Absolute luminosity measurements with the LHCb detector at the LHC

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Aaij, R; Adinolfi, M; Adrover, C; Affolder, A; Ajaltouni, Z; Albrecht, J; Alessio, F; Alexander, M; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amhis, Y; Anderson, J; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Arrabito, L; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Bachmann, S; Back, J J; Bailey, D S; Balagura, V; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Bates, A; Bauer, C; Bauer, Th; Bay, A; Bediaga, I; Belous, K; Belyaev, I; Ben-Haim, E; Benayoun, M; Bencivenni, G; Benson, S; Benton, J; Bernet, R; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bizzeti, A; Bjørnstad, P M; Blake, T; Blanc, F; Blanks, C; Blouw, J; Blusk, S; Bobrov, A; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borgia, A; Bowcock, T J V; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Brisbane, S; Britsch, M; Britton, T; Brook, N H; Brown, H; Büchler-Germann, A; Burducea, I; Bursche, A; Buytaert, J; Cadeddu, S; Caicedo Carvajal, J M; Callot, O; Calvi, M; Calvo Gomez, M; Camboni, A; Campana, P; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carson, L; Carvalho Akiba, K; Casse, G; Cattaneo, M; Charles, M; Charpentier, Ph; Chiapolini, N; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coca, C; Coco, V; Cogan, J; Collins, P; Constantin, F; Conti, G; Contu, A; Cook, A; Coombes, M; Corti, G; Cowan, G A; Currie, R; D'Almagne, B; D'Ambrosio, C; David, P; De Bonis, I; De Capua, S; De Cian, M; De Lorenzi, F; De Miranda, J M; De Paula, L; De Simone, P; Decamp, D; Deckenhoff, M; Degaudenzi, H; Deissenroth, M; Del Buono, L; Deplano, C; Deschamps, O; Dettori, F; Dickens, J; Dijkstra, H; Diniz Batista, P; Donleavy, S; Dordei, F; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dupertuis, F; Dzhelyadin, R; Eames, C; Easo, S; Egede, U; Egorychev, V; Eidelman, S; van Eijk, D; Eisele, F; Eisenhardt, S; Ekelhof, R; Eklund, L; Elsasser, Ch; d'Enterria, D G; Esperante Pereira, D; Estève, L; Falabella, A; Fanchini, E; Färber, C; Fardell, G; Farinelli, C; Farry, S; Fave, V; Fernandez Albor, V; Ferro-Luzzi, M; Filippov, S; Fitzpatrick, C; Fontana, M; Fontanelli, F; Forty, R; Frank, M; Frei, C; Frosini, M; Furcas, S; Gallas Torreira, A; Galli, D; Gandelman, M; Gandini, P; Gao, Y; Garnier, J-C; Garofoli, J; Garra Tico, J; Garrido, L; Gaspar, C; Gauvin, N; Gersabeck, M; Gershon, T; Ghez, Ph; Gibson, V; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gordon, H; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graziani, G; Grecu, A; Gregson, S; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Haefeli, G; Haen, C; Haines, S C; Hampson, T; Hansmann-Menzemer, S; Harji, R; Harnew, N; Harrison, J; Harrison, P F; He, J; Heijne, V; Hennessy, K; Henrard, P; Hernando Morata, J A; van Herwijnen, E; Hicks, E; Hofmann, W; Holubyev, K; Hopchev, P; Hulsbergen, W; Hunt, P; Huse, T; Huston, R S; Hutchcroft, D; Hynds, D; Iakovenko, V; Ilten, P; Imong, J; Jacobsson, R; Jaeger, A; Jahjah Hussein, M; Jans, E; Jansen, F; Jaton, P; Jean-Marie, B; Jing, F; John, M; Johnson, D; Jones, C R; Jost, B; Kandybei, S; Karacson, M; Karbach, T M; Keaveney, J; Kerzel, U; Ketel, T; Keune, A; Khanji, B; Kim, Y M; Knecht, M; Koblitz, S; Koppenburg, P; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kruzelecki, K; Kucharczyk, M; Kukulak, S; Kumar, R; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanciotti, E; Lanfranchi, G; Langenbruch, C; Latham, T; Le Gac, R; van Leerdam, J; Lees, J-P; Lefèvre, R; Leflat, A; Lefrançois, J; Leroy, O; Lesiak, T; Li, L; Li Gioi, L; Lieng, M; Liles, M; Lindner, R; Linn, C; Liu, B; Liu, G; Lopes, J H; Lopez Asamar, E; Lopez-March, N; Luisier, J; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Magnin, J; Malde, S; Mamunur, R M D; Manca, G; Mancinelli, G; Mangiafave, N; Marconi, U; Märki, R; Marks, J; Martellotti, G; Martens, A; Martin, L; Martín Sánchez, A; Martinez Santos, D; Massafferri, A; Matev, R; Mathe, Z; Matteuzzi, C; Matveev, M; Maurice, E; Maynard, B; Mazurov, A; McGregor, G; McNulty, R; Mclean, C; Meissner, M; Merk, M; Merkel, J; Messi, R; Miglioranzi, S; Milanes, D A; Minard, M-N; Monteil, S; Moran, D; Morawski, P; Mountain, R; Mous, I; Muheim, F; Müller, K; Muresan, R; Muryn, B; Musy, M; Mylroie-Smith, J; Naik, P; Nakada, T; Nandakumar, R; Nardulli, J; Nasteva, I; Nedos, M; Needham, M; Neufeld, N; Nguyen-Mau, C; Nicol, M; Nies, S; Niess, V; Nikitin, N; Oblakowska-Mucha, A; Obraztsov, V; Oggero, S; Ogilvy, S; Okhrimenko, O; Oldeman, R; Orlandea, M; Otalora Goicochea, J M; Owen, P; Pal, B; Palacios, J; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Parkes, C; Parkinson, C J; Passaleva, G; Patel, G D; Patel, M; Paterson, S K; Patrick, G N; Patrignani, C; Pavel-Nicorescu, C; Pazos Alvarez, A; Pellegrino, A; Penso, G; Pepe Altarelli, M; Perazzini, S; Perego, D L; Perez Trigo, E; Pérez-Calero Yzquierdo, A; Perret, P; Perrin-Terrin, M; Pessina, G; Petrella, A; Petrolini, A; Pie Valls, B; Pietrzyk, B; Pilar, T; Pinci, D; Plackett, R; Playfer, S; Plo Casasus, M; Polok, G; Poluektov, A; Polycarpo, E; Popov, D; Popovici, B; Potterat, C; Powell, A; du Pree, T; Prisciandaro, J; Pugatch, V; Puig Navarro, A; Qian, W; Rademacker, J H; Rakotomiaramanana, B; Rangel, M S; Raniuk, I; Raven, G; Redford, S; Reid, M M; dos Reis, A C; Ricciardi, S; Rinnert, K; Roa Romero, D A; Robbe, P; Rodrigues, E; Rodrigues, F; Rodriguez Perez, P; Rogers, G J; Roiser, S; Romanovsky, V; Rouvinet, J; Ruf, T; Ruiz, H; Sabatino, G; Saborido Silva, J J; Sagidova, N; Sail, P; Saitta, B; Salzmann, C; Sannino, M; Santacesaria, R; Santamarina Rios, C; Santinelli, R; Santovetti, E; Sapunov, M; Sarti, A; Satriano, C; Satta, A; Savrie, M; Savrina, D; Schaack, P; Schiller, M; Schleich, S; Schmelling, M; Schmidt, B; Schneider, O; Schopper, A; Schune, M -H; Schwemmer, R; Sciubba, A; Seco, M; Semennikov, A; Senderowska, K; Sepp, I; Serra, N; Serrano, J; Seyfert, P; Shao, B; Shapkin, M; Shapoval, I; Shatalov, P; Shcheglov, Y; Shears, T; Shekhtman, L; Shevchenko, O; Shevchenko, V; Shires, A; Silva Coutinho, R; Skottowe, H P; Skwarnicki, T; Smith, A C; Smith, N A; Sobczak, K; Soler, F J P; Solomin, A; Soomro, F; Souza De Paula, B; Spaan, B; Sparkes, A; Spradlin, P; Stagni, F; Stahl, S; Steinkamp, O; Stoica, S; Stone, S; Storaci, B; Straticiuc, M; Straumann, U; Styles, N; Subbiah, V K; Swientek, S; Szczekowski, M; Szczypka, P; Szumlak, T; T'Jampens, S; Teodorescu, E; Teubert, F; Thomas, C; Thomas, E; van Tilburg, J; Tisserand, V; Tobin, M; Topp-Joergensen, S; Tran, M T; Tsaregorodtsev, A; Tuning, N; Ubeda Garcia, M; Ukleja, A; Urquijo, P; Uwer, U; Vagnoni, V; Valenti, G; Vazquez Gomez, R; Vazquez Regueiro, P; Vecchi, S; Velthuis, J J; Veltri, M; Vervink, K; Viaud, B; Videau, I; Vilasis-Cardona, X; Visniakov, J; Vollhardt, A; Voong, D; Vorobyev, A; Voss, H; Wacker, K; Wandernoth, S; Wang, J; Ward, D R; Webber, A D; Websdale, D; Whitehead, M; Wiedner, D; Wiggers, L; Wilkinson, G; Williams, M P; Williams, M; Wilson, F F; Wishahi, J; Witek, M; Witzeling, W; Wotton, S A; Wyllie, K; Xie, Y; Xing, F; Yang, Z; Young, R; Yushchenko, O; Zavertyaev, M; Zhang, F; Zhang, L; Zhang, W C; Zhang, Y; Zhelezov, A; Zhong, L; Zverev, E; Zvyagin, A

2012-01-01

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic ``van der Meer scan'' method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5\\% in the absolute lumi...

LHCb detector performance

NARCIS (Netherlands)

Aaij, R.; Adeva, B.; Adinol, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Anderson, J.; Andreassen, R.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Gutierrez, O. Aquines; Archilli, F.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Bay, A.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Belogurov, S.; Onderwater, C. J. G.; Pellegrino, A.; Wilschut, H. W.

2015-01-01

The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are

LHCb brochure (French version)

CERN Multimedia

Marcastel, Fabienne

2014-01-01

LHCb is one of the four big experiments for the LHC, the most powerful particle accelerator in the world, which will start up in 2008. LHCb studies a phenomenon which could partly explain why the Universe is all matter and practically no antimatter.

LHCb brochure (English version)

CERN Multimedia

Marcastel, Fabienne

2014-01-01

LHCb is one of the four big experiments for the LHC, the most powerful particle accelerator in the world, which will start up in 2008. LHCb studies a phenomenon which could partly explain why the Universe is all matter and practically no antimatter.

LHCb brochure (Italian version)

CERN Multimedia

Marcastel, Fabienne

2014-01-01

LHCb is one of the four big experiments for the LHC, the most powerful particle accelerator in the world, which will start up in 2008. LHCb studies a phenomenon which could partly explain why the Universe is all matter and practically no antimatter.

LHCb: Performance and Radiation Damage Effects in the LHCb Vertex Locator

CERN Multimedia

Carvalho Akiba, K

2014-01-01

LHCb is a dedicated experiment to study New Physics in the decays of heavy hadrons at the LHC. Heavy hadrons are identified through their flight distance in the Vertex Locator (VELO), hence the detector is critical for both the trigger and offline physics analyses. The VELO is the retractable silicon-strip detector surrounding the LHCb interaction point. It is located only 7 mm from the LHC beam during normal LHC operation, once moved into its closed position for each LHC fill when stable beams are obtained. During insertion the detector is centred around the LHC beam by the online reconstruction of the primary vertex position. Both VELO halves comprise 21 silicon micro-strip modules each. A module is made of two n-on-n 300 $\\mu$m thick half-disc sensors with R-measuring and $\\phi$-measuring micro-strip geometry, mounted on a carbon fibre support paddle. The minimum pitch is approximately 40 $\\mu$m. The detector is also equipped with the only n-on-p sensors operating at the LHC. The detectors are operated in ...

LHCb brochure (German version)

CERN Multimedia

Lefevre, C

2008-01-01

LHCb is one of the four big experiments for the LHC, the most powerful particle accelerator in the world, which will start up in 2008. LHCb will study a phenomenon which could partly explain why the Universe is all matter and practically no antimatter.

LHCb brochure (German version)

CERN Multimedia

Lefevre, Christiane

2012-01-01

LHCb is one of the four big experiments for the LHC, the most powerful particle accelerator in the world, which will start up in 2008. LHCb will study a phenomenon which could partly explain why the Universe is all matter and practically no antimatter.

LHCb brochure (Spanish version)

CERN Multimedia

Lefevre, C

2008-01-01

LHCb is one of the four big experiments for the LHC, the most powerful particle accelerator in the world, which will start up in 2008. LHCb will study a phenomenon which could partly explain why the Universe is all matter and practically no antimatter.

The LHCb Silicon Tracker

Energy Technology Data Exchange (ETDEWEB)

Tobin, Mark, E-mail: Mark.Tobin@epfl.ch

2016-09-21

The LHCb experiment is dedicated to the study of heavy flavour physics at the Large Hadron Collider (LHC). The primary goal of the experiment is to search for indirect evidence of new physics via measurements of CP violation and rare decays of beauty and charm hadrons. The LHCb detector has a large-area silicon micro-strip detector located upstream of a dipole magnet, and three tracking stations with silicon micro-strip detectors in the innermost region downstream of the magnet. These two sub-detectors form the LHCb Silicon Tracker (ST). This paper gives an overview of the performance and operation of the ST during LHC Run 1. Measurements of the observed radiation damage are shown and compared to the expectation from simulation.

LHCb: The LHCb Trigger Architecture beyond LS1

CERN Multimedia

Albrecht, J; Neubert, S; Raven, G; Sokoloff, M D; Williams, M

2013-01-01

The LHCb experiment is a spectrometer dedicated to the study of heavy flavor at the LHC. The rate of proton-proton collisions at the LHC is 15 MHz, but resource limitations mean that only 5 kHz can be written to storage for offline analytsis. For this reason the LHCb data acquisition system -- trigger -- plays a key role in selecting signal events and rejecting background. In contrast to previous experiments at hadron colliders like for example CDF or D0, the bulk of the LHCb trigger is implemented in software and deployed on a farm of 20k parallel processing nodes. This system, called the High Level Trigger (HLT) is responsible for reducing the rate from the maximum at which the detector can be read out, 1.1 MHz, to the 5 kHz which can be processed offline,and has 20 ms in which to process and accept/reject each event. In order to minimize systematic uncertainties, the HLT was designed from the outset to reuse the offline reconstruction and selection code. During the long shutdown it is proposed to extend th...

LHCb: Radiation Damage in the LHCb VELO

CERN Multimedia

Rodriguez Perez, P

2012-01-01

LHCb is a dedicated experiment to study new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The beauty and charm hadrons are identified through their flight distance in the Vertex Locator (VELO), and hence the detector is critical for both the trigger and offline physics analyses. The 88 VELO sensors are all n-on-n type but one, which is made from n-on-p silicon, and is the only n-on-p module silicon sensor operated at the LHC. The sensors have an inner radius of only 7 mm from the LHC beam and an outer radius of 42 mm, consequently the sensors receive a large and non-uniform radiation dose. The LHCb is planned to record an integrated luminosity up to 5 $fb^{-1}$ with collision energies between 7 and 14 TeV before 2018. The leakage current in the sensors has increased significantly following the delivered luminosity, and decreased during shutdown periods due to annealing. The effective depletion voltage of the sensors is measured from the charge collection effi...

Expression of Interest for a Phase-II LHCb Upgrade: Opportunities in flavour physics, and beyond, in the HL-LHC era

CERN Document Server

Aaij, Roel; Adinolfi, Marco; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Andreassi, Guido; Andreotti, Mirco; Andrews, Jason; Anelli, Mario; Appleby, Robert; Archilli, Flavio; d'Argent, Philippe; Arnau Romeu, Joan; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Babuschkin, Igor; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baker, Sophie; Balagura, Vladislav; Baldini, Wander; Balla, Alessandro; Baranov, Alexander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Baryshnikov, Fedor; Baszczyk, Mateusz; Batozskaya, Varvara; Batsukh, Baasansuren; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Beiter, Andrew; Bel, Lennaert; Bellee, Violaine; Belloli, Nicoletta; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Beranek, Sarah; Berezhnoy, Alexander; Bernet, Roland; Bertolin, Alessandro; Betancourt, Christopher; Betti, Federico; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bezshyiko, Iaroslava; Bifani, Simone; Billoir, Pierre; Birnkraut, Alex; Bitadze, Alexander; Bizzeti, Andrea; Blake, Thomas; Blanc, Frederic; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Boettcher, Thomas; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Bordyuzhin, Igor; Borgheresi, Alessio; Borghi, Silvia; Borisyak, Maxim; Borsato, Martino; Bossu, Francesco; Boubdir, Meriem; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Braun, Svende; Britton, Thomas; Brodzicka, Jolanta; Brundu, Davide; Buchanan, Emma; Burr, Christopher; Bursche, Albert; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Camboni, Alessandro; Campana, Pierluigi; Campora Perez, Daniel Hugo; Capriotti, Lorenzo; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carletti, Maurizio; Carniti, Paolo; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Casu, Luigi; Cattaneo, Marco; Cavallero, Giovanni; Cenci, Riccardo; Chamont, David; Charles, Matthew; Charpentier, Philippe; Chatzikonstantinidis, Georgios; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chobanova, Veronika; Chrzaszcz, Marcin; Chubykin, Alexsei; Ciambrone, Paolo; Cid Vidal, Xabier; Ciezarek, Gregory; Citterio, Mauro; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Coelli, Simone; Cogan, Julien; Cogneras, Eric; Cogoni, Violetta; Cojocariu, Lucian; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombs, George; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Costa Sobral, Cayo Mar; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Crocombe, Andrew; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Da Cunha Marinho, Franciole; Dall'Occo, Elena; Dalseno, Jeremy; David, Pieter; Davis, Adam; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Serio, Marilisa; De Simone, Patrizia; Dean, Cameron Thomas; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Demmer, Moritz; Dendek, Adam; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Dey, Biplab; Di Canto, Angelo; Di Nezza, Pasquale; Dijkstra, Hans; Dordei, Francesca; Dorigo, Mirco; Dosil Su{á}rez, Alvaro; Dovbnya, Anatoliy; Dreimanis, Karlis; Dufour, Laurent; Dujany, Giulio; Dungs, Kevin; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; D{é}l{é}age, Nicolas; Easo, Sajan; Ebert, Marcus; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Farley, Nathanael; Farry, Stephen; Fay, Robert; Fazzini, Davide; Felici, Giulietto; Ferguson, Dianne; Fernandez, Gerard; Fernandez Prieto, Antonio; Ferrari, Fabio; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fini, Rosa Anna; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fleuret, Frederic; Fohl, Klaus; Fontana, Marianna; Fontanelli, Flavio; Forshaw, Dean Charles; Forty, Roger; Franco Lima, Vinicius; Frank, Markus; Frei, Christoph; Fresch, Paolo; Fu, Jinlin; Funk, Wolfgang; Furfaro, Emiliano; F{ä}rber, Christian; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; Garcia Martin, Luis Miguel; Garc{í}a Pardi{ñ}as, Juli{á}n; Garra Tico, Jordi; Garrido, Lluis; Garsed, Philip John; Gascon, David; Gaspar, Clara; Gatta, Maurizio; Gavardi, Laura; Gazzoni, Giulio; Gerick, David; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gian{ì}, Sebastiana; Gibson, Valerie; Girard, Olivier G{ö}ran; Giubega, Lavinia-Helena; Gizdov, Konstantin; Gligorov, Vladimir; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gorelov, Igor Vladimirovich; Gotti, Claudio; Govorkova, Ekaterina; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto; Graug{é}s, Eugeni; Graverini, Elena; Graziani, Giacomo; Grecu, Alexandru; Greim, Roman; Griffith, Peter; Grillo, Lucia; Gruberg Cazon, Barak Raimond; Gr{ü}nberg, Oliver; Gushchin, Evgeny; Guz, Yury; Gys, Thierry; G{ö}bel, Carla; Hadavizadeh, Thomas; Hadjivasiliou, Christos; Haefeli, Guido; Haen, Christophe; Haines, Susan; Hamilton, Brian; Han, Xiaoxue; Hansmann-Menzemer, Stephanie; Harnew, Neville; Harnew, Samuel; Harrison, Jonathan; Hatch, Mark; He, Jibo; Head, Timothy; Heister, Arno; Hennessy, Karol; Henrard, Pierre; Henry, Louis; van Herwijnen, Eric; Heß, Miriam; Hicheur, Adl{è}ne; Hill, Donal; Hombach, Christoph; Hopchev, P H; Huard, Zachary; Hulsbergen, Wouter; Humair, Thibaud; Hushchyn, Mikhail; Hutchcroft, David; Idzik, Marek; Ilten, Philip; Jacobsson, Richard; Jalocha, Pawel; Jans, Eddy; Jawahery, Abolhassan; Jiang, Feng; John, Malcolm; Johnson, Daniel; Jones, Christopher; Joram, Christian; Jost, Beat; Jurik, Nathan; Kandybei, Sergii; Karacson, Matthias; Kariuki, James Mwangi; Karodia, Sarah; Kecke, Matthieu; Kelsey, Matthew; Kenzie, Matthew; Ketel, Tjeerd; Khairullin, Egor; Khanji, Basem; Khurewathanakul, Chitsanu; Kirn, Thomas; Klaver, Suzanne; Klimaszewski, Konrad; Klimkovich, Tatsiana; Koliiev, Serhii; Kolpin, Michael; Komarov, Ilya; Koppenburg, Patrick; Kosmyntseva, Alena; Kotriakhova, Sofia; Kozachuk, Anastasiia; Kozeiha, Mohamad; Kravchuk, Leonid; Kreplin, Katharina; Kreps, Michal; Krokovny, Pavel; Kruse, Florian; Krzemien, Wojciech; Kucewicz, Wojciech; Kucharczyk, Marcin; Kudryavtsev, Vasily; Kuonen, Axel Kevin; Kurek, Krzysztof; Kvaratskheliya, Tengiz; Lacarrere, Daniel; Lafferty, George; Lai, Adriano; Langenbruch, Christoph; Latham, Thomas; Lazzeroni, Cristina; Le Gac, Renaud; van Leerdam, Jeroen; Leflat, Alexander; Lefran{ç}ois, Jacques; Lef{è}vre, Regis; Lemaitre, Florian; Lemos Cid, Edgar; Leroy, Olivier; Lesiak, Tadeusz; Leverington, Blake; Li, Tenglin; Li, Yiming; Li, Zhuoming; Likhomanenko, Tatiana; Lindner, Rolf; Lionetto, Federica; Liu, Xuesong; Loh, David; Loi, Angelo; Longstaff, Iain; Lopes, Jose; Lucchesi, Donatella; Lucio Martinez, Miriam; Luo, Haofei; Lupato, Anna; Luppi, Eleonora; Lupton, Oliver; Lusiani, Alberto; Lyu, Xiao-Rui; Machefert, Frederic; Maciuc, Florin; Maev, Oleg; Maguire, Kevin; Malde, Sneha; Malinin, Alexander; Maltsev, Timofei; Manca, Giulia; Mancinelli, Giampiero; Manning, Peter Michael; Maratas, Jan; Marchand, Jean Fran{ç}ois; Marconi, Umberto; Marin Benito, Carla; Marinangeli, Matthieu; Marino, Pietro; Marks, J{ö}rg; Marras, Davide; Martellotti, Giuseppe; Martin, Morgan; Martinelli, Maurizio; Martinez Santos, Diego; Martinez Vidal, Fernando; Martins Tostes, Danielle; Massacrier, Laure Marie; Massafferri, Andr{é}; Matev, Rosen; Mathad, Abhijit; Mathe, Zoltan; Matteuzzi, Clara; Mauri, Andrea; Maurice, Emilie; Maurin, Brice; Mazurov, Alexander; McCann, Michael; McNab, Andrew; McNulty, Ronan; Meadows, Brian; Meier, Frank; Melnychuk, Dmytro; Merk, Marcel; Merli, Andrea; Michielin, Emanuele; Milanes, Diego Alejandro; Minard, Marie-Noelle; Mitzel, Dominik Stefan; Mogini, Andrea; Molina Rodriguez, Josue; Monroy, Igancio Alberto; Monteil, Stephane; Morandin, Mauro; Morawski, Piotr; Morello, Michael Joseph; Morgunova, Olga; Moron, Jakub; Morris, Adam Benjamin; Mountain, Raymond; Muheim, Franz; Mulder, Mick; Mussini, Manuel; M{ü}ller, Dominik; M{ü}ller, Janine; M{ü}ller, Katharina; M{ü}ller, Vanessa; Naik, Paras; Nakada, Tatsuya; Nandakumar, Raja; Nandi, Anita; Nasteva, Irina; Needham, Matthew; Neri, Nicola; Neubert, Sebastian; Neufeld, Niko; Neuner, Max; Nguyen, Thi Dung; Nguyen-Mau, Chung; Nieswand, Simon; Niet, Ramon; Nikitin, Nikolay; Nikodem, Thomas; Nogay, Alla; Novoselov, Alexey; O'Hanlon, Daniel Patrick; Oblakowska-Mucha, Agnieszka; Obraztsov, Vladimir; Ogilvy, Stephen; Oldeman, Rudolf; Onderwater, Gerco; Otalora Goicochea, Juan Martin; Otto, Adam; Owen, Patrick; Oyanguren, Maria Aranzazu; Pais, Preema Rennee; Palano, Antimo; Palutan, Matteo; Papanestis, Antonios; Pappagallo, Marco; Pappalardo, Luciano; Pappenheimer, Cheryl; Parker, William; Parkes, Christopher; Passaleva, Giovanni; Pastore, Alessandra; Patel, Mitesh; Patrignani, Claudia; Pearce, Alex; Pellegrino, Antonio; Penso, Gianni; Pepe Altarelli, Monica; Perazzini, Stefano; Perret, Pascal; Pescatore, Luca; Petridis, Konstantinos; Petrolini, Alessandro; Petrov, Aleksandr; Petruzzo, Marco; Picatoste Olloqui, Eduardo; Pietrzyk, Boleslaw; Pikies, Malgorzata; Pinci, Davide; Pistone, Alessandro; Piucci, Alessio; Placinta, Vlad-Mihai; Playfer, Stephen; Plo Casasus, Maximo; Poikela, Tuomas; Polci, Francesco; Poli Lener, Marco; Poluektov, Anton; Polyakov, Ivan; Polycarpo, Erica; Pomery, Gabriela Johanna; Ponce, Sebastien; Popov, Alexander; Popov, Dmitry; Popovici, Bogdan; Poslavskii, Stanislav; Potterat, C{é}dric; Price, Eugenia; Prisciandaro, Jessica; Prouve, Claire; Pugatch, Valery; Puig Navarro, Albert; Punzi, Giovanni; Qian, Chen; Qian, Wenbin; Quagliani, Renato; Rachwal, Bartolomiej; Rademacker, Jonas; Rama, Matteo; Ramos Pernas, Miguel; Rangel, Murilo; Raniuk, Iurii; Ratnikov, Fedor; Raven, Gerhard; Redi, Federico; Reichert, Stefanie; dos Reis, Alberto; Remon Alepuz, Clara; Renaudin, Victor; Ricciardi, Stefania; Richards, Sophie; Rihl, Mariana; Rinnert, Kurt; Rives Molina, Vicente; Robbe, Patrick; Rodrigues, Ana Barbara; Rodrigues, Eduardo; Rodriguez Lopez, Jairo Alexis; Rodriguez Perez, Pablo; Rogozhnikov, Alexey; Roiser, Stefan; Rollings, Alexandra Paige; Romanovskiy, Vladimir; Romero Vidal, Antonio; Ronayne, John William; Rotondo, Marcello; Rudolph, Matthew Scott; Ruf, Thomas; Ruiz Valls, Pablo; Saborido Silva, Juan Jose; Sadykhov, Elnur; Sagidova, Naylya; Saitta, Biagio; Salustino Guimaraes, Valdir; Sanchez Gonzalo, David; Sanchez Mayordomo, Carlos; Sanmartin Sedes, Brais; Santacesaria, Roberta; Santamarina Rios, Cibran; 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Vacca, Claudia; Vagnoni, Vincenzo; Valassi, Andrea; Valat, Sebastien; Valenti, Giovanni; Van Dijk, Maarten; Vazquez Gomez, Ricardo; Vazquez Regueiro, Pablo; Vecchi, Stefania; van Veghel, Maarten; Velthuis, Jaap; Veltri, Michele; Veneziano, Giovanni; Venkateswaran, Aravindhan; Verlage, Tobias Anton; Vernet, Maxime; Vesterinen, Mika; Viana Barbosa, Joao Vitor; Viaud, Benoit; Vieira, Daniel; Vieites Diaz, Maria; Viemann, Harald; Vilasis-Cardona, Xavier; Vitti, Marcela; Volkov, Vladimir; Vollhardt, Achim; Voneki, Balazs; Vorobyev, Alexey; Vorobyev, Vitaly; Voß, Christian; de Vries, Jacco; V{á}zquez Sierra, Carlos; Waldi, Roland; Wallace, Charlotte; Wallace, Ronan; Walsh, John; Wang, Jianchun; Ward, David; Wark, Heather Mckenzie; Watson, Nigel; Websdale, David; Weiden, Andreas; Whitehead, Mark; Wicht, Jean; Wilkinson, Guy; Wilkinson, Michael; Williams, Mark Richard James; Williams, Matthew; Williams, Mike; Williams, Timothy; Wilson, Fergus; Wimberley, Jack; Winn, Michael Andreas; Wishahi, Julian; 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Geneva. The LHC experiments Committee; LHCC

2017-01-01

A Phase-II Upgrade is proposed for the LHCb experiment in order to take full advantage of the flavour-physics opportunities at the HL-LHC, and other topics that can be studied with a forward spectrometer. This Upgrade, which will be installed in Long Shutdown 4 of the LHC (2030), will build on the strengths of the current experiment and the Phase-I Upgrade, but will consist of re-designed sub-systems that can operate at a luminosity of $2 \\times 10^{34}\\,{\\rm cm}^{-2} s^{-1}$, ten times that of the Phase-I Upgrade detector. New and improved detector components will increase the intrinsic performance of the experiment in certain key areas. In particular the installation of a tungsten sampling electromagnetic calorimeter will widen LHCb's capabilities for decays involving $\\pi^0$ and $\\eta$ mesons, electrons, and photons from loop-level penguin processes. The physics motivation is presented, and the prospects for operating the LHCb Interaction Point at high luminosity are assessed. The challenges for the detect...

