 7.2.3 Performance 207 7.3 Resistive Plate Chamber system 216 7.3.1 Detector layout 217 7.3.2 Readout electronics 222 7.3.3 Low voltage and high voltage systems 223 7.3.4 Temperature control system 225 7.3.5 Gas system 225 7.3.6 Chamber construction and testing 230 7.4 Optical alignment system 235 7.4.1 System layout and calibration procedures 236 7.4.2 Geometry reconstruction 243 7.4.3 System commissioning and operating performance 243 8 Trigger 247 8.1 Calorimeter trigger 248 8.2 Muon trigger 251 8.3 Global Trigger 258 8.4 Trigger Control System 259 9 Data Acquisition 261 9.1 Sub-detector read-out interface 263 9.2 The Trigger Throttling System and sub-detector fast-control interface 265 9.3 Testing 267 9.4 The Event Builder 267 9.5 The Event Filter 271 9.6 Networking and Computing Infrastructure 273 9.7 DAQ software, control and monitor 274 9.8 Detector Control System 279 10 Detector infrastructures and safety systems 283 10.1 Detector powering 283 – xxvi – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 10.2 Detector cooling 285 10.2.1 Front-end electronics cooling 285 10.2.2 Cryogenics 285 10.3 Detector cabling 286 10.4 Detector moving system 287 10.4.1 Sliding system 287 10.4.2 Pulling system 287 10.5 The Detector Safety System 287 10.5.1 DSS Requirements 288 10.5.2 DSS Architecture 289 10.5.3 CMS Implementation of DSS 290 10.6 Beam and Radiation Monitoring systems 290 10.6.1 Introduction 290 10.6.2 Protection systems 291 10.6.3 Monitoring systems 293 11 Computing 297 11.1 Overview 297 11.2 Application framework 298 11.3 Data formats and processing 299 11.4 Computing centres 301 11.5 Computing services 303 11.6 System commissioning and tests 305 12 Conclusions 307 CMS acronym list 309 Bibliography 317 – xxvii – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Chapter 1 Introduction The Compact Muon Solenoid (CMS) detector is a multi-purpose apparatus due to operate at the Large Hadron Collider (LHC) at CERN. The LHC is presently being constructed in the already existing 27-km LEP tunnel in the Geneva region. It will yield head-on collisions of two pro- ton (ion) beams of 7 TeV (2.75 TeV per nucleon) each, with a design luminosity of 1034 cm−2s−1 (1027 cm−2s−1). This paper provides a description of the design and construction of the CMS detec- tor. CMS is installed about 100 metres underground close to the French village of Cessy, between Lake Geneva and the Jura mountains. The prime motivation of the LHC is to elucidate the nature of electroweak symmetry break- ing for which the Higgs mechanism is presumed to be responsible. The experimental study of the Higgs mechanism can also shed light on the mathematical consistency of the Standard Model at energy scales above about 1 TeV. Various alternatives to the Standard Model invoke new symme- tries, new forces or constituents. Furthermore, there are high hopes for discoveries that could pave the way toward a unified theory. These discoveries could take the form of supersymmetry or extra dimensions, the latter often requiring modification of gravity at the TeV scale. Hence there are many compelling reasons to investigate the TeV energy scale. The LHC will also provide high-energy heavy-ion beams at energies over 30 times higher than at the previous accelerators, allowing us to further extend the study of QCD matter under extreme conditions of temperature, density, and parton momentum fraction (low-x). Hadron colliders are well suited to the task of exploring new energy domains, and the region of 1 TeV constituent centre-of-mass energy can be explored if the proton energy and the luminosity are high enough. The beam energy and the design luminosity of the LHC have been chosen in order to study physics at the TeV energy scale. A wide range of physics is potentially possible with the seven-fold increase in energy and a hundred-fold increase in integrated luminosity over the previous hadron collider experiments. These conditions also require a very careful design of the detectors. The total proton-proton cross-section at √ s = 14 TeV is expected to be roughly 100 mb. At design luminosity the general-purpose detectors will therefore observe an event rate of approxi- mately 109 inelastic events/s. This leads to a number of formidable experimental challenges. The online event selection process (trigger) must reduce the huge rate to about 100 events/s for storage and subsequent analysis. The short time between bunch crossings, 25 ns, has major implications for the design of the read-out and trigger systems. – 1 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 At the design luminosity, a mean of about 20 inelastic collisions will be superimposed on the event of interest. This implies that around 1000 charged particles will emerge from the interaction region every 25 ns. The products of an interaction under study may be confused with those from other interactions in the same bunch crossing. This problem clearly becomes more severe when the response time of a detector element and its electronic signal is longer than 25 ns. The effect of this pile-up can be reduced by using high-granularity detectors with good time resolution, resulting in low occupancy. This requires a large number of detector channels. The resulting millions of detector electronic channels require very good synchronization. The large flux of particles coming from the interaction region leads to high radiation levels, requiring radiation-hard detectors and front-end electronics. The detector requirements for CMS to meet the goals of the LHC physics programme can be summarised as follows: • Good muon identification and momentum resolution over a wide range of momenta and angles, good dimuon mass resolution (≈ 1% at 100 GeV), and the ability to determine un- ambiguously the charge of muons with p < 1 TeV; • Good charged-particle momentum resolution and reconstruction efficiency in the inner tracker. Efficient triggering and offline tagging of τ’s and b-jets, requiring pixel detectors close to the interaction region; • Good electromagnetic energy resolution, good diphoton and dielectron mass resolution (≈ 1% at 100 GeV), wide geometric coverage, π0 rejection, and efficient photon and lepton isolation at high luminosities; • Good missing-transverse-energy and dijet-mass resolution, requiring hadron calorimeters with a large hermetic geometric coverage and with fine lateral segmentation. The design of CMS, detailed in the next section, meets these requirements. The main distin- guishing features of CMS are a high-field solenoid, a full-silicon-based inner tracking system, and a homogeneous scintillating-crystals-based electromagnetic calorimeter. The coordinate system adopted by CMS has the origin centered at the nominal collision point inside the experiment, the y-axis pointing vertically upward, and the x-axis pointing radially inward toward the center of the LHC. Thus, the z-axis points along the beam direction toward the Jura mountains from LHC Point 5. The azimuthal angle φ is measured from the x-axis in the x-y plane and the radial coordinate in this plane is denoted by r. The polar angle θ is measured from the z- axis. Pseudorapidity is defined as η =− ln tan(θ/2). Thus, the momentum and energy transverse to the beam direction, denoted by pT and ET , respectively, are computed from the x and y components. The imbalance of energy measured in the transverse plane is denoted by Emiss T . 1.1 General concept An important aspect driving the detector design and layout is the choice of the magnetic field configuration for the measurement of the momentum of muons. Large bending power is needed – 2 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 C ompac t Muon S olenoid Pixel Detector Silicon Tracker Very-forward Calorimeter Electromagnetic Calorimeter Hadron Calorimeter Preshower Muon Detectors Superconducting Solenoid Figure 1.1: A perspective view of the CMS detector. to measure precisely the momentum of high-energy charged particles. This forces a choice of superconducting technology for the magnets. The overall layout of CMS [1] is shown in figure 1.1. At the heart of CMS sits a 13-m- long, 6-m-inner-diameter, 4-T superconducting solenoid providing a large bending power (12 Tm) before the muon bending angle is measured by the muon system. The return field is large enough to saturate 1.5 m of iron, allowing 4 muon stations to be integrated to ensure robustness and full geometric coverage. Each muon station consists of several layers of aluminium drift tubes (DT) in the barrel region and cathode strip chambers (CSC) in the endcap region, complemented by resistive plate chambers (RPC). The bore of the magnet coil is large enough to accommodate the inner tracker and the calorimetry inside. The tracking volume is given by a cylinder of 5.8-m length and 2.6-m di- ameter. In order to deal with high track multiplicities, CMS employs 10 layers of silicon microstrip detectors, which provide the required granularity and precision. In addition, 3 layers of silicon pixel detectors are placed close to the interaction region to improve the measurement of the impact parameter of charged-particle tracks, as well as the position of secondary vertices. The expected muon momentum resolution using only the muon system, using only the inner tracker, and using both sub-detectors is shown in figure 1.2. The electromagnetic calorimeter (ECAL) uses lead tungstate (PbWO4) crystals with cov- erage in pseudorapidity up to |η | < 3.0. The scintillation light is detected by silicon avalanche photodiodes (APDs) in the barrel region and vacuum phototriodes (VPTs) in the endcap region. A preshower system is installed in front of the endcap ECAL for π0 rejection. The energy resolution – 3 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 [GeV/c] T p 10 210 310 T )/ p T (p ∆ -210 -110 1 Muon system only Full system Inner tracker