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Aaij, Roel; Adinolfi, Marco; Affolder, Anthony; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Anderson, Jonathan; Andreassen, Rolf; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Aquines Gutierrez, Osvaldo; Archilli, Flavio; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baldini, Wander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Belogurov, Sergey; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Benton, Jack; Berezhnoy, Alexander; Bernet, Roland; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bien, Alexander; Bifani, Simone; Bird, Thomas; Bizzeti, Andrea; Bjørnstad, Pål Marius; Blake, Thomas; Blanc, Frédéric; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Borghi, Silvia; Borgia, Alessandra; Borsato, Martino; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Brambach, Tobias; Bressieux, Joël; Brett, David; Britsch, Markward; Britton, Thomas; Brodzicka, Jolanta; Brook, Nicholas; Brown, Henry; Bursche, Albert; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Campana, Pierluigi; Campora Perez, Daniel; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cauet, Christophe; Cenci, Riccardo; Charles, Matthew; Charpentier, Philippe; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chiapolini, Nicola; Chrzaszcz, Marcin; Ciba, Krzystof; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Cogan, Julien; Cogneras, Eric; Cogoni, Violetta; Cojocariu, Lucian; Collazuol, Gianmaria; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombes, Matthew; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Counts, Ian; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Crocombe, Andrew; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Dalseno, Jeremy; David, Pascal; David, Pieter; Davis, Adam; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Silva, Weeraddana; De Simone, Patrizia; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Déléage, Nicolas; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Di Canto, Angelo; Dijkstra, Hans; Donleavy, Stephanie; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Dossett, David; Dovbnya, Anatoliy; Dreimanis, Karlis; Dujany, Giulio; Dupertuis, Frederic; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; El Rifai, Ibrahim; Elsasser, Christian; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Färber, Christian; Farinelli, Chiara; Farley, Nathanael; Farry, Stephen; Fay, Robert; Ferguson, Dianne; Fernandez Albor, Victor; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fol, Philip; Fontana, Marianna; Fontanelli, Flavio; Forty, Roger; Francisco, Oscar; Frank, Markus; Frei, Christoph; Frosini, Maddalena; Fu, Jinlin; Furfaro, Emiliano; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; García Pardiñas, Julián; Garofoli, Justin; Garra Tico, Jordi; Garrido, Lluis; Gascon, David; Gaspar, Clara; Gauld, Rhorry; Gavardi, Laura; Geraci, Angelo; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gianelle, Alessio; Gianì, Sebastiana; Gibson, Valerie; Giubega, Lavinia-Helena; Gligorov, V.V.; Göbel, Carla; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gotti, Claudio; Grabalosa Gándara, Marc; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto; Graugés, Eugeni; Graverini, Elena; Graziani, Giacomo; Grecu, Alexandru; Greening, Edward; Gregson, Sam; Griffith, Peter; Grillo, Lucia; Grünberg, Oliver; Gui, Bin; Gushchin, Evgeny; Guz, Yury; Gys, Thierry; Hadjivasiliou, Christos; Haefeli, Guido; Haen, Christophe; Haines, Susan; Hall, Samuel; Hamilton, Brian; Hampson, Thomas; Han, Xiaoxue; Hansmann-Menzemer, Stephanie; Harnew, Neville; Harnew, Samuel; Harrison, Jonathan; He, Jibo; Head, Timothy; Heijne, Veerle; Hennessy, Karol; Henrard, Pierre; Henry, Louis; Hernando Morata, Jose Angel; van Herwijnen, Eric; Heß, Miriam; Hicheur, Adlène; Hill, Donal; Hoballah, Mostafa; Hombach, Christoph; Hulsbergen, Wouter; Hunt, Philip; Hussain, Nazim; Hutchcroft, David; Hynds, Daniel; Idzik, Marek; Ilten, Philip; Jacobsson, Richard; Jaeger, Andreas; Jalocha, Pawel; Jans, Eddy; Jaton, Pierre; Jawahery, Abolhassan; Jing, Fanfan; John, Malcolm; Johnson, Daniel; Jones, Christopher; Joram, Christian; Jost, Beat; Jurik, Nathan; Kandybei, Sergii; Kanso, Walaa; Karacson, Matthias; Karbach, Moritz; Karodia, Sarah; Kelsey, Matthew; Kenyon, Ian; Ketel, Tjeerd; Khanji, Basem; Khurewathanakul, Chitsanu; Klaver, Suzanne; Klimaszewski, Konrad; Kochebina, Olga; Kolpin, Michael; Komarov, Ilya; Koopman, Rose; Koppenburg, Patrick; Korolev, Mikhail; Kozlinskiy, Alexandr; Kravchuk, Leonid; Kreplin, Katharina; Kreps, Michal; Krocker, Georg; Krokovny, Pavel; Kruse, Florian; Kucewicz, Wojciech; Kucharczyk, Marcin; Kudryavtsev, Vasily; Kurek, Krzysztof; Kvaratskheliya, Tengiz; La Thi, Viet Nga; Lacarrere, Daniel; Lafferty, George; Lai, Adriano; Lambert, Dean; Lambert, Robert W; Lanfranchi, Gaia; Langenbruch, Christoph; Langhans, Benedikt; Latham, Thomas; Lazzeroni, Cristina; Le Gac, Renaud; van Leerdam, Jeroen; Lees, Jean-Pierre; Lefèvre, Regis; Leflat, Alexander; Lefrançois, Jacques; Leo, Sabato; Leroy, Olivier; Lesiak, Tadeusz; Leverington, Blake; Li, Yiming; Likhomanenko, Tatiana; Liles, Myfanwy; Lindner, Rolf; Linn, Christian; Lionetto, Federica; Liu, Bo; Lohn, Stefan; Longstaff, Iain; Lopes, Jose; Lopez-March, Neus; Lowdon, Peter; Lucchesi, Donatella; Luo, Haofei; Lupato, Anna; Luppi, Eleonora; Lupton, Oliver; Machefert, Frederic; Machikhiliyan, Irina V; Maciuc, Florin; Maev, Oleg; Malde, Sneha; Malinin, Alexander; Manca, Giulia; Mancinelli, Giampiero; Mapelli, Alessandro; Maratas, Jan; Marchand, Jean François; Marconi, Umberto; Marin Benito, Carla; Marino, Pietro; Märki, Raphael; Marks, Jörg; Martellotti, Giuseppe; Martens, Aurelien; Martín Sánchez, Alexandra; Martinelli, Maurizio; Martinez Santos, Diego; Martinez Vidal, Fernando; Martins Tostes, Danielle; Massafferri, André; Matev, Rosen; Mathe, Zoltan; Matteuzzi, Clara; Mazurov, Alexander; McCann, Michael; McCarthy, James; McNab, Andrew; McNulty, Ronan; McSkelly, Ben; Meadows, Brian; Meier, Frank; Meissner, Marco; Merk, Marcel; Milanes, Diego Alejandro; Minard, Marie-Noelle; Moggi, Niccolò; Molina Rodriguez, Josue; Monteil, Stephane; Morandin, Mauro; Morawski, Piotr; Mordà, Alessandro; Morello, Michael Joseph; Moron, Jakub; Morris, Adam Benjamin; Mountain, Raymond; Muheim, Franz; Müller, Katharina; Mussini, Manuel; Muster, Bastien; Naik, Paras; Nakada, Tatsuya; Nandakumar, Raja; Nasteva, Irina; Needham, Matthew; Neri, Nicola; Neubert, Sebastian; Neufeld, Niko; Neuner, Max; Nguyen, Anh Duc; Nguyen, Thi-Dung; Nguyen-Mau, Chung; Nicol, Michelle; Niess, Valentin; Niet, Ramon; Nikitin, Nikolay; Nikodem, Thomas; Novoselov, Alexey; O'Hanlon, Daniel Patrick; Oblakowska-Mucha, Agnieszka; Obraztsov, Vladimir; Oggero, Serena; Ogilvy, Stephen; Okhrimenko, Oleksandr; Oldeman, Rudolf; Onderwater, Gerco; Orlandea, Marius; Otalora Goicochea, Juan Martin; Owen, Patrick; Oyanguren, Maria Arantza; Pal, Bilas Kanti; Palano, Antimo; Palombo, Fernando; Palutan, Matteo; Panman, Jacob; Papanestis, Antonios; Pappagallo, Marco; Pappalardo, Luciano; Parkes, Christopher; Parkinson, Christopher John; Passaleva, Giovanni; Patel, Girish; Patel, Mitesh; Patrignani, Claudia; Pearce, Alex; Pellegrino, Antonio; Penso, Gianni; Pepe Altarelli, Monica; Perazzini, Stefano; Perret, Pascal; Perrin-Terrin, Mathieu; Pescatore, Luca; Pesen, Erhan; Pessina, Gianluigi; Petridis, Konstantin; Petrolini, Alessandro; Picatoste Olloqui, Eduardo; Pietrzyk, Boleslaw; Pilař, Tomas; Pinci, Davide; Pistone, Alessandro; Playfer, Stephen; Plo Casasus, Maximo; Polci, Francesco; Poluektov, Anton; Polyakov, Ivan; Polycarpo, Erica; Popov, Alexander; Popov, Dmitry; Popovici, Bogdan; Potterat, Cédric; Price, Eugenia; Price, Joseph David; Prisciandaro, Jessica; Pritchard, Adrian; Prouve, Claire; Pugatch, Valery; Puig Navarro, Albert; Punzi, Giovanni; Qian, Wenbin; Rachwal, Bartolomiej; Rademacker, Jonas; Rakotomiaramanana, Barinjaka; Rama, Matteo; Rangel, Murilo; Raniuk, Iurii; Rauschmayr, Nathalie; Raven, Gerhard; Redi, Federico; Reichert, Stefanie; Reid, Matthew; dos Reis, Alberto; Ricciardi, Stefania; Richards, Sophie; Rihl, Mariana; Rinnert, Kurt; Rives Molina, Vincente; Robbe, Patrick; Rodrigues, Ana Barbara; Rodrigues, Eduardo; Rodriguez Perez, Pablo; Roiser, Stefan; Romanovsky, Vladimir; Romero Vidal, Antonio; Rotondo, Marcello; Rouvinet, Julien; Ruf, Thomas; Ruiz, Hugo; Ruiz Valls, Pablo; Saborido Silva, Juan Jose; Sagidova, Naylya; Sail, Paul; Saitta, Biagio; Salustino Guimaraes, Valdir; Sanchez Mayordomo, Carlos; Sanmartin Sedes, Brais; Santacesaria, Roberta; Santamarina Rios, Cibran; Santovetti, Emanuele; Sarti, Alessio; Satriano, Celestina; Satta, Alessia; Saunders, Daniel Martin; Savrina, Darya; Schiller, Manuel; Schindler, Heinrich; Schlupp, Maximilian; Schmelling, Michael; Schmidt, Burkhard; Schneider, Olivier; Schopper, Andreas; Schune, Marie Helene; Schwemmer, Rainer; Sciascia, Barbara; Sciubba, Adalberto; Semennikov, Alexander; Sepp, Indrek; Serra, Nicola; Serrano, Justine; Sestini, Lorenzo; Seyfert, Paul; Shapkin, Mikhail; Shapoval, Illya; Shcheglov, Yury; Shears, Tara; Shekhtman, Lev; Shevchenko, Vladimir; Shires, Alexander; Silva Coutinho, Rafael; Simi, Gabriele; Sirendi, Marek; Skidmore, Nicola; Skillicorn, Ian; Skwarnicki, Tomasz; Smith, Anthony; Smith, Edmund; Smith, Eluned; Smith, Jackson; Smith, Mark; Snoek, Hella; Sokoloff, Michael; Soler, Paul; Soomro, Fatima; Souza, Daniel; Souza De Paula, Bruno; Spaan, Bernhard; Sparkes, Ailsa; Spradlin, Patrick; Sridharan, Srikanth; Stagni, Federico; Stahl, Marian; Stahl, Sascha; Steinkamp, Olaf; Stenyakin, Oleg; Stevenson, Scott; Stoica, Sabin; Stone, Sheldon; Storaci, Barbara; Stracka, Simone; Straticiuc, Mihai; Straumann, Ulrich; Stroili, Roberto; Subbiah, Vijay Kartik; Sun, Liang; Sutcliffe, William; Swientek, Krzysztof; Swientek, Stefan; Syropoulos, Vasileios; Szczekowski, Marek; Szczypka, Paul; Szumlak, Tomasz; T'Jampens, Stephane; Teklishyn, Maksym; Tellarini, Giulia; Teubert, Frederic; Thomas, Christopher; Thomas, Eric; van Tilburg, Jeroen; Tisserand, Vincent; Tobin, Mark; Tolk, Siim; Tomassetti, Luca; Tonelli, Diego; Topp-Joergensen, Stig; Torr, Nicholas; Tournefier, Edwige; Tourneur, Stephane; Tran, Minh Tâm; Tresch, Marco; Tsaregorodtsev, Andrei; Tsopelas, Panagiotis; Tuning, Niels; Ubeda Garcia, Mario; Ukleja, Artur; Ustyuzhanin, Andrey; Uwer, Ulrich; Vacca, Claudia; Vagnoni, Vincenzo; Valenti, Giovanni; Vallier, Alexis; Vazquez Gomez, Ricardo; Vazquez Regueiro, Pablo; Vázquez Sierra, Carlos; Vecchi, Stefania; Velthuis, Jaap; Veltri, Michele; Veneziano, Giovanni; Vesterinen, Mika; Viaud, Benoit; Vieira, Daniel; Vieites Diaz, Maria; Vilasis-Cardona, Xavier; Vollhardt, Achim; Volyanskyy, Dmytro; Voong, David; Vorobyev, Alexey; Vorobyev, Vitaly; Voß, Christian; de Vries, Jacco; Waldi, Roland; Wallace, Charlotte; Wallace, Ronan; Walsh, John; Wandernoth, Sebastian; Wang, Jianchun; Ward, David; Watson, Nigel; Websdale, David; Whitehead, Mark; Wicht, Jean; Wiedner, Dirk; Wilkinson, Guy; Williams, Matthew; Williams, Mike; Wilschut, Hans; Wilson, Fergus; Wimberley, Jack; Wishahi, Julian; Wislicki, Wojciech; Witek, Mariusz; Wormser, Guy; Wotton, Stephen; Wright, Simon; Wyllie, Kenneth; Xie, Yuehong; Xing, Zhou; Xu, Zhirui; Yang, Zhenwei; Yuan, Xuhao; Yushchenko, Oleg; Zangoli, Maria; Zavertyaev, Mikhail; Zhang, Liming; Zhang, Wen Chao; Zhang, Yanxi; Zhelezov, Alexey; Zhokhov, Anatoly; Zhong, Liang; Zvyagin, Alexander

2015-03-05

The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are described, using data taken from 2010 to 2012. It is shown that the design criteria of the experiment have been met. The excellent performance of the detector has allowed the LHCb collaboration to publish a wide range of physics results, demonstrating LHCb's unique role, both as a heavy flavour experiment and as a general purpose detector in the forward region.

Recent results from LHCb

CERN Document Server

Oblakowska-Mucha, A

2016-01-01

The LHCb detector is a single-arm forward spectrometer that collects data at the LHC. In this review, a few of recent results in the field of $b$-hadron decays performed by the LHCb Collaboration are presented. The analyses use proton-proton collision data corresponding to 3 fb$^{-1}$ collected by the LHCb detector during 2011 and 2012 physics runs with the center-of-mass energies of 7 and 8 TeV.

The LHCb VeLo for Phase 1 upgrade

CERN Document Server

Dean, Cameron

2016-01-01

Large Hadron Collider beauty (LHCb) is a dedicated experiment for studying b and c hadrons at the Large Hadron Collider (LHC). LHCb uses a silicon-strip detector, the Vertex Locator (VELO), for high precision tracking of collisions from the LHC. During Long Shutdown 2 (LS2) of the LHC, the LHCb collaboration will upgrade the detector, switching from the current VELO, ca- pable of a 1 MHz readout, to a hybrid pixel detector capable of reading out at the full bunch crossing rate of the LHC. Substantial progress has been made in the development of the new de- tector. The status of the silicon sensors, custom designed VeloPix ASIC and electronic system will be discussed in detail. The current status of the cooling system and RF foil will also be presented.

The LHCb VeLo for Phase 1 upgrade

CERN Document Server

Dean, Cameron

2017-01-01

Large Hadron Collider beauty (LHCb) is a dedicated experiment for studying b and c hadrons at the Large Hadron Collider (LHC). LHCb uses a silicon-strip detector, the Vertex Locator (VELO), for high precision tracking of collisions from the LHC. During Long Shutdown 2 (LS2) of the LHC, the LHCb collaboration will upgrade the detector, switching from the current VELO, ca- pable of a 1 MHz readout, to a hybrid pixel detector capable of reading out at the full bunch crossing rate of the LHC. Substantial progress has been made in the development of the new de- tector. The status of the silicon sensors, custom designed VeloPix ASIC and electronic system will be discussed in detail. The current status of the cooling system and RF foil will also be presented.

Improved performance of the LHCb Outer Tracker in LHC Run 2

Science.gov (United States)

d'Argent, P.; Dufour, L.; Grillo, L.; de Vries, J. A.; Ukleja, A.; Aaij, R.; Archilli, F.; Bachmann, S.; Berninghoff, D.; Birnkraut, A.; Blouw, J.; De Cian, M.; Ciezarek, G.; Färber, C.; Demmer, M.; Dettori, F.; Gersabeck, E.; Grabowski, J.; Hulsbergen, W. D.; Khanji, B.; Kolpin, M.; Kucharczyk, M.; Malecki, B. P.; Merk, M.; Mulder, M.; Müller, J.; Mueller, V.; Pellegrino, A.; Pikies, M.; Rachwal, B.; Schmelzer, T.; Spaan, B.; Szczekowski, M.; van Tilburg, J.; Tolk, S.; Tuning, N.; Uwer, U.; Wishahi, J.; Witek, M.

2017-11-01

The LHCb Outer Tracker is a gaseous detector covering an area of 5 × 6 m2 with 12 double layers of straw tubes. The performance of the detector is presented based on data of the LHC Run 2 running period from 2015 and 2016. Occupancies and operational experience for data collected in pp, pPb and PbPb collisions are described. An updated study of the ageing effects is presented showing no signs of gain deterioration or other radiation damage effects. In addition several improvements with respect to LHC Run 1 data taking are introduced. A novel real-time calibration of the time-alignment of the detector and the alignment of the single monolayers composing detector modules are presented, improving the drift-time and position resolution of the detector by 20%. Finally, a potential use of the improved resolution for the timing of charged tracks is described, showing the possibility to identify low-momentum hadrons with their time-of-flight.

LHCb: The LHCb Silicon Tracker: Running experience

CERN Multimedia

Saornil Gamarra, S

2012-01-01

The LHCb Silicon Tracker is part of the main tracking system of the LHCb detector at the LHC. It measures very precisely the particle trajectories coming from the interaction point in the region of high occupancies around the beam axis. After presenting our production and comissioning issues in TWEPP 2008, we report on our running experience. Focusing on electronic and hardware issues as well as operation and maintenance adversities, we describe the lessons learned and the pitfalls encountered after three years of successful operation.

Beam, background and luminosity monitoring in LHCb and upgrade of the LHCb fast readout control

CERN Document Server

Alessio, Federico; Le Gac, R

2011-01-01

The work described in this thesis was developed, implemented and completely put in operations during the first year of physics data taking at the LHC. It is shown here that it is aimed at studying beam and background characteristics, monitor the global timing of the experiment, monitor online the luminosity at LHCb and monitor most the experimental conditions which can affect the LHCb physics data quality. The many functionalities of the presented systems are outlined in great detail and some selected topics of analysis are presented in order to validate the good performance. The various systems in fact showed high reliability, completeness and robustness and hence it heavily contributed to the global efficiency of the LHCb experiment and also contributed directly to the commissioning and running of the LHC machine for first physics runs. Some important concepts are also brought to attention in this thesis as possible solutions to be taken into account at the LHC. A scintillator system for beam, background an...

LHCb Distributed Data Analysis on the Computing Grid

CERN Document Server

Paterson, S; Parkes, C

2006-01-01

LHCb is one of the four Large Hadron Collider (LHC) experiments based at CERN, the European Organisation for Nuclear Research. The LHC experiments will start taking an unprecedented amount of data when they come online in 2007. Since no single institute has the compute resources to handle this data, resources must be pooled to form the Grid. Where the Internet has made it possible to share information stored on computers across the world, Grid computing aims to provide access to computing power and storage capacity on geographically distributed systems. LHCb software applications must work seamlessly on the Grid allowing users to efficiently access distributed compute resources. It is essential to the success of the LHCb experiment that physicists can access data from the detector, stored in many heterogeneous systems, to perform distributed data analysis. This thesis describes the work performed to enable distributed data analysis for the LHCb experiment on the LHC Computing Grid.

LHCb: Study of the Performance of the LHCb Muon System with First LHC Data

CERN Multimedia

Cardini, A

2010-01-01

The LHCb Muon System is composed by five detection stations (M1-M5), one upstream and four downstream of the calorimeter system, equipped on the 99% of the surface with a total of 1368 Multi-Wire Proportional Chambers (MWPC). Triple-GEM detectors with digital pad readout were chosen for the innermost region of the first station thanks to their excellent performances, in particular for what concerns rate capability and radiation hardness. In order to allow a fast evaluation of the transverse momentum of muons, all detectors are required to have a high efficiency, a fast response and a good space resolution with a readout granularity that decreases with the distance from the beam axis. The detector installation phase (2006-2009) was followed by an extensive commissioning and events were acquired with pulse trigger to several millions of cosmic tracks already in the commissioning phase and are being used for the first LHC collisions.

Upgrade of the LHCb ECAL monitoring system

CERN Document Server

Guz, Yu

2015-01-01

The LHCb ECAL is a shashlik calorimeter of 6016 cells, covering 7.68 x 6.24 m$^2$ area. To monitor the readout chain of each ECAL cell, the LHCb ECAL is equipped with a LED based monitoring system. During the LHC Run I (2009-2012) it was found that the precision of the monitoring suffers from the radiation degradation of transparency of polystyrene clear fibers used to transport the LED light to the ECAL photomultipliers. In order to improve the performance of the monitoring system, and especially in view of significant increase of LHCb working luminosity foreseen after 2018, the present plastic fibers have been replaced by radiation hard quartzfi bers. The performance of the old LHCb ECAL monitoring system during LHC Run I and the design of the upgraded system are discussed here.

LHCb: full-steam strategy pays off

CERN Multimedia

CERN Bulletin

2011-01-01

LHCb looks at LHC proton collisions from a special angle. The experiment studies rare decays of the B particle to look into the physical processes that might hide new physics. Designed to operate at moderate luminosity, LHCb has been more daring for the last year and is running at conditions tougher than the nominal. The new strategy is paying off, as important physics results have just started to emerge…   Event display presented at the EPS-HEP 2011 conference showing a B0s meson decaying into a μ+ and μ- pair.  The LHCb detector was originally designed to run at moderate luminosity and low interaction pile-up. In other words, unlike the CMS and ATLAS experiments, the whole LHCb experimental set-up and data-taking infrastructure was designed to process just one proton interaction for each bunch crossing. For the last year, however, this has all been old news. A change in LHCb strategy was made possible when it became clear that the LHC was going to first i...

Use of $B \\to h^+ h^{'-}$ as control channels for the measurement of BR$(B^0_s \\to \\mu^+ \\mu^-)$ at LHC$b$

CERN Document Server

López Asamar, Elías; Ruiz Pérez, H

2011-01-01

In spite of the impressive success of the Standard Model, some theoretical and experimental facts suggest that it might not be the $final$ theory, and hence that $new$ $physics$ exists. Decays of $B$ meson are an exceptional source of observables where physics beyond the SM could lead to unambiguous effects. Indeed, measurements in this sector provide some of the first possibilities of observing effects from new physics at the LHC. This is the case of the branching ratio of the yet unobserved decay $B^0_s \\to \\mu^+ \\mu^-$. This observable is precisely predicted by the Standard Model and hence it is also very sensitive to new physics. The conception of LHC$b$ as a dedicated experiment for $B$ physics studies puts it is an outstanding position for measuring this branching ratio with respect to other experiments operating at the LHC. The measurement of the branching ratio of $B^0_s \\to \\mu^+ \\mu^-$ at LHC$b$ widely uses methods for both calibrating and normalizing independently of the Monte Carlo simulations, ba...

LHCb: The LHCb tracking concept and performance

CERN Multimedia

Rodrigues, E

2009-01-01

The LHCb tracking system is designed to reconstruct charged particle trajectories in the forward spectrometer, in view of high precision studies of CP-violating phenomena and searches for rare b-hadron decays at the LHC. The system is composed of four major subdetectors and a dedicated magnet, providing an excellent momentum resolution just above 0.4%. The tracking model is based on the innovative trajectories concept introduced by the BaBar collaboration to reconstruct and fit the tracks, and has been further developed and improved. It is now able to cope with realistic geometries and misalignments in a sophisticated, robust and detector-independent way. The LHCb tracking concept including the interplay of various complementary pattern recognition algorithms and the bi-directional Kalman fitter will be described. The current performance of the tracking, based on the latest simulations, will be presented. Recent results obtained with the first LHC beam tracks from injection tests will be discussed.

LHCb : The LHCb Turbo stream

CERN Multimedia

Puig Navarro, Albert

2015-01-01

The LHCb experiment will record an unprecedented dataset of beauty and charm hadron decays during Run II of the LHC, set to take place between 2015 and 2018. A key computing challenge is to store and process this data, which limits the maximum output rate of the LHCb trigger. So far, LHCb has written out a few kHz of events containing the full raw sub-detector data, which are passed through a full offline event reconstruction before being considered for physics analysis. Charm physics in particular is limited by trigger output rate constraints. A new streaming strategy includes the possibility to perform the physics analysis with candidates reconstructed in the trigger, thus bypassing the offline reconstruction. In the "turbo stream" the trigger will write out a compact summary of "physics" objects containing all information necessary for analyses, and this will allow an increased output rate and thus higher average efficiencies and smaller selection biases. This idea will be commissioned and developed during...

LHCb unveils new particles

CERN Multimedia

Stefania Pandolfi

2016-01-01

The LHCb collaboration announces the observation of four “exotic” particles from its analysis of the LHC data.   The LHCb experimental cavern. On 28 June, the LHCb collaboration reported the observation of three new "exotic" particles and confirmation of the existence of a fourth one in data from the LHC. These particles each appear to be formed by four quarks (the fundamental constituents of the matter inside all the atoms of the universe): two quarks and two antiquarks (that is, a tetraquark). Due to their non-standard quark content, the newly observed particles have been included in the broad category of so-called exotic particles, although their exact theoretical interpretation is still under study.            The quark model, proposed by Murray Gell-Mann and George Zweig in 1964, is considered to be the most valid scheme for the classification of hadrons (all the composite particles) that has been fou...

LHCb jet reconstruction

International Nuclear Information System (INIS)

Francisco, Oscar; Rangel, Murilo; Barter, William; Bursche, Albert; Potterat, Cedric; Coco, Victor

2012-01-01

Full text: The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than 4 X 10 32 cm -2 s -1 and the integrated luminosity reached the value of 1,02fb -1 on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test perturbative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space ηX φ and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the colorimeters are used on the LHCb experiment to create objects called particle flow objects that are used as input to anti-kt algorithm. The LHCb is specially interesting for jets studies because its η region is complementary to the others main experiments on LHC. We will present the first results of jet reconstruction using 2011 LHCb data. (author)

LHCb jet reconstruction

Energy Technology Data Exchange (ETDEWEB)

Francisco, Oscar; Rangel, Murilo [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Barter, William [University of Cambridge, Cambridge (United Kingdom); Bursche, Albert [Universitat Zurich, Zurich (Switzerland); Potterat, Cedric [Universitat de Barcelona, Barcelona (Spain); Coco, Victor [Nikhef National Institute for Subatomic Physics, Amsterdam (Netherlands)

2012-07-01

Full text: The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than 4 X 10{sup 32} cm{sup -2}s{sup -1} and the integrated luminosity reached the value of 1,02fb{sup -1} on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test perturbative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space {eta}X {phi} and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the colorimeters are used on the LHCb experiment to create objects called particle flow objects that are used as input to anti-kt algorithm. The LHCb is specially interesting for jets studies because its {eta} region is complementary to the others main experiments on LHC. We will present the first results of jet reconstruction using 2011 LHCb data. (author)

LHCb: LHCb VELO TELL1 Algorithms

CERN Multimedia

Hennessy, Karol

2012-01-01

The LHCb experiment is dedicated to searching for New Physics effects in the heavy flavour sector, precise measurements of CP violation and rare heavy meson decays. Precise tracking and vertexing around the interaction point is crucial in achieving these physics goals. The LHCb VELO (VErtex LOcator) silicon micro-strip detector is the highest precision vertex detector at the LHC and is located at only 8 mm from the proton beams. The high spatial resolution (up to 4 microns single hit precision) is obtained by a complex chain of processing algorithms to suppress noise and reconstruct clusters. These are implemented in large FPGAs, with over one million parameters that need to be individually optimised. Previously we presented a novel approach that has been developed to optimise the parameters and integrating their determination into the full software framework of the LHCb experiment. Presently we report on the experience gained from regular operation of the calibration and monitoring software with the collisio...

LHCB : The upgraded LHCb RICH detector: status and perspectives

CERN Multimedia

Cardinale, Roberta

2015-01-01

The LHCb experiment is designed to perform high-precision measurements of CP violation and search for New Physics using the enormous flux of beauty and charmed hadrons produced at the Large Hadron Collider (LHC). The two RICH detectors installed in LHCb have performed successfully during the 2010-2012 data taking period. The data from these detectors were essential to most of the physics results published by LHCb. In order to extend its potential for discovery and study of new phenomena it is planned to upgrade the LHCb experiment in 2018 with a 40MHz readout and a much more flexible software-based triggering system. This would increase the readout rate and occupancies for the RICH detectors. The RICH detector will require new photon detectors and modifications of the optics of the upstream RICH detector. Tests of the complete opto-electronic chain have been performed during testbeam sessions in autumn 2014. The status and perspectives of the RICH upgrade project will be presented.

The LHCb Turbo stream

Energy Technology Data Exchange (ETDEWEB)

Puig, A., E-mail: albert.puig@cern.ch

2016-07-11

The LHCb experiment will record an unprecedented dataset of beauty and charm hadron decays during Run II of the LHC, set to take place between 2015 and 2018. A key computing challenge is to store and process this data, which limits the maximum output rate of the LHCb trigger. So far, LHCb has written out a few kHz of events containing the full raw sub-detector data, which are passed through a full offline event reconstruction before being considered for physics analysis. Charm physics in particular is limited by trigger output rate constraints. A new streaming strategy includes the possibility to perform the physics analysis with candidates reconstructed in the trigger, thus bypassing the offline reconstruction. In the Turbo stream the trigger will write out a compact summary of physics objects containing all information necessary for analyses. This will allow an increased output rate and thus higher average efficiencies and smaller selection biases. This idea will be commissioned and developed during 2015 with a selection of physics analyses. It is anticipated that the turbo stream will be adopted by an increasing number of analyses during the remainder of LHC Run II (2015–2018) and ultimately in Run III (starting in 2020) with the upgraded LHCb detector.

LHCb: Magnetic Distortion Measurement System of the LHCb RICH2 Detector

CERN Multimedia

Storaci, B

2007-01-01

The LHCb experiment at the CERN LHC collider is optimized for the study of CP violation and rare B-decays. Two Ring Imaging Cherenkov detectors provide particle identification in the momentum range 1-100 GeV/c

LHCb experiment magnets

CERN Multimedia

Maximilien Brice

2004-01-01

The leading members of the LHCb magnet project, from left to right: Pierre-Ange Giudici, who organized and supervised the industrial production of the coils; Marcello Losasso, who performed the 3D calculations to optimise the magnetic field; Olivier Jamet, responsible for the 3D design; Jean Renaud, in charge of the magnet assembly, and Wilfried Flegel, project leader. The LHCb detector will investigate matter-antimatter differences in B mesons at the LHC. The coils of the detector's huge dipole magnet are seen here in April 2004.

LHCb

CERN Multimedia

Frank, M; Neufeld, N; Ruf, T; Batista lopes, J C; Martinelli, M; Perazzini, S; Stagni, F; Dorigo, M; Di canto, A; Nolte, N S; Battista, V; Birnkraut, A; Uwer, U; Zhelezov, A; Han, X; Kolpin, M; Le gac, R; Wormser, G H M; Barsuk, S; Maurice, E A; Renaudin, V; Benayoun, M C; Polci, F; Watson, N; Souza covacich, D; Barlow, R J; Pastore, A; Lax, I; Peco, G; Bortolotti, D; Vilaca pinheiro soares, M; Leflat, A; Krokovnyi, P; Gibson, V; Ward, D R; Doherty, F; Longstaff, I R; Dean, C T; Traill, M T; Fiorini, M; Campana, P; Saputi, A; Ciambrone, P; Michielin, E; Morello, M J; Carboni, G; Van veghel, M; Raven, G H; Witek, M; Ossowska, A; Fiutowski, T A; Dzhelyadin, R; Stenyakin, O; Popov, A; Wang, J; Artuso, M; Rudolph, M S; Batsukh, B; Mendes gandelman, M; Garrido beltran, L; Rosello canal, M D M; Luengo alvarez, S; Picatoste olloqui, E; Sanchez gonzalo, D; Wilson, F F; Nandakumar, R; Wark, H M; Hecker, M; Kochenda, L; Petrolini, A; Saitta, B; Belin, S; Calvi, M; Pessina, G E; Shao, B; Zeng, M; Sun, J; Kechadi, M T; Zheng, Y; Lyu, X; Polukhina, N; Gromov, S; Seco miguelez, M A; Vazquez regueiro, P; Fernandez prieto, A; Buytaert, J; Camilleri, L L; Lindner, R; Corti, G; Ponce, S; Coco, V; Schwemmer, R A; Ravonel salzgeber, M; Gruber, L; Seyfert, P; Stahl, S; De aguiar francisco, O A; Chrzaszcz, M J; Voneki, B; Masson, G A; Rodrigues cavalcante, A B; Marino, P; Vollhardt, A; Zhukov, V; Haas, T; Leroy, O; Mancinelli, G; Hachon, F; Stocchi, A; Lisovskyi, V; Naik, P P; Richards, S E; John, M; Nandi, A K; Palano, A; Iarocci, E; Sciubba, A; Auriemma, G; Shapoval, I; Philippov, S; Petrov, A; Basiladze, S; Kozachuk, A; Berdiouguine, A; Weisser, C N; Graziani, G; Anderlini, L; Evans, H M; Garsed, P J; Eklund, L M; Alexander, M T; Tellarini, G; Capon, G; Bloise, C; Santimaria, M; Lucchesi, D; Bedeschi, F; Van beuzekom, M G; Berkien, A; Giubega, L; Koliiev, S; Volkov, V; Sokoloff, M D; Pappenheimer, C A; Da silva, C L; Blusk, S R; Ely, S E; Wilkinson, M K; Marangotto, D; Santana rangel, M; Camboni, A; Orellana martin, D; Niess, V; Franek, B; Loveridge, P; Hutchcroft, D E; Shears, T G; Smith, A N; Whitley, M D A; Marshall, P J; Sutcliffe, W L; Sagidova, N; Vznuzdaev, M; Aidala, C A; Sun, Y; Fontana, M; Mazza, R; Cheng, J; Huang, Y; Luo, Y; Hushchyn, M; Hess, M; Perez trigo, E; Borsato, M; Crocombe, A C; Needham, M D; Petrucci, S; Jacobsson, R; Khanji, B; Mathe, Z; Rauschmayr, N; Pearce, A; Byczynski, W; Frei, R; Nakada, T; Nguyen mau, C; Pinard, A; Schulte, S; Bernet, R; Serra, N; Bezshyiko, I; Wang, Y; Kirn, T; Guth, A; Kruse, F; Bauer, C; Dembinski, H P; Braun, S A; Piucci, A; Kecke, M; Minard, M; Aslanides, E; Barrand, G C; Lefrancois, J; Chamont, D; Usachov, A; Billoir, P; Del buono, L; Ben haim, E; Bertholet, E; Plews, J P; Velthuis, J J; Dalseno, J P; Borghi, S; Appleby, R B; Hombach, C; Sarpis, G; Capriotti, L; Hilton, M; Pullen, H L; Galli, D; Garibaldi, F; Shatalov, P; Nikitin, N; Williams, J M; Boettcher, T J; Smith, J W; Williams, I; Spradlin, P M; Calabrese, R; Neri, I; Skiba, I; Bencivenni, G; Lanfranchi, G; Simi, G; Ceelie, L; Van petten, O R; Pellegrino, A; Roeland, E; Dendek, A M; Obraztsov, V; Stone, S L; Olejnik, L; Petruzzo, M; Hicheur, A; Silva de oliveira, L G; Lebsir, B; Golutvin, A; Humair, T; Moise, R; Bartolini, M; Gao, Y; Liu, X; Zhu, X; Milanes carreno, D A; Rodriguez lopez, J A; Borisyak, M; Szymanski, M P; Krasilnikova, I; Meinert, N; Adeva andany, B; Hernando morata, J A; Sanmartin sedes, B; Millard, E J; Webster, J; Correa dos reis, A; Gomes dos santos neto, A; Brarda, L; D'ambrosio, C; Ferro-luzzi, M; Gys, T; Schopper, A; Teubert, F; Wyllie, K; Couturier, B; Kristic, R; Fournier, C; Haen, C D; Ciezarek, G M; Durante, P; Lupton, O J; Pais, P R; Kirsebom, V S; Straumann, U D; Mueller, K; Buonaura, A; Spaan, B; Albrecht, J; Ekelhof, R J; Shires, A; Schlupp, M; Demmer, M; Muller, J; Schmelzer, T; Lindemann, T; Bachmann, S; Cachemiche, J; De abreu barbosa coelho, J; Tou, D Y; Calladine, R B; Pomery, G J; Bhasin, S; De capua, S; Burr, C M; Topp-joergensen, S; Bjorn, M; Patrignani, C; Vagnoni, V M; Kandybei, S; Shekhtman, L; Jones, C R; Cliff, H V; Sirendi, M; Tully, A M; Soler jermyn, P F; Luppi, E; Vecchi, S; De simone, P; Rotondo, M; Satta, A; Merk, M; Jans, E; Krzemien, W J; Merkin, M; Vasilyev, A; Durham, J M; Poliakova, M; Merli, A; Souza de paula, B; Pinto eboli, O J; Vilasis cardona, J; Ajaltouni, Z; Quintana, B J; Casse, G; Hennessy, K P; Rinnert, K; Dornan, P J; Patel, M; Savidge, T E; Baker, S K; Spiridenkov, E; Makarenkov, G; Filimonov, A; Stepanova, M; Jawahery, A; Parker, W C; Belloli, N; Gong, G; Zhang, W; Gan, Y; Ruiz vidal, J; Raab, N V; Huang, W; Cai, H; Bian, L; Waldi, R G; Gershon, T J; Playfer, S M; Gizdov, K; Marques de miranda, J; De bediaga hickman, I A; Marujo da silva, F; Silveira mizher, A J; Dijkstra, H; Van herwijnen, E; Forty, R; Gaspar, C; Hatch, M; Jost, B; Piedigrossi, D; Alessio, F; Vazquez gomez, R; Johnson, D; Pisani, F; Tran, M; Repond, J; Macko, V; Yu, J; Heister, A; Tekampe, T; Hofmann, W; Schmelling, M T; Rummel, C; Machefert, F; Fleuret, F D; Bossu, F; Lazzeroni, C; Zarebski, K A; Saunders, D M; Mcnab, I A; Maguire, K S; Dutta, D; Pinci, D; Shevchenko, O; Gushchin, E; Nogay, A; Belyaev, I; Semennikov, A; Danilina, A; Gorelov, I V; Haines, S C; Delaney, B; Bozzi, C; Sciascia, B; Fantechi, R; Groep, D L; Onderwater, C; Glab, S M; Idzik, M A; Firlej, M; Guzik, Z; Maciuc, F; Pirghie, A; Pugatch, V; Okhrimenko, O; Belous, K; Ostankov, A; Meadows, B; Niu, N; Salazar de paula, L; Polycarpo macedo, E; Lefevre, R P; Websdale, D M; Maev, E; Mattioli, K R; Hamilton, B K; Lai, A; Liu, B; Jiang, F; Cang, J; Vagner, A; Saborido silva, J J; Muheim, F; Collins, P; Schneider, T H; Granado cardoso, L A; Valat, S J; Dordei, F; Karacson, M; Schneider, O P; Haefeli, G J; Hopchev, P H; Maurin, B E; Redi, F L; Stefko, P; Wang, Z; Schael, S; Knopf, J M; D'argent, P; Pietrzyk, B; Drancourt, C; T'jampens, S; Duval, P; Cogan, J; Beigbeder-beau, C; Slater, M W; Farley, N; Williams, T; Adinolfi, M; Prouve, C; Parkes, C J; Gronbech, P D; Hancock, T H; Rollings, A P; Zucchelli, S; Bocci, V; Satriano, C; Golubkov, D; Kvaratskheliya, T; Egorychev, V; Bondar, A; Eydelman, S; Kuzmin, A; Krokovny, P; Veltri, M; Bettler, M O; Schiller, M T; Felici, G; Morandin, M; Doets, M; Schimmel, A; Kraan, M J; Vink, W; Vitkovskiy, A; Szumlak, T; Straticiuc, M; Guz, Y; Artamonov, A; Rodrigues figueiredo, E M; Xing, Z; Beiter, A; Lopes, H J; Gascon, D; Casajus ramo, A; Trenado garcia, J; Golobardes ribe, E; Alfonso albero, A; Deschamps, O; Cooke, P A; Wormald, M; Stefkova, S; Tilley, M J; Newcombe, R; Levitskaya, O; Golovtcov, V; Semenchuk, G; Roth, J D; Dean, W; Matteuzzi, C; Martinez vidal, F; Henry, L; Garcia martin, L M; Qin, J; Xu, Q; Didenko, S; Gallas torreira, A A; Chobanova, V G; Ramos pernas, M; Poluektov, A; Latham, T E; Blake, T; Eisenhardt, S; Cattaneo, M; Chadaj, B; Charpentier, P; Closier, J; Jamet, O; Lacarrere, D; Schmidt, B; Clemencic, M; Thomas, E P C; Schindler, H; Faerber, C; Matev, R I; Colombo, T; Muller, D; Bay, A; Gonzalez, R; Girard, O G; Atzeni, M; Xiao, D; Mueller, V; Hansmann-menzemer, S; Nikodem, T; Leverington, B D; Ghez, P; Xu, Z; Tsaregorodtsev, A; Serrano, J; Schune, M; Jouvin, M; Robbe, P A; Duarte, O; Balagura, V; Vom bruch, D; Rademacker, J H; Kariuki, J M; Lafferty, G D; Gersabeck, M; Harnew, N; Malde, S S; Gruberg cazon, B R; Marconi, U; Valenti, G; Carbone, A; Betti, F; Santacesaria, R; Kravchuk, L; Maltsev, T; Gobel burlamaqui de mello, C; Wotton, S; Garra tico, J; Baldini, W; Tomassetti, L; Andreotti, M; Siddi, B G; Palutan, M; Tagnani, D; Busetto, G; Walsh, J J; Punzi, G; Santovetti, E; Berbee, E M; Lesiak, T; Wiechczynski, J P; Baszczyk, M K; Muryn, B; Ukleja, A; Batozskaya, V; Cojocariu, L N; Shapkin, M; Romanovskiy, V; Luchinskii, A; Huard, Z C; Otalora goicochea, J M; Graciani diaz, R; Grauges pous, E; Coquereau, S; Monteil, S; Chanal, H P; Cogneras, E R D; Vert, P; Puech, G; Easo, S; Bowcock, T; Egede, U; Neustroev, P; Kashchuk, A; Petrov, G; Fontanelli, F; Cadeddu, S; Cogoni, V; De oyanguren campos, M A; Mcnulty, R C; Ratnikov, F; He, J; Li, P; Baryshnikov, F; Shmanin, E; Viemann, H M; Santamarina rios, C; Mathad, A; Loh, D J; Costa sobral, C M; Cowan, G A; Smith, I T; Kos antunes maciel, A; Santana, R; Pepe-altarelli, M; Dumps, R; Frei, C M; Roy, L; De bruyn, K A M; Tolk, S; Brodski, M; Sciuccati, A; Fernandez declara, P; Blanc, F H; Graverini, E; Mukherjee, M; Yin, H; Voss, H H; Moch, M; Decamp, D L; Arnau romeu, J; Breton, D R; Charlet, D M; Amhis, Y S; Buchanan, E; Hidalgo charman, R; Harris, F J; Hill, D; Hadavizadeh, T B; De serio, M; Martellotti, G; Dovbnya, A; Kutuzov, V; Zhivaeva, L; Bogdanova, G; Vorobyev, V; Kaminer, I E; Bizzeti, A; Passaleva, G; Lovell, G H; Smeaton, J G; Pappalardo, L L; Anelli, M; Amerio, S; Lupato, A; Sluijk, T; Munneke, B; Mulder, M; Dufour, L; Dorosz, P A; Melnychuk, D; Grecu, A T; Pirghie, C; Yushchenko, O; Likhoded, A; Soldatov, M; Schreiner, H F; Mountain, R J; Skwarnicki, T; Kelsey, M J; Venkateswaran, A; Yao, Y; Neri, N; Amato, S F; Calvo gomez, M G; Gonzalez bano, C; Henrard, P; Perret, P; Magne, M M; Maratas, J; Gazzoni, G; Ricciardi, S; Gamet, R; Noor, A; Liles, M M; Pritchard, A A; Cunliffe, S T; Alkhazov, G; Trofimov, V; Shapkin, G; Smirenin, Y; Yang, Z; Cardini, A; Brundu, D; Gong, H; Yang, Z; Mazorra de cos, J; Sanchez mayordomo, C; Evangelho vieira, D; Pazos alvarez, A; Kreps, M; Clarke, P; Gabriel, E P M

2002-01-01

The LHCb detector is designed to study CP violation and other rare phenomena in decays of hadrons with heavy flavours, in particular $ \\rm B_s$ mesons. Interest in CP violation comes not only from elementary particle physics but also from cosmology, in order to explain the dominance of matter over antimatter observed in our universe, which could be regarded as the largest CP violation effect ever seen. The LHCb experiment will improve significantly results from earlier experiments both quantitatively and qualitatively, by exploiting the large number of different kinds of b hadrons produced at LHC. This is done by constructing a detector which has \\begin{enumerate} \\item Good trigger efficiencies for b-hadron final states with only hadrons, as well as those containing leptons. \\item Capability of identifying kaons and pions in a momentum range of $\\sim 1$ to above 100 GeV/$c$. \\item Excellent decay time and mass resolution. \\end{enumerate} The LHCb spectrometer shown in the figure consists of the following det...

LHCb: Beam and Background Monitoring and the Development of an Online Condition Analysis Tool for the LHCb Experiment at CERN

CERN Multimedia

Alessio, F

2010-01-01

The LHCb experiment has been taking data since more than half a year at the LHC, recording events from collisions at the highest energy ever achieved. For its physics purposes in the sector of CP violation, the experiment will record data with the best precision achievable. An online and offline beam and background monitoring became therefore essential to understand the performance of the LHC accelerator at CERN, to monitor and study the behavior of the background around the LHCb experiment and to optimize the experimental conditions. During my second year as a Doctoral Student at CERN, I have been working on the timing and readout control as well as on the online Beam, Background, and Luminosity Monitoring of the LHCb experiment in the frame of the LHCb Online group. The group is responsible for the complete data acquisition of the LHCb experiment, from the Front-End Electronics (FEE) to the storage of the data for offline analysis, including the Timing and Fast Control (TFC) system. The latter controls and...

Fixed target measurements at LHCb for cosmic rays physics

CERN Document Server

AUTHOR|(CDS)2069608

2018-01-01

The LHCb experiment has the unique possibility, among the LHC experiments, to be operated in fixed target mode, using its internal gas target. The energy scale achievable at the LHC, combined with the LHCb forward geometry and detector capabilities, allow to explore particle production in a wide Bjorken-$x$ range at the $\\sqrt {s_{NN}} ~$ ~ 100 GeV energy scale, providing novel inputs to nuclear and cosmic ray physics. The first measurement of antiproton production in collisions of LHC protons on helium nuclei at rest is presented. The knowledge of this cross-section is of great importance for the study of the cosmic antiproton flux, and the LHCb results are expected to improve the interpretation of the recent high-precision measurements of cosmic antiprotons performed by the space-borne PAMELA and AMS-02 experiments.

Radiation Damage in the LHCb VELO

CERN Multimedia

Harrison, Jon

2011-01-01

The VErtex LOcator (VELO) is a silicon strip detector designed to reconstruct particle tracks and vertices produced by proton-proton interactions near to the LHCb interaction point. The excellent track resolution and decay vertex separation provided by the VELO are essential to all LHCb analyses. For the integrated luminosity delivered by the LHC up to the end of $2011$ the VELO is exposed to higher particle fluences than any other silicon detector of the four major LHC experiments. These proceedings present results from radiation damage studies carried out during the first two years of data taking at the LHC. Radiation damage has been observed in all of the $88$ VELO silicon strip sensors, with many sensors showing evidence of type-inversion in the highest fluence regions. Particular attention has been given to the two \

Novel strategies at Lhcb for particle identification

CERN Document Server

Ferrari, Fabio

2017-01-01

The LHCb experiment at the Large Hadron Collider (LHC) is performing high precision measurements in the avour sector. An excellent performance of the particle identication (PID) detectors as well as the development of new data taking techniques are of fundamental importance in order to cope with increasingly harder challenges posed by the LHC Run 2. The approach of data-driven calibration of particle identication performance at LHCb has changed significantly from Run 1 to Run 2 and calibration samples are now selected directly in the LHCb high-level trigger. This change of data-taking paradigm enables larger calibration samples with respect to Run 1 to be collected, giving access to low-level detector informations useful for studies of systematic effects, while retaining the same (or improving) the PID performances observed Run 1.

LHCb: LHCb Muon System Performance at High Luminosity

CERN Multimedia

Pinci, D

2013-01-01

The LHCb detector was conceived to operate with an average Luminosity of $2 \\times 10^{32}$ cm$^{-2}$ s$^{-1}$. During the last year of LHC run, the whole apparatus has shown to be able to perfectly acquire and manage data produced at a Luminosity as high as $4 \\times 10^{32}$ cm$^{-2}$ s$^{-1}$. In these conditions, all sub-detectors operated at average particle rates higher than the design ones and in particular the Multi-Wire Proportional Chambers equipping the Muon System had to sustain a particle rate as high as 250 kHz/cm$^{2}$. In order to study the possibility of increasing the Luminosity of operation of the whole experiment several tests were performed. The effective beam Luminosity at the interaction point of LHCb was increased in several steps up to $10^{33}$ cm$^{-2}$ s$^{-1}$ and in each step the behavior of all the detectors in the Muon System was recorded. The data analysis has allowed to study the performance of the Muon System as a function of the LHC Luminosity and the results are r...

Job prioritization in LHCb

CERN Document Server

Castellani, G

2007-01-01

LHCb is one of the four high-energy experiments running in the near future at the Large Hadron Collider (LHC) at CERN. LHCb will try to answer some fundamental questions about the asymmetry between matter and anti-matter. The experiment is expected to produce about 2PB of data per year. Those will be distributed to several laboratories all over Europe and then analyzed by the Physics community. To achieve this target LHCb fully uses the Grid to reprocess, replicate and analyze data. The access to the Grid happens through LHCb's own distributed production and analysis system, DIRAC (Distributed Infrastructure with Remote Agent Control). Dirac implements the ‘pull’ job scheduling paradigm, where all the jobs are stored in a central task queues and then pulled via generic grid jobs called Pilot Agents. The whole LHCb community (about 600 people) is divided in sets of physicists, developers, production and software managers that have different needs about their jobs on the Grid. While a Monte Carlo simulation...

The LHCb VELO (VErtex LOcator) and the LHCb VELO upgrade

International Nuclear Information System (INIS)

Collins, P.

2013-01-01

LHCb is a forward spectrometer experiment dedicated to the study of new physics in the decays of beauty and charm hadrons produced in proton collisions at the Large Hadron Collider (LHC) at CERN. The VErtex LOcator (VELO) is the silicon detector surrounding the LHCb interaction point. The beauty and charm hadrons are identified through their flight distance in the Vertex Locator (VELO), and hence the detector is critical for both the trigger and the offline physics analyses. The sensors, which have an inner radius of ∼7mm from the beam axis at the edge, and the first sensitive strips at a radius of ∼8.2mm are exposed to maximum radiation doses of ∼0.6×10 14 1MeVn eq /cm 2 per integrated luminosity of fb −1 . The performance of the VELO during the first two years of LHC running is described, together with the methods used to monitor radiation damage. The detector so far shows no significant performance degradation, however many interesting effects have been observed in the sensors, including a coupling of charge to the second metal routing line layer after irradiation. In 2018 the VELO will be upgraded together with the rest of the LHCb detector to a 40 MHz readout. The modules together with their front end electronics will be completely replaced with a radiation hard system capable of driving the signals out at the required rates. The current status of the R and D for the LHCb VELO Upgrade is outlined.

LHCb: FPGA-based, radiation-tolerant on-detector electronics for the upgrade of the LHCb Outer Tracker Detector

CERN Multimedia

Vink, W

2013-01-01

The LHCb experiment studies B-decays at the LHC. The Outer Tracker straw tubes detects charged decay particles. The on-detector electronics will be upgraded to be able to digitize and transmit drift-times at every LHC crossing without the need for a hardware trigger. FPGAs have been preferred to application-specific integrated circuits to implement dead-time free TDCs, able to transmit data volumes of up to 36 Gbits/s per readout unit, including the possibility of performing zero suppression. Extensive irradiation tests have been carried out to validate the usage of field-programmable devices in the hostile environment of the LHCb tracking system.

Highlights from the LHCb ion physics program

International Nuclear Information System (INIS)

Schmelling, Michael

2017-01-01

Following the successful participation of LHCb in the 2013 proton-lead run of the LHC, in 2015 the collaboration decided to further extend its physics program to study also lead-lead collisions and fixed target interactions. These proceedings discuss the physics reach of the detector and the first results from the LHCb ion physics and fixed target program. (paper)

LHCb: Measurement of $b$-hadron lifetimes at LHCb

CERN Multimedia

Amhis, Y

2014-01-01

Lifetimes are among the most fundamental properties of elementary particles. Precision Measurements of $b$-hadron lifetimes are an important tool to test theoretical models such as HQET. These models allow to predict various observables related to B-mixing. Using data collected during Run 1 at the LHC, LHCb measured the lifetime of B-decays including a $J/\\psi$ in the final state.

Direct search for Higgs boson in LHCb

CERN Document Server

Currat, C

2001-01-01

The LHCb detector is a forward one-arm spectrometer to precision measurements of CP violation in the B-meson systems. The motivation of the present work is to assess the potential of LHCb to observe a Standard Model (SM) Higgs signal. The recent results obtained at LEP give a hint of a SM Higgs boson with a mass mH = 115.0 +1.3 –0.9 GeV/c2 with a statistical significance of 2.9 standard deviations. Because of the high longitudinal boost encountered by the products in the pp collisions at LHC, a significant fraction (~30%) of light Higgs (mH = 115 GeV/c2) are produced in the LHCb acceptance 1.8 < h < 4.9. These facts potentially place LHCb in the race for the observation of the SM Higgs. Given a relatively low running luminosity of 2 x 1032 cm-2s-1- compared to the nominal 1034 cm-2s-1 at LHC and a limited geometrical acceptance, we have shown that the channels accessible to LHCb are H + W± Z0 b`b + l± X for Higgs masses in the range 100-130 GeV/c2. This work pioneered a setup for the pro...

6 March 2013 - Committee for Employment and Learning, Northern Ireland Legislative Assembly, United Kingdom of Great Britain and Northern Ireland in the LHC tunnel and visiting the LHCb experiment at LHC Point 8. Director for Accelerators and Technology S. Myers with Vice-Chair T. Buchanan.

CERN Multimedia

Anna Pantelia

2013-01-01

6 March 2013 - Committee for Employment and Learning, Northern Ireland Legislative Assembly, United Kingdom of Great Britain and Northern Ireland in the LHC tunnel and visiting the LHCb experiment at LHC Point 8. Director for Accelerators and Technology S. Myers with Vice-Chair T. Buchanan.

The LHCb RICH system: current detector performance and status of the upgrade program

CERN Document Server

Fiorini, Massimiliano

2016-01-01

LHCb is a precision experiment devoted to the study of CP violation and rare decays of b and c quarks, and to the search for new physics beyond the Standard Model at the Large Hadron Collider (LHC) at CERN. The Ring-Imaging Cherenkov (RICH) system is a key component of the LHCb experiment: it consists of two RICH detectors that provide charged particle identification over a wide momentum range (2-100 GeV/c) and angular acceptance (15-300 mrad). The LHCb RICH system has been performing extremely well during Run 1 and is providing the LHCb experiment also in Run 2 with a robust, reliable and precise particle identification system. Performance of the RICH detectors measured from data will be presented, with special reference to its dependence on calibration parameters and event multiplicities. The LHCb experiment is preparing for an upgrade during the second LHC long shutdown (2019-2020) in order to fully exploit the LHC flavour physics potential. A five-fold increase in instantaneous luminosity is foreseen reac...

Low-$p_T$ dimuon triggers at LHCb in Run 2

CERN Document Server

Dettori, Francesco; Prisciandaro, Jessica

2017-01-01

The LHCb trigger efficiency for strange hadron decays to final states containing dimuon pairs was substantially improved for Run 2 of the LHC. This note describes the updated strategy, and its impact on the LHCb rare strange physics programme.

Electroweak boson production at LHCb

CERN Document Server

Sestini, Lorenzo

2018-01-01

The LHCb experiment offers a complementary phase space to ATLAS and CMS to study electroweak processes, thanks to the forward acceptance and the large bandwidth of the trigger allowing low energy thresholds. For this reason electroweak measurements at LHCb can provide unique constraints to the Parton Distribution Functions. Moreover these measurements can be used to validate reconstruction techniques. In these proceedings the latest measurements on W and Z bosons production performed during the LHC Run I and Run II data taking are presented.

LHCb: Beam and Background Monitoring and the Upgrade of the Timing and Fast Control System of the LHCb experiment at CERN

CERN Multimedia

Alessio, F

2009-01-01

The LHCb experiment at CERN is preparing for first real data taking, foreseen by the end of the year 2009 with the start-up of the LHC. A large amount of work of commissioning, tests and improvements of the full detector has been done in order to optimize its performance. During my first year as a Doctoral Student at CERN, I have been working on the timing and readout control of the LHCb experiment in the frame of the LHCb Online group. The group is responsible for the full data acquisition of the LHCb experiment, from the Front-End Electronics (FEE) to the storage of the data for offline analysis, as well as the Timing and Fast Control (TFC) system. The latter controls and distributes centrally timing and trigger information, as well as synchronous and asynchronous commands to the readout system. It is also responsible for receiving and adjusting the bunch and orbit clocks of the LHC machine and distributing it to the electronics of the whole experiment. It is of vital importance to assure that the timing o...

The upgrade of the LHCb trigger system

CERN Document Server

INSPIRE-00259834; Fitzpatrick, C.; Gligorov, V.; Raven, G.

2014-10-20

The LHCb experiment will operate at a luminosity of $2\\times10^{33}$ cm$^{-2}$s$^{-1}$ during LHC Run 3. At this rate the present readout and hardware Level-0 trigger become a limitation, especially for fully hadronic final states. In order to maintain a high signal efficiency the upgraded LHCb detector will deploy two novel concepts: a triggerless readout and a full software trigger.

The LHCb RICH silica aerogel performance with LHC data

CERN Multimedia

Perego, D L

2010-01-01

In the LHCb detector at the Large Hadron Collider, powerful charged particle identification is performed by Ring Imaging Cherenkov (RICH) technology. In order to cover the full geometric acceptance and the wide momentum range (1-100 GeV/c), two detectors with three Cherenkov radiators have been designed and installed. In the medium (10-40 GeV/c) and high (30-100 GeV/c) momentum range, gas radiators are used (C4F10 and CF4 respectively). In the low momentum range (1 to a few GeV/c) pion/kaon/proton separation will be done with photons produced in solid silica aerogel. A set of 16 tiles, with the large transverse dimensions ever (20x20 cm$^2$) and nominal refractive index 1.03 have been produced. The tiles have excellent optical properties and homogeneity of refractive index within the tile of ~1%. The first data collected at LHC are used to understand the behaviour of the RICH: preliminary results will be presented and discussed on the performance of silica aerogel and of the gas radiators C4F10 and CF4.

Results on LHCb Data Challenge 06

CERN Document Server

Santinelli, R

2007-01-01

The Large Hadron Collider (LHC) at CERN is the front end machine for the high-energy physics (HEP) and will start operating in 2007. The expected amount of data that will be produced and that has to be analyzed is unprecedented. LHCb, one of the large experiments at the LHC, moved toward grid technologies to cope with their requirements. The integration of the experiment specific computing framework into the underlying production grid has not been always effortless. Grid technologies represent the only way to deal with HEP today’s computing needs. The complexity of these new techniques brought the need of designing, for each experiment, a model for processing and analyzing the data. The 2006 data challenge – LHCb DC06 – is the latest of a series of big activities on the Grid and represents the final benchmark before the real data taking. Its goal is validating the computing model and the computing framework of LHCb but it is also the last opportunity for exercising the whole simulation chain on WLCG res...

No mission is impossible for LHCb

CERN Multimedia

CERN Bulletin

2011-01-01

Time: 01:37:51 am, 3 October, 2011. The LHC is producing million collisions per second in its detectors. But at that time, one collision is “more special” than the others in the LHCb detector: the milestone of 1 inverse femtobarn of luminosity is surpassed. What was considered as “mission impossible” at the beginning of the year is now “mission accomplished”.   Mike Lamont (Operations Group Leader), Pierluigi Campana (LHCb Spokesperson), Steve Myers (Director for Accelerators and Technology), and Paul Collier (Head of the Beams Department) celebrate the LHCb milestone. LHCb is the CERN experiment specialising in the study of b-quarks, whose properties and behaviour are likely to provide physicists with important hints on several physics processes, including some new physics. “One inverse femtobarn of luminosity corresponds to about seventy billion b-quark pairs decayed in the LHCb detector,” explains Pierluigi Cam...

LHCb: Measurement of the $\\gamma$ angle from tree decays at LHCb

CERN Multimedia

Martín Sánchez, Alexandra

2011-01-01

An overview of plans for the measurement of $\\gamma$ at the LHCb experiment will be shown. The $\\gamma$ angle is the parameter of the CKM unitary triangle that is known least well. The LHCb experiment at the CERN LHC aims to perform precision b-physics and CP violation measurements, including improving the knowledge of $\\gamma$. Focus will be put on methods where B mesons decay at the tree level, within the Standard Model framework. The early data recorded by the experiment, from $pp$ collisions at $\\sqrt{s}$ = 7 TeV, has allowed observations of the first signals of the B decay modes that will be used to perform this measurement.

Time-dependent measurements of the CKM angle $\\gamma$ at LHCb

CERN Document Server

Gligorov, Vladimir Vava

2011-01-01

The startup of the LHC opens many new frontiers in precision flavour physics, in particular expanding the field of precision time-dependent CP violation measurements to the $B^0_s$ system. This contribution reviews the status of time-dependent measurements of the CKM angle $\\gamma$ at the LHC's dedicated flavour physics experiment, LHCb. Particular attention is given to the measurement of $\\gamma$ from the decay mode $B^0_s \\to D^{\\pm}_s K^{\\mp}$, a theoretically clean and precise method which is unique to LHCb. The performance of the LHCb detector for this and related modes is reviewed in light of early data taking and found to be close to the nominal simulation performance, and the outlook for these measurements in 2011 is briefly touched on.

Supervision de l'écriture de données de l'expérience LHCb

CERN Document Server

Fanane, C

2008-01-01

Located on the French-Swiss border near Geneva, CERN is one of the world's biggest scientific laboratories in particles physics, home for both theoretical and experimental research. At CERN the world's most powerful particle collider was build and is now being commissioned, the Large Hadron Collider (LHC). The LHC, designed as a ring collider, is hosting several big physics experiments,including the Large Hadron Collider beauty experiment (LHCb). The LHC, together with the LHCb experiment are expected to go officially into operation in the middle of September 2008. It is precisely in this commissioning phase of the LHCb detector that my internship between April and September 2008 takes place. The aim of my project is to implement a monitoring system for the event data writing of physics data coming from the LHCb DAQ System. Event data writing is the last stage of the LHCb DAQ System and is a crucial part for the success of the experiment. It is a fully redundant distributed system composed of various tasks an...

B Physics at LHCb

CERN Document Server

Pepe Altarelli, Monica

2008-01-01

LHCb is a dedicated detector for b physics at the LHC. In this article we present a concise review of the detector design and performance together with the main physics goals and their relevance for a precise test of the Standard Model and search of New Physics beyond it.

LHCb: Control and Monitoring of the Online Computer Farm for Offline processing in LHCb

CERN Multimedia

Granado Cardoso, L A; Closier, J; Frank, M; Gaspar, C; Jost, B; Liu, G; Neufeld, N; Callot, O

2013-01-01

LHCb, one of the 4 experiments at the LHC accelerator at CERN, uses approximately 1500 PCs (averaging 12 cores each) for processing the High Level Trigger (HLT) during physics data taking. During periods when data acquisition is not required most of these PCs are idle. In these periods it is possible to profit from the unused processing capacity to run offline jobs, such as Monte Carlo simulation. The LHCb offline computing environment is based on LHCbDIRAC (Distributed Infrastructure with Remote Agent Control). In LHCbDIRAC, job agents are started on Worker Nodes, pull waiting tasks from the central WMS (Workload Management System) and process them on the available resources. A Control System was developed which is able to launch, control and monitor the job agents for the offline data processing on the HLT Farm. This control system is based on the existing Online System Control infrastructure, the PVSS SCADA and the FSM toolkit. It has been extensively used launching and monitoring 22.000+ agents simultaneo...

ALICE & LHCb: refinements for the restart

CERN Multimedia

2009-01-01

Following the previous issue, the Bulletin continues its series to find out what the six LHC experiments have been up to since last September, and how they are preparing for the restart. Previously we looked at CMS and ATLAS; this issue we will round up the past 10 months of activity at ALICE and LHCb. LHCb The cavern of the LHCb experiment. This year has given LHCb the chance to install the 5th and final plane of muon chambers, which will improve the triggering at nominal luminosity. This is the final piece of the experiment to be installed. "Now the detector looks exactly as it does in the technical design report," confirms Andrei Golutvin, LHCb Spokesperson. "We also took advantage of this shutdown to make several improvements. For example, we modified the high voltage system of the electromagnetic calorimeter to reduce noise further to a negligible level. We also took some measures to improve ...

Synergy of BESIII and LHCb physics programmes

CERN Document Server

Malde, Sneha Sirirshkumar

2016-01-01

There is potential for BESIII open-charm measurements to have a significant impact on the LHCb physics programme. Despite the general purpose design of the LHCb detector there are certain inputs that can be better determined in other environments or in production mechanisms not accessible at the LHC. With the unprecedented amount of LHCb data that will become available over the one-to-two decades it is necessary to consider where additional inputs are essential, to avoid the situation where the uncertainty on a measurement is dominated by the lack of knowledge of an external input. This document considers the capabilities of the BESIII experiment to provide vital inputs into key LHCb measurements. A number of different potential measurements that could be pursued are discussed.

V0 particle production studies at LHCb

CERN Multimedia

Knecht, M

2009-01-01

Although QCD is firmly established as the fundamental theory of strong interactions, the fragmentation process from partons into hadrons is still poorly understood. Phenomenological models tuned to Tevatron data show significant differences when extrapolated to LHC energies. The hadronization process can be probed at the LHC by studying V0 production, i.e. the production of KS mesons and Lambda hyperons. The LHCb experiment, with a rapidity range complementary to that of the other LHC detectors, offers a particularly interesting environment, covering the forward region where the existing models are very tunable but lack predictive power. The first 100 millions minimum bias events at LHCb will already provide a high-statistics and high-purity V0 sample. Measurements will include differential cross sections and production ratios for different strange particles as a function of rapidity and transverse momentum. The analysis can naturally be extended to cover heavier hyperons as well, and eventually lead, w...

LHCb: The LHCb Silicon Tracker - Control system specific tools and challenges

CERN Multimedia

Saornil Gamarra, S

2013-01-01

The experiment control system of the LHCb experiment is continuously evolving and improving. The guidelines and structure initially defined are kept, and more common tools are made available to all sub-detectors. Although the main system control is mostly integrated and actions are executed in common for the whole LHCb experiment, there is some degree of freedom for each sub-system to implement the control system using these tools or by creating new ones. The implementation of the LHCb Silicon Tracker control system was extremely disorganized and with little documentation. This was due to either lack of time and manpower, and/or to limited experience and specifications. Despite this, the Silicon Tracker control system has behaved well during the first LHC run. It has continuously evolved since the start of operation and been adapted to the needs of operators with very different degrees of expertise. However, improvements and corrections have been made on a best effort basis due to time constraints placed by t...

LHCb detector and trigger performance in Run II

Science.gov (United States)

Francesca, Dordei

2017-12-01

The LHCb detector is a forward spectrometer at the LHC, designed to perform high precision studies of b- and c- hadrons. In Run II of the LHC, a new scheme for the software trigger at LHCb allows splitting the triggering of events into two stages, giving room to perform the alignment and calibration in real time. In the novel detector alignment and calibration strategy for Run II, data collected at the start of the fill are processed in a few minutes and used to update the alignment, while the calibration constants are evaluated for each run. This allows identical constants to be used in the online and offline reconstruction, thus improving the correlation between triggered and offline selected events. The required computing time constraints are met thanks to a new dedicated framework using the multi-core farm infrastructure for the trigger. The larger timing budget, available in the trigger, allows to perform the same track reconstruction online and offline. This enables LHCb to achieve the best reconstruction performance already in the trigger, and allows physics analyses to be performed directly on the data produced by the trigger reconstruction. The novel real-time processing strategy at LHCb is discussed from both the technical and operational point of view. The overall performance of the LHCb detector on the data of Run II is presented as well.

Prospect for measuring the branching ratio of $B_{s}\\rightarrow\\mu\\mu$ at LHC$b$

CERN Document Server

Lopez Asamar, E

2009-01-01

The Standard Model predicts a branching ratio for the decay mode $B_{s}\\rightarrow\\mu\\mu$ of (3.32$\\pm$0.32)$\\times$10 $^{-9}$ while some SUSY models predict enhancements of up to 2 orders of magnitude. It is expected that at the end of its life the Tevatron will set an exclusion limit for this branching ratio of the order of 10 $^{-8}$, leaving one order of magnitude to explore. The efficient trigger, excellent vertex reconstruction and invariant mass resolution, and muon identification of the LHC$b$ detector makes it well suited to observe a branching ratio in this range in the first years of running of the LHC. In this article an overview of the analysis that has been developed for the measurement of this branching ratio is presented. The event selection and the statistical tools used for the extraction of the branching ratio are discussed. Special emphasis is placed on the use of control channels for calibration and normalization in order to make the analysis as independent of simulation as possible. Fina...

3D Monitoring of LHCb Inner Tracker

CERN Multimedia

Sainvitu, Pascal

2015-01-01

The positions of the Inner Tracker (IT) detectors of the LHCb experiment installed in the LHC at CERN are impacted by the LHCb dipole magnet powering. In the past the movements of the stations have been measured using standard survey methods during magnet tests in shutdown periods. But the survey targets are visible only in very narrow spaces and the access to the IT is very difficult, even impossible in the central region when the detector is closed. Finally the precision of the standard survey measurement is affected by the poor configuration. In 2013 and 2014, during the first long shutdown of the LHC (LS1), the CERN Survey team (EN/MEF-SU) in collaboration with the LHCb Technical Coordination and the EPFL (Ecole Polytechnique Fédérale de LAUSANNE, CH), developed a permanent monitoring system which has been tested and installed in order to allow the 3D position measurement of the IT stations, even during the run periods, with a precision of 100 microns at 1 sigma level. The 3D Monitoring system of the LH...

LHCb Upgrades and operation at 1034 cm-2 s-1 luminosity –A first study

CERN Document Server

Efthymiopoulos, Ilias; Baglin, Vincent; Burkhardt, Helmut; Cerutti, Francesco; Claudet, Serge; Di Girolamo, Beniamino; De Maria, Riccardo; Esposito, Luigi Salvatore; Karastathis, Nikos; Lindner, Rolf; Papaphilippou, Yannis; Pellegrini, Dario; Redaelli, Stefano; Roesler, Stefan; Sanchez Galan, Francisco; Thomas, Eric; Tsinganis, Andrea; Wollmann, Daniel; Wilkinson, Guy; Schwarz, Philip; CERN. Geneva. ATS Department

2018-01-01

Presently, the LHCb experiment at IP8 operates at reduced luminosity (~4.0 1032 cm-2 s-1) compared to ATLAS and CMS experiments. The LHCb collaboration is proposing an Upgrade II during HL-LHC operation, where the beams at IP8 will collide at high-luminosity (~1-2 1034 cm-2 s-1), comparable to the present high-luminosity regions IP1&IP5. The LHCb experiment aims to collect more than 300 fb-1 by the end of the HL-LHC operation. A feasibility study of operating IP8 at high-luminosity whilst preserving the performance at IP1 and IP5 and on the impact to the LHC machine and experimental cavern was done. Optics studies shows that solutions allowing to reach an integrated luminosity of 40 to 50 fb-1 per year to LHCb/IP8 at the cost of a reduction of about 5% in the integrated luminosity of the main experiments ATLAS and CMS, under the assumption that there are no lifetime limitations besides burn-off, are feasible. Energy deposition in the machine elements of the IR straight section 8 and LHC infrastructure and...

LHCb: Machine assisted histogram classification

CERN Multimedia

Somogyi, P; Gaspar, C

2009-01-01

LHCb is one of the four major experiments under completion at the Large Hadron Collider (LHC). Monitoring the quality of the acquired data is important, because it allows the verification of the detector performance. Anomalies, such as missing values or unexpected distributions can be indicators of a malfunctioning detector, resulting in poor data quality. Spotting faulty components can be either done visually using instruments such as the LHCb Histogram Presenter, or by automated tools. In order to assist detector experts in handling the vast monitoring information resulting from the sheer size of the detector, a graph-theoretic based clustering tool, combined with machine learning algorithms is proposed and demonstrated by processing histograms representing 2D event hitmaps. The concept is proven by detecting ion feedback events in the LHCb RICH subdetector.

LHCb Topological Trigger Reoptimization

CERN Document Server

INSPIRE-00400931; Ilten, Philip; Khairullin, Egor; Rogozhnikov, Alex; Ustyuzhanin, Andrey; Williams, Michael

2015-12-23

The main b-physics trigger algorithm used by the LHCb experiment is the so-called topological trigger. The topological trigger selects vertices which are a) detached from the primary proton-proton collision and b) compatible with coming from the decay of a b-hadron. In the LHC Run 1, this trigger, which utilized a custom boosted decision tree algorithm, selected a nearly 100% pure sample of b-hadrons with a typical efficiency of 60-70%; its output was used in about 60% of LHCb papers. This talk presents studies carried out to optimize the topological trigger for LHC Run 2. In particular, we have carried out a detailed comparison of various machine learning classifier algorithms, e.g., AdaBoost, MatrixNet and neural networks. The topological trigger algorithm is designed to select all "interesting" decays of b-hadrons, but cannot be trained on every such decay. Studies have therefore been performed to determine how to optimize the performance of the classification algorithm on decays not used in the training. ...