only < 0.8η0 < [GeV/c] T p 10 210 310 T )/ p T (p ∆ -210 -110 1 Muon system only Full system Inner tracker only < 2.4η1.2 < Figure 1.2: The muon transverse-momentum resolution as a function of the transverse-momentum (pT ) using the muon system only, the inner tracking only, and both. Left panel: |η | < 0.8, right panel: 1.2 < |η |< 2.4. of the ECAL, for incident electrons as measured in a beam test, is shown in figure 1.3; the stochas- tic (S), noise (N), and constant (C) terms given in the figure are determined by fitting the measured points to the function ( σ E )2 = ( S√ E )2 + ( N E )2 +C2 . (1.1) The ECAL is surrounded by a brass/scintillator sampling hadron calorimeter (HCAL) with cov- erage up to |η | < 3.0. The scintillation light is converted by wavelength-shifting (WLS) fibres embedded in the scintillator tiles and channeled to photodetectors via clear fibres. This light is detected by photodetectors (hybrid photodiodes, or HPDs) that can provide gain and operate in high axial magnetic fields. This central calorimetry is complemented by a tail-catcher in the bar- rel region (HO) ensuring that hadronic showers are sampled with nearly 11 hadronic interaction lengths. Coverage up to a pseudorapidity of 5.0 is provided by an iron/quartz-fibre calorime- ter. The Cerenkov light emitted in the quartz fibres is detected by photomultipliers. The forward calorimeters ensure full geometric coverage for the measurement of the transverse energy in the event. An even higher forward coverage is obtained with additional dedicated calorimeters (CAS- TOR, ZDC, not shown in figure 1.1) and with the TOTEM [2] tracking detectors. The expected jet transverse-energy resolution in various pseudorapidity regions is shown in figure 1.4. The CMS detector is 21.6-m long and has a diameter of 14.6 m. It has a total weight of 12500 t. The ECAL thickness, in radiation lengths, is larger than 25 X0, while the HCAL thickness, in interaction lengths, varies in the range 7–11 λI (10–15 λI with the HO included), depending on η . – 4 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 E (G eV ) 0 50 100 150 200 250 σ( E )/ E ( % ) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 S = 2.8 (%) (G eV ) N= 0.12 (G eV ) C = 0.3 (%) 1 2 _ Figure 1.3: ECAL energy resolution, σ(E)/E, as a function of electron energy as measured from a beam test. The energy was measured in an array of 3× 3 crystals with an electron impacting the central crystal. The points correspond to events taken restricting the incident beam to a narrow (4×4 mm2) region. The stochastic (S), noise (N), and constant (C) terms are given. (G eV )TE 0 50 100 150 200 250 300 T )/ E T (Eσ� 0 0.1 0.2 0.3 0.4 0.5 0.6 |<1.4|η |<3.01.4<|η |<5.03.0<|η Figure 1.4: The jet transverse-energy resolution as a function of the jet transverse energy for barrel jets (|η |< 1.4), endcap jets (1.4 < |η |< 3.0), and very forward jets (3.0 < |η |< 5.0). The jets are reconstructed with an iterative cone algorithm (cone radius = 0.5). – 5 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Chapter 2 Superconducting magnet 2.1 Overview The superconducting magnet for CMS [3–6] has been designed to reach a 4-T field in a free bore of 6-m diameter and 12.5-m length with a stored energy of 2.6 GJ at full current. The flux is re- turned through a 10 000-t yoke comprising 5 wheels and 2 endcaps, composed of three disks each (figure 1.1). The distinctive feature of the 220-t cold mass is the 4-layer winding made from a stabilised reinforced NbTi conductor. The ratio between stored energy and cold mass is high (11.6 KJ/kg), causing a large mechanical deformation (0.15%) during energising, well beyond the values of previous solenoidal detector magnets. The parameters of the CMS magnet are summarised in table 2.1. The magnet was designed to be assembled and tested in a surface hall (SX5), prior to being lowered 90 m below ground to its final position in the experimental cavern. After provi- sional connection to its ancillaries, the CMS Magnet has been fully and successfully tested and commissioned in SX5 during autumn 2006. 2.2 Main features of the magnet components 2.2.1 Superconducting solenoid The superconducting solenoid (see an artistic view in figure 2.1 and a picture taken during assembly in the vertical position in SX5 in figure 2.2) presents three new features with respect to previous detector magnets: • Due to the number of ampere-turns required for generating a field of 4 T (41.7 MA-turn), the winding is composed of 4 layers, instead of the usual 1 (as in the Aleph [7] and Delphi [8] coils) or maximum 2 layers (as in the ZEUS [9] and BaBar [10] coils); • The conductor, made from a Rutherford-type cable co-extruded with pure aluminium (the so-called insert), is mechanically reinforced with an aluminium alloy; • The dimensions of the solenoid are very large (6.3-m cold bore, 12.5-m length, 220-t mass). For physics reasons, the radial extent of the coil (∆R) had to be kept small, and thus the CMS coil is in effect a “thin coil” (∆R/R ∼ 0.1). The hoop strain (ε) is then determined by the – 6 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.1: General artistic view of the 5 modules composing the cold mass inside the cryostat, with details of the supporting system (vertical, radial and longitudinal tie rods). magnetic pressure (P = B2 0 2µ0 = 6.4 MPa), the elastic modulus of the material (mainly aluminium with Y = 80 GPa) and the structural thickness (∆Rs = 170 mm i.e., about half of the total cold mass thickness), according to PR ∆Rs = Y ε , giving ε = 1.5× 10−3. This value is high compared to the strain of previous existing detector magnets. This can be better viewed looking at a more significant figure of merit, i.e. the E/M ratio directly proportional to the mechanical hoop strain according to E M = PR 2∆Rsδ ∆Rs ∆R = ∆Rs ∆R Y ε 2δ , where δ is the mass density. Figure 2.3 shows the values of E/M as function of stored energy for several detector magnets. The CMS coil is distinguishably far from other detector magnets when combining stored energy and E/M ratio (i.e. mechanical deformation). In order to provide the necessary hoop strength, a large fraction of the CMS coil must have a structural function. To limit the shear stress level inside the winding and prevent cracking the insulation, especially at the border defined by the winding and the external mandrel, the structural material cannot be too far from the current-carrying elements (the turns). On the basis of these considerations, the innovative design of the CMS magnet uses a self-supporting conductor, by including in it the structural material. The magnetic hoop stress (130 MPa) is shared between the layers (70%) and the support cylindrical mandrel (30%) rather than being taken by the outer mandrel only, as was the case in the previous generation of thin detector solenoids. A cross section of the cold mass is shown in figure 2.4. The construction of a winding using a reinforced conductor required technological develop- ments for both the conductor [11] and the winding. In particular, for the winding many problems had to be faced mainly related to the mandrel construction [12], the winding method [13], and the module-to-module mechanical coupling. The modular concept of the cold mass had to face the problem of the module-to-module mechanical connection. These interfaces (figure 2.5) are critical – 7 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Table 2.1: Main parameters of the CMS magnet. General parameters Magnetic length 12.5 m Cold bore diameter 6.3 m Central magnetic induction 4 T Total Ampere-turns 41.7 MA-turns Nominal current 19.14 kA Inductance 14.2 H Stored energy 2.6 GJ Cold mass Layout Five modules mechanically and electrically coupled Radial thickness of cold mass 312 mm Radiation thickness of cold mass 3.9 X0 Weight of cold mass 220 t Maximum induction on conductor 4.6 T Temperature margin wrt operating temperature 1.8 K Stored energy/unit cold mass 11.6 kJ/kg Iron yoke Outer diameter of the iron flats 14 m Length of barrel 13 m Thickness of the iron layers in barrel 300, 630 and 630 mm Mass of iron in barrel 6000 t Thickness of iron disks in endcaps 250, 600 and 600 mm Mass of iron in each endcap 2000 t Total mass of iron in return yoke 10 000 t because they have to transmit the large magnetic axial force corresponding to 14 700 t, without allowing local displacements due to possible gaps. These displacements can be partially converted into heat, causing a premature quench. A construction method which involved the machining of the upper surface of the modules and a local resin impregnation during the mechanical mounting allowed us to get an excellent mechanical coupling between the modules. – 8 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.2: The cold mass mounted vertically before integration with thermal shields and insertion in the vacuum chamber. Figure 2.3: The energy-over-mass ratio E/M, for several detector magnets. – 9 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.4: Cross section of the cold mass with the details of the 4-layer winding with reinforced conductor. Figure 2.5: Detail of the interface region between 2 modules. In order to guarantee mechanical continuity, false turns are involved. The modules are connected through bolts and pins fixed through the outer mandrels. – 10 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.6: A view of the yoke at an early stage of magnet assembly at SX5. The central barrel supports the vacuum chamber of the superconducting coil. At the rear, one of the closing end cap disks is visible. 