LHCb: Experience with LHCb alignment software on first data

CERN Multimedia

Deissenroth, M

2009-01-01

We report results obtained with different track-based algorithms for the alignment of the LHCb detector with first data. The large-area Muon Detector and Outer Tracker have been aligned with a large sample of tracks from cosmic rays. The three silicon detectors --- VELO, TT-station and Inner Tracker --- have been aligned with beam-induced events from the LHC injection line. We compare the results from the track-based alignment with expectations from detector survey.

Electroweak scale physics & exotic searches at LHCb

CERN Document Server

Lupton, Olli

2018-01-01

The LHCb detector is a single-arm forward spectrometer covering the pseudorapidity range 2–5 that is principally designed for the study of b- and c-hadrons, but which is well-suited to a wide variety of electroweak scale measurements and exotic searches that are highly complementary to other experiments at the LHC and elsewhere. Several features of the detector that are crucial for the core flavour physics programme, such as excellent vertex and momentum resolution, and a powerful trigger system, contribute to excellent jet tagging performance and sensitivity to low mass exotic states. LHCb operates at a substantially lower instantaneous luminosity than the general purpose detectors at the LHC, ATLAS and CMS, which results in a clean, low pile-up environment in which to search for physics beyond the Standard Model (SM).

LHCb Results on Semileptonic B/B$_s$/$\\Lambda_b$ Decays

CERN Document Server

Bozzi, Concezio

2013-01-01

Studies of semileptonic decays of b hadrons with the LHCb experiment are reported. In particular, measurements of the b hadron production fractions at the LHC and Bs semileptonic decays in P-wave charmed mesons are presented. An outlook of the LHCb potential in measuring the CKM matrix elements Vub and Vcb, as well as decays involving taus, is given.

Developments in Silicon Detectors and their impact on LHCb Physics Measurements

CERN Document Server

Gouldwell-Bates, A

2005-01-01

The LHCb experiment is a high energy physics detector at the Large Hadron Collider (LHC) which will probe the current understanding of the Standard Model through precise measurements of CP violation and rare decays. The LHCb detector heavily depends on the silicon vertexing (VELO) sub-detector for excellent vertex and proper decay time resolutions. The VELO detector sits at a position of only 7 mm from the LHC proton beams. However, the proximity of the silicon sensors to the proton beams results in the detectors suffering radiation damage. Radiation damage results in three changes in the macroscopic properties of the silicon detector: an increase of the leakage current, a decrease in the charge collection efficiency, and changes in the operation voltage required to fully deplete the silicon detector of the free charge carriers. Due to this radiation damage, it is expected that a replacement or upgrade of the LHCb vertex detector will be required by 2010, only 3 years after the turn-on of the LHC. This thesis...

Anti-deuteron sensitivity studies at LHCb

CERN Multimedia

Baker, Sophie Katherine

2018-01-01

Measurements of anti-deuterons in collider experiments can help to reduce systematic uncertainties in indirect searches for dark matter. Two predominant unknowns in these searches are the production of secondary anti-deuterons in the cosmos from spallation processes, and anti-deuteron production from annihilating dark matter. LHCb is a forward spectrometer on the LHC ring, designed to measure b-hadron decays from high energy proton-proton collisions. With the detector's excellent particle identification capabilities, deuteron and anti-deuteron measurements at LHCb could help to parametrise the two cosmological processes. Recent studies of (anti-)deuteron identification at LHCb and the prospects for measuring prompt (anti-)deuterons from pp-collisions will be presented, as well as a working analysis of b-baryrons decaying to deuterons.

Forward physics with the LHCb experiment

International Nuclear Information System (INIS)

Volyanskyy, Dmytro

2013-01-01

Due to its unique pseudorapidity coverage and the ability to perform measurements at low transverse momenta p T , the LHCb detector allows a unique insight into particle production in the forward region at the LHC. Using large samples of proton-proton collision data accumulated at √(s) = 7TeV, the LHCb collaboration has performed a series of dedicated analyses providing important input to the knowledge of the parton density functions, underlying event activity, low Bjorken-x QCD dynamics and exclusive processes. Some of these are briefly summarised here.

Forward physics with the LHCb experiment

Energy Technology Data Exchange (ETDEWEB)

Volyanskyy, Dmytro [Max-Planck-Institut fuer Kernphysik, PO Box 103980, 69029 Heidelberg(Germany); Collaboration: LHCb Collaboration

2013-04-15

Due to its unique pseudorapidity coverage and the ability to perform measurements at low transverse momenta p{sub T}, the LHCb detector allows a unique insight into particle production in the forward region at the LHC. Using large samples of proton-proton collision data accumulated at {radical}(s) = 7TeV, the LHCb collaboration has performed a series of dedicated analyses providing important input to the knowledge of the parton density functions, underlying event activity, low Bjorken-x QCD dynamics and exclusive processes. Some of these are briefly summarised here.

Forward physics with the LHCb experiment

CERN Document Server

INSPIRE-00312886

2012-01-01

Due to its unique pseudorapidity coverage and the ability to perform measurements at low transverse momenta $p_{\\rm T}$, the LHCb detector allows a unique insight into particle production in the forward region at the LHC. Using large samples of proton-proton collision data accumulated at $\\sqrt{s}=7$ TeV, the LHCb collaboration has performed a series of dedicated analyses providing important input to the knowledge of the parton density functions, underlying event activity, low Bjorken-x QCD dynamics and exclusive processes. Some of these are briefly summarised here.

24 May 2013 - Rector of the Polish Stanislaw Staszic AGH University of Science and Technology T. Slomka in the LHC tunnel at Point 8 with Senior Polish Staff Member A. Siemko, in LHCb experimental cavern with LHCb Collaboration Spokesperson P. Campana and signing the guest book with Director-General R. Heuer. Adviser for Eastern Europe T. Kurtyka present.

CERN Multimedia

Jean-Claude Gadmer

2013-01-01

24 May 2013 - Rector of the Polish Stanislaw Staszic AGH University of Science and Technology T. Slomka in the LHC tunnel at Point 8 with Senior Polish Staff Member A. Siemko, in LHCb experimental cavern with LHCb Collaboration Spokesperson P. Campana and signing the guest book with Director-General R. Heuer. Adviser for Eastern Europe T. Kurtyka present.

The LHCb Turbo stream

CERN Document Server

AUTHOR|(CDS)2070171

2016-01-01

The LHCb experiment will record an unprecedented dataset of beauty and charm hadron decays during Run II of the LHC, set to take place between 2015 and 2018. A key computing challenge is to store and process this data, which limits the maximum output rate of the LHCb trigger. So far, LHCb has written out a few kHz of events containing the full raw sub-detector data, which are passed through a full offline event reconstruction before being considered for physics analysis. Charm physics in particular is limited by trigger output rate constraints. A new streaming strategy includes the possibility to perform the physics analysis with candidates reconstructed in the trigger, thus bypassing the offline reconstruction. In the Turbo stream the trigger will write out a compact summary of physics objects containing all information necessary for analyses. This will allow an increased output rate and thus higher average efficiencies and smaller selection biases. This idea will be commissioned and developed during 2015 wi...

The Latest from LHCb

CERN Multimedia

2009-01-01

This month the LHCb Collaboration has observed the first Cherenkov rings from the RICH1 detector. These rings were emitted by cosmic particles passing through the detector. Cherenkov radiation occurs when a charged particle passes through a medium faster than the speed of light. As it travels, the particle emits photons along a cone. This cone is measured and, along with a measurement of momentum, is used to identify the particle. There are two types of radiators in RICH1, the first gaseous and the other made from aerogel. Both rings seen on the picture are from the same particle passing through the two different radiators. This is the fist time that the RICH detector has seen a particle as it will see them when the LHC re-starts. It has also been a time for the experiment to begin commissioning. After network upgrades, LHCb held a commissioning week, an opportunity for physicists working on all the different detectors within LHCb...

The LHCb Silicon Tracker

CERN Document Server

Elsasser, Ch; Gallas Torreira, A; Pérez Trigo, A; Rodríguez Pérez, P; Bay, A; Blanc, F; Dupertuis, F; Haefeli, G; Komarov, I; Märki, R; Muster, B; Nakada, T; Schneider, O; Tobin, M; Tran, M T; Anderson, J; Bursche, A; Chiapolini, N; Saornil, S; Steiner, S; Steinkamp, O; Straumann, U; Vollhardt, A; Britsch, M; Schmelling, M; Voss, H; Okhrimenko, O; Pugatch, V

2013-01-01

The aim of the LHCb experiment is to study rare heavy quark decays and CP vio- lation with the high rate of beauty and charmed hadrons produced in $pp$ collisions at the LHC. The detector is designed as a single-arm forward spectrometer with excellent tracking and particle identification performance. The Silicon Tracker is a key part of the tracking system to measure the particle trajectories to high precision. This paper reports the performance as well as the results of the radiation damage monitoring based on leakage currents and on charge collection efficiency scans during the data taking in the LHC Run I.

Upgrade of the monitoring system of LHCb ECAL

CERN Document Server

Guz, Iouri; Chernov, Evgeny; Egorychev, Victor; Kandybei, Sergii; Kvaratskheliya, Tengiz; Obraztsov, Vladimir; Perret, Pascal; Philippov, Sergey; Savrina, Daria; Shatalov, Sppavel; Zakoriuchkina, Tatiana; Zhokhov, Anatoli; Zvyagintsev, Serguei

2016-01-01

The LHCb ECAL is a shashlik calorimeter of 6016 cells, covering 7.686.24 m2 area. To monitor the readout chain of each ECAL cell, the LHCb ECAL is equipped with a LED based monitoring system. During the LHC Run I (2009-2012) it was found that the precision of the monitoring suffers from the radiation degradation of transparency of polystyrene clear fibers used to transport the LED light to the ECAL photomultipliers. In order to improve the performance of the monitoring system, and especially in view of significant increase of LHCb working luminosity foreseen after 2018, the present plastic fibers have been replaced by radiation hard quartz fibers. The design of the upgraded version of the LHCb ECAL monitoring system is described here. The usage and performance of the new system for the ECAL calibration during the LHCb Run II are discussed.

submitter LHC experiments

CERN Document Server

Tanaka, Shuji

2001-01-01

Large Hadron Collider (LHC) is under construction at the CERN Laboratory in Switzerland. Four experiments (ATLAS, CMS, LHCb, ALICE) will try to study the new physics by LHC from 2006. Its goal to explore the fundamental nature of matter and the basic forces. The PDF file of the transparency is located on http://www-atlas.kek.jp/sub/documents/lepsymp-stanaka.pdf.

Particle ID in LHCb

International Nuclear Information System (INIS)

Powell, Andrew

2010-01-01

Particle identification (PID) is a fundamental requirement for LHCb and is provided by CALO, MUON and RICH sub-detectors. The Calorimeters provide identification of electrons, photons and hadrons in addition to the measurement of their energies and positions. As well as being part of the LHCb trigger, the MUON system provides identification of muons to a very high level of purity, essential for many CP-sensitive measurements that have J/ψ's in their final states. Hadron identification, in particular the ability to distinguish kaons and pions, is crucial to many LHCB analyses, particularly where the final states of interest are purely hadronic. The LHCb RICH system provides this, covering a momentum range between 1 and 100 GeV/c. To maintain the integrity of the LHCb physics performance, it is essential to measure and monitor the particle identification efficiency and mis-identification fraction over time. This can be done by using specific decays, such as K-shorts, φ's, Λ's, J/ψ's and D*'s, for which pure samples can be isolated using only kinematic quantities, due to their unique decay topologies. This allows for clean samples of known particle types to be selected, which can then be used to calibrate and monitor the PID performance from data. The procedures for performing this will be presented, together with preliminary results from the 2009 and 2010 LHC runs. (author)

Past, Present and Future of the LHCb Detector

CERN Document Server

Cogoni, Violetta

2016-01-01

The LHCb experiment has been designed as a high precision experiment devoted to the search of physics beyond the Standard Model through the study of CP violation and rare decays in hadrons containing b and c quarks. During the Run 1 of LHC, the LHCb detector has performed very well producing a large number of physics results on a vast number of subjects. The first Long Shutdown offered the opportunity to further optimise the detector, anticipating in some cases the interventions foreseen for Run 3. Nevertheless, the phase of upgrade of the detector, foreseen for 2019–2020, will be crucial to exploit the full potential of the LHCb experiment. In this context, an overview of the LHCb detector is presented, concerning its past, present, and foreseen future performances

Preliminary studies for the LHCb vertex detector vacuum system

CERN Document Server

Doets, M; Van Bakel, N; Van den Brand, J F J; van den Brand, Jo

2000-01-01

We lay down some general considerations which will serve as a starting point for design studies of a realistic LHCb vertex detector vacuum system. Based on these considerations, we propose a design strategy and identify issues to be further studied. In particular we try to outline some boundary conditions imposed by LHC and LHCb on the vacuum system. We discuss two possibilities for the LHCb vertex detector vacuum system. The preferred strategy uses a differentially pumped vacuum system with the silicon detectors separated from the beam line vacuum. Some estimations on static vacuum pressures and gas flows are presented.

LHCb: A novel method for an absolute luminosity measurement at LHCb using beam-gas imaging

CERN Multimedia

Barschel, C

2013-01-01

A novel technique to measure the absolute luminosity at the Large Hadron Collider (LHC) using beam-gas interactions has been successfully used in the LHCb experiment. A gas injection device (SMOG) has been installed in the LHCb experiment to increase the pressure around the interaction point during dedicated fills. The Beam Gas Imaging method (BGI) has now the potential to surpass the accuracy of the commonly used van der Meer scan method (VDM). This poster presents the principles of the Beam Gas Imaging method used to measure the beam overlap integral. Furthermore the gas injection increased the accuracy measurement of the so-called ghost charges and also intensities per bunch.

Latest LHCb measurements of Electroweak Boson Production in Run-1

CERN Document Server

CERN. Geneva

2015-01-01

We present the latest LHCb measurements of forward Electroweak Boson Production using proton-proton collisions recorded in LHC Run-1. The seminar shall discuss measurements of the 8 TeV W & Z boson production cross-sections. These results make use of LHCb's excellent integrated luminosity determination to provide constraints on the parton distribution functions which describe the inner structure of the proton. These LHCb measurements probe a region of phase space at low Bjorken-x where the other LHC experiments have limited sensitivity. We also present measurements of cross-section ratios, and ratios of results in 7 TeV and 8 TeV proton-proton collisions. These results provide precision tests of the Standard Model. The seminar shall also present a measurement of the forward-backward asymmetry (A_FB) in Z boson decays to two muons. This result allows for precision tests of the coupling of the Z boson to left and right handed particles, providing sensitivity to the effective weak mixing angle (...

Protons on ions bring new physics to LHCb

CERN Multimedia

Antonella Del Rosso

2013-01-01

The research opportunities offered by proton-lead collisions at the LHC are generating increasing interest among theorists and experimentalists. During this recent run, LHCb, the asymmetric detector originally designed to study CP asymmetries and rare decays involving heavy quarks, took data with proton and ion beams for the first time. Using these collisions, the experiment can provide a different perspective on specific physics processes, so new developments may be in sight.   A proton-lead ion collision observed by the LHCb detector during the 2013 data taking period. LHCb is a smaller detector than the gigantic multi-purpose CMS and ATLAS detectors. It is also smaller than ALICE, the detector designed in particular to study ion-ion collisions. However, LHCb has something special: it can study physics processes that involve particles scattered from collisions at very small angles and close to the collision point. LHCb does not take data during ion-ion r...

LHCb: Measurement of $D^{\\pm}$ Production Asymmetry at LHCb

CERN Multimedia

Xing, Zhou

2012-01-01

Heavy quark production in 7 TeV pp collisions at the LHC need not be flavour symmetric. Here the production asymmetry, $A_p$ , between $D_s^+$ and $D_s^-$ mesons is measured using the $\\phi\\pi$ decay mode. The difference between $\\pi^+$ and $\\pi^-$ detection efficiencies is measured using the ratio of fully reconstructed to partially reconstructed $D^*$ decays. Using 1 fb$^{-1}$ of data collected with the LHCb detector, we find $A_p = (-0.39 \\pm 0.22 \\pm 0.08)$%.

The LHCb Upstream Tracker Project

CERN Document Server

Steinkamp, Olaf

2015-01-01

The LHCb detector performs searches for New Physics in CP-violating observables and rare heavy-quark decays at the LHC. A comprehensive upgrade is planned for the long shutdown of the LHC in 2018/19. A goal of this upgrade is to abolish hardware triggers and read out the full detector at 40 MHz. This requires to replace the existing TT station upstream of the LHCb magnet by a new silicon micro-strip detector, the Upstream Tracker (UT). The UT will have a new front-end chip compatible with 40 MHz readout, silicon sensors with improved radiation hardness, finer readout granularity, and improved acceptance coverage at small polar angles. The outer region of each detection layer will be covered by p-in-n sensors with 10 cm long strips and a pitch of about 180 mum, while n-in-p sensors with half the pitch and strip length will be employed in the regions of highest particle density close to the beam pipe. The innermost sensors will have a circular cutout to optimize the forward acceptance. The front-end chip is bei...

Layout of LHCb

CERN Multimedia

CERN AC

1998-01-01

This diagram shows the layout for the LHCb detector, which will be part of the LHC project at CERN. The main purpose of this detector is to look for rare decays of a heavy quark known as 'bottom', a version of the down quark that is found in protons and neutrons. In particular, decays by a process known as 'CP violation' will be studied to investigate Nature's preference for matter over antimatter.

A computer-generated image of the LHCb detector

CERN Multimedia

Richard Jacobsson

2004-01-01

Unlike most of the detectors on the LHC, which use barrel detectors, the LHCb detector will use walls of sub-detectors to study the particles produced in the 14 TeV proton-proton collisions. This arrangement is used as the bottom and anti-bottom quark pairs produced in the collision, whose decays will be studied, travel close to the path of the colliding beams. LHCb will investigate Naure's preference for matter over antimatter through a process known as CP violation.

The Software Architecture of the LHCb High Level Trigger

CERN Multimedia

CERN. Geneva

2012-01-01

The LHCb experiment is a spectrometer dedicated to the study of heavy flavor at the LHC. The rate of proton-proton collisions at the LHC is 15 MHz, but disk space limitations mean that only 3 kHz can be written to tape for offline processing. For this reason the LHCb data acquisition system -- trigger -- plays a key role in selecting signal events and rejecting background. In contrast to previous experiments at hadron colliders like for example CDF or D0, the bulk of the LHCb trigger is implemented in software and deployed on a farm of 20k parallel processing nodes. This system, called the High Level Trigger (HLT) is responsible for reducing the rate from the maximum at which the detector can be read out, 1.1 MHz, to the 3 kHz which can be processed offline,and has 20 ms in which to process and accept/reject each event. In order to minimize systematic uncertainties, the HLT was designed from the outset to reuse the offline reconstruction and selection code, and is based around multiple independent and redunda...

Construction of the Inner Tracker and Sensitivity to the $B^{0}_{s} \\to \\mu \\mu$ Decay at LHCb

CERN Document Server

Bettler, Marc-Olivier

2010-01-01

LHCb is one of the four main experiments hosted at the Large Hadron Collider (LHC) at CERN. The LHC first started in September 2008 and, after a one-year hiccough, restarted in November 2009. In the course of three weeks, the HEP community witnessed the first LHC proton-proton collisions and a new record of the most energetic particle beam. The ease shown by the operators of the complex LHC machine augurs very well for the extended period of data-taking scheduled to start at the end of February 2010. LHCb is the LHC experiment primarily dedicated to the $b$ realm, through the study of $\\mathcal{CP}$ violation and rare decays. Its physics goals are ambitious: it aims at the indirect search of New Physics and at the precise measurements of $\\mathcal{CP}$ violation parameters. The LHCb detector was designed as a single-arm forward spectrometer. The branching fraction of the yet-unobserved $B^{0}_{s}\\to\\mu^{+}\\mu^{-}$ decay is currently considered as one of the most stringent tests for the existence of physics be...

Software for the LHCb experiment

CERN Document Server

Corti, Gloria; Belyaev, Ivan; Cattaneo, Marco; Charpentier, Philippe; Frank, Markus; Koppenburg, Patrick; Mato-Vila, P; Ranjard, Florence; Roiser, Stefan

2006-01-01

LHCb is an experiment for precision measurements of CP-violation and rare decays in B mesons at the LHC collider at CERN. The LHCb software development strategy follows an architecture-centric approach as a way of creating a resilient software framework that can withstand changes in requirements and technology over the expected long lifetime of the experiment. The software architecture, called GAUDI, supports event data processing applications that run in different processing environments ranging from the real-time high- level triggers in the online system to the final physics analysis performed by more than one hundred physicists. The major architectural design choices and the arguments that lead to these choices will be outlined. Object oriented technologies have been used throughout. Initially developed for the LHCb experiment, GAUDI has been adopted and extended by other experiments. Several iterations of the GAUDI software framework have been released and are now being used routinely by the physicists of...

The LHCb DAQ system

CERN Document Server

Jost, B

2000-01-01

The LHCb experiment is the most recently approved of the 4 experiments under construction at CERN's LHC accelerator. It is a special purpose experiment designed to precisely measure the CP violation parameters in the B-B system. Triggering poses special problems since the interesting events containing B-mesons are immersed in a large background of inelastic p-p reactions. We therefore decided to implement a 4 level triggering scheme. The LHCb Data Acquisition (DAQ) system will have to cope with an average trigger rate of similar to 40 kHz, after two levels of hardware triggers, and an average event size of similar to 150 kB. Thus an event-building network which can sustain an average bandwidth of 6 GB /s is required. A powerful software trigger farm will have to be installed to reduce the rate from the 40 kHz to similar to 200 Hz of events written to permanent storage. In this paper we will concentrate on the networking aspects of the LHCb data acquisition and the controls system. 11 Refs.

Fixed-target physics at LHCb

CERN Document Server

Maurice, Emilie Amandine

2017-01-01

The LHCb experiment has the unique possibility, among the LHC experiments, to be operated in fixed target mode, using its internal gas target SMOG. The energy scale achievable at the LHC and the excellent detector capabilities for vertexing, tracking and particle identification allow a wealth of measurements of great interest for cosmic ray and heavy ions physics. We report the first measurements made in this configuration: the measurement of antiproton production in proton-helium collisions and the measurements of open and hidden charm production in proton-argon collisions at $\\sqrt{s_\\textrm{NN}} =$ 110 GeV.

New results in LU/LFV tests with LHCb

CERN Document Server

Prisciandaro, Jessica

2017-01-01

During the Run 1 of the LHC, the LHCb experiment has collected a large sample of beauty-hadrons that corresponds to an integrated luminosity of 3.0 fb$^{−1}$ at $pp$ centre-of-mass energy of 7 and 8 TeV. In the following, an overview of the rare decay measurements the LHCb collaboration performed during Run 1 is presented. In particular, recent tests of lepton flavour universality, with deviations also observed in semileptonic decays, and searches for lepton flavour violation decays will be presented.

Physics at 13 TeV: LHCb - a new data-processing strategy

CERN Multimedia

Antonella Del Rosso

2014-01-01

Originally, the LHCb detector was designed for operation with moderate luminosity and low pile-up. However, in 2010, the collaboration opted for “luminosity levelling”, a novel solution which allows the experiment to adapt automatically to normal variations in luminosity which occur during an LHC run.   In this way, the detector operates optimally at all times. “For the second LHC run, we will have to redefine the luminosity, to adapt to the conditions at the new energy of 13 TeV,” explains Patrick Koppenburg, physics coordinator of the LHCb collaboration. “However, the most important experimental challenge for us will be the new trigger system.” The trigger rapidly sorts the most interesting data from the data that can be discarded without a significant loss of information. The zero-level (i.e. the first level) trigger system of LHCb “only” lets through one sixteenth of the initial data, but even that is too muc...

Selected CPV Results from LHCb Run 1 and Prospects for CKM $\\gamma $ Angle Measurements in Run 2

CERN Document Server

Oblakowska-Mucha, Agniezka

2016-01-01

The LHCb detector is a single-arm forward spectrometer that collects data at the LHC, designed for studies of flavour physics with high precision. In this review, a few selected results regarding CP violation are discussed with particular emphasis on the CKM angle measurements. This sum- mary covers results based on the data collected by the LHCb detector during 2011 and 2012 proton–proton LHC runs at the centre-of-mass ener- gies of 7 and 8 TeV, respectively. Some remarks on prospects for analyses foreseen in the ongoing LHC Run 2 are also presented

LHCb PID Upgrade Technical Design Report

CERN Document Server

LHCb Collaboration

2013-01-01

The LHCb upgrade will take place in the second long shutdown of the LHC, currently scheduled to begin in 2018. The upgrade will enable the experiment to run at luminosities of $2 \\times 10^{33}cm^{-2}s^{-1}$ and will read out data at a rate of 40MHz into a exible software-based trigger. All sub-detectors of LHCb will be re-designed to comply with these new operating conditions. This Technical Design Report presents the upgrade plans of the Ring Imaging Cherenkov (RICH) system, the calorimeter system and the muon system, which together provide the particle identication capabilities of the experiment.

New LHCb Management readies for run 2 challenges

CERN Multimedia

Antonella Del Rosso

2014-01-01

As of 1 July, LHCb, one of the four biggest experiments at the LHC, will have a new Management. Ahead are the huge challenges of run 2 and the following long technical shutdown during which LHCb will undergo a major upgrade. In the meantime, the discovery of new physics could be a dream within reach…   New LHCb Spokesperson, Guy Wilkinson.   “We have to make sure that the detector wakes up after its long hibernation and goes back to data taking in the most efficient way and that we are able to process all these data to produce high-quality physics results,” says Guy Wilkinson, new Spokesperson of the LHCb collaboration. Although this already sounds like a considerable “to-do” list for the coming months, it’s just the beginning of a much longer and ambitious plan. “The previous management has done an excellent job in analysing the data we took during run 1. They also put on a very sound footing the LHCb upgrade, whi...

Performance, Radiation Damage Effects and Upgrade of the LHCb Vertex Locator

CERN Document Server

De Capua, S

2013-01-01

LHCb is a dedicated experiment to study New Physics in the decays of heavy hadrons at the Large Hadron Collider (LHC). Heavy hadrons are identified through their flight distance in the VELO, the retractable silicon-strip vertex detector surrounding the LHCb interaction point at only 7 mm from the beam during normal LHC operation. Both VELO halves comprise 21 silicon micro-strip modules each. A module is made of two n-on-n 300 µm thick half-disc sensors with R- and phi-measuring geometry, mounted on a carbon fibre support paddle. The minimum pitch is approximately 40 µm. The detector is also equipped with the only n-on-p module operating at the LHC. The performance of the VELO in its three years of successful operation during the LHC physics runs will be presented. Highlights will include alignment, cluster finding efficiency, single hit resolution, and impact parameter and vertex resolutions. The VELO module sensors receive a large and non-uniform radiation dose having inner and outer radii of only 7 and 42...

Time-dependent asymmetries in Bs decays at LHCb

CERN Document Server

Blouw, Johan

2007-01-01

The LHCb experiment will search for New Physics in Bs mixing. The Bs mixing phase will be extracted from the measurement of the time-dependent CP asymmetry in exclusive Bs decays governed by the $b \\to c\\bar{c}s$ quark level transition. Large New Physics effects can be discovered or excluded with the data collected during the very first physics run of LHC. Based on Monte Carlo simulations of the LHCb detector, the expected sensitivity with 2 fb$^{-1}$ on the CP-violation parameter $\\phi_s$, is $\\sigma(\\phi_s)$ = 0.022.

Jagiellonian University Heavy flavour highlights from the LHCb

CERN Document Server

INSPIRE-00640989

2017-01-01

This document presents an overview of the flavour anomalies observed by the LHCb experiment. All results are based on the dataset collected during the full LHC Run 1 by the LHCb Collaboration. Measurements of branching fractions of several $b \\rightarrow sll$ decays are presented together with the angular analysis of $B^{0} \\rightarrow K∗ \\mu^{+}\\mu^{−}$ decays and the lepton flavour universality tests R(K) and R(D∗). In addition, a direct search for a new light scalar particle in the $B^{+} \\rightarrow K^{+}\\chi$ decay, with $\\chi \\rightarrow \\mu^{+} \\mu^{-}$, is presented.

LHC Report: Level best

CERN Multimedia

Mike Lamont for the LHC team

2012-01-01

The LHCb experiment is special: there is a limit to the number of the events the detector can handle per bunch crossing. Consequently the maximum luminosity provided in 2012 has been around 4 x1032 cm-2s-1 (compared to the maximum of 7.7 x1033 cm-2s-1 seen by ATLAS and CMS). Nonetheless LHCb still wants to integrate as much luminosity as possible.    To meet LHCb's requirements a luminosity leveling technique is used. A machine setup is chosen that would give a peak luminosity well above the required maximum if the beams are collided head-on at LHCb's interaction point. This peak luminosity is then reduced to the required maximum by moving the two beams transversely apart at the interaction point. As the beam current goes down during a fill, the beams can be moved together in small increments to keep the collision rate constant throughout the fill. In practice, when the LHC goes into collisions in LHCb, the initial luminosity is safely below LHCb's demanded le...

LHCb: First year of running for the LHCb calorimeter system

CERN Multimedia

Guz, Y

2011-01-01

The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva) [1, 2]. LHCb is a single-arm spectrometer with a forward angular coverage from approximately 10 mrad to 300 mrad. It comprises a calorimeter system composed of four subdetectors [3]. It selects transverse energy hadron, electron and photon candidates for the first trigger level (L0), which makes a decision 4µs after the interaction. It provides the identification of electrons, photons and hadrons as well as the measurement of their energies and positions. The set of constraints resulting from these functionalities defines the general structure and the main characteristics of the calorimeter system and its associated electronics. A classical structure of an electromagnetic calorimeter (ECAL) followed by a hadron calorimeter (HCAL) has been adopted. In addition the system includes in front of them the Scintillating Pad Detector (SPD) and Pre-Showe...

LHCb Online event processing and filtering

Science.gov (United States)

Alessio, F.; Barandela, C.; Brarda, L.; Frank, M.; Franek, B.; Galli, D.; Gaspar, C.; Herwijnen, E. v.; Jacobsson, R.; Jost, B.; Köstner, S.; Moine, G.; Neufeld, N.; Somogyi, P.; Stoica, R.; Suman, S.

2008-07-01

The first level trigger of LHCb accepts one million events per second. After preprocessing in custom FPGA-based boards these events are distributed to a large farm of PC-servers using a high-speed Gigabit Ethernet network. Synchronisation and event management is achieved by the Timing and Trigger system of LHCb. Due to the complex nature of the selection of B-events, which are the main interest of LHCb, a full event-readout is required. Event processing on the servers is parallelised on an event basis. The reduction factor is typically 1/500. The remaining events are forwarded to a formatting layer, where the raw data files are formed and temporarily stored. A small part of the events is also forwarded to a dedicated farm for calibration and monitoring. The files are subsequently shipped to the CERN Tier0 facility for permanent storage and from there to the various Tier1 sites for reconstruction. In parallel files are used by various monitoring and calibration processes running within the LHCb Online system. The entire data-flow is controlled and configured by means of a SCADA system and several databases. After an overview of the LHCb data acquisition and its design principles this paper will emphasize the LHCb event filter system, which is now implemented using the final hardware and will be ready for data-taking for the LHC startup. Control, configuration and security aspects will also be discussed.

LHCb Online event processing and filtering

International Nuclear Information System (INIS)

Alessio, F; Barandela, C; Brarda, L; Frank, M; Gaspar, C; Herwijnen, E v; Jacobsson, R; Jost, B; Koestner, S; Moine, G; Neufeld, N; Somogyi, P; Stoica, R; Suman, S; Franek, B; Galli, D

2008-01-01

The first level trigger of LHCb accepts one million events per second. After preprocessing in custom FPGA-based boards these events are distributed to a large farm of PC-servers using a high-speed Gigabit Ethernet network. Synchronisation and event management is achieved by the Timing and Trigger system of LHCb. Due to the complex nature of the selection of B-events, which are the main interest of LHCb, a full event-readout is required. Event processing on the servers is parallelised on an event basis. The reduction factor is typically 1/500. The remaining events are forwarded to a formatting layer, where the raw data files are formed and temporarily stored. A small part of the events is also forwarded to a dedicated farm for calibration and monitoring. The files are subsequently shipped to the CERN Tier0 facility for permanent storage and from there to the various Tier1 sites for reconstruction. In parallel files are used by various monitoring and calibration processes running within the LHCb Online system. The entire data-flow is controlled and configured by means of a SCADA system and several databases. After an overview of the LHCb data acquisition and its design principles this paper will emphasize the LHCb event filter system, which is now implemented using the final hardware and will be ready for data-taking for the LHC startup. Control, configuration and security aspects will also be discussed

$B^{0}_{s} \\to J \\psi \\eta$ decays and sensitivity to the $B^{0}_{s}$ mixing phase at LHCb

CERN Document Server

Carron, B

2005-01-01

The LHCb experiment will be installed in the proton-proton Large Hadron Collider (LHC) at CERN, Geneva. The detector is a single arm spectrometer currently under construction: LHC running and LHCb data taking will start in 2007. LHCb will then benefit from the prolific source of B-mesons provided by the LHC. The main goals of the LHCb experiment are to measure the CP asymmetries in the B-meson sector and to study rare decays of b-hadrons. These will extend the measurements presently made with B_d mesons by the Belle (Japan) and BABAR (USA) experiments. The expected accuracy on the comprehensive measurements with both B_d and B s mesons will allow to open new windows on physics beyond the Standard Model. The Standard Model of particle physics (SM) provides the framework for the description of a possible violation of the CP symmetry in the neutral B-meson sector. In particular, it predicts an asymmetry due to CP violation in the time dependent rates for B_{d,s} and B_{d,s}- bar to a common CP eigenstate when th...

LHCb : Full Experiment System Test

CERN Multimedia

Cattaneo, M

2009-01-01

LHCb had been planning to commission its High Level Trigger software and Data Quality monitoring procedures using real collisions data from the LHC pilot run. Following the LHC incident on 19th September 2008, it was decided to commission the system using simulated data. This “Full Experiment System Test” consists of: - Injection of simulated minimum bias events into the full HLT farm, after selection by a simulated Level 0 trigger. - Processing in the HLT farm to achieve the output rate expected for nominal LHC luminosity running, sustained over the typical duration of an LHC fill. - Real time Data Quality validation of the HLT output, validation of calibration and alignment parameters for use in the reconstruction. - Transmission of the event data, calibration data and book-keeping information to Tier1 sites and full reconstruction of the event data. - Data Quality validation of the reconstruction output. We will report on the preparations and results of FEST09, and on the status of commissioning for no...

TELL1: development of a common readout board for LHCb

International Nuclear Information System (INIS)

Legger, Federica; Bay, Aurelio; Haefeli, Guido; Locatelli, Laurent

2004-01-01

LHCb is one of the four experiments currently under construction at LHC (Large Hadron Collider) at CERN, and its aim is the study of b-quark physics (LHCb Collaboration, CERN-LHCC/98-4). LHCb trigger strategy is based on three levels, and will reduce the event rate from 40 MHz to a few hundred Hz (LHCb Collaboration, CERN/LHCC 2003-031, LHCb TDR 10, September 2003). The first two levels (L0 and L1) will use signals from some part of the detector in order to take fast decisions, while the last one, called High Level Trigger (HLT), will have access to the full event data. An 'off detector' readout board (TELL1) has been developed and will be used by the majority of LHCb subdetectors. It takes L0 accepted data as input and, after data processing which includes event synchronization, L1 Trigger pre-processing and zero suppression, L1 buffering, and HLT zero suppression, the output is sent to L1 Trigger and HLT

LHCb RICH Online-Monitor and Data-Quality

CERN Multimedia

Kerzel, U

2009-01-01

The LHCb experiment at the LHC (CERN) has been optimised for high precision measurements of the beauty quark sector. Its main objective is to precisely determine and over-constrain the parameters of the CKM mixing matrix, and to search for further sources of CP violation and new physics beyond the Standard Model in rare B-decays. Efficient particle identification at high purities over a wide momentum range from around 1 to ~100GeV/c is vital to many LHCb analyses. Central to the LHCb particle identification strategy are two Ring Imaging CHerenkov (RICH) detectors which use Silica Aerogel and C4F10 and CF4 gas radiators. A rigorous quality control scheme is being developed to insure that the data recorded by the RICH detector meets the stringent requirements of the physics analyses. The talk summarises the LHCb RICH online monitoring and data-quality strategy. Multiple dedicated algorithms are deployed to detect any potential issue already during data-taking ranging from integrity checks, mis-alignments to cha...

b-JETS AT LHCb

CERN Document Server

Coco, Victor

2008-01-01

LHCb 1 is a LHC experiment dedicated to pre-jets. LHCh detector is a one arm spectrometer. It covers the forward region of interaction point, from 30 mrad to 300 (250) mrad in bending (non-bending) plane. The choice of such a limited acceptance is motivated by the fact that most of the 500 µb correlated bb pairs are produced in this region. LHCb experiment will take data at a luminosity of 2 x ID32cm-2s-1, where bunch crossing are dominated by single pp interactions. Good particle identification, excellent tracking and vcrtcxing arc needed for B physic mcasurmcnts. Expected resolution on track momentum is about bp/p = 0.35% around 10 GeV /c to bp/p = 0.55% around 140 GeV /c. Impact parameter resolution is expected to be aIP = 14µm + 35µm/p-r.

Fast calorimeter simulation in LHCb

CERN Multimedia

CERN. Geneva

2018-01-01

Fast calorimeter simulation in LHCb In HEP experiments CPU resources required by MC simulations are constantly growing and become a very large fraction of the total computing power (greater than 75%). At the same time the pace of performance improvements from technology is slowing down, so the only solution is a more efficient use of resources. Efforts are ongoing in the LHC experiments to provide multiple options for simulating events in a faster way when higher statistics is needed. A key of the success for this strategy is the possibility of enabling fast simulation options in a common framework with minimal action by the final user. In this talk we will describe the solution adopted in Gauss, the LHCb simulation software framework, to selectively exclude particles from being simulated by the Geant4 toolkit and to insert the corresponding hits generated in a faster way. The approach, integrated within the Geant4 toolkit, has been applied to the LHCb calorimeter but it could also be used for other subdetec...

Real time analysis with the upgraded LHCb trigger in Run-III

CERN Multimedia

Szumlak, Tomasz

2016-01-01

The current LHCb trigger system consists of a hardware level, which reduces the LHC bunch-crossing rate of 40 MHz to 1 MHz, a rate at which the entire detector is read out. A second level, implemented in a farm of around 20k parallel processing CPUs, the event rate is reduced to around 12.5 kHz. The LHCb experiment plans a major upgrade of the detector and DAQ system in the LHC long shutdown II (2018-2019 ). In this upgrade, a purely software based trigger system is being developed and it will have to process the full 30 MHz of bunch crossings with inelastic collisions. LHCb will also receive a factor of 5 increase in the instantaneous luminosity, which further contributes to the challenge of reconstructing and selecting events in real time with the CPU farm. We discuss the plans and progress towards achieving efficient reconstruction and selection with a 30 MHz throughput. Another challenge is to exploit the increased signal rate that results from removing the 1 MHz readout bottleneck, combined with the high...

The LHCb electromagnetic calorimeter

CERN Multimedia

Maximilien Brice

2005-01-01

This huge 6X7 square metre wall consists of 3300 blocks containing scintillator, fibre optics and lead, which took engineers on the LHCb experiment at CERN only one month to construct. It will measure the energy of particles produced in proton-proton collisions at the LHC when it is started in 2008. Photons, electrons and positrons will pass through the layers of material in these modules and deposit their energy in the detector through a shower of particles.

Amplitude Analysis of $D^+ \\rightarrow K^- K^+ \\pi^+$ Decay with LHCb 2012 Data and RF-foil Simulations for the LHCb Upgrade

CERN Document Server

AUTHOR|(CDS)2073713

The $D^{+} \\to K^{-}K^{+}\\pi^{+}$ decay is a hadronic process dominated by resonant intermediate states. In order to quantify and understand the nature of each contribution, an amplitude analysis must be performed. The most common approach for this task is the Isobar Model, where each resonant contribution is described by a combination of Breit-Wigner functions, form factors and angular distribution functions. Achieving a precise description using the Isobar model is a challenging task since it does not provide an adequate framework for broad, overlapping structures typical from the S-wave amplitudes. Due to the huge statistics provided by LHCb, subtle effects might become relevant to our model. The LHCb experiment is going through an upgrade process for the next LHC run period. LHC will provide a much higher luminosity and all subsystems are required to upgrade in order to improve the experiment performance and make good use of the available data. The Vertex Locator, in particular, will be upgraded to a hybr...

Looking for New Physics: Prospects for B Physics at LHCb

CERN Document Server

Uwer, Ulrich

2009-01-01

With the startup of LlICb, the dedicated heavy flavor experiment at the LHC, the next round of precision B-experiments will be launched. LHCb has access to about $10^{12}$ B meson decays per year. allowing significant mcasurcmel)ts of even very rare B decays and, in particular, the precision study of the $B_s$ system. With the measurement of rates, angular distributions and CP asymmetries of loop suppressed B decays, LHCb will probe the quantum corrections predicted by the Standard Model. Many observables show a large sensitivity to New Physics contributions. In the following the expected LHCb physics performance and the potential to search for New Physics is discussed for a set of key measurements.

Central Exclusive Production at LHCb

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00392425

2017-01-01

The LHCb detector, with its excellent momentum resolution and flexible trigger strategy, is ideally suited for measuring particles produced exclusively. In addition, a new system of forward shower counters has been installed upstream and downstream of the detector, and has been used to facilitate studies of Central Exclusive Production. Such measurements of integrated and differential cross-section in both Run 1 and Run 2 of the LHC, are summarised here.

LHCb Exotica and Higgs searches

CERN Multimedia

Lucchesi, Donatella

2016-01-01

The unique phase space coverage and features of the LHCb detector at the LHC makes it an ideal environment to probe complementary New Physics parameter regions. In particular, recently developed jet tagging algorithms are ideal for searches involving $b$ and $c$ jets. This poster will review different jet-related exotica searches together with the efforts in the search for a Higgs boson decaying to a pair of heavy quarks.

Absolute luminosity measurement at LHCb with beam-gas imaging

CERN Document Server

Barschel, C

2013-01-01

A novel technique to measure the absolute luminosity at the Large Hadron Collider (LHC) using beam-gas interactions has been successfully used in the LHCb experiment. A gas injection device (SMOG) has been installed in the LHCb experiment to increase the pressure around the interaction point during dedicated fills. The Beam-Gas Imaging method (BGI) has now the potential to surpass the accuracy of the commonly used *van der Meer scan* method (VDM). The technique has been used in 10 LHC fills during 2012 including and also provided a first luminosity measurement for proton-lead collisions. This talk presents the principles of the gas injection and the improvements reached with the increased pressure. Furthermore the gas injection increased the accuracy measurement of the so-called ghost charges and also intensities per bunch. Those uncertainties are becoming the dominating factor because the uncertainty on the total beam current have been reduced.

LHCb: Radiative decays of B hadrons at LHCb

CERN Multimedia

Soomro, F

2009-01-01

Flavour physics is an excellent probe of physics beyond the Standard Model. It offers the possibility to measure effects from heavy virtual particles with masses above the experimental reach in terms of direct production. LHCb is well positioned to exploit the large statistics of B hadrons available at LHC, to make competitive measurements in various radiative decays like B_d->K^{*} , B_s\\phi\\gamma, \\Lambda_b->\\Lambda ^{0\\gamma} and B^+->\\phiK^{+\\gamma}.. For example, the direct CP asymmetry in K^{*\\gamma} decay can be measured to the level of 1.8%[1], better than the current experimental accuracy, with only 100 pb-1of integrated luminosity.

LHCb: Beam-gas background for LHCb at 3.5 TeV

CERN Multimedia

Brett, D R; Corti, G; Alessio, F; Jacobsson, R; Talanov, V; Lieng, M H

2011-01-01

We consider the machine induced backgrounds for LHCb arising from collisions of the beam with residual gas in the long straight sections of the LHC close to the experiment. We concentrate on the background particle fluxes initiated by inelastic beam-gas interactions with a direct line of sight to the experiment, with the potential impact on the experiment increasing for larger beam currents and changing gas pressures. In this paper we calculate the background rates for parameters foreseen with LHC running in 2011, using realistic residual pressure profiles. We also discuss the effect of using a pressure profile formulated in terms of equivalent hydrogen, through weighting of other residual gases by their cross section, upon the radial fluxes from the machine and the detector response. We present the expected rates and the error introduced through this approximation.

LHCb Topological Trigger Reoptimization

International Nuclear Information System (INIS)

Likhomanenko, Tatiana; Khairullin, Egor; Rogozhnikov, Alex; Ustyuzhanin, Andrey; Ilten, Philip; Williams, Michael

2015-01-01

The main b-physics trigger algorithm used by the LHCb experiment is the so- called topological trigger. The topological trigger selects vertices which are a) detached from the primary proton-proton collision and b) compatible with coming from the decay of a b-hadron. In the LHC Run 1, this trigger, which utilized a custom boosted decision tree algorithm, selected a nearly 100% pure sample of b-hadrons with a typical efficiency of 60-70%; its output was used in about 60% of LHCb papers. This talk presents studies carried out to optimize the topological trigger for LHC Run 2. In particular, we have carried out a detailed comparison of various machine learning classifier algorithms, e.g., AdaBoost, MatrixNet and neural networks. The topological trigger algorithm is designed to select all ’interesting” decays of b-hadrons, but cannot be trained on every such decay. Studies have therefore been performed to determine how to optimize the performance of the classification algorithm on decays not used in the training. Methods studied include cascading, ensembling and blending techniques. Furthermore, novel boosting techniques have been implemented that will help reduce systematic uncertainties in Run 2 measurements. We demonstrate that the reoptimized topological trigger is expected to significantly improve on the Run 1 performance for a wide range of b-hadron decays. (paper)

The LHCb RICH Upgrade: Development of the DCS and DAQ system.

CERN Multimedia

Cavallero, Giovanni

2018-01-01

The LHCb experiment is preparing for an upgrade during the second LHC long shutdown in 2019-2020. In order to fully exploit the LHC flavour physics potential with a five-fold increase in the instantaneous luminosity, a trigger-less readout will be implemented. The RICH detectors will require new photon detectors and a brand new front-end electronics. The status of the integration of the RICH photon detector modules with the MiniDAQ, the prototype of the upgraded LHCb readout architecture, has been reported. The development of the prototype of the RICH Upgrade Experiment Control System, integrating the DCS and DAQ partitions in a single FSM, has been described. The status of the development of the RICH Upgrade Inventory, Bookkeeping and Connectivity database has been reported as well.

28 August 2013 - Ambassador Extraordinary and Plenipotentiary Permanent Representative of Ireland to the United Nations Office and specialized institutions in Geneva Mr G. Corr signing the guest book with CERN Director-General R. Heuer; visiting the LHCb experimental area with LHCb Collaboration Spokesperson P. Campana and visiting the LHC tunnel at Point 8 with International Relations Adviser for Ireland E. Tsesmelis. Accompanied throughout by R. McNulty.

CERN Multimedia

Jean-Claude Gadmer

2013-01-01

28 August 2013 - Ambassador Extraordinary and Plenipotentiary Permanent Representative of Ireland to the United Nations Office and specialized institutions in Geneva Mr G. Corr signing the guest book with CERN Director-General R. Heuer; visiting the LHCb experimental area with LHCb Collaboration Spokesperson P. Campana and visiting the LHC tunnel at Point 8 with International Relations Adviser for Ireland E. Tsesmelis. Accompanied throughout by R. McNulty.

LHC an unprecedented technological challenge

International Nuclear Information System (INIS)

Baruch, J.O.

2002-01-01

This article presents the future LHC (large hadron collider) in simple terms and gives some details concerning radiation detectors and supra-conducting magnets. LHC will take the place of the LEP inside the 27 km long underground tunnel near Geneva and is scheduled to operate in 2007. 8 years after its official launching the LHC project has piled up 2 year delay and has exceeded its initial budget (2 milliard euros) by 18%. Technological challenges and design difficulties are the main causes of these shifts. The first challenge has been carried out successfully, it was the complete clearing out of the LEP installation. In order to release 14 TeV in each proton-proton collision, powerful magnetic fields (8,33 Tesla) are necessary. 1248 supra-conducting 15 m-long bipolar magnets have to be built. 30% of the worldwide production of niobium-titanium wires will be used each year for 5 years in the design of these coils. The global cryogenic system will be gigantic and will use 94 tons of helium. 4 radiation detectors are being built: ATLAS (a toroidal LHC apparatus), CMS (compact muon solenoid), ALICE (a large ion collider experiment) and LHC-b (large hadron collider beauty). The 2 first will search after the Higgs boson, ALICE will be dedicated to the study of the quark-gluon plasma and LHC-b will gather data on the imbalance between matter and anti-matter. (A.C.)

Characterisation and commissioning of the LHCb VELO detector

CERN Document Server

AUTHOR|(CDS)2069345; Jans, E

2009-01-01

The LHCb detector is a one-armed spectrometer at the Large Hadron Collider. It has been designed to look for physics beyond the Standard Model through high precision measurements of CP-violation in the B-system and through the detection of rare B-decays. The success of LHCb relies heavily on its vertex detector, the VELO (VErtex LOcator), which will be used to trigger on B decay vertices and reconstruct them with micrometre accuracy. While small in size, comprising just 84 sensors, the VELO construction poses special challenges due to the high accuracy required and the proximity to the LHC beams. The detector will be required to operate under vacuum and will be exposed to high radiation levels. The first section of the thesis gives a brief introduction to the LHCb detector and the physics programme of the LHCb collaboration. The following sections review the VELO design and give and in-depth report on measurements of the detector performance based on data collected in beam tests. Topics covered are hit resolu...

LHCb - A SciFi production center in NRC KI FOR LHCb upgrade

CERN Multimedia

Shevchenko, Vladimir

2015-01-01

The Scintillating Fiber Tracker, SciFi for short, will be the main new tracking detector in LHCb. It will provide better than 100 µm spatial resolution, and high rate capability and radiation hardness enabling a fast, 40 MHz, trigger rate with a capability to withstand 50 fb$^{-1}$ integrated luminosity, delivered by LHC, without a major performance degradation. The main active element of the tracker is a scintillating fiber ribbon with the SiPM readout. The ribbons consist of 6 layers of the 250 µm scintillating fibers Kuraray SCSF-78MJ, assembled by winding and bound together by the epoxy glue. NRC Kurchatov Institute, Moscow, together with the colleagues from ITEP, CERN, TU of Dortmund and RWTH of Aachen are developing dedicated production centers with the aim to reach by 2016 production rate one ribbon per day per center, necessary to supply more than 1300 fibre ribbons (mats) needed for the new LHCb tracker.

Hadron spectroscopy in LHCb

CERN Document Server

Palano, Antimo

2018-01-01

The LHCb experiment is designed to study the properties and decays of heavy flavored hadrons produced in pp collisions at the LHC. The data collected in the LHC Run I enables precision spectroscopy studies of beauty and charm hadrons. The latest results on spectroscopy of conventional and exotic hadrons are reviewed. In particular the discovery of the first charmonium pentaquark states in the $J/\\psi p$ system, the possible existence of four-quark states decaying to $J/\\psi \\phi$ and the confirmation of resonant nature of the $Z_c(4430)^−$ mesonic state are discussed. In the sector of charmed baryons, the observation of five new $\\Omega_c$ states, the observation of the $\\Xi^+_{cc}$ and the study of charmed baryons decaying to $D^0 p$ are presented.

Jagiellonian University Selected Results on the CKM Angle $\\gamma $ Measurement at the LHCb

CERN Document Server

Krupa, Wojciech

2017-01-01

The LHCb is a single arm forward spectrometer designed to study heavy-flavour physics at the LHC. Its very precise tracking and excellent particle identification play currently a major role in providing the world-best measurements of the Unitary Triangle parameters. In this paper, selected results of the Cabibbo–Kobayashi–Maskawa (CKM) angle $\\gamma$ measurements, with special attention for $B \\rightarrow DK$ decays family, obtained at the LHCb, are presented.

Evaluation of the Radiation Environment of the LHCb Experiment

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00341385; Corti, Gloria

The unprecedented radiation levels of the Large Hadron Collider (LHC) during high-energy proton-proton collisions will have an impact on the operation of its experiments’ detectors and electronics. LHCb, one of the 4 major LHC experiments, has started operation in 2009 and from 2011 onward it has been collecting data at and above its design luminosity. Detectors and associated detector electronics are prone to damage if the radiation levels exceed the expected values. It is essential to monitor the radiation environment of the experimental area and compare it with predictions obtained from simulation studies in order to assess the situation and take corrective action in case of need. Understanding the existing radiation environment will also provide important input to the planning of maintenance and for operation at upgrade luminosity. A set of radiation detectors has been installed in the LHCb experimental area to measure different aspects of its radiation environment. Passive dosimeters including Thermo-L...

LHCb Data Management: consistency, integrity and coherence of data

CERN Document Server

Bargiotti, Marianne

2007-01-01

The Large Hadron Collider (LHC) at CERN will start operating in 2007. The LHCb experiment is preparing for the real data handling and analysis via a series of data challenges and production exercises. The aim of these activities is to demonstrate the readiness of the computing infrastructure based on WLCG (Worldwide LHC Computing Grid) technologies, to validate the computing model and to provide useful samples of data for detector and physics studies. DIRAC (Distributed Infrastructure with Remote Agent Control) is the gateway to WLCG. The Dirac Data Management System (DMS) relies on both WLCG Data Management services (LCG File Catalogues, Storage Resource Managers and File Transfer Service) and LHCb specific components (Bookkeeping Metadata File Catalogue). Although the Dirac DMS has been extensively used over the past years and has proved to achieve a high grade of maturity and reliability, the complexity of both the DMS and its interactions with numerous WLCG components as well as the instability of facilit...

Gas system proposal for the LHCb muon system

CERN Document Server

Hahn, F; Lindner, R

2001-01-01

This document describes the gas system proposed for the LHCb Muon system, following the Gas Working Group mandate to ensure the uniform approach to gas technology and controls across the LHC detectors. Standard technical design modules are employed as fas as possible, in order to minimise design overheads and long term support costs.

Test of multi-anode photomultiplier tubes for the LHCb scintillator pad detector

CERN Document Server

Aguiló, Ernest; Comerma-Montells, A; Garrido, Lluis; Gascon, David; Graciani, Ricardo; Grauges, Eugeni; Vilasis Cardona, Xavier; Xirgu, Xavier; Bohner, Gerard; Bonnefoy, Romeo; Borras, David; Cornat, Remi; Crouau, Michel; Deschamps, Olivier; Jacquet, Philippe; Lecoq, Jacques; Monteil, Stephane; Perret, Pascal; Reinmuth, Guy

2005-01-01

The LHCb experiment (The LHCb Technical Proposal, CERN/LHCC 98-4) is designed to study B meson physics in the LHC proton-proton collider at CERN. The Scintillator Pad Detector (SPD) has been designed to complete the calorimeter information performing an e/gamma identification for the experiment level-0 trigger system. The detection technology consists in transmitting scintillation light by means of both Wavelength Shifting and clear fibers to fast multi- anode photomultiplier tubes. In this paper, it is described the instrumentation and setup used to characterize the baseline photomultiplier solution (Hamamatsu R5900-00-M64) together with the scintillators and optical fibers for the SPD at LHCb.

Time-dependent CP asymmetries $B_s$ decays at LHCb

CERN Document Server

Blouw, J

2008-01-01

The LHCb experiment will search for New Physics in $b_s$ mixing. The $b_s$ mixing phase will be extracted from the measurement of the time-dependent CP asymmetry in exclusive $\\mathrm{B}_s$ decays governed by the $b \\rightarrow c\\bar{c} s$ quark-level transition. Large New Physics effects can be discovered or excluded with the data collected during the very first physics run of LHC. Based on Monte Carlo simulations of the LHCb detector, the expected sensitivity with $2~\\mathrm{fb}^{-1}$ on the CP-violation parameter $\\phi_s$, is $\\sigma(\\phi_s) = 0.022$.

LHCb calorimeter electronics. Photon identification. Calorimeter calibration

International Nuclear Information System (INIS)

Machefert, F.

2011-01-01

LHCb is one of the four large experiments installed on the LHC accelerator ring. The aim of the detector is to precisely measure CP violation observables and rare decays in the B meson sector. The calorimeter system of LHCb is made of four sub-systems: the scintillating pad detector, the pre-shower, the electromagnetic (ECAL) and hadronic (HCAL) calorimeters. It is essential to reconstruct B decays, to efficiently trigger on interesting events and to identify electrons and photons. After a review of the LHCb detector sub-systems, the first part of this document describes the calorimeter electronics. First, the front-end electronics in charge of measuring the ECAL and HCAL signals from the photomultipliers is presented, then the following section is an overview of the control card of the four calorimeters. The chapters three and four concern the test software of this electronics and the technological choices making it tolerant to radiations in the LHCb cavern environment. The measurements performed to ensure this tolerance are also given. The second part of this document concerns both the identification of the photons with LHCb and the calibration of the calorimeters. The photon identification method is presented and the performances given. Finally, the absolute energy calibration of the PRS and ECAL, based on the data stored in 2010 is explained. (author)

arXiv Searching for Long-lived Particles: A Compact Detector for Exotics at LHCb

CERN Document Server

INSPIRE-00260081; Papucci, Michele; Robinson, Dean J.

2018-02-01

We advocate for the construction of a new detector element at the LHCb experiment, designed to search for displaced decays of beyond Standard Model long-lived particles, taking advantage of a large shielded space in the LHCb cavern that is expected to soon become available. We discuss the general features and putative capabilities of such an experiment, as well as its various advantages and complementarities with respect to the existing LHC experiments and proposals such as SHiP and MATHUSLA. For two well-motivated beyond Standard Model benchmark scenarios—Higgs decay to dark photons and B meson decays via a Higgs mixing portal—the reach either complements or exceeds that predicted for other LHC experiments.

Wrong vertex displacements due to Lee-Wick resonances at LHC

International Nuclear Information System (INIS)

Alvarez, E.; Schat, C.; Rold, L. da; Szynkman, A.

2009-01-01

We show how a resonance from the recently proposed Lee-Wick Standard Model could lead to wrong vertex displacements at LHCb. We study which could be the possible 'longest lived' Lee-Wick particle that could be created at LHC, and we study its possible decays and detections. We conclude that there is a region in the parameter space which would give wrong vertex displacements as a unique signature of the Lee-Wick Standard Model at LHCb. Further numerical simulation shows that LHC era could explore these wrong vertex displacements through Lee-Wick leptons below 500 GeV. (author)

Full offline reconstruction in real-time with the LHCb detector

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00341115

2016-01-01

This document describes the novel, unique in High Energy Physics, real-time alignment and calibration of the full LHCb detector. The LHCb experiment has been designed as a dedicated heavy flavour physics experiment focused on the reconstruction of c and b hadrons. The LHCb detector is a single-arm forward spectrometer, which measures proton-proton interactions at the LHC. The operational bunch crossing rate is several orders of magnitude above the current abilities of data recording and storage. Therefore, a trigger system has been implemented to reduce this rate to an acceptable value. The LHCb trigger system has been redesigned during the 2013-2015 long shutdown, achieving oine-quality alignment and calibration online. It also allows analyses to be performed entirely at the trigger level. In addition, having the best performing reconstruction in the trigger gives the possibility to fully use the particle identification selection criteria and greatly increases the eciency, in particular for the selection of ...

First LHCb results from pA and Pb-Pb collisions

CERN Document Server

Massacrier, L.

2016-09-21

In 2015, the LHCb collaboration endorsed the proposal to pursue an ambitious heavy-ion physics program. In 2013, LHCb has demonstrated its capabilities to operate successfully in p-Pb and Pb-p collisions, leading already to several important publications in the field. The measurements of the nuclear modification factor and forward-backward production of prompt and displaced J/$\\psi$, $\\psi$(2S) and $\\Upsilon$(1S) states, as well as the production of prompt $D^{0}$ mesons, have allowed to extend the knowledge of Cold Nuclear Matter effects on open heavy flavours and quarkonium production. The measurement of Z-boson production, important to constrain nuclear PDFs, and the measurement of two-particle angular correlations, probing collective effects in the dense environment of high energy collisions, have also been performed. Furthermore, LHCb is the only experiment at the LHC that can be operated in fixed-target mode, owing to the injection of a small amount of gas inside the LHCb collision area. There have been...

Searching for confining hidden valleys at LHCb, ATLAS, and CMS

Science.gov (United States)

Pierce, Aaron; Shakya, Bibhushan; Tsai, Yuhsin; Zhao, Yue

2018-05-01

We explore strategies for probing hidden valley scenarios exhibiting confinement. Such scenarios lead to a moderate multiplicity of light hidden hadrons for generic showering and hadronization similar to QCD. Their decays are typically soft and displaced, making them challenging to probe with traditional LHC searches. We show that the low trigger requirements and excellent track and vertex reconstruction at LHCb provide a favorable environment to search for such signals. We propose novel search strategies in both muonic and hadronic channels. We also study existing ATLAS and CMS searches and compare them with our proposals at LHCb. We find that the reach at LHCb is generically better in the parameter space we consider here, even with optimistic background estimations for ATLAS and CMS searches. We discuss potential modifications at ATLAS and CMS that might make these experiments competitive with the LHCb reach. Our proposed searches can be applied to general hidden valley models as well as exotic Higgs boson decays, such as in twin Higgs models.

Real time analysis with the upgraded LHCb trigger in Run III

Science.gov (United States)

Szumlak, Tomasz

2017-10-01

The current LHCb trigger system consists of a hardware level, which reduces the LHC bunch-crossing rate of 40 MHz to 1.1 MHz, a rate at which the entire detector is read out. A second level, implemented in a farm of around 20k parallel processing CPUs, the event rate is reduced to around 12.5 kHz. The LHCb experiment plans a major upgrade of the detector and DAQ system in the LHC long shutdown II (2018-2019). In this upgrade, a purely software based trigger system is being developed and it will have to process the full 30 MHz of bunch crossings with inelastic collisions. LHCb will also receive a factor of 5 increase in the instantaneous luminosity, which further contributes to the challenge of reconstructing and selecting events in real time with the CPU farm. We discuss the plans and progress towards achieving efficient reconstruction and selection with a 30 MHz throughput. Another challenge is to exploit the increased signal rate that results from removing the 1.1 MHz readout bottleneck, combined with the higher instantaneous luminosity. Many charm hadron signals can be recorded at up to 50 times higher rate. LHCb is implementing a new paradigm in the form of real time data analysis, in which abundant signals are recorded in a reduced event format that can be fed directly to the physics analyses. These data do not need any further offline event reconstruction, which allows a larger fraction of the grid computing resources to be devoted to Monte Carlo productions. We discuss how this real-time analysis model is absolutely critical to the LHCb upgrade, and how it will evolve during Run-II.

Search for a Higgs boson decaying to a pair of $b$ quarks in the forward region of $pp$ collisions with the LHCb detector

CERN Document Server

AUTHOR|(CDS)2087375

LHCb is a forward spectrometer (pseudorapidity coverage 2 < $\\eta$ < 5) designed for heavy flavour physics, located at the Large Hadron Collider (LHC). Thanks to its unique features LHCb is able to perform electroweak and jets measurements in a complementary phase space with respect to the General Purpose Detectors (GPD) at LHC, ATLAS and CMS. In this thesis techniques to identify and reconstruct $b \\bar{b}$ resonances with the LHCb detector are developed. First the data collected by LHCb during the Run I data taking are analyzed to identify the $Z \\rightarrow b \\bar{b}$ decay, to measure its cross section and to determine the jet energy scale. Then the dataset is used to set experimental limit on the Standard Model (SM) $H \\rightarrow b \\bar{b}$ production in the forward region.

Road map for selected key measurements from LHCb

CERN Document Server

Adeva, B.; Affolder, A.; Ajaltouni, Z.; Albrecht, J.; Alessio, F.; Alexander, M.; Alvarez Cartelle, P.; Alves, A.A., Jr; Amato, S.; Amhis, Y.; Amoraal, J.; Anderson, J.; Aquines Gutierrez, O.; Arrabito, L.; Artuso, M.; Aslanides, E.; Auriemma, G.; Bachmann, S.; Bagaturia, Y.; Bailey, D.S.; Balagura, V.; Baldini, W.; Pazos, MdC.Barandela; Barlow, R.J.; Barsuk, S.; Bates, A.; Bauer, C.; Bauer, Th.; Bay, A.; Bediaga, I.; Belous, K.; Belyaev, I.; Benayoun, M.; Bencivenni, G.; Bernet, R.; Bettler, M.O.; Bizzeti, A.; Blake, T.; Blanc, F.; Blanks, C.; Blouw, J.; Blusk, S.; Bobrov, A.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borgia, A.; Bos, E.; Bowcock, T.J.V.; Bozzi, C.; Bressieux, J.; Brisbane, S.; Britsch, M.; Brook, N.H.; Brown, H.; Buchler-Germann, A.; Buytaert, J.; Cachemiche, J.P.; Cadeddu, S.; Caicedo Carvajal, J.M.; Callot, O.; Calvi, M.; Calvo Gomez, M.; Camboni, A.; Cameron, W.; Campana, P.; Carbone, A.; Carboni, G.; Cardini, A.; Carson, L.; Carvalho Akiba, K.; Casse, G.; Cattaneo, M.; Charles, M.; Charpentier, Ph.; Chlopik, A.; Ciambrone, P.; Cid Vidal, X.; Clark, P.J.; Clarke, P.E.L.; Clemencic, M.; Cliff, H.V.; Closier, J.; Coca, C.; Coco, V.; Cogan, J.; Collins, P.; Constantin, F.; Conti, G.; Contu, A.; Corti, G.; Cowan, G.A.; D'Almagne, B.; D'Ambrosio, C.; d'Enterria, D.G.; Da Silva, W.; David, P.; De Bonis, I.; De Capua, S.; De Cian, M.; De Lorenzi, F.; De Miranda, J.M.; De Paula, L.; De Simone, P.; De Vries, H.; Decamp, D.; Degaudenzi, H.; Deissenroth, M.; Del Buono, L.; Deplano, C.; Deschamps, O.; Dettori, F.; Dickens, J.; Dijkstra, H.; Dima, M.; Donleavy, S.; Reis, A.C.dos; Dovbnya, A.; Pree, T.Du; Duval, P.Y.; Dwyer, L.; Dzhelyadin, R.; Eames, C.; Easo, S.; Egede, U.; Egorychev, V.; Eisele, F.; Eisenhardt, S.; Eklund, L.; Esperante Pereira, D.; Esteve, L.; Eydelman, S.; Fanchini, E.; Farber, C.; Fardell, G.; Farinelli, C.; Farry, S.; Fave, V.; Fernandez Albor, V.; Ferro-Luzzi, M.; Filippov, S.; Fitzpatrick, C.; Fontanelli, F.; Forty, R.; Frank, M.; Frei, C.; Frosini, M.; Fungueirino Pazos, J.L.; Furcas, S.; Gallas Torreira, A.; Galli, D.; Gandelman, M.; Gao, Y.; Garnier, J-C.; Garrido, L.; Gaspar, C.; Gauvin, N.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gibson, V.; Gilitsky, Yu.; Gligorov, V.V.; Gobel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.; Grabalosa Gandara, M.; Graciani Diaz, R.; Granado Cardoso, L.A.; Grauges, E.; Graziani, G.; Grecu, A.; Guerrer, G.; Gushchin, E.; Guz, Yu.; Guzik, Z.; Gys, T.; Hachon, F.; Haefeli, G.; Haines, S.C.; Hampson, T.; Hansmann-Menzemer, S.; Harji, R.; Harnew, N.; Harrison, P.F.; He, J.; Hennessy, K.; Henrard, P.; Hernando Morata, J.A.; Hicheur, A.; Hicks, E.; Hofmann, W.; Holubyev, K.; Hopchev, P.; Hulsbergen, W.; Hunt, P.; Huse, T.; Huston, R.S.; Hutchcroft, D.; Iakovenko, V.; Escudero, C.Iglesias; Imong, J.; Jacobsson, R.; Jahjah Hussein, M.; Jans, E.; Jansen, F.; Jaton, P.; Jean-Marie, B.; John, M.; Jones, C.R.; Jost, B.; Kapusta, F.; Karbach, T.M.; Keaveney, J.; Kerzel, U.; Ketel, T.; Keune, A.; Khalil, S.; Khanji, B.; Kim, Y.M.; Knecht, M.; Knopf, J.; Koblitz, S.; Konoplyannikov, A.; Koppenburg, P.; Korolko, I.; Kozlinskiy, A.; Krasowski, M.; Kravchuk, L.; Krokovny, P.; Kruzelecki, K.; Kucharczyk, M.; Kudryashov, I.; Kvaratskheliya, T.; Lacarrere, D.; Lai, A.; Lambert, R.W.; Lanfranchi, G.; Langenbruch, C.; Latham, T.; Le Gac, R.; Lefevre, R.; Leflat, A.; Lefrancois, J.; Leroy, O.; Lessnoff, K.; Li, L.; Li, Y.Y.; Libby, J.; Lieng, M.; Lindner, R.; Lindsey, S.; Linn, C.; Liu, B.; Liu, G.; Lopes, J.H.; Lopez Asamar, E.; Luisier, J.; Machefert, F.; Machikhiliyan, I.; Maciuc, F.; Maev, O.; Magnin, J.; Maier, A.; Mamunur, R.M.D.; Manca, G.; Mancinelli, G.; Mangiafave, N.; Marconi, U.; Marin, F.; Marks, J.; Martellotti, G.; Martens, A.; Martin, L.; Martinez Santos, D.; Mathe, Z.; Matteuzzi, C.; Matveev, V.; Mazurov, A.; McGregor, G.; Mcharek, B.; Mclean, C.; McNulty, R.; Merk, M.; Merkel, J.; Merkin, M.; Messi, R.; Metlica, F.C.D.; Michalowski, J.; Miglioranzi, S.; Minard, M.N.; Monteil, S.; Moran, D.; Morris, J.V.; Mountain, R.; Mous, I.; Muheim, F.; Muresan, R.; Murtas, F.; Muryn, B.; Musy, M.; Mylroie-Smith, J.; Naik, P.; Nakada, T.; Nandakumar, R.; Nardulli, J.; Natkaniec, Z.; Nedos, M.; Needham, M.; Neufeld, N.; Nicolas, L.; Nies, S.; Niess, V.; Nikitin, N.; Noor, A.; Oblakowska-Mucha, A.; Obraztsov, V.; Oggero, S.; Okhrimenko, O.; Oldeman, R.; Orlandea, M.; Ostankov, A.; Palacios, J.; Palutan, M.; Panman, J.; Papadelis, A.; Papanestis, A.; Pappagallo, M.; Parkes, C.; Passaleva, G.; Patel, G.D.; Patel, M.; Paterson, S.K.; Patrick, G.N.; Pauna, E.; Pauna, C.; Pavel, C.; Pazos Alvarez, A.; Pellegrino, A.; Penso, G.; Pepe Altarelli, M.; Perazzini, S.; Perego, D.L.; Perez-Calero Yzquierdo, A.; Perez Trigo, E.; Perret, P.; Pessina, G.; Petrella, A.; Petrolini, A.; Pietrzyk, B.; Pinci, D.; Playfer, S.; Plo Casasus, M.; Polok, G.; Poluektov, A.; Polycarpo, E.; Popov, D.; Popovici, B.; Poss, S.; Potterat, C.; Powell, A.; Pozzi, S.; Pugatch, V.; Puig Navarro, A.; Qian, W.; Rademacker, J.H.; Rakotomiaramanana, B.; Raniuk, I.; Raven, G.; Redford, S.; Reece, W.; Ricciardi, S.; Rinnert, K.; Robbe, P.; Rodrigues, E.; Rodrigues, F.; Rodriguez Cobo, C.; Rodriguez Perez, P.; Rogers, G.J.; Romanovsky, V.; Rospabe, G.; Ruf, T.; Ruiz, H.; Sabatino, G.; Saborido Silva, J.J.; Sagidova, N.; Saitta, B.; Salzmann, C.; Sambade Varela, A.; Sannino, M.; Santacesaria, R.; Santinelli, R.; Santovetti, E.; Sapunov, M.; Sarti, A.; Satriano, C.; Satta, A.; Savrie, M.; Savrina, D.; Schaack, P.; Schiller, M.; Schleich, S.; Schmelling, M.; Schmidt, B.; Schneider, O.; Schopper, A.; Schune, M.H.; Schwemmer, R.; Sciubba, A.; Seco, M.; Semennikov, A.; Senderowska, K.; Serra, N.; Serrano, J.; Shao, B.; Shapkin, M.; Shapoval, I.; Shatalov, P.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, V.; Simioni, E.; Skottowe, H.P.; Skwarnicki, T.; Smith, A.C.; Sobczak, K.; Soler, F.J.P.; Solomin, A.; Somogy, P.; Soomro, F.; De Paula, B.Souza; Spaan, B.; Sparkes, A.; Spiridenkov, E.; Spradlin, P.; Stagni, F.; Steinkamp, O.; Stoica, S.; Stone, S.; Straumann, U.; Styles, N.; Syryczynski, K.; Szczekowski, M.; Szczypka, P.; Szumlak, T.; T'Jampens, S.; Terrier, H.; Teubert, F.; Thomas, C.; Thomas, E.; Tobin, M.; Topp-Joergensen, S.; Tran, M.T.; Traynor, S.; Tsaregorodtsev, A.; Tuning, N.; Ukleja, A.; Ullaland, O.; Uwer, U.; Vagnoni, V.; Valenti, G.; van Beuzekom, M.; van den Brand, J.; van Eijk, D.; van Herwijnen, E.; van Lysebetten, A.; van Tilburg, J.; Vazquez Gomez, R.; Vazquez Regueiro, P.; Vecchi, S.; Velthuis, J.J.; Veltri, M.; Vervink, K.; Viaud, B.; Videau, I.; Vilasis-Cardona, X.; Vollhardt, A.; Vorobyev, A.; Vorobyev, An.; Voss, H.; Wacker, K.; Wandernoth, S.; Wang, J.; Ward, D.R.; Websdale, D.; Whitehead, M.; Wiedner, D.; Wiggers, L.; Wilkinson, G.; Williams, M.; Wilson, F.F.; Witek, M.; Witzeling, W.; Wotton, S.A.; Wyllie, K.; Xie, Y.; Xing, F.; Yang, Z.; Ybeles Smit, G.; Young, R.; Yushchenko, O.; Zhang, L.; Zhang, Y.; Zhelezov, A.; Zwahlen, N.