2.2.2 Yoke The yoke (figure 2.6) is composed of 11 large elements, 6 endcap disks, and 5 barrel wheels, whose weight goes from 400 t for the lightest up to 1920 t for the central wheel, which includes the coil and its cryostat. The easy relative movement of these elements facilitates the assembly of the sub-detectors. To displace each element a combination of heavy-duty air pads plus grease pads has been chosen. This choice makes the system insensitive to metallic dust on the floor and allows transverse displacements. Two kinds of heavy-duty high-pressure air pads with a capacity of either 250 t (40 bars) or 385 t (60 bars) are used. This is not favourable for the final approach when closing the detector, especially for the YE1 endcap that is protruding into the vacuum tank. A special solution has been adopted: for the last 100 mm of approach, flat grease-pads (working pressure 100 bar) have been developed in order to facilitate the final closing of the detector. Once they touch the axially-installed z-stops, each element is pre-stressed with 100 t to the adjacent element. This assures good contact before switching on the magnet. In the cavern the elements will be moved on the 1.23% inclined floor by a strand jacking hydraulic system that ensures safe operation for uphill pulling as well as for downhill pushing by keeping a retaining force. The maximum movements possible in the cavern are of the order of 11 meters; this will take one hour. To easily align the yoke elements, a precise reference system of about 70 points was installed in the surface assembly hall. The origin of the reference system is the geometrical center of the coil. The points were made after loading the coil cryostat with the inner detectors, the hadronic barrel in particular which weights 1000 t. A mark on the floor was made showing the position of each foot in order to pre-position each element within a± 5 mm tolerance. Finally, all the elements were aligned with an accuracy of 2 mm with respect to the ideal axis of the coil. – 11 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.7: The electrical scheme of the magnet with the protection circuit. One of the main components of the protection is the dump resistor, made of three elements. 2.2.3 Electrical scheme The CMS solenoid can be represented as a 14 H inductance mutually coupled with its external mandrel. This inductive coupling allows for the so-called quench back effect, as the eddy currents, induced in the external mandrel at the trigger of a current fast discharge, heat up the whole coil above the superconducting critical temperature. This is the fundamental basis of the protection system, which, in case of a superconducting to resistive transition of the coil, aims at keeping the lowest possible thermal gradients and temperature increase in the superconducting windings, and prevents the occurrence of local overheating, hence reducing the thermal stresses inside the winding. A diagram of the powering circuit with protection is shown in figure 2.7. A bipolar thyristor power converter rated at 520 kW with passive L-C filters is used to power the CMS solenoid. It covers a range of voltages from +26 V to -23 V, with a nominal DC current of 19.1 kA. In case of a sudden switch off of the power converter, the current decays naturally in the bus-bar resistance and through the free-wheel thyristors until the opening of the main breakers. Inside the power converter, an assembly of free-wheel thyristors, mounted on naturally air-cooled heat sinks, is installed. In case of non-opening of the main switch breakers, the thyristors are rated to support 20 kA DC for 4 minutes. The current discharge is achieved by disconnecting the electrical power source by the use of two redundant 20 kA DC normally-open switch breakers, leaving the solenoid in series with a resistor, in a L-R circuit configuration. The stored magnetic energy is therefore extracted by thermal dissipation in the so-called dump resistor. This resistor is external to the solenoid cryostat and is designed to work without any active device. It is positioned – 12 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 outdoors taking advantage of natural air convection cooling. The fast discharge (FD) is automat- ically triggered by hardwired electronics only in case of a superconductive-to-resistive transition, a so-called quench, and for unrecoverable faults which require fast current dumping. The FD time constant is about 200 s. An emergency FD button is also available to the operator in case of need. As the coil becomes resistive during the FD, energy is dissipated inside the coil, which heats up. As a consequence, this necessitates a post-FD cool-down of the coil. The FD is performed on a 30 mΩ dump resistor, as a compromise to keep the dump voltage lower than 600 V, and to limit the coil warm-up and subsequent cool-down time. For faults involving the 20 kA power source, a slow discharge (SD) is triggered through hardwired electronics on a 2 mΩ dump resistor. The SD current evolution is typically exponential, and its time constant is 7025 s, but the coil stays in the superconducting state as the heat load, about 525 W, is fully absorbed by the cooling refrigerator. For current lower than 4 kA, a FD is performed in any case, as the heat load is small enough for the refrigerator. The same resistor is used in both cases for the FD and the SD, using normally open contactors, leaving the dump resistor modules either in series (FD) or in parallel (SD). For other cases, and depending on the alarms, the coil current can be adjusted by the operator, or ramped down to zero, taking advantage of the two-quadrant converter. 2.2.4 Vacuum system The vacuum system has been designed to provide a good insulation inside the 40 m3 vacuum volume of the coil cryostat. It consists of 2 double-primary pumping stations, equipped with 2 rotary pumps and 2 Root’s pumps, that provide the fore vacuum to the two oil diffusion pumps located at the top of CMS and connected to the coil cryostat via the current leads chimney and the helium phase separator. The rotary pumps have a capacity of 280 m3/h while the two Root’s pumps have a flow of 1000 m3/h. The biggest oil diffusion pump, installed via a DN 400 flange on the current leads chimney, has a nominal flow of 8000 l/s at 10−4 mbar of fore vacuum. The smallest one delivers 3000 l/s at the phase separator. 2.2.5 Cryogenic plant The helium refrigeration plant for CMS is specified for a cooling capacity of 800 W at 4.45 K, 4500 W between 60 and 80 K, and simultaneously 4 g/s liquefaction capacity. The primary compressors of the plant have been installed, in their final position, while the cold box, as well as the intermedi- ate cryostat which interfaces the phase separator and the thermo-syphon, were moved underground after the completion of the magnet test. These components were commissioned with the help of a temporary heat load of 6.5 kW that simulated the coil cryostat which was not yet available. The performance of the cold box has been measured in cool-down mode and in nominal and operation mode. 2.2.6 Other ancillaries • Current leads. The two 20-kA current leads are made of a high purity copper braid, having a cross section of 1800 mm2 and RRR (Residual Resistivity Ratio) of 130, placed inside a conduit and cooled by circulating helium gas. Without cooling, the current leads are able – 13 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.8: The layout for the surface test at SX5, showing only the central barrel. The magnet is connected to the cryoplant (through the proximity cryogenics), the vacuum and the power systems. to hold a current of 20 kA for 5 minutes, followed by a FD without any damage, as the temperature at the hot spot stays below 400 K [14]. • Grounding circuit. The grounding circuit is connected across the solenoid terminals. It fixes the coil circuit potential, through a 1 kΩ resistor, dividing by two the potential to ground. The winding insulation quality is monitored by continuously measuring the leakage current through a 10 Ω grounding resistor. • Quench detection system. The quench detection system is a key element of the Magnet Safety System (MSS). The role of the quench detection system is to detect a resistive voltage be- tween two points of the coil, whose value and duration are compared to adjustable thresholds. The voltage taps are protected by 4.7 kΩ, 6 W resistors. There are 2 redundant systems, with resistor bridge detectors and differential detectors. For each system, there are 5 detectors. Each resistor bridge detector spans two modules and one detector spans the whole solenoid. Each coil module is compared with two other modules through two differential detectors. 2.3 Operating test The magnet and all its ancillaries were assembled for testing in SX5 and ready for cool-down in January 2006. Figure 2.8 shows the test layout. – 14 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.9: Graph of the coil minimum and maximum temperatures during the cool-down from room temperature to 4.5 K. 2.3.1 Cool-down The cool-down of the solenoid started on February, the 2nd, 2006 and in a smooth way brought the cold mass to 4.6 K in 24 days. Figure 2.9 shows the cool-down curve. The only glitch was due to an overpressure on a safety release valve that stopped cooling for one night before the system was restarted. One important aspect monitored during the cool-down was the amount of coil shrinkage. In order to explain this point, we refer to the coil suspension system inside the cryostat (figure 2.1), made of longitudinal, vertical, and axial tie-rods in Ti alloy. The magnet is supported by 2× 9 longitudinal tie rods, 4 vertical tie rods, and 8 radial tie rods. The tie rods are equipped with compensated strain gauges to measure the forces on 2×3 longitudinal, plus the vertical and radial tie rods. The tie rods are loaded in tension and flexion. To measure the tension and flexion strain, 3 strain gauges are placed on the tie rods at 0◦, 90◦, and 180◦. The measured stresses in the tie bars due to the cool-down, causing a shrinkage of the cold mass and putting the tie-bars in tension, are shown in table 2.2. A comparison with the expected values is provided as well. The measured axial and radial shrinkage of the cold mass is shown in figure 2.10. 2.3.2 Charge and discharge cycles The magnetic tests took place during August 2006, with additional tests during the magnet field mapping campaign in October 2006. The current ramps for the field mapping are detailed in fig- ure 2.11. The tests were carried out through magnet charges to progressively higher currents, setting increasing dI/dt, followed by slow or fast discharges. During these current cycles all the relevant parameters related to electrical, magnetic, thermal, and mechanical behaviours have been – 15 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Table 2.2: Calculated and measured cold mass displacements and related stresses on tie-rods due to the cool-down to 4.5 K. Expected value Measured value Cold Mass Shrinkage Longitudinal 26 mm 27 mm Radial 14 mm 15 mm Tie rod stress due to cool-down Vertical 315 MPa 310±45 MPa Radial 167 MPa 153±20 MPa Longitudinal 277 MPa 260±20 MPa Figure 2.10: Axial (a) and radial (b) shrinkage of the cold mass from 300 K to 4.5 K. – 16 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.11: Magnet cycles during the CMS magnet tests in October 2006. recorded. Depending on the level of the current at the trigger of a fast discharge, the time needed for re-cooling the coil can be up to 3 days. 2.3.3 Cold mass misalignment The support system is designed to withstand the forces created by a 10 mm magnetic misalign- ment, in any direction of the cold mass with respect to the iron yoke. Geometrical surveys were performed at each step of the magnet assembly to ensure a good positioning. Nevertheless, the monitoring of the coil magnetic misalignment is of prime importance during magnet power test. The misalignment can be calculated either by analysing the displacement of the cold mass or the stresses of the tie rods when the coil is energised. The displacement is measured at several loca- tions and directions at both ends of the coil with respect to the external vacuum tank wall, by the use of rectilinear potentiometers. Results are displayed in figures 2.12 and 2.13. The displacement of the coil’s geometric centre is found to be 0.4 mm in z, in the +z direction. According to the computations, such a displacement indicates that the coil centre should be less than 2 mm off the magnetic centre in +z. As the coil supporting system is hyper-static, the tie rods are not all ini- tially identically loaded. But the force increase during energising is well distributed, as shown in figure 2.14 and figure 2.15, giving the force measurements on several tie rods. These figures also indicate the forces computed in the case of a 10-mm magnetic misalignment, together with forces calculated for the ideally-centred model, showing there is no noticeable effect of misalignment on the forces. Using the strain gauges glued on the cold mass (outer mandrel of the central module, CB0), one can determine the Von Mises stress. The cold mass Von Mises stress versus the coil current is given in figure 2.16. The measured value of Von Mises stress at 4.5 K and zero current is 23 MPa. The value at 19.1 kA is 138 MPa. These values are in agreement with computations done during design [3, 6]. – 17 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.12: Axial displacement in Z at both ends of the coil in different positions during energis- ing. Figure 2.13: Radial displacement at both ends of the coil in different positions during energising. 2.3.4 Electrical measurements The apparent coil inductance measured through the inductive voltage V = LdI/dt is decreasing while increasing the current, as the iron yoke reaches the saturation region. From voltage measure- ments at the coil ends in the cryostat, while ramping up the coil current at a regulated dI/dt, the inductance is calculated and results are given in figure 2.17. Initially the apparent inductance of the coil is 14.7 H at zero current, and then it decreases to 13.3 H at 18 kA. The 21 resistive electrical joints, which connect the 5 modules together and, for each module, the 4 layers, are positioned ex- ternally to the coil, on the outer radius of the external mandrel, in low magnetic field regions. The – 18 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.14: Force increase on several axial tie rods; the average force at zero current is 45 t. Figure 2.15: Force increase on several radial tie rods; the average force at zero current is 15 tons. resistance measurements of the joints indicate values ranging from 0.7 nΩ to 1.6 nΩ at 19.1 kA, corresponding to a maximum dissipation in the joint of 0.6 W. The specific joint cooling system is fully efficient to remove this local heat deposit in order to avoid that the resistive joints generate a local quench of the conductor. As mentioned above, the fast discharge causes a quench of the coil, through the quench-back process. The typical current decay at the nominal current of 19.14 kA is given in figure 2.18. The effect of the mutual coupling of the coil with the external mandrel is clearly visible at the beginning of the current fast discharge as shown in the zoomed detail of figure 2.18. It appears clearly that a high dI/dt of about 500 A/s occurs at the very beginning of the discharge. The – 19 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.16: Stresses measured on the CB0 module as a function of the current. Figure 2.17: Coil inductance as a function of the magnet current. minimum and maximum temperatures of the coil are displayed in figure 2.19 for a fast discharge at 19.14 kA. A maximum temperature difference of 32 K is measured on the coil between the warmest part, located on the coil central module internal radius, and the coldest part, located on the external radius of the mandrel. It should be noted that the thermal gradient is mainly radial. The temperature tends to equilibrate over the whole coil 2 hours after the trigger of the fast discharge. The average cold mass temperature after a fast discharge at 19 kA is 70 K. During a magnet discharge, the dump resistor warms up, with a maximum measured temper- ature increase of 240°C, resulting in an increase of the total dump resistance value by up to 19%. Also the coil internal electrical resistance is increased by up to 0.1 Ω at the end of a FD at 19.14 kA. – 20 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.18: Magnet current during fast discharge at the nominal field of 4 T. The insert shows the details at the beginning of the discharge. Figure 2.19: Minimum and maximum temperatures detected on the cold mass during the fast discharge from 19.1 kA. The effect of both the dump resistor and the magnet electrical resistance increasing was revealed through the measurement of the discharge time constant, which was equal to 177 s, 203 s, 263 s, 348 s and 498 s for fast discharges respectively at 19 kA, 17.5 kA, 15 kA, 12.5 kA and 7.5 kA. This is visible in figure 2.20. The temperature recovery of the dump resistor is achieved in less than 2 hours after the trigger of a fast dump. It is 5 hours after the trigger of a slow dump. In the case of a fast dump at 19.14 kA, typically half of the total energy (1250 MJ) is dissipated as heat in the external dump resistor. The energy dissipated in the dump resistor as a function of the – 21 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.20: The normalised discharge current as a function of time for different initial currents, showing the effect of the increase in magnet and external dump resistance with current. Figure 2.21: Energy dissipated in the external dump resistor and the mean and maximum temper- atures of the coil during FD. magnet current at the trigger of a FD was measured for each FD performed during the magnet tests and is given in figure 2.21. The magnet current is precisely measured by the use of two redundant DCCTs (DC current transformer). The peak-to-peak stability of the current is 7 ppm with a voltage ripple of 2.5% (0.65 V). In order to gain on the operation time, an acceleration of the slow dump has been tested and validated by switching to the fast dump configuration at 4 kA. It has been checked that the cryogenic refrigerator can take the full heat load, and the magnet stays in the superconducting state. This Slow Dump Accelerated (SDA) mode was tested in semi-automatic mode through the cryogenics supervisory system and the magnet control system, and it will be fully automatic for the final installation in the cavern. – 22 – 2 0 0 8 J I N S T 3 S 0 8 0 0 4 Figure 2.22: Axial forces acting on the yoke Z-stops during the coil energising. 2.3.5 Yoke mechanical measurements The elements of the return yoke, barrels and endcaps, are attached with several hydraulic locking jacks, which are fixed on each barrel and endcap. They are pre-stressed in order to bring the barrels and endcaps into contact at specific areas using the aluminium-alloy Z-stop blocks. There are 24 Z-stops between each barrel and endcap. A computation of the total axial compressive force gives 8900 tons. The stresses are measured on some Z-stops; the forces on these Z-stops are given in figure 2.22 and compared to the case of a uniformly distributed load on all the Z-stops. To allow for uniform load distribution and distortion during magnet energising, the yoke elements are positioned on grease pads. During magnet energising, the displacement of the barrel yoke elements under the compressive axial force is very limited, while the displacement of the yoke end cap disk YE+1 is clearly noticeable on the outer radius of the disk, due to the axial attraction of the first yoke endcaps towards the interaction point. The measurement of the distance between the barrel elements parallel to the axial axis of the detector is given in figure 2.23. Th