2010-01-01

Six of the key physics measurements that will be made by the LHCb experiment, concerning CP asymmetries and rare B decays, are discussed in detail. The "road map" towards the precision measurements is presented, including the use of control channels and other techniques to understand the performance of the detector with the first data from the LHC.

LHCb: Self managing experiment resources

CERN Multimedia

Stagni, F

2013-01-01

Within this paper we present an autonomic Computing resources management system used by LHCb for assessing the status of their Grid resources. Virtual Organizations Grids include heterogeneous resources. For example, LHC experiments very often use resources not provided by WLCG and Cloud Computing resources will soon provide a non-negligible fraction of their computing power. The lack of standards and procedures across experiments and sites generated the appearance of multiple information systems, monitoring tools, ticket portals, etc... which nowadays coexist and represent a very precious source of information for running HEP experiments Computing systems as well as sites. These two facts lead to many particular solutions for a general problem: managing the experiment resources. In this paper we present how LHCb, via the DIRAC interware addressed such issues. With a renewed Central Information Schema hosting all resources metadata and a Status System ( Resource Status System ) delivering real time informatio...

LHCb Upgrade: Scintillating Fibre Tracker

International Nuclear Information System (INIS)

Tobin, Mark

2016-01-01

The LHCb detector will be upgraded during the Long Shutdown 2 (LS2) of the LHC in order to cope with higher instantaneous luminosities and to read out the data at 40 MHz using a trigger-less read-out system. All front-end electronics will be replaced and several sub-detectors must be redesigned to cope with higher occupancy. The current tracking detectors downstream of the LHCb dipole magnet will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker will use scintillating fibres read out by Silicon Photomultipliers (SiPMs). State-of-the-art multi-channel SiPM arrays are being developed to read out the fibres and a custom ASIC will be used to digitise the signals from the SiPMs. The evolution of the design since the Technical Design Report in 2014 and the latest R & D results are presented.

VeloPix ASIC for the LHCb VELO Upgrade

CERN Multimedia

Cid Vidal, Xabier

2015-01-01

The LHCb Vertex Detector (VELO) will be upgraded in 2018 along with the other subsystems of LHCb in order to enable full detector readout at 40 MHz. LHCb will run without a hardware trigger and all data will be fed directly to the software triggering algorithms in the CPU farm. The upgraded VELO is a lightweight silicon hybrid pixel detector with 55 um square pixels, operating in vacuum in close proximity to the LHC beams. The readout will be provided by a dedicated front end ASIC, dubbed VeloPix, matched to the LHCb luminosity requirements. VeloPix is a binary pixel chip with a matrix of 256 x 256 pixels, covering an area of 2 cm^2. It is designed in a 130 nm CMOS technology, and is closely related to the Timepix3, from the Medipix family of ASICs. The principal challenge that the chip has to meet is a hit rate of up to 900 Mhits/s/ASIC, resulting in a data rate of more than 16 Gbit/s. Combining pixels into groups of 2x4 super-pixels enables the use of shared logic and a reduction of bandwidth due to combine...

The early career, gender, and diversity actions within the LHCb Collaboration

CERN Document Server

Rademacker, Jonas

2017-01-01

The LHCb collaboration has, as the first (and so far only) LHC collaboration, created a dedicated office for Early Career, Gender and Diversity (ECGD). The ECGD office’s role is to advise the management on ECGD matters; provide a point of contact for anybody experiencing any kind discrimination, bullying or harassment; collate regular statistics and other relevant information related to gender and, where appropriate, other ECGD matters; organise regular open meetings where ECGD matters are discussed. We report on the first two years of the LHCb ECGD office.

Start of run2 physics at the Large Hadron Collider (LHC)

CERN Multimedia

Brice, Maximilien

2015-01-01

Images from the CERN Control Centre (CCC), where operators control the LHC, and from the control rooms of the ALICE, ATLAS, CMS and LHCb experiments, where operators control huge detectors that capture data from collisions between beams of protons in the LHC.

LHCb; LHCb Jet Reconstruction

CERN Multimedia

Augusto, O

2012-01-01

The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than $4 \\times 10^{32} cm^{-2} s^{-1}$ and the integrated luminosity reached the value of 1.02 $fb^{-1}$ on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test pertubative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space $\\eta \\times \\phi$ and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the calo...

LHCb: LHCbDirac is a DIRAC extension to support LHCb specific workflows

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Stagni, Federico

2012-01-01

We present LHCbDIRAC, an extension of the DIRAC community Grid solution to handle the LHCb specificities. The DIRAC software has been developed for many years within LHCb only. Nowadays it is a generic software, used by many scientific communities worldwide. Each community wanting to take advantage of DIRAC has to develop an extension, containing all the necessary code for handling their specific cases. LHCbDIRAC is an actively developed extension, implementing the LHCb computing model and workflows. LHCbDIRAC extends DIRAC to handle all the distributed computing activities of LHCb. Such activities include real data processing (reconstruction, stripping and streaming), Monte-Carlo simulation and data replication. Other activities are groups and user analysis, data management, resources management and monitoring, data provenance, accounting for user and production jobs. LHCbDIRAC also provides extensions of the DIRAC interfaces, including a secure web client, python APIs and CLIs. While DIRAC and LHCbDIRAC f...

Thermal study and design of a cooling system for the electronics boards of the LHCb SciFi tracker

CERN Multimedia

Hamrat, Sonia

2017-01-01

The LHCb detector, one of the four large LHC detectors, has launched a major upgrade program with the goal to enormously boost the rate and selectivity of the data taking. The LHCb upgrade comprises the complete replacement of several sub-detectors, the substantial upgrade of the front-end electronics and the introduction of a new paradigm, namely the suppression of a hardware trigger by reading out the whole experiment synchronously at a rate of 40 MHz. The high readout frequency, unprecedented in a particle physics experiment, and the harsh radiation environment related to the increased LHC intensity, are the major challenges to be addressed by the new sub-detectors. The development and construction of a new large-scale tracking detector, based on a novel scintillating fibre (SciFi) technology, read out with silicon photomultipliers (SiPM), is one of the key projects of the LHCb upgrade program. The LHCb SciFi detector will count more than 500,000 channels. It is composed of 12 layers arranged in 3 tracking...

Integration of Cloud resources in the LHCb Distributed Computing

CERN Document Server

Ubeda Garcia, Mario; Stagni, Federico; Cabarrou, Baptiste; Rauschmayr, Nathalie; Charpentier, Philippe; Closier, Joel

2014-01-01

This contribution describes how Cloud resources have been integrated in the LHCb Distributed Computing. LHCb is using its specific Dirac extension (LHCbDirac) as an interware for its Distributed Computing. So far, it was seamlessly integrating Grid resources and Computer clusters. The cloud extension of DIRAC (VMDIRAC) allows the integration of Cloud computing infrastructures. It is able to interact with multiple types of infrastructures in commercial and institutional clouds, supported by multiple interfaces (Amazon EC2, OpenNebula, OpenStack and CloudStack) – instantiates, monitors and manages Virtual Machines running on this aggregation of Cloud resources. Moreover, specifications for institutional Cloud resources proposed by Worldwide LHC Computing Grid (WLCG), mainly by the High Energy Physics Unix Information Exchange (HEPiX) group, have been taken into account. Several initiatives and computing resource providers in the eScience environment have already deployed IaaS in production during 2013. Keepin...

Heavy ion and fixed target physics at LHCb: results and prospects

CERN Multimedia

CERN. Geneva

2016-01-01

In 2015, the LHCb collaboration endorsed the proposal to pursue an ambitious heavy ion physics program. In 2013, LHCb has demonstrated its capabilities to operate successfully in p-Pb and Pb-p collisions, leading already to several important publications in the field. The measurements of the nuclear modification factors and forward-backward production of prompt and displaced J/psi, psi(2S) and Upsilon states, as well as the production of prompt D0 mesons, have allowed to extend the knowledge of Cold Nuclear Matter effects on open heavy flavours and quarkonium production. The measurement of Z-boson production, important to constrain nuclear PDFs, and the measurement of two-particle angular correlations, probing collective effects in the dense environment of high energy collisions, have also been performed. Furthermore, LHCb is the only experiment at the LHC that can be operated in fixed-target mode, owing to the injection of a small amount of gas inside the LHCb collision area. There have been several p-gas an...

Power Load from Collision Debris on the LHC Point 8 Insertion Magnets implied by the LHCB Luminosity Increase

CERN Document Server

Esposito, L S; Lechner, A; Mereghetti, A; Vlachoudis, V; Patapenka, A

2013-01-01

LHCb is aiming to upgrade its goal peak luminosity up to a value of 2 × 1033 cm−2 s−1 after LS2. We investigate the collision debris impact on the machine elements by extensive FLUKA simulations, showing that the present machine layout is substantially compatible with such a luminosity goal. In particular the installation of a TAS (Target Absorber of Secondaries, installed in front of the final focus Q1-Q3 quadrupole triplet in the LHC high luminosity insertions) turns out not to be necessary on the basis of the expected peak power deposition in the Q1 superconducting coils. A warm protection may be desirable to further reduce heat load and dose on the D2 recombination dipole, due to the absence of the TAN (Target Absorber of Neutrals, present in Point 1 and 5).

SciFi - A large Scintillating Fibre Tracker for LHCb

CERN Multimedia

Quagliani, Renato

2016-01-01

The LHCb detector will be upgraded during the Long Shutdown 2 (LS2) of the LHC in order to cope with higher instantaneous luminosities and to read out the data at 40MHz using a trigger-less read-out system. All front-end electronics will be replaced and several sub-detectors must be redesigned to cope with higher occupancy. The current tracking detectors downstream of the LHCb dipole magnet will be replaced by the Scintillating Fibre (SciFi) Tracker. Concept, design and operational parameters are driven by the challenging LHC environment including significant ionising and neutron radiation levels. Over a total active surface of 360 m2 the SciFi Tracker will use scintillating fibres (Ø 0.25 mm) read out by Silicon Photomultipliers (SiPMs). State-of-the-art multi-channel SiPM arrays are being developed to read out the fibres and a custom ASIC will be used to digitise the signals from the SiPMs. The project is now at the transition from R&D to series production. We will present the evolution of the design a...

LHCb Early Career Scientist Awards

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Patrick Koppenburg for the LHCb Collaboration

2016-01-01

On 15 September 2016, the LHCb collaboration awarded the first set of prizes for outstanding contributions of early career scientists.   From left to right: Guy Wilkinson (LHCb spokesperson), Sascha Stahl, Kevin Dungs, Tim Head, Roel Aaij, Conor Fitzpatrick, Claire Prouvé, Patrick Koppenburg (chair of committee) and Sean Benson. Twenty-five nominations were submitted and considered by the committee, and 5 prizes were awarded to teams or individuals for works that had a significant impact within the last year. The awardees are: Roel Aaij, Sean Benson, Conor Fitzpatrick, Rosen Matev and Sascha Stahl for having implemented and commissioned the revolutionary changes to the LHC Run-2 high-level-trigger, including the first widespread deployment of real-time analysis techniques in High Energy Physics;   Kevin Dungs and Tim Head for having launched the Starterkit initiative, a new style of software tutorials based on modern programming methods. “Starterkit is a group of ph...

First mass measurements at LHCb

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Bressieux, J

2011-01-01

The LHC opens new frontiers in heavy flavour physics through an unprecedented statistical reach for a variety of interesting states produced in pp collisions. The LHCb spectrometer provides a good mass resolution and is suitable for spectroscopy studies. We present first preliminary mass measurements of several $b$ hadrons and of the exotic $X(3872)$ meson, reconstructed in final states containing a $J/\\psi$ using the data collected in 2010 by the LHCb experiment. An important aspect of the analysis is the calibration of the momentum scale using $J/\\psi \\to \\mu^+ \\mu^-$ decays, as well as the control of systematic uncertainties. While the already very competitive mass measurements for the $B^+$, $B^0$ and $B^0_s$ mesons receive similar contributions from systematic and statistical uncertainties, those of the $\\Lambda_b$, $B^+_c$ and $X(3872)$ particles are dominated by statistical uncertainties, and will therefore substantially improve with more data in the future.

Enabling Real-Time Analysis at LHCb

CERN Multimedia

Govorkova, Katya

2017-01-01

A new streaming strategy of the LHCb experiment includes the possibility to perform the physics analysis with candidates reconstructed in the trigger, thus bypassing the offline reconstruction. In the Turbo stream the trigger writes out a compact summary of physics objects containing all information necessary for analyses. This allows an increased output rate and thus higher average efficiencies. The Turbo stream was introduced in 2015 and has allowed for and expanded physics program in Run 2 of the LHC.

The Large Hadron Collider (LHC): The Energy Frontier

Science.gov (United States)

Brianti, Giorgio; Jenni, Peter

The following sections are included: * Introduction * Superconducting Magnets: Powerful, Precise, Plentiful * LHC Cryogenics: Quantum Fluids at Work * Current Leads: High Temperature Superconductors to the Fore * A Pumping Vacuum Chamber: Ultimate Simplicity * Vertex Detectors at LHC: In Search of Beauty * Large Silicon Trackers: Fast, Precise, Efficient * Two Approaches to High Resolution Electromagnetic Calorimetry * Multigap Resistive Plate Chamber: Chronometry of Particles * The LHCb RICH: The Lord of the Cherenkov Rings * Signal Processing: Taming the LHC Data Avalanche * Giant Magnets for Giant Detectors

Partially Reconstructed Beauty Decays at LHCb for the Phase-II Upgrade

CERN Multimedia

Smith, Iwan Thomas

2017-01-01

Semileptonic beauty decays provide a theoretically clean probe of CKM Unitarity since their decay rates factorise into leptonic and hadronic currents. At hadron colliders the full kinematic properties of these decays cannot be determined due to the unreconstructable neutrino. The kinematics can however be inferred through the conservation of momentum perpendicular to the flight direction that can be resolved by the LHCb Vertex Locator (VELO). The RF foil is an essential component of the LHCb vertex locator (VELO), separating the secondary vacuum of the VELO from the primary vacuum of the LHC. The foil protects the VELO modules from beam induced effects such as RF waves, and protects the LHC vacuum from hardware effects such as outgassing. The RF foil contributes to the material budget of the experiment and degrades the quality of tracks resulting in a worsened resolution for the reconstructed production and decay vertices. The phase-II upgrade can greatly improve the performance of semileptonic measurements a...

LHCb : First years of running for the LHCb calorimeter system and preparation for run 2

CERN Multimedia

Chefdeville, Maximilien

2015-01-01

The LHCb experiment is dedicated to precision measurements of CP violation and rare decays of B hadrons at the Large Hadron Collider (LHC) at CERN (Geneva). It comprises a calorimeter system composed of four subdetectors: a Scintillating Pad Detector (SPD) and a Pre-Shower detector (PS) in front of an electromagnetic calorimeter (ECAL) which is followed by a hadron calorimeter (HCAL). They are used to select transverse energy hadron, electron and photon candidates for the first trigger level and they provides the identification of electrons, photons and hadrons as well as the measurement of their energies and positions. The calorimeter has been pre-calibrated before its installation in the pit. The calibration techniques have been tested with data taken in 2010 and used regularly during run 1. For run 2, new calibration methods have been devised to follow and correct online the calorimeter detector response. The design and construction characteristics of the LHCb calorimeter will be recalled. Strategies for...

From the CERN web: LHCb, ATLAS, ILC and more

CERN Multimedia

2015-01-01

This new section highlights articles, blog posts and press releases published in the CERN web environment over the past weeks. This way, you won’t miss a thing...     LHCb sees small deviations from the lepton universality 1 September – LHCb collaboration The LHCb experiment at CERN has made the first measurement at a hadron collider of B meson decays that have already shown small deviations from the predictions of the Standard Model in earlier studies at an electron-positron collider. Continue to read…     The figure shows the density of allowed supersymmetric models before and after the ATLAS Run 1 searches. The missing points have been ruled out by the LHC data. The x-axis shows the mass of the supersymmetric dark matter particle, while the y-axis shows the predicted density of those particles in the universe.     ATLAS is narrowing down the theoretical candidates for dark matter 25 August – ATLAS collab...

Distributed control and monitoring of high-level trigger processes on the LHCb online farm

CERN Document Server

Vannerem, P; Jost, B; Neufeld, N

2003-01-01

The on-line data taking of the LHCb experiment at the future LHC collider will be controlled by a fully integrated and distributed Experiment Control System (ECS). The ECS will supervise both the detector operation (DCS) and the trigger and data acquisition (DAQ) activities of the experiment. These tasks require a large distributed information management system. The aim of this paper is to show how the control and monitoring of software processes such as trigger algorithms are integrated in the ECS of LHCb.

LHCb siliicon detectors: the Run 1 to Run 2 transition and first experience of Run 2

CERN Document Server

Rinnert, Kurt

2015-01-01

LHCb is a dedicated experiment to study New Physics in the decays of heavy hadrons at the Large Hadron Collider (LHC) at CERN. The detector includes a high precision tracking system consisting of a silicon-strip vertex detector (VELO) surrounding the pp interaction region, a large- area silicon-strip detector located upstream of a dipole magnet (TT), and three stations of silicon- strip detectors (IT) and straw drift tubes placed downstream (OT). The operational transition of the silicon detectors VELO, TT and IT from LHC Run 1 to Run 2 and first Run 2 experiences will be presented. During the long shutdown of the LHC the silicon detectors have been maintained in a safe state and operated regularly to validate changes in the control infrastructure, new operational procedures, updates to the alarm systems and monitoring software. In addition, there have been some infrastructure related challenges due to maintenance performed in the vicinity of the silicon detectors that will be discussed. The LHCb silicon dete...

Measurements of the $B$ meson production cross-sections at LHCb

CERN Document Server

LIU, Bo; ROBBE, Patrick; HE, Jibo

Quantum Chromodynamics (QCD), one of the most fundamental components of the Standard Model theory of Particle Physics, is dedicated to describe the strong interactions among quarks and gluons. For the $B$ meson production cross-sections in hadron-hadron collisions, perturbative QCD (pQCD) calculations are available at next-to-leading order (NLO) and with the fixed-order plus next-to-leading logarithms (FONLL) approximations. Measuring $B$ meson production cross-sections at the Large Hadron Collider (LHC) is of great importance to test the pQCD calculations. The LHCb detector is a single-arm forward spectrometer. It collects the physical information of the products in proton-proton collisions at the LHC. The differential and total production cross-sections of $B$ mesons (including $B^+$, $B^0$ and $B_s^0$) in proton-proton collisions at $\\sqrt{s}=7\\,{\\rm TeV}$ are studied using 35${\\rm pb}^{-1}$ of data in 2010 and 370${\\rm pb}^{-1}$ of data in 2011 collected by the LHCb detector, and reported in this dissert...

LHC Report: The beam is back at the LHC

CERN Multimedia

Reyes Alemany

2015-01-01

A series of sector beam tests paved the way for the start-up of the LHC in 2008 and 2009. These tests and the follow-up of the issues that arose were part of the process that led to a smooth start-up with beam.   Given this experience, sector tests were scheduled to take place several weeks before the 2015 start-up. On the weekend of 6-9 March, beam from the SPS was injected into both LHC injection regions, followed by a first pass through the downstream LHC sectors. For the clockwise LHC beam (called “beam 1”) this meant passing through ALICE and into Sector 2-3, while the anticlockwise beam (called “beam 2”) was threaded through LHCb and all the way from Point 8 to Point 6, where it was extracted by the beam dump kickers onto the beam dump block. The dry runs in the previous weeks were mainly targeted at preparation for the sector tests. The systems tested included: injection, timing, synchronisation and beam instrumentation. The beam interlock ...

Heavy flavour production in proton-lead and lead-lead collisions with LHCb

Science.gov (United States)

Winn, Michael

2017-11-01

The LHCb experiment offers the unique opportunity to study heavy-ion interactions in the forward region (2 kinematic domain complementary to the other 3 large experiments at the LHC. The detector has excellent capabilities for reconstructing quarkonia and open charm states, including baryons, down to zero pT. It can separate the prompt and displaced charm components. In pPb collisions, both forward and backward rapidities are covered thanks to the possibility of beam reversal. Results include measurements of the nuclear modification factor and forward-backward ratio for charmonium, open charm and bottomonium states. These quantities are sensitive probes for nuclear effects in heavy flavour production. Perspectives are given with the large accumulated luminosity during the 2016 pPb run at the LHC. In 2015, LHCb participated successfully for the first time in the PbPb data-taking. The status of the forward prompt J/ψ nuclear modification factor measurement in lead-lead collisions is discussed.

A tracking algorithm for the reconstruction of the daughters of long-lived particles in LHCb

CERN Document Server

Dendek, Adam Mateusz

2018-01-01

A tracking algorithm for the reconstruction of the daughters of long-lived particles in LHCb 5 Jun 2018, 16:00 1h 30m Library, Centro San Domenico () LHC experiments Posters session Speaker Katharina Mueller (Universitaet Zuerich (CH)) Description The LHCb experiment at CERN operates a high precision and robust tracking system to reach its physics goals, including precise measurements of CP-violation phenomena in the heavy flavour quark sector and searches for New Physics beyond the Standard Model. The track reconstruction procedure is performed by a number of algorithms. One of these, PatLongLivedTracking, is optimised to reconstruct "downstream tracks", which are tracks originating from decays outside the LHCb vertex detector of long-lived particles, such as Ks or Λ0. After an overview of the LHCb tracking system, we provide a detailed description of the LHCb downstream track reconstruction algorithm. Its computational intelligence part is described in details, including the adaptation of the employed...

Inclusive production at LHC energies

International Nuclear Information System (INIS)

Merino, C.; Pajares, C.; Shabelski, Yu.M.

2011-01-01

We consider the first LHC data for pp collisions in the framework of Regge theory. The integral cross sections and inclusive densities of secondaries are determined by the Pomeron exchange, and we present the corresponding predictions for them. The first measurements of inclusive densities in the midrapidity region are in agreement with these predictions. The contribution of the baryon-number transfer due to String Junction diffusion in the rapidity space is at the origin of the differences in the inclusive spectra of particle and antiparticle in the central region, and this effect could be significant at LHC energies. We discuss the first data of ALICE and LHCb collaborations on the baryon/antibaryon asymmetry at LHC. (orig.)

W, Z and top production measurements at LHCb

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00258880

2018-01-01

Due to its unique pseudorapidity coverage between 2 and 5 and excellent performance, the LHCb detector allows for complementary probe of electroweak and QCD processes to those at ATLAS and CMS experiments. Studies of electroweak boson and top production provide important probes of the Standard Model at LHC energies and constrain parton distribution functions. The recent results on theW, Z and top production are briefly summarized in the present proceedings.

Automated Grid Monitoring for LHCb through HammerCloud

CERN Multimedia

CERN. Geneva

2015-01-01

The HammerCloud system is used by CERN IT to monitor the status of the Worldwide LHC Computing Grid (WLCG). HammerCloud automatically submits jobs to WLCG computing resources, closely replicating the workflow of Grid users (e.g. physicists analyzing data). This allows computation nodes and storage resources to be monitored, software to be tested (somewhat like continuous integration), and new sites to be stress tested with a heavy job load before commissioning. The HammerCloud system has been in use for ATLAS and CMS experiments for about five years. This summer's work involved porting the HammerCloud suite of tools to the LHCb experiment. The HammerCloud software runs functional tests and provides data visualizations. HammerCloud's LHCb variant is written in Python, using the Django web framework and Ganga/DIRAC for job management.

Fast neural-net based fake track rejection in the LHCb reconstruction

CERN Document Server

De Cian, Michel; Seyfert, Paul; Stahl, Sascha

2017-01-01

A neural-network based algorithm to identify fake tracks in the LHCb pattern recognition is presented. This algorithm, called ghost probability, retains more than 99 % of well reconstructed tracks while reducing the number of fake tracks by 60 %. It is fast enough to fit into the CPU time budget of the software trigger farm and thus reduces the combinatorics of the decay reconstructions, as well as the number of tracks that need to be processed by the particle identification algorithms. As a result, it strongly contributes to the achievement of having the same reconstruction online and offline in the LHCb experiment in Run II of the LHC.

LHCb: Not just a precision experiment but also a detector ready for discoveries

CERN Multimedia

CERN Bulletin

2010-01-01

The first proton run has confirmed that LHCb has powerful capabilities in the field of flavour physics and that many possible signatures of non-Standard Model effects are within the experiment's reach. Furthermore, this run has confirmed that LHCb is able to make important contributions beyond the flavour sector. The collaboration is working on a Letter of Intent for an upgrade, which will take advantage of the open geometry of the experiment, and will aim at improved sensitivity both in the flavour sector and in a wider physics programme.   Unlike ATLAS and CMS, LHCb does not have a cylindrical geometry. Rather, it is laid out horizontally along the beam line. This layout prevented the collaboration from testing the detector with cosmic rays prior to starting to collect data from the LHC collisions. However, despite these more challenging initial conditions, LHCb was soon able to demonstrate excellent performance during the LHC’s first proton run. “Just a few years ago, we co...

Searches for $CP$ violation in multi-body charm decays and studies of radiation damage in the LHCb VELO detector

CERN Document Server

Chen, Shanzhen; Gersabeck, Marco

This thesis presents two searches for direct charge-parity ($CP$) violation in multi-body decays in the charm-sector at LHCb, the development of techniques for performing model-independent searches for direct $CP$ violation in multi-body decays, and the development of studies of radiation damage effects in the LHCb vertex detector. LHCb is a dedicated experiment to study New Physics in the decays of heavy hadrons at the Large Hadron Collider (LHC) at CERN. The detector includes a high precision vertex detector surrounding the $pp$ interaction region made with silicon strip sensors. Studies of the effects of radiation damage in LHC run-2 for the operation of this detector are presented and the determination of the operational bias voltages of the silicon strip sensors is discussed. An unbinned model independent technique for $CP$ violation searches in multi-body decays called the energy test is used for the first time. The selection and treatment of the coordinates used to describe the phase-space of the de...

The LHCb VELO upgrade

International Nuclear Information System (INIS)

Rodríguez Pérez, Pablo

2013-01-01

LHCb is a forward spectrometer experiment dedicated to the study of new physics in the decays of beauty and charm hadrons produced in proton collisions at the Large Hadron Collider (LHC) at CERN. The VErtex LOcator (VELO) is the microstrip silicon detector surrounding the interaction point, providing tracking and vertexing measurements. The upgrade of the LHCb experiment, planned for 2018, will increase the luminosity up to 2×10 33 cm −2 s −1 and will perform the readout as a trigger-less system with an event rate of 40 MHz. Extremely non-uniform radiation doses will reach up to 5×10 15 1 MeV n eq /cm 2 in the innermost regions of the VELO sensors, and the output data bandwidth will be increased by a factor of 40. An upgraded detector is under development based in a pixel sensor of the Timepix/Medipix family, with 55×55μm 2 pixels. In addition a microstrip solution with finer pitch, higher granularity and thinner than the current detector is being developed in parallel. The current status of the VELO upgrade program will be described together with recent testbeam results

Measurements of $B \\to \\mu^{+} \\mu^{-}$ decays using the LHCb experiment

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00400160

This dissertation documents a study of very rare $B$-meson decays at the LHCb experiment, using data taken during the first experiment run of the Large Hadron Collider (LHC) and during the second experiment run until September 2016. The LHCb experiment was designed to test the Standard Model of particle physics and to search for New Physics effects that go beyond the scope of the Standard Model through the decay of $b$ hadrons produced in high energy proton-proton collisions at the LHC. The measurements described in this dissertation are made using data samples of proton-proton collisions with integrated luminosities of 1.0, 2.0 and 1.4 fb$^{-1}$, collected at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The branching fractions of the very rare $B^{0} \\to \\mu^{+} \\mu^{-}$ and $B_{s}^{0} \\to \\mu^{+} \\mu^{-}$ decays and the effective lifetime of $B_{s}^{0} \\to \\mu^{+} \\mu^{-}$ decays are precisely predicted by the Standard Model and are sensitive to effects from New Physics. New Physics processes...

Primary Vertex Reconstruction for Upgrade at LHCb

CERN Document Server

Wanczyk, Joanna

2016-01-01

The aim of the LHCb experiment is the study of beauty and charm hadron decays with the main focus on CP violating phenomena and searches for physics beyond the Standard Model through rare decays. At the present, the second data taking period is ongoing, which is called Run II. After 2018 during the long shutdown, the replacement of signicant parts of the LHCb detector is planned. One of main changes is upgrade of the present software and hardware trigger to a more rapid full software trigger. Primary Vertex (PV) is a basis for the further tracking and it is sensitive to the LHC running conditions, which are going to change for the Upgrade. In particular, the center-of-mass collision energy should reach the maximum value of 14 TeV. As a result the quality of the reconstruction has to be studied and the reconstruction algorithms have to be optimized.

Radiation damage at LHCb, results and expectations

CERN Multimedia

Faerber, Christian

2011-01-01

The LHCb Detector is a single-arm spectrometer at the LHC designed to detect new physics through measuring CP violation and rare decays of heavy flavor mesons. The detector consists of vertex detector, tracking system, dipole magnet, 2 RICH detectors, em. calorimeter, hadron calorimeter, muon detector which all use different technologies and suffer differently from radiation damage. These radiation damage results and the investigation methods will be shown. The delivered luminosity till July 2011 was about 450 pb−1. The Vertex detector receives the highest particle flux at LHCb. The currents drawn by the silicon sensors are, as expected, increasing proportional to the integrated luminosity. The highest irradiaton regions of the n-bulk silicon sensors are observed to have recently undergone space charge sign inversion. The Silicon Trackers show increasing leakage currents comparable with earlier predictions. The electromagentic calorimeter and hadron calorimeter suffer under percent-level signal decrease whi...

Measurement of Indirect CP Violation in Charm at LHCb

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00342046

This thesis describes two pieces of work. The first is a study of the resolution of the LHCb vertex locator throughout Run 1. The second comprises analyses to measure the charm mixing and $CP$ violation observables $A_{\\Gamma}$ and $y_{CP}$. An estimate of the resolution of the LHCb vertex locator is required for use in the track fits. A method to measure the resolution with collision data has been developed and tested. The performance of the sub-detector throughout Run 1 of the LHC has been assessed. A significant degrading of the resolution has been seen. The effects of this on the track reconstruction has been examined with little change in the measured quantities being observed. The measurement of indirect $CP$ violation in neutral $D$ meson transitions has been measured through the observables $A_{\\Gamma}$ and $y_{CP}$, using $fb^{-1}$ of $pp$ collisions with a centre of mass energy $7 TeV$, collected by the LHCb detector in 2011. $A_{\\Gamma}$ describes the $CP$ asymmetry of the lifetime of the $D^0$ dec...

Development and operation of tracking detectors in silicon technology for the LHCb upgrade

CERN Document Server

Rodriguez Perez, Pablo; Adeva, Bernardo

The LHCb experiment is one of the four main experiments at the Large Hadron Collider (LHC) at CERN. It uses the energy density provided by the LHC to attempt to probe asymmetries between particles and antiparticles that can not be explained by the Standard Model, and thus provide evidence that would allow us to build a new model of fundamental physics. This thesis covers the author's work in the Silicon Tracker $(\\textit{ST})$ and VErtex LOcator $(\\textit{VELO})$ detectors of the LHCb experiment. The thesis explains the installation and commissioning of the $ST$, as well as the development of the slow control for the detector. The $ST$ is a silicon micro-strip detector which provides precise momentum measurements of ionizing particles coming from the collisions. The $ST$consists of two sub-detectors: the Tracker Turicensis $ (TT)$, located upstream of the 4 Tm dipole magnet covering the full acceptance of the experiment, and the Inner Tracker $(IT)$, which covers the region of highest particle density closest...

Optimizing the Stripping Procedure for LHCb

CERN Document Server

Richardson, Rachel

2017-01-01

The LHCb experiment faces a major challenge from the large amounts of data received while the LHC is running. The ability to sort this information in a useful manner is important for working groups to perform physics analyses. Both hardware and software triggers are used to decrease the data rate and then the stripping process is used to sort the data into streams and further into stripping lines. This project studies the hundreds of stripping lines to look for overlaps between them in order to make the stripping process more efficient.

Physics at LHC and beyond

CERN Document Server

2014-01-01

The topics addressed during this Conference are as follows. ---An overview of the legacy results of the LHC experiments with 7 and 8 TeV data on Standard Model physics, Scalar sector and searches for New Physics. ---A discussion of the readiness of the CMS, ATLAS, and LHCb experiments for the forthcoming high-energy run and status of the detector upgrades ---A review of the most up-to-date theory outcome on cross-sections and uncertainties, phenomenology of the scalar sector, constraints and portals for new physics. ---The presentation of the improvements and of the expected sensibilities for the Run 2 of the LHC at 13 TeV and beyond. ---A comparison of the relative scientific merits of the future projects for hadron and e+e- colliders (HL-LHC, HE-LHC, ILC, CLIC, TLEP, VHE-LHC) towards precision measurements of the Scalar boson properties and of the Electroweak-Symmetry-Breaking parameters, and towards direct searches for New Physics.

The great adventure of the LHC - From big bang to the Higgs boson

International Nuclear Information System (INIS)

Denegri, D.; Guyot, C.; Hoecker, A.; ); Roos, L.; Rubbia, C.

2014-03-01

This book presents what has been the biggest scientific equipment ever designed on earth: the LHC (large hadron collider) and its associated experiments (ATLAS, CMS, LHCb and ALICE) that led to the discovery of the Higgs boson in 2012. About 10.000 physicists and engineers from 50 countries have taken part into the project that began in 1989. This book is composed of the following chapters: 1) the standard model (SM) of particle physics, 2) the experimental success of SM, 3) the shortfalls of SM, 4) the new physics, 5) the original big bang, 6) the LHC, 7) particle detection, 8) ATLAS and CMS experiments, 9) the first data from LHC, 10) data analysis, 11) the quest for the Higgs boson, 12) the search for new physics, 13) LHCb and ALICE experiments, and 14) future prospects

Test of the photon detection system for the LHCb RICH Upgrade in a charged particle beam

CERN Document Server

Baszczyk, M.K.

2017-01-16

The LHCb detector will be upgraded to make more efficient use of the available luminosity at the LHC in Run III and extend its potential for discovery. The Ring Imaging Cherenkov detectors are key components of the LHCb detector for particle identification. In this paper we describe the setup and the results of tests in a charged particle beam, carried out to assess prototypes of the upgraded opto-electronic chain from the Multi-Anode PMT photosensor to the readout and data acquisition system.

Generators, Calorimeter Trigger and J/ψ production at LHCb

CERN Document Server

Robbe, P

This document presents results related to the preparation of the physics program ofLHCb: generator software development, calorimeter trigger commissioning and measurement of J/psi production. A detailed simulation is mandatory to developthe analysis tools needed for this program and a detailed generator framework hasbeen implemented which describes for example B mixing and CP violation in B decays in the LHCb hadronic environment. For hadronic decay modes, the trigger of the experiment is based at the first level on information provided by the calorimeters, and in particular the hadronic calorimeter. The large J/psi production cross-section at the LHC allows to perform, with the first data recorded, a measurement of the J/psi differential cross-section and to confront it with theoretical models to test QCD in the heavy quark sector.

The early career, gender, and diversity actions at the LHCb Collaboration

CERN Multimedia

Rademacker, Jonas

2016-01-01

Numerous surveys of modern particle physics indicate that the discipline is still largely a male pursuit, and one in which women and other marginalised groups continue to face discriminatory practices. The fraction of female particle physicists reduces with each career stage. Early career particle physicists face precarious employment conditions with serial short term contracts, long working hours, the frequent need to relocate, and little prospect for a permanent academic position. There are indications that these employment conditions add to the gender-imbalance in the field, but clearly, this problem directly affects both male and female early career scientists. The LHCb experiment has, as the first (and so far only) LHC experiment, created a dedicated office for Early Career Gender and Diversity (ECGD) (see http://lhcb.web.cern.ch/lhcb/ECGD_Office/ECGD-intro.html ). The ECGD office’s role is to to advise the management on ECGD matters; provide a point of contact for anybody experiencing any kind discrim...

The silicon vertex locator for the LHCb upgrade

CERN Document Server

Head, Tim

2014-01-01

The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a triggerless system being read out at 40 MHz. The upgraded silicon vertex detector (VELO) must be light weight, radiation hard, and compatible with LHC vacuum requirements. It must be capable of fast pattern recognition, fast track reconstruction and high precision vertexing. This challenge is being met with a new VELO design based on hybrid pixel detectors positioned to within 5 mm of the LHC colliding beams. The detector will be shielded from the beam by a View the MathML source~300μm thick aluminium foil. Evaporative CO2 coolant circulating in micro-channels embedded in a thin silicon substrate will be used for cooling.

LHCb: Radiation hard programmable delay line for LHCb Calorimeter Upgrade

CERN Multimedia

Mauricio Ferre, J; Vilasís Cardona, X; Picatoste Olloqui, E; Machefert, F; Lefrançois, J; Duarte, O

2013-01-01

This poster describes the implementation of a SPI-programmable clock delay chip based on a Delay Locked Loop (DLL) in order to shift the phase of the LHC clock (25 ns) in steps of 1ns, with a 4ps jitter and 18ps of DNL. The delay lines will be integrated into ICECAL, the LHCb calorimeter front-end ASIC in the near future. The stringent noise requirements on the ASIC imply minimizing the noise contribution of digital components. This is accomplished by implementing the DLL in differential mode. To achieve the required radiation tolerance several techniques are applied: double guard rings between PMOS and NMOS transistors as well as glitch suppressors and TMR Registers. This 5.7 mm2 chip has been implemented in CMOS 0.35um technology.

LHCb: Managing Large Data Productions in LHCb

CERN Multimedia

Tsaregorodtsev, A

2009-01-01

LHC experiments are producing very large volumes of data either accumulated from the detectors or generated via the Monte-Carlo modeling. The data should be processed as quickly as possible to provide users with the input for their analysis. Processing of multiple hundreds of terabytes of data necessitates generation, submission and following a huge number of grid jobs running all over the Computing Grid. Manipulation of these large and complex workloads is impossible without powerful production management tools. In LHCb, the DIRAC Production Management System (PMS) is used to accomplish this task. It enables production managers and end-users to deal with all kinds of data generation, processing and storage. Application workflow tools allow to define jobs as complex sequences of elementary application steps expressed as Directed Acyclic Graphs. Specialized databases and a number of dedicated software agents ensure automated data driven job creation and submission. The productions are accomplished by thorough ...

LHCb: The Front-End electronics for the LHCb scintillating fibres detector

CERN Multimedia

Chanal, H; Pillet, N

2014-01-01

The LHCb detector will be upgraded during the next LHC shutdown in 2018/19. The tracker system will have a major overhaul. Its components will be replaced with new technologies in order to cope with the increased hit occupancy and radiation environment. A detector made of scintillating fibres read out by silicon photomultipliers (SiPM) is studied for this upgrade. Even if this technology has proven to achieve high efficiency and spatial resolution, its integration within a LHC experiment bears new challenges. This detector will consist of 12 planes of 5 to 6 layers of 250 $\\mu$m fibres with an area of 5×6 m$^2$. Its lead to a total of 500k SiPM channels which need to will be read out at 40MHz. This talk gives an overview of the R&D status of the readout board and the PACIFIC chip. The readout board is connected to the SiPM on one side and to the experiment data-acquisition, experimental control system and services on the other side . The PACIFIC chip is a 128 channel ASIC which can be connected to one 12...

Contribution to the alignment of the LHCb tracking system and measurement of the mean lifetimes of $B_{d(s)} \\to D_{(s)} \\pi$, $D_{(s)}\\to KK\\pi$

CERN Document Server

Fave, Vincent

The LHCb experiment is one of the four large experiment of the Large Hadron Collider (LHC) situated at CERN, on the swiss-french border near Geneva. The LHCb detector is a single-arm spectrometer dedicated to the study of rare $b$-hadrons decays and to precision CP violation measurements. The LHCb experiment has so far collected $1\\mathrm{fb^{-1}}$ of data at a center of mass energy of $7\\,\\mathrm{TeV}$. This thesis addresses three topics related to the LHCb experiment. The first part concerns the alignment of the LHCb Inner Tracker with the first LHC data. Misalignments in the tracking system degrade the momentum measurement and flight distance determination of particles. Such quantities are vital for accurate lifetime and mass measurements. A standalone alignment of the Inner Tracker was performed using a method to stabilize the Inner Tracker alignment without the need of fixing elements. The Inner Tracker was aligned to a precision of $102\\pm 10\\,\\mathrm{\\mu m}$, with a bias of $0\\pm 13\\,\\mathrm{\\mu m}$. I...

The search for τ→μμμ at LHCb

Energy Technology Data Exchange (ETDEWEB)

Seyfert, Paul

2015-01-14

The charged lepton flavour violating decay τ→μμμ is searched for, using the LHCb experiment. Violation of lepton flavour in the charged lepton sector is unobserved to date. Within the Standard Model of particle physics including neutrino oscillation, the branching fraction is expected to be umeasureable small and an observation would be an unambiguous sign for physics beyond the Standard Model. Over 10{sup 11} τ leptons have been produced in proton-proton collisions at LHCb during the first run of the LHC. Most of them in decays of D{sub s} mesons. Compared to previous experiments at electron-positron colliders, the signature of τ→μμμ is harder to identify in hadronic collisions and background processes are more abundant. A multivariate event classification has been developed to distinguish a possible signal from background events. The number of τ leptons produced in the LHCb acceptance is estimated by measuring the yield of D{sub s}→φ(μμ)π decays. The sensitivity reached by analysing LHCb data corresponding to 3 fb{sup -1} is sufficient to constrain the branching fraction of τ→μμμ to be smaller than 7.1 x 10{sup -8} at 90% confidence level.

Machine learning and parallelism in the reconstruction of LHCb and its upgrade

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00260810

2016-01-01

The LHCb detector at the LHC is a general purpose detector in the forward region with a focus on reconstructing decays of c- and b-hadrons. For Run II of the LHC, a new trigger strategy with a real-time reconstruction, alignment and calibration was employed. This was made possible by implementing an oine-like track reconstruction in the high level trigger. However, the ever increasing need for a higher throughput and the move to parallelism in the CPU architectures in the last years necessitated the use of vectorization techniques to achieve the desired speed and a more extensive use of machine learning to veto bad events early on. This document discusses selected improvements in computationally expensive parts of the track reconstruction, like the Kalman filter, as well as an improved approach to get rid of fake tracks using fast machine learning techniques. In the last part, a short overview of the track reconstruction challenges for the upgrade of LHCb, is given. Running a fully software-based trigger, a l...

LHCb's Time-Real Alignment in RunII

CERN Multimedia

Batozskaya, Varvara

2015-01-01

LHCb has introduced a novel real-time detector alignment and calibration strategy for LHC Run 2. Data collected at the start of the fill will be processed in a few minutes and used to update the alignment, while the calibration constants will be evaluated for each run. This procedure will improve the quality of the online alignment. Critically, this new real-time alignment and calibration procedure allows identical constants to be used in the online and offline reconstruction, thus improving the correlation between triggered and offline selected events. This offers the opportunity to optimise the event selection in the trigger by applying stronger constraints. The required computing time constraints are met thanks to a new dedicated framework using the multi-core farm infrastructure for the trigger. The motivation for a real-time alignment and calibration of the LHCb detector is discussed from both the operational and physics performance points of view. Specific challenges of this novel configur...

Performance of the RASNIK Optical Alignment Monitoring System for the LHCb Outer Tracker Detector

CERN Document Server

Szczekowski, Marek; Ukleja, Artur; Pellegrino, Antonio; Hart, Robert; Syryczynski, Krzysztof

2017-01-01

We present the results collected by an optical system for position control of the Outer Tracker detector stations in the LHCb experiment. This system has been constructed using the RASNIK three-point alignment monitors. The measurements are based on data taken in Run 2 of LHC.

Challenges to Software/Computing for Experimentation at the LHC

Science.gov (United States)

Banerjee, Sunanda

The demands of future high energy physics experiments towards software and computing have led the experiments to plan the related activities as a full-fledged project and to investigate new methodologies and languages to meet the challenges. The paths taken by the four LHC experiments ALICE, ATLAS, CMS and LHCb are coherently put together in an LHC-wide framework based on Grid technology. The current status and understandings have been broadly outlined.

LHC Startup

CERN Document Server

AUTHOR|(CDS)2067853

2008-01-01

The Large Hadron Collider will commence operations in the latter half of 2008. The plans of the LHC experiments ALICE, ATLAS, CMS and LHCb are described. The scenario for progression of luminosity and the strategies of these 4 experiments to use the initial data are detailed. There are significant measurements possible with integrated luminosities of 1, 10 and 100 pb^-1. These measurements will provide essential calibration and tests of the detectors, understanding of the Standard Model backgrounds and a first oportunity to look for new physics.

Integration of Cloud resources in the LHCb Distributed Computing

Science.gov (United States)

Úbeda García, Mario; Méndez Muñoz, Víctor; Stagni, Federico; Cabarrou, Baptiste; Rauschmayr, Nathalie; Charpentier, Philippe; Closier, Joel

2014-06-01

This contribution describes how Cloud resources have been integrated in the LHCb Distributed Computing. LHCb is using its specific Dirac extension (LHCbDirac) as an interware for its Distributed Computing. So far, it was seamlessly integrating Grid resources and Computer clusters. The cloud extension of DIRAC (VMDIRAC) allows the integration of Cloud computing infrastructures. It is able to interact with multiple types of infrastructures in commercial and institutional clouds, supported by multiple interfaces (Amazon EC2, OpenNebula, OpenStack and CloudStack) - instantiates, monitors and manages Virtual Machines running on this aggregation of Cloud resources. Moreover, specifications for institutional Cloud resources proposed by Worldwide LHC Computing Grid (WLCG), mainly by the High Energy Physics Unix Information Exchange (HEPiX) group, have been taken into account. Several initiatives and computing resource providers in the eScience environment have already deployed IaaS in production during 2013. Keeping this on mind, pros and cons of a cloud based infrasctructure have been studied in contrast with the current setup. As a result, this work addresses four different use cases which represent a major improvement on several levels of our infrastructure. We describe the solution implemented by LHCb for the contextualisation of the VMs based on the idea of Cloud Site. We report on operational experience of using in production several institutional Cloud resources that are thus becoming integral part of the LHCb Distributed Computing resources. Furthermore, we describe as well the gradual migration of our Service Infrastructure towards a fully distributed architecture following the Service as a Service (SaaS) model.

Integration of cloud resources in the LHCb distributed computing

International Nuclear Information System (INIS)

García, Mario Úbeda; Stagni, Federico; Cabarrou, Baptiste; Rauschmayr, Nathalie; Charpentier, Philippe; Closier, Joel; Muñoz, Víctor Méndez

2014-01-01

This contribution describes how Cloud resources have been integrated in the LHCb Distributed Computing. LHCb is using its specific Dirac extension (LHCbDirac) as an interware for its Distributed Computing. So far, it was seamlessly integrating Grid resources and Computer clusters. The cloud extension of DIRAC (VMDIRAC) allows the integration of Cloud computing infrastructures. It is able to interact with multiple types of infrastructures in commercial and institutional clouds, supported by multiple interfaces (Amazon EC2, OpenNebula, OpenStack and CloudStack) – instantiates, monitors and manages Virtual Machines running on this aggregation of Cloud resources. Moreover, specifications for institutional Cloud resources proposed by Worldwide LHC Computing Grid (WLCG), mainly by the High Energy Physics Unix Information Exchange (HEPiX) group, have been taken into account. Several initiatives and computing resource providers in the eScience environment have already deployed IaaS in production during 2013. Keeping this on mind, pros and cons of a cloud based infrasctructure have been studied in contrast with the current setup. As a result, this work addresses four different use cases which represent a major improvement on several levels of our infrastructure. We describe the solution implemented by LHCb for the contextualisation of the VMs based on the idea of Cloud Site. We report on operational experience of using in production several institutional Cloud resources that are thus becoming integral part of the LHCb Distributed Computing resources. Furthermore, we describe as well the gradual migration of our Service Infrastructure towards a fully distributed architecture following the Service as a Service (SaaS) model.

Investigation of Sn-Pb solder bumps of prototype photo detectors for the LHCb experiment

CERN Document Server

Delsante, M L; Arnau-Izquierdo, G

2004-01-01

The Large Hadron Collider (LHC) is now under construction at the European Organization for Nuclear Research (CERN). LHCb is one of the dedicated LHC experiments, allowing high energy proton-proton collisions to be exploited. This paper presents the results of the metallurgic studies carried out on Sn-Pb solder bumps of prototype vacuum photo detectors under development for LHCb, and in particular for the ring imaging Cherenkov-hybrid photo diode (RICH-HPD) project. These detectors encapsulate, in a vacuum tube, an assembly made of two silicon chips bonded together by a matrix of solder bumps. Each bump lies on a suitable system of under-bump metallic layers ensuring mechanical and electrical transition between the chip pad and the solder alloy. During manufacturing of the detector, bump-bonded (BB) assemblies are exposed to severe heat cycles up to 400 degree C inducing, in the present fabrication process, a clear degradation of electrical connectivity. Several investigations such as microstructural observati...

Study of charmless three-body decays of neutral B mesons with the LHCb spectrometer

CERN Document Server

Sobczak, Krzysztof Grzegorz

This thesis describes an exploratory work on three-body charmless neutral $B$ mesons decays containing either a $K_S$ or $\\pi^0$. The events are reconstructed with the LHCb spectrometer installed at Cern (Geneva, CH) recording the proton-proton collisions delivered by the Large Hadron Collider (LHC). The phenomenology of such modes is rich and covers the possibility to measure all angles of the unitarity triangle linked to the Cabibbo-Kobayashi-Maskawa (CKM) matrix. The single example of the $\\gamma$ measurement is explored in this document. The LHC accelerator and the most relevant sub-detector elements of the LHCb spectrometer are described in details. In particular, emphasis is given to the calorimetry system for which the calibration and alignment of the PreShower (PRS) of the electromagnetic calorimeter has been performed. We used particles at minimum ionisation deposit for such a task. The calibration results until year 2011 are reported as well as the method of the PS alignment with respect to the tra...

First Results from the LHCb Vertex Locator

CERN Multimedia

Borghi, S

2010-01-01

LHCb is a dedicated experiment to study new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The beauty and charm hadrons are identified through their flight distance in the Vertex Locator (VELO), and hence the detector is critical for both the trigger and offline physics analyses. The VELO is the silicon detector surrounding the interaction point, and is the closest LHC vertex detector to the interaction point, located only 7 mm from the LHC beam during normal operation. The detector will operate in an extreme and highly non-uniform radiation environment. The VELO consists of two retractable detector halves with 21 silicon micro-strip tracking modules each. A module is composed of two n+-on-n 300 micron thick half disc sensors with R-measuring and Phi-measuring micro-strip geometry, mounted on a carbon fibre support paddle. The minimum pitch is approximately 40 $\\mu$m. The detector is also equipped with one n-on-p module. The detectors are operated in vacuum and a...

The LHCb trigger and its performance in 2011

International Nuclear Information System (INIS)

Aaij, R; Beuzekom, M van; Coco, V; Albrecht, J; Alessio, F; Bonaccorsi, E; Brarda, L; Cattaneo, M; Chebbi, M; Clemencic, M; Closier, J; Amato, S; Aslanides, E; Cogan, J; Belyaev, I; Bonnefoy, R; Chanal, H; Deschamps, O; Callot, O; Vidal, X Cid

2013-01-01

This paper presents the design of the LHCb trigger and its performance on data taken at the LHC in 2011. A principal goal of LHCb is to perform flavour physics measurements, and the trigger is designed to distinguish charm and beauty decays from the light quark background. Using a combination of lepton identification and measurements of the particles' transverse momenta the trigger selects particles originating from charm and beauty hadrons, which typically fly a finite distance before decaying. The trigger reduces the roughly 11 MHz of bunch-bunch crossings that contain at least one inelastic pp interaction to 3 kHz. This reduction takes place in two stages; the first stage is implemented in hardware and the second stage is a software application that runs on a large computer farm. A data-driven method is used to evaluate the performance of the trigger on several charm and beauty decay modes.

JACoW Configuring and automating an LHC experiment for faster and better physics output

CERN Document Server

Gaspar, Clara; Alessio, Federico; Barbosa, Joao; Cardoso, Luis; Frank, Markus; Jost, Beat; Neufeld, Niko; Schwemmer, Rainer

2018-01-01

LHCb has introduced a novel online detector alignment and calibration for LHC Run II. This strategy allows for better trigger efficiency, better data quality and direct physics analysis at the trigger output. This implies: running a first High Level Trigger (HLT) pass synchronously with data taking and buffering locally its output; use the data collected at the beginning of the fill, or on a run-by-run basis, to determine the new alignment and calibration constants; run a second HLT pass on the buffered data using the new constants. Operationally, it represented a challenge: it required running different activities concurrently in the farm, starting at different times and load balanced depending on the LHC state. However, these activities are now an integral part of LHCb's dataflow, seamlessly integrated in the Experiment Control System and completely automated under the supervision of LHCb's 'Big Brother'. In total, for all activities, there are usually around 60000 tasks running in the ~1600 nodes of the fa...

Critical services in the LHC computing

International Nuclear Information System (INIS)

Sciaba, A

2010-01-01

The LHC experiments (ALICE, ATLAS, CMS and LHCb) rely for the data acquisition, processing, distribution, analysis and simulation on complex computing systems, running using a variety of services, provided by the experiments, the Worldwide LHC Computing Grid and the different computing centres. These services range from the most basic (network, batch systems, file systems) to the mass storage services or the Grid information system, up to the different workload management systems, data catalogues and data transfer tools, often internally developed in the collaborations. In this contribution we review the status of the services most critical to the experiments by quantitatively measuring their readiness with respect to the start of the LHC operations. Shortcomings are identified and common recommendations are offered.

Test of lepton flavour universality at LHCb

CERN Document Server

Lionetto, Federica

2016-01-01

This contribution presents the $R_D{\\ast}$ and $R_K$ measurements, which are a clean probe of lepton flavour universality, and the angular analyses of the $B^0 \\to K^\\ast {0} \\mu^+ \\mu^-$ and $B^0 \\to K^\\ast{0} ~e^+ e^-$ decays, which allow to search for New Physics in rare decays proceeding through ${\\text a} ~b \\to s \\ell^+ \\ell^-$ transition. All measurements have been performed by the LHCb collaboration using the full statistics of LHC Run I. An overview of the ongoing and future measurements is given in the conclusions.

Beam test results for the upgraded LHCb RICH opto-electronic readout system

CERN Multimedia

Carniti, Paolo

2016-01-01

The LHCb experiment is devoted to high-precision measurements of CP violation and search for New Physics by studying the decays of beauty and charmed hadrons produced at the Large Hadron Collider (LHC). Two RICH detectors are currently installed and operating successfully, providing a crucial role in the particle identification system of the LHCb experiment. Starting from 2019, the LHCb experiment will be upgraded to operate at higher luminosity, extending its potential for discovery and study of new phenomena. Both the RICH detectors will be upgraded and the entire opto-electronic system has been redesigned in order to cope with the new specifications, namely higher readout rates, and increased occupancies. The new photodetectors, readout electronics, mechanical assembly and cooling system have reached the final phase of development and their performance was thoroughly and successfully validated during several beam test sessions in 2014 and 2015 at the SPS facility at CERN. Details of the test setup and perf...

The LHCb VERTEX LOCATOR performance and VERTEX LOCATOR upgrade

International Nuclear Information System (INIS)

Rodríguez Pérez, P

2012-01-01

LHCb is an experiment dedicated to the study of new physics in the decays of beauty and charm hadrons at the Large Hadron Collider (LHC) at CERN. The Vertex Locator (VELO) is the silicon detector surrounding the LHCb interaction point. The detector operates in a severe and highly non-uniform radiation environment. The small pitch and analogue readout result in a best single hit precision of 4 μm. The upgrade of the LHCb experiment, planned for 2018, will transform the entire readout to a trigger-less system operating at 40 MHz event rate. The vertex detector will have to cope with radiation levels up to 10 16 1 MeVn eq /cm 2 , more than an order of magnitude higher than those expected at the current experiment. A solution is under development with a pixel detector, based on the Timepix/Medipix family of chips with 55 x 55 μm pixels. In addition a micro-strip solution is also under development, with finer pitch, higher granularity and lower mass than the current detector. The current status of the VELO will be described together with recent testbeam results.

Management, Optimization and Evolution of the LHCb Online Network

CERN Document Server

Liu, G; Savriè, M; Neufeld, N

2010-01-01

The LHCb experiment is one of the four large particle detectors operated at the Large Hadron Collider (LHC) at CERN. It is a forward single-arm spectrometer dedicated to test the Standard Model through precision measurements of Charge-Parity (CP) violation and rare decays in the b quark sector. The LHCb experiment will operate at a luminosity of 2 x 10$^{32}cm^{-2}s^{-1}$, the proton-proton bunch crossings rate will be approximately 10 MHz. To select the interesting events, a two-level trigger scheme is applied: the first level trigger (L0) and the high level trigger (HLT). The L0 trigger is implemented in custom hardware, while HLT is implemented in software running on the CPUs of the Event Filter Farm (EFF). The L0 trigger rate is limited to about 1 MHz, and the event size for each event is about 35 kByte. It is a big challenge to handle the resulting data rate (35GByte/s). The online system is a key part of the LHCb experiment, providing all the IT services. It consists of three major components: the Data ...

Automated Grid Monitoring for the LHCb Experiment Through HammerCloud

CERN Document Server

Dice, Bradley

2015-01-01

The HammerCloud system is used by CERN IT to monitor the status of the Worldwide LHC Computing Grid (WLCG). HammerCloud automatically submits jobs to WLCG computing resources, closely replicating the workflow of Grid users (e.g. physicists analyzing data). This allows computation nodes and storage resources to be monitored, software to be tested (somewhat like continuous integration), and new sites to be stress tested with a heavy job load before commissioning. The HammerCloud system has been in use for ATLAS and CMS experiments for about five years. This summer's work involved porting the HammerCloud suite of tools to the LHCb experiment. The HammerCloud software runs functional tests and provides data visualizations. HammerCloud's LHCb variant is written in Python, using the Django web framework and Ganga/DIRAC for job management.

Supersymmetry in Light of 1/fb of LHC Data

CERN Document Server

Buchmueller, O; De Roeck, A; Dolan, M J; Ellis, J R; Flacher, H; Heinemeyer, S; Isidori, G; Martinez Santos, D; Olive, K A; Rogerson, S; Ronga, F J; Weiglein, G

2012-01-01

We update previous frequentist analyses of the CMSSM and NUHM1 parameter spaces to include the public results of searches for supersymmetric signals using ~1 /fb of LHC data recorded by ATLAS and CMS and ~0.3/fb of data recorded by LHCb in addition to electroweak precision and B-physics observables. We also include the constraints imposed by the cosmological dark matter density and the XENON100 search for spin-independent dark matter scattering. The LHC data set includes ATLAS and CMS searches for jets + missing ET events and for the heavier MSSM Higgs bosons, and the upper limits on B_s to mu^+ mu^- from LHCb and CMS. The absences of jets + missing ET signals in the LHC data favour heavier mass spectra than in our previous analyses of the CMSSM and NUHM1, which may be reconciled with (g-2)_mu if tan beta ~ 40, a possibility that is however under pressure from heavy Higgs searches and the upper limits on B_s to mu^+ mu^-. As a result, the p-value for the CMSSM fit is reduced to ~ 15 (38)%, and that for the NU...

$B_{s}^{0} \\rightarrow D_{s}^{+(*)} D_{s}^{-(*)}$ decays in LHCb

CERN Multimedia

Pritchard, A

2014-01-01

The decay of a $B_{s}^{0}$ meson to two oppositely charged $D_{s}$ mesons is one that is postulated to be almost exclusively CP even. Measuring the properties of this decay can therefore give important information about the behaviour of the $B_{s}^{0}$ system. This poster presents two of these measurements, made by LHCb, using data from run 1 of the LHC.

Prompt double J/ψ production in proton-proton collisions at the LHC

International Nuclear Information System (INIS)

Baranov, S.P.; Rezaeian, Amir H.

2015-11-01

We provide a detailed study of prompt double J/ψ production within the non-relativistic QCD (NRQCD) framework in proton-proton collisions at the LHC.We confront the recent LHC data with the results obtained at leading-order (LO) in the NRQCD framework within two approaches of the collinear factorization and the k T -factorization. We show that the LHCb data can be fairly described within the k T -factorized LO NRQCD, while the collinearly factorized LO NRQCD significantly overshoots the LHCb data at low J/ψ-pair invariant mass. We show that the LO NRQCD formalism cannot describe the recent CMS data, with about one order of magnitude discrepancy. If the CMS data are confirmed, this indicates rather large higher-order corrections for prompt double J/ψ production. We provide various predictions which can further test the NRQCD-based approach at the LHC in a kinematic region that LO contributions dominate. We also investigate long-range in rapidity double J/ψ correlations. We found no evidence of a ridge-like structure for double J/ψ production in proton-proton collisions at the LHC up to subleading α 6 s accuracy.

The LHC: a week for taking stock, pushing boundaries and for long-term planning

CERN Multimedia

2011-01-01

This has been a week full of LHC news, beginning and ending in Paris with results presented by the ATLAS, CMS and LHCb collaborations at the Hadron Collider Physics Symposium, HCP2011. In between came the first lead-ion collisions of 2011, tests with protons and lead-ions circulating in the LHC, and the kick-off meeting for an LHC luminosity upgrade.   HCP2011 brings this year’s particle physics conference cycle to a close, and is the last chance for the LHC experiments to present new results before the December Council meeting. It began with all eyes on LHCb’s results from its D0-anti D0 particle asymmetry analysis. In this decay channel, LHCb seems to see an excursion from the Standard Model’s prediction. However, even though such a result is precisely what physicists have been waiting for, no predictions for physics beyond the Standard Model show an excursion in this particular decay channel. So it’s safe to say that the jury’s still out, a...

Particles are back in the LHC!

CERN Multimedia

2009-01-01

Last weekend (23-25 October) particles once again entered the LHC after the one-year interruption following the incident of September 2008. Particles travelled through one sector clockwise and one anticlockwise. ALICE and LHCb, the two experiments sitting along the portion of the beam lines in question, were able to observe the first effects of real beams in the machine.

LHCb is trying to crack the Standard Model

CERN Multimedia

2011-01-01

LHCb will reveal new results tomorrow that will shed more light on the possible CP-violation measurement reported recently by the Tevatron experiments, different from Standard Model predictions. Quantum Diaries blogger for CERN, Pauline Gagnon, explains how.   LHCb, one of the Large Hadron Collider (LHC) experiments, was designed specifically to study charge-parity or CP violation. In simple words, its goal is to explain why more matter than antimatter was produced when the Universe slowly cooled down after the Big Bang, leading to a world predominantly composed of matter. This is quite puzzling since in laboratory experiments we do not measure a preference for the creation of matter over antimatter. Hence the CP-conservation law in physics that states that Nature should not have a preference for matter over antimatter. So why did the Universe evolve this way? One of the best ways to study this phenomenon is with b quarks. Since they are heavy, they can decay (i.e break down into smaller parts) ...

Measurement of Charmonium Polarization with the LHCb Detector

CERN Document Server

Zhang, Yanxi

In particle physics, quantum chromodynamics (QCD) is the theory used to describe the interaction of colored particles. Heavy quarkonium is the bound state of heavy quark and its anti-quark, and its production cross section and polarization can be used to test the theory models in the framework of QCD. The computation of the heavy quarkonium production cross section by color singlet mechanism (CSM) underestimates the experimental measurements, while results from the calculation of non-relativistic QCD (NRQCD) can describe experimental data very well. However, the NRQCD predicts that the $S$ wave heavy quarkonium is heavily transversely polarized in the large transverse momentum region, which is contrary to experimental observations. LHCb, dedicated for precision measurement in bottom and charm physics, is one of the experiments located at the Large Hadron Collider (LHC). The LHCb detector, which is a forward region spectrometer covering the pseudo rapidity range 2-5, has fine particle reconstruction and identi...

Precision luminosity measurements at LHCb

CERN Document Server

Aaij, Roel; Adinolfi, Marco; Affolder, Anthony; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Anderson, Jonathan; Andreassen, Rolf; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Aquines Gutierrez, Osvaldo; Archilli, Flavio; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baldini, Wander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Belogurov, Sergey; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Benton, Jack; Berezhnoy, Alexander; Bernet, Roland; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bien, Alexander; Bifani, Simone; Bird, Thomas; Bizzeti, Andrea; Bjørnstad, Pål Marius; Blake, Thomas; Blanc, Frédéric; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Borghi, Silvia; Borgia, Alessandra; Borsato, Martino; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Brambach, Tobias; Bressieux, Joël; Brett, David; Britsch, Markward; Britton, Thomas; Brodzicka, Jolanta; Brook, Nicholas; Brown, Henry; Bursche, Albert; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Campana, Pierluigi; Campora Perez, Daniel; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cauet, Christophe; Cenci, Riccardo; Charles, Matthew; Charpentier, Philippe; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chiapolini, Nicola; Chrzaszcz, Marcin; Ciba, Krzystof; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Cogan, Julien; Cogneras, Eric; Cojocariu, Lucian; Collazuol, Gianmaria; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombes, Matthew; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Counts, Ian; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Dalseno, Jeremy; David, Pascal; David, Pieter; Davis, Adam; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Silva, Weeraddana; De Simone, Patrizia; Dean, Cameron Thomas; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Déléage, Nicolas; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Di Canto, Angelo; Dijkstra, Hans; Donleavy, Stephanie; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Dossett, David; Dovbnya, Anatoliy; Dreimanis, Karlis; Dujany, Giulio; Dupertuis, Frederic; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; El Rifai, Ibrahim; Elsasser, Christian; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Färber, Christian; Farinelli, Chiara; Farley, Nathanael; Farry, Stephen; Fay, Robert; Ferguson, Dianne; Fernandez Albor, Victor; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fol, Philip; Fontana, Marianna; Fontanelli, Flavio; Forty, Roger; Francisco, Oscar; Frank, Markus; Frei, Christoph; Frosini, Maddalena; Fu, Jinlin; Furfaro, Emiliano; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; García Pardiñas, Julián; Garofoli, Justin; Garra Tico, Jordi; Garrido, Lluis; Gascon, David; Gaspar, Clara; Gauld, Rhorry; Gavardi, Laura; Geraci, Angelo; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gianelle, Alessio; Gianì, Sebastiana; Gibson, Valerie; Giubega, Lavinia-Helena; Gligorov, V.V.; Göbel, Carla; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gotti, Claudio; Grabalosa Gándara, Marc; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto; Graugés, Eugeni; Graziani, Giacomo; Grecu, Alexandru; Greening, Edward; Gregson, Sam; Griffith, Peter; Grillo, Lucia; Grünberg, Oliver; Gui, Bin; Gushchin, Evgeny; Guz, Yury; Gys, Thierry; Hadjivasiliou, Christos; Haefeli, Guido; Haen, Christophe; Haines, Susan; Hall, Samuel; Hamilton, Brian; Hampson, Thomas; Han, Xiaoxue; Hansmann-Menzemer, Stephanie; Harnew, Neville; Harnew, Samuel; Harrison, Jonathan; He, Jibo; Head, Timothy; Heijne, Veerle; Hennessy, Karol; Henrard, Pierre; Henry, Louis; Hernando Morata, Jose Angel; van Herwijnen, Eric; Heß, Miriam; Hicheur, Adlène; Hill, Donal; Hoballah, Mostafa; Hombach, Christoph; Hulsbergen, Wouter; Hunt, Philip; Hussain, Nazim; Hutchcroft, David; Hynds, Daniel; Idzik, Marek; Ilten, Philip; Jacobsson, Richard; Jaeger, Andreas; Jalocha, Pawel; Jans, Eddy; Jaton, Pierre; Jawahery, Abolhassan; Jing, Fanfan; John, Malcolm; Johnson, Daniel; Jones, Christopher; Joram, Christian; Jost, Beat; Jurik, Nathan; Kandybei, Sergii; Kanso, Walaa; Karacson, Matthias; Karbach, Moritz; Karodia, Sarah; Kelsey, Matthew; Kenyon, Ian; Ketel, Tjeerd; Khanji, Basem; Khurewathanakul, Chitsanu; Klaver, Suzanne; Klimaszewski, Konrad; Kochebina, Olga; Kolpin, Michael; Komarov, Ilya; Koopman, Rose; Koppenburg, Patrick; Korolev, Mikhail; Kozlinskiy, Alexandr; Kravchuk, Leonid; Kreplin, Katharina; Kreps, Michal; Krocker, Georg; Krokovny, Pavel; Kruse, Florian; Kucewicz, Wojciech; Kucharczyk, Marcin; Kudryavtsev, Vasily; Kurek, Krzysztof; Kvaratskheliya, Tengiz; La Thi, Viet Nga; Lacarrere, Daniel; Lafferty, George; Lai, Adriano; Lambert, Dean; Lambert, Robert W; Lanfranchi, Gaia; Langenbruch, Christoph; Langhans, Benedikt; Latham, Thomas; Lazzeroni, Cristina; Le Gac, Renaud; van Leerdam, Jeroen; Lees, Jean-Pierre; Lefèvre, Regis; Leflat, Alexander; Lefrançois, Jacques; Leo, Sabato; Leroy, Olivier; Lesiak, Tadeusz; Leverington, Blake; Li, Yiming; Likhomanenko, Tatiana; Liles, Myfanwy; Lindner, Rolf; Linn, Christian; Lionetto, Federica; Liu, Bo; Lohn, Stefan; Longstaff, Iain; Lopes, Jose; Lopez-March, Neus; Lowdon, Peter; Lu, Haiting; Lucchesi, Donatella; Luo, Haofei; Lupato, Anna; Luppi, Eleonora; Lupton, Oliver; Machefert, Frederic; Machikhiliyan, Irina V; Maciuc, Florin; Maev, Oleg; Malde, Sneha; Malinin, Alexander; Manca, Giulia; Mancinelli, Giampiero; Mapelli, Alessandro; Maratas, Jan; Marchand, Jean François; Marconi, Umberto; Marin Benito, Carla; Marino, Pietro; Märki, Raphael; Marks, Jörg; Martellotti, Giuseppe; Martens, Aurelien; Martín Sánchez, Alexandra; Martinelli, Maurizio; Martinez Santos, Diego; Martinez Vidal, Fernando; Martins Tostes, Danielle; Massafferri, André; Matev, Rosen; Mathe, Zoltan; Matteuzzi, Clara; Maurin, Brice; Mazurov, Alexander; McCann, Michael; McCarthy, James; McNab, Andrew; McNulty, Ronan; McSkelly, Ben; Meadows, Brian; Meier, Frank; Meissner, Marco; Merk, Marcel; Milanes, Diego Alejandro; Minard, Marie-Noelle; Moggi, Niccolò; Molina Rodriguez, Josue; Monteil, Stephane; Morandin, Mauro; Morawski, Piotr; Mordà, Alessandro; Morello, Michael Joseph; Moron, Jakub; Morris, Adam Benjamin; Mountain, Raymond; Muheim, Franz; Müller, Katharina; Mussini, Manuel; Muster, Bastien; Naik, Paras; Nakada, Tatsuya; Nandakumar, Raja; Nasteva, Irina; Needham, Matthew; Neri, Nicola; Neubert, Sebastian; Neufeld, Niko; Neuner, Max; Nguyen, Anh Duc; Nguyen, Thi-Dung; Nguyen-Mau, Chung; Nicol, Michelle; Niess, Valentin; Niet, Ramon; Nikitin, Nikolay; Nikodem, Thomas; Novoselov, Alexey; O'Hanlon, Daniel Patrick; Oblakowska-Mucha, Agnieszka; Obraztsov, Vladimir; Oggero, Serena; Ogilvy, Stephen; Okhrimenko, Oleksandr; Oldeman, Rudolf; Onderwater, Gerco; Orlandea, Marius; Otalora Goicochea, Juan Martin; Owen, Patrick; Oyanguren, Maria Arantza; Pal, Bilas Kanti; Palano, Antimo; Palombo, Fernando; Palutan, Matteo; Panman, Jacob; Papanestis, Antonios; Pappagallo, Marco; Pappalardo, Luciano; Parkes, Christopher; Parkinson, Christopher John; Passaleva, Giovanni; Patel, Girish; Patel, Mitesh; Patrignani, Claudia; Pearce, Alex; Pellegrino, Antonio; Pepe Altarelli, Monica; Perazzini, Stefano; Perret, Pascal; Perrin-Terrin, Mathieu; Pescatore, Luca; Pesen, Erhan; Pessina, Gianluigi; Petridis, Konstantin; Petrolini, Alessandro; Picatoste Olloqui, Eduardo; Pietrzyk, Boleslaw; Pilař, Tomas; Pinci, Davide; Pistone, Alessandro; Playfer, Stephen; Plo Casasus, Maximo; Polci, Francesco; Poluektov, Anton; Polycarpo, Erica; Popov, Alexander; Popov, Dmitry; Popovici, Bogdan; Potterat, Cédric; Price, Eugenia; Price, Joseph David; Prisciandaro, Jessica; Pritchard, Adrian; Prouve, Claire; Pugatch, Valery; Puig Navarro, Albert; Punzi, Giovanni; Qian, Wenbin; Rachwal, Bartolomiej; Rademacker, Jonas; Rakotomiaramanana, Barinjaka; Rama, Matteo; Rangel, Murilo; Raniuk, Iurii; Rauschmayr, Nathalie; Raven, Gerhard; Redi, Federico; Reichert, Stefanie; Reid, Matthew; dos Reis, Alberto; Ricciardi, Stefania; Richards, Sophie; Rihl, Mariana; Rinnert, Kurt; Rives Molina, Vincente; Robbe, Patrick; Rodrigues, Ana Barbara; Rodrigues, Eduardo; Rodriguez Perez, Pablo; Roiser, Stefan; Romanovsky, Vladimir; Romero Vidal, Antonio; Rotondo, Marcello; Rouvinet, Julien; Ruf, Thomas; Ruiz, Hugo; Ruiz Valls, Pablo; Saborido Silva, Juan Jose; Sagidova, Naylya; Sail, Paul; Saitta, Biagio; Salustino Guimaraes, Valdir; Sanchez Mayordomo, Carlos; Sanmartin Sedes, Brais; Santacesaria, Roberta; Santamarina Rios, Cibran; Santovetti, Emanuele; Sarti, Alessio; Satriano, Celestina; Satta, Alessia; Saunders, Daniel Martin; Savrina, Darya; Schiller, Manuel; Schindler, Heinrich; Schlupp, Maximilian; Schmelling, Michael; Schmidt, Burkhard; Schneider, Olivier; Schopper, Andreas; Schubiger, Maxime; Schune, Marie Helene; Schwemmer, Rainer; Sciascia, Barbara; Sciubba, Adalberto; Semennikov, Alexander; Sepp, Indrek; Serra, Nicola; Serrano, Justine; Sestini, Lorenzo; Seyfert, Paul; Shapkin, Mikhail; Shapoval, Illya; Shcheglov, Yury; Shears, Tara; Shekhtman, Lev; Shevchenko, Vladimir; Shires, Alexander; Silva Coutinho, Rafael; Simi, Gabriele; Sirendi, Marek; Skidmore, Nicola; Skwarnicki, Tomasz; Smith, Anthony; Smith, Edmund; Smith, Eluned; Smith, Jackson; Smith, Mark; Snoek, Hella; Sokoloff, Michael; Soler, Paul; Soomro, Fatima; Souza, Daniel; Souza De Paula, Bruno; Spaan, Bernhard; Sparkes, Ailsa; Spradlin, Patrick; Sridharan, Srikanth; Stagni, Federico; Stahl, Marian; Stahl, Sascha; Steinkamp, Olaf; Stenyakin, Oleg; Stevenson, Scott; Stoica, Sabin; Stone, Sheldon; Storaci, Barbara; Stracka, Simone; Straticiuc, Mihai; Straumann, Ulrich; Stroili, Roberto; Subbiah, Vijay Kartik; Sun, Liang; Sutcliffe, William; Swientek, Krzysztof; Swientek, Stefan; Syropoulos, Vasileios; Szczekowski, Marek; Szczypka, Paul; Szumlak, Tomasz; T'Jampens, Stephane; Teklishyn, Maksym; Tellarini, Giulia; Teubert, Frederic; Thomas, Christopher; Thomas, Eric; van Tilburg, Jeroen; Tisserand, Vincent; Tobin, Mark; Tolk, Siim; Tomassetti, Luca; Tonelli, Diego; Topp-Joergensen, Stig; Torr, Nicholas; Tournefier, Edwige; Tourneur, Stephane; Tran, Minh Tâm; Tresch, Marco; Trisovic, Ana; Tsaregorodtsev, Andrei; Tsopelas, Panagiotis; Tuning, Niels; Ubeda Garcia, Mario; Ukleja, Artur; Ustyuzhanin, Andrey; Uwer, Ulrich; Vacca, Claudia; Vagnoni, Vincenzo; Valenti, Giovanni; Vallier, Alexis; Vazquez Gomez, Ricardo; Vazquez Regueiro, Pablo; Vázquez Sierra, Carlos; Vecchi, Stefania; Velthuis, Jaap; Veltri, Michele; Veneziano, Giovanni; Vesterinen, Mika; Viaud, Benoit; Vieira, Daniel; Vieites Diaz, Maria; Vilasis-Cardona, Xavier; Vollhardt, Achim; Volyanskyy, Dmytro; Voong, David; Vorobyev, Alexey; Vorobyev, Vitaly; Voß, Christian; de Vries, Jacco; Waldi, Roland; Wallace, Charlotte; Wallace, Ronan; Walsh, John; Wandernoth, Sebastian; Wang, Jianchun; Ward, David; Watson, Nigel; Websdale, David; Whitehead, Mark; Wicht, Jean; Wiedner, Dirk; Wilkinson, Guy; Williams, Matthew; Williams, Mike; Wilschut, Hans; Wilson, Fergus; Wimberley, Jack; Wishahi, Julian; Wislicki, Wojciech; Witek, Mariusz; Wormser, Guy; Wotton, Stephen; Wright, Simon; Wyllie, Kenneth; Xie, Yuehong; Xing, Zhou; Xu, Zhirui; Yang, Zhenwei; Yuan, Xuhao; Yushchenko, Oleg; Zangoli, Maria; Zavertyaev, Mikhail; Zhang, Liming; Zhang, Wen Chao; Zhang, Yanxi; Zhelezov, Alexey; Zhokhov, Anatoly; Zhong, Liang; Zvyagin, Alexander

2014-12-05

Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy $\\sqrt{s}$. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for $\\sqrt{s}$ = 2.76, 7 and 8 TeV (proton-proton collisions) and for $\\sqrt{s_{NN}}$ = 5 TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves significantly the consistency of the results. For proton-proton interactions at $\\sqrt{s}$ = 8 TeV a relative precision of the luminosity calibration of 1.47% is obtained using van der Meer scans and 1.43% using beam-gas imaging, resulting in a combined precision of 1.12%. Applying the calibration to the full data set determin...

Filling the vacuum at LHCb

CERN Multimedia

Katarina Anthony

2013-01-01

Last month, the Vacuum, Surfaces and Coatings (VSC) group was tasked with an unusually delicate operation in the LHCb experiment cavern: removing the LHC beam pipe while keeping the sensitive Vertex Locator vacuum vessel (VELO) completely isolated from the action.   The VSC group seal off the VELO beam pipe with a flange. Image: Gloria Corti. LHCb’s VELO detector is one of the crown jewels of the experiment. With detector elements surrounded by a vacuum, it gets as close as 5 cm from the beam. Fantastic for physics, but difficult for all-important access. “Because of the sensitivity of the VELO detector and its proximity to the beam, the collaboration decided not to bake (see box) its portion of the beam pipe,” says Giulia Lanza (TE-VSC-LBV), the expert in charge of the beam vacuum operation. “Our group was therefore asked to remove the rest of the LHC beam pipe while keeping the VELO portion of the pipe completely isolated. This work...

The LHCb Experience on the Grid from the DIRAC Accounting Data

CERN Document Server

Puig, A; Graciani, R; Casajús, A

2011-01-01

DIRAC is the software framework developed by LHCb to manage all its computing operations on the Grid. Since 2003 it has been used for large scale Monte Carlo simulation productions and for user analysis of these data. Since the end of 2009, with the start-up of LHC, DIRAC also takes care of the distribution, reconstruction, selection and analysis of the physics data taken by the detector apparatus. During 2009, DIRAC executed almost 5 million jobs for LHCb. In order to execute this workload slightly over 6 million of pilot jobs were submitted, out of which approximately one third were aborted by the Grid infrastructure. In 2010, thanks to their improved efficiency, DIRAC pilots are able, on average, to match and execute between 2 and 3 LHCb jobs during their lifetime, largely reducing the load on the Grid infrastructure. Given the large amount of submitted jobs and used resources, it becomes essential to store detailed information about their execution to track the behaviour of the system. The DIRAC Accountin...

Machine Learning and Parallelism in the Reconstruction of LHCb and its Upgrade

Science.gov (United States)

De Cian, Michel

2016-11-01

The LHCb detector at the LHC is a general purpose detector in the forward region with a focus on reconstructing decays of c- and b-hadrons. For Run II of the LHC, a new trigger strategy with a real-time reconstruction, alignment and calibration was employed. This was made possible by implementing an offline-like track reconstruction in the high level trigger. However, the ever increasing need for a higher throughput and the move to parallelism in the CPU architectures in the last years necessitated the use of vectorization techniques to achieve the desired speed and a more extensive use of machine learning to veto bad events early on. This document discusses selected improvements in computationally expensive parts of the track reconstruction, like the Kalman filter, as well as an improved approach to get rid of fake tracks using fast machine learning techniques. In the last part, a short overview of the track reconstruction challenges for the upgrade of LHCb, is given. Running a fully software-based trigger, a large gain in speed in the reconstruction has to be achieved to cope with the 40 MHz bunch-crossing rate. Two possible approaches for techniques exploiting massive parallelization are discussed.

Machine Learning and Parallelism in the Reconstruction of LHCb and its Upgrade

International Nuclear Information System (INIS)

Cian, Michel De

2016-01-01

The LHCb detector at the LHC is a general purpose detector in the forward region with a focus on reconstructing decays of c- and b-hadrons. For Run II of the LHC, a new trigger strategy with a real-time reconstruction, alignment and calibration was employed. This was made possible by implementing an offline-like track reconstruction in the high level trigger. However, the ever increasing need for a higher throughput and the move to parallelism in the CPU architectures in the last years necessitated the use of vectorization techniques to achieve the desired speed and a more extensive use of machine learning to veto bad events early on. This document discusses selected improvements in computationally expensive parts of the track reconstruction, like the Kalman filter, as well as an improved approach to get rid of fake tracks using fast machine learning techniques. In the last part, a short overview of the track reconstruction challenges for the upgrade of LHCb, is given. Running a fully software-based trigger, a large gain in speed in the reconstruction has to be achieved to cope with the 40 MHz bunch-crossing rate. Two possible approaches for techniques exploiting massive parallelization are discussed

Implementation and performance analysis of the LHCb LFC replica using Oracle streams technology

CERN Document Server

Düllmann, D; Martelli, B; Peco, G; Bonifazzi, F; Da Fonte Perez, E; Baranowski, Z; Vagnoni, V

2007-01-01

The presentation will describe the architecture and the deployment of the LHCb read-only File Catalogue for the LHC Computing Grid (LFC) replica implemented at the Italian INFN National Centre for Telematics and Informatics (CNAF), and evaluate a series of tests on the LFC with replica. The LHCb computing model foresees the replication of the central LFC database in every Tier-1, in order to assure more scalability and fault tolerance to LHCb applications Scientific data intensive applications use a large collection of files for storing data. In particular, as regards the HEP community, data generated by large detectors will be managed and stored using databases. The intensive access to information stored in databases by the Grid computing applications requires a distributed database replication in order to guarantee the scalability and, in case of failure, redundancy. Besides the results of the tests will be an important reference for all the Grid users This talk will describe the replica implementation of L...

Handling of the Generation of Primary Events in Gauss, the LHCb Simulation Framework

CERN Multimedia

Corti, G; Brambach, T; Brook, N H; Gauvin, N; Harrison, K; Harrison, P; He, J; Ilten, P J; Jones, C R; Lieng, M H; Manca, G; Miglioranzi, S; Robbe, P; Vagnoni, V; Whitehead, M; Wishahi, J

2010-01-01

The LHCb simulation application, Gauss, consists of two independent phases, the generation of the primary event and the tracking of particles produced in the experimental setup. For the LHCb experimental program it is particularly important to model B meson decays: the EvtGen code developed in CLEO and BaBar has been chosen and customized for non coherent B production as occuring in pp collisions at the LHC. The initial proton-proton collision is provided by a different generator engine, currently Pythia 6 for massive production of signal and generic pp collisions events. Beam gas events, background events originating from proton halo, cosmics and calibration events for different detectors can be generated in addition to pp collisions. Different generator packages are available in the physics community or specifically developed in LHCb, and are used for the different purposes. Running conditions affecting the events generated such as the size of the luminous region, the number of collisions occuring in a bunc...

Event building in an intelligent network interface card for the LHCb readout network

CERN Document Server

Dufey, J P; Neufeld, N; Zuin, M

2001-01-01

LHCb is an experiment being constructed at CERN's LHC accelerator for the purpose of studying precisely the CP violation parameters in the B-B system. Triggering poses special problems since the interesting events containing B-mesons are immersed in a large background of inelastic p-p reactions. Therefore, a 4 Level Triggering scheme (Level 0 to Level 3) has been implemented. Powerful embedded processors, used in modern intelligent Network Interface Cards (smart NICs), make it attractive to use them to handle the event building protocol in the high-speed data acquisition system of the LHCb experiment. The implementation of an event building algorithm developed for a specific Gigabit Ethernet NIC is presented and performance data are discussed. 5 Refs.

Forward Physics at LHCb – Prospects for the Study of Diffractive Interactions

CERN Document Server

Schmelling, Michael

2010-01-01

LHCb, the smallest of the large LHC experiments is a forward spectrometer covering the angular range 2 < $\\eta$ < 5 with tracking, calorimetry and particle identification. Partial coverage of the backward hemisphere is also provided by the vertex detector (Vertex Locator, VeLo), a silicon strip detector surrounding the interaction region. Generator level Monte Carlo studies suggest that using the VeLo to ask for a rapidity gap of $\\delta\\eta$ = 2.5 in the backward region allows to select event samples dominated by diffractive processes. Making use of the excellent tracking, vertexing and particle identification capabilities of the LHCb detector, the characteristics of diffractive particle production thus can be studied in detail in the forward acceptance covered by the experiment.

The LHCb trigger and data acquisition system

CERN Document Server

Dufey, J P; Harris, F; Harvey, J; Jost, B; Mato, P; Müller, E

2000-01-01

The LHCb experiment is the most recently approved of the 4 experiments under construction at CERNs LHC accelerator. It is a special purpose experiment designed to precisely measure the CP violation parameters in the B-B system. Triggering poses special problems since the interesting events containing B-mesons are immersed in a large background of inelastic p-p reactions. We therefore decided to implement a 4 level triggering scheme. The LHCb Data Acquisition (DAQ) system will have to cope with an average trigger rate of ~40 kHz, after two levels of hardware triggers, and an average event size of ~100 kB. Thus an event-building network which can sustain an average bandwidth of 4 GB/s is required. A powerful software trigger farm will have to be installed to reduce the rate from the 40 kHz to ~100 Hz of events written to permanent storage. In this paper we outline the general architecture of the Trigger and DAQ system and the readout protocols we plan to implement. First results of simulations of the behavior o...

Study of charmless $B_{(s)}$ meson decays involving $\\eta'$ and $\\phi$ intermediate states at the LHCb experiment

CERN Document Server

Prisciandaro, Jessica; Blanc, Frédéric

LHCb is one of the four main experiments located at the Large Hadron Collider (LHC) at CERN, and has collected about 3 ${\\rm fb}^{-1}$ of proton-proton collisions at $\\sqrt{s}= 7$ TeV and 8 TeV between December 2009 and December 2012. Designed for the study of $B$-meson decays and for precision $CP$-violation measurements, the LHCb detector requires a high resolution vertex reconstruction, a precise measurement of the charged particle's momentum and an excellent particle identification. In this thesis, a study of the LHCb magnetic field map and two physics analyses are presented. Based on the magnetic field measurements collected during a dedicated campaign in February 2011, the magnetic field map is corrected for mis-alignments, considering global translations and rotations. A more reliable mapping of the field is provided, and is used for the LHCb event reconstruction since June 2011. As a consequence of this study, the mass resolution is improved, and a better agreement between the software alignment and t...

LHCb: The Evolution of the LHCb Grid Computing Model

CERN Multimedia

Arrabito, L; Bouvet, D; Cattaneo, M; Charpentier, P; Clarke, P; Closier, J; Franchini, P; Graciani, R; Lanciotti, E; Mendez, V; Perazzini, S; Nandkumar, R; Remenska, D; Roiser, S; Romanovskiy, V; Santinelli, R; Stagni, F; Tsaregorodtsev, A; Ubeda Garcia, M; Vedaee, A; Zhelezov, A

2012-01-01

The increase of luminosity in the LHC during its second year of operation (2011) was achieved by delivering more protons per bunch and increasing the number of bunches. Taking advantage of these changed conditions, LHCb ran with a higher pileup as well as a much larger charm physics introducing a bigger event size and processing times. These changes led to shortages in the offline distributed data processing resources, an increased need of cpu capacity by a factor 2 for reconstruction, higher storage needs at T1 sites by 70\\% and subsequently problems with data throughput for file access from the storage elements. To accommodate these changes the online running conditions and the Computing Model for offline data processing had to be adapted accordingly. This paper describes the changes implemented for the offline data processing on the Grid, relaxing the Monarc model in a first step and going beyond it subsequently. It further describes other operational issues discovered and solved during 2011, present the ...

LHCb Upgraded RICH 2 Engineering Design Review Report

CERN Document Server

Garsed, Philip John; Cardinale, Roberta; Petrolini, Alessandro; Benettoni, Massimo; Simi, Gabriele; Zago, M; Easo, Sajan; D'Ambrosio, Carmelo; Frei, Christoph; He, Jibo; Piedigrossi, Didier

2016-01-01

During the Long Shutdown 2 of the LHC, the LHCb experiment and, specifically, its two Ring Imaging Cherenkov (RICH) detectors will undergo a major upgrade. RICH 2 will be refurbished with new photon detectors and their associated electronics, with the capability of up to 40 MHz sustained acquisition rate. A new support and cooling system has been developed for the two photodetector arrays, retaining the vessel, gas and optical systems unchanged. This document describes their new mechanical arrangement, its engineering design, installation and alignment. A summary of the project schedule and Institute responsibilities is provided.

LHCb: Measuring B to mu mu K

CERN Document Server

De Cian, M

2009-01-01

The Flavour Changing Neutral Current decay B to mu mu K, which only occurs via loop processes in the SM, is sensitive to contributions from a variety of possible new physics sources. LHCb, the dedicated b physics experiment at the LHC, will record an unprecedented number of B to mu mu K decays, allowing precision measurements of a large number of variables, which will provide evidence or place constraints for physics beyond the SM. This poster gives a short overview of the detector, introduces some of these variables and presents a selection for B to mu mu K.

Prompt physics analysis from the trigger candidates at LHCb: strategy and new dedicated "TURBO" and PID calibration streams

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00038235

2016-01-01

During the first long shutdown of the LHC (2013-2014), the LHCb detector remained essentially unchanged, while the trigger system has been completely revised. Upgrades to the LHCb computing infrastructure have allowed for high quality decay information to be calculated by the software trigger, making separate offline event reconstruction unnecessary. The storage space of the triggered candidate is an order of magnitude smaller than the entire raw event that would otherwise need to be persisted. An application has been designed to process the information calculated by the trigger, with the resulting output used to directly perform physics measurements. Reaching the ultimate precision of the LHCb experiment in real time as the data arrive has the power to transform the experimental approach to processing large quantities of data.

Proceedings of the second workshop of LHC Computing Grid, LCG-France

International Nuclear Information System (INIS)

Chollet, Frederique; Hernandez, Fabio; Malek, Fairouz; Gaelle, Shifrin

2007-03-01

The second LCG-France Workshop was held in Clermont-Ferrand on 14-15 March 2007. These sessions organized by IN2P3 and DAPNIA were attended by around 70 participants working with the Computing Grid of LHC in France. The workshop was a opportunity of exchanges of information between the French and foreign site representatives on one side and delegates of experiments on the other side. The event allowed enlightening the place of LHC Computing Task within the frame of W-LCG world project, the undergoing actions and the prospects in 2007 and beyond. The following communications were presented: 1. The current status of the LHC computation in France; 2.The LHC Grid infrastructure in France and associated resources; 3.Commissioning of Tier 1; 4.The sites of Tier-2s and Tier-3s; 5.Computing in ALICE experiment; 6.Computing in ATLAS experiment; 7.Computing in the CMS experiments; 8.Computing in the LHCb experiments; 9.Management and operation of computing grids; 10.'The VOs talk to sites'; 11.Peculiarities of ATLAS; 12.Peculiarities of CMS and ALICE; 13.Peculiarities of LHCb; 14.'The sites talk to VOs'; 15. Worldwide operation of Grid; 16.Following-up the Grid jobs; 17.Surveillance and managing the failures; 18. Job scheduling and tuning; 19.Managing the site infrastructure; 20.LCG-France communications; 21.Managing the Grid data; 22.Pointing the net infrastructure and site storage. 23.ALICE bulk transfers; 24.ATLAS bulk transfers; 25.CMS bulk transfers; 26. LHCb bulk transfers; 27.Access to LHCb data; 28.Access to CMS data; 29.Access to ATLAS data; 30.Access to ALICE data; 31.Data analysis centers; 32.D0 Analysis Farm; 33.Some CMS grid analyses; 34.PROOF; 35.Distributed analysis using GANGA; 36.T2 set-up for end-users. In their concluding remarks Fairouz Malek and Dominique Pallin stressed that the current workshop was more close to users while the tasks for tightening the links between the sites and the experiments were definitely achieved. The IN2P3 leadership expressed

LHCb: Quarkonium Production at LHCb

CERN Multimedia

Frosini, M

2011-01-01

Despite large experimental and theoretical efforts, quarkonium production in hadronic collisions is not yet satisfactorily understood. Due to its forward geometry, LHCb has the unique opportunity to explore the field of quarkonium production at high rapidity, thus exploring new and unknown territory. We report he measurement of the double differential $J/\\psi, \\psi (2S)$ and $\\Upsilon$ cross section at LHCb with the data sample recorded by the LHCb experiment during the 2010 data taking. The $J/\\psi$ and $\\psi (2S)$ prompt components are separated from the products of b-hadrons decays using topological information. The results are compared with several theoretical models and other experiments. Preliminary results and prospects for the other quarkonium states will also be given.

$B_d \\to K^*\\mu\\mu$ as a lab for discovering new physics at LHCb

CERN Document Server

Skottowe, H

2010-01-01

The analysis of the penguin decay $B_d \\to K^*\\mu\\mu$ at LHCb can act as a laboratory for the discovery and understanding of new physics. Through the Operator Product Expansion, the decay kinematics are well understood in both the Standard Model and in a large range of new physics scenarios. The theoretical errors from QCD effects can be characterized and a set of observables have been derived which minimise their influence in measurements. We will describe how these measurements can be made in LHCb with special emphasis on what can be done with a first run of the LHC with a few hundred pb$^{-1}$ of integrated luminosity.

Highlights of LHC experiments – Part I

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00072301; The ATLAS collaboration

2017-01-01

The superb performance of the LHC accelerator in 2016, in both live time and peak luminosity, has provided a large data sample of collisions at 13 TeV. Excellent performances of the ATLAS and LHCb detectors, together with highly performant offline and analysis systems, mean that a wealth of results are already available from 13 TeV data. Selected highlights are reported here.

Long lived neutralinos at LHCb in GMSB models

Energy Technology Data Exchange (ETDEWEB)

Magro, Mauricio B. [Fundacao Santo Andre (FSA), SP (Brazil); Campos, Fernando de [Universidade Estadual Paulista Julio de Mesquita Filho (FEG/UNESP), SP (Brazil). Fac. de Engenharia de Guaratingueta; Eboli, Oscar [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica

2011-07-01

Full text: We study the signatures of long-lived neutralinos at the LHCb detector considering that SUSY is broken via gauge mediation. In such kind of models the LSP is the gravitino and, most of the time, the first neutralino is the NLSP. Since the coupling of neutralino and gravitino is usually small, the neutralino lives long enough to produce a displaced vertex within the LHC detectors. Using the Spheno code we show that, is GMSB models, a sizeable fraction of the lightest neutralinos, around 10% of the time, decays into a Z-boson plus a gravitino, leaving as a signal charged particles coming from a displaced vertex plus missing energy. Specifically, we focus on the case of a neutralino NLSP decaying to Z and gravitino within the context of Gauge Meditated Symmetry Breaking with the Z-bosons further decaying into charged leptons to leave a clean signature. We point out that events from Z {yields} {iota}{sup +}{iota}{sup -} can be used for detailed kinematic reconstruction. In particular, we examine the prospects for detailed event study at LHCb using a toy detector with help from Pythia code. Finally, we demonstrate that there is a region in parameter space where the LHCb could potentially discover new physics searching for displaced vertices containing {iota}{sup +}{iota}{sup -} plus missing energy channel. (author)

Long lived neutralinos at LHCb in GMSB models

International Nuclear Information System (INIS)

Magro, Mauricio B.; Campos, Fernando de; Eboli, Oscar

2011-01-01

Full text: We study the signatures of long-lived neutralinos at the LHCb detector considering that SUSY is broken via gauge mediation. In such kind of models the LSP is the gravitino and, most of the time, the first neutralino is the NLSP. Since the coupling of neutralino and gravitino is usually small, the neutralino lives long enough to produce a displaced vertex within the LHC detectors. Using the Spheno code we show that, is GMSB models, a sizeable fraction of the lightest neutralinos, around 10% of the time, decays into a Z-boson plus a gravitino, leaving as a signal charged particles coming from a displaced vertex plus missing energy. Specifically, we focus on the case of a neutralino NLSP decaying to Z and gravitino within the context of Gauge Meditated Symmetry Breaking with the Z-bosons further decaying into charged leptons to leave a clean signature. We point out that events from Z → ι + ι - can be used for detailed kinematic reconstruction. In particular, we examine the prospects for detailed event study at LHCb using a toy detector with help from Pythia code. Finally, we demonstrate that there is a region in parameter space where the LHCb could potentially discover new physics searching for displaced vertices containing ι + ι - plus missing energy channel. (author)

Parton distributions with LHC data

CERN Document Server

Ball, Richard D.; Carrazza, Stefano; Deans, Christopher S.; Del Debbio, Luigi; Forte, Stefano; Guffanti, Alberto; Hartland, Nathan P.; Latorre, Jose I.; Rojo, Juan; Ubiali, Maria

2013-01-01

We present the first determination of parton distributions of the nucleon at NLO and NNLO based on a global data set which includes LHC data: NNPDF2.3. Our data set includes, besides the deep inelastic, Drell-Yan, gauge boson production and jet data already used in previous global PDF determinations, all the relevant LHC data for which experimental systematic uncertainties are currently available: ATLAS and LHCb W and Z lepton rapidity distributions from the 2010 run, CMS W electron asymmetry data from the 2011 run, and ATLAS inclusive jet cross-sections from the 2010 run. We introduce an improved implementation of the FastKernel method which allows us to fit to this extended data set, and also to adopt a more effective minimization methodology. We present the NNPDF2.3 PDF sets, and compare them to the NNPDF2.1 sets to assess the impact of the LHC data. We find that all the LHC data are broadly consistent with each other and with all the older data sets included in the fit. We present predictions for various ...

Measurement of branching fractions and CP violation for charmless charged two-body B decays at LHCb

CERN Document Server

Perazzini, Stefano

Charmless charged two-body B decays are sensitive probes of the CKM matrix, that parameterize CP violation in the Standard Model (SM), and have the potential to reveal the presence of New Physics. The framework of CP violation within the SM, the role of the CKM matrix, with its basic formalism, and the current experimental status are presented. The theoretical tools commonly used to deal with hadronic B decays and an overview of the phenomenology of charmless two-body B decays are outlined. LHCb is one of the four main experiments operating at the Large Hadron Collider (LHC), devoted to the measurement of CP violation and rare decays of charm and beauty hadrons. The LHCb detector is described, focusing on the technologies adopted for each sub-detector and summarizing their performances. The status-of-the-art of the LHCb measurements with charmless two-body B decays is then presented. Using the 37/pb of integrated luminosity collected at sqrt(s) = 7 TeV by LHCb during 2010, the direct CP asymmetries ACP(B0 -> ...

Open Access to the LHC takes on a new meaning

CERN Multimedia

2008-01-01

Complete scientific documentation on the LHC machine and detectors is now freely available on the Web. The ATLAS collaboration, shown here, contributed to the 1,600-page scientific documentation of the LHC, along with staff from the other five detectors and the LHC machine.Now that the LHC tunnel and the experimental caverns are shut down for public visits, "Open Access to the LHC" has taken on an entirely new meaning. Last Thursday, 14 August, seven major articles were published electronically in a special issue of the Journal of Instrumentation (JINST). Together they form the complete scientific documentation on the design and construction of the LHC machine and the six detectors (ALICE, ATLAS, CMS, LHCb, LHCf and TOTEM), and thus on the entire LHC project, well before start-up on 10 September. For many years to come, these papers will serve as key references for the stream of scientific results that will begin to emerge from the ...

LHCb : Performance, radiation resistance, and expectations of the Outer Tracker straw

CERN Multimedia

Tuning, Niels

2015-01-01

The LHCb experiment is a single arm spectrometer, designed to study CP violation in B-decays at the LHC. It is crucial to accurately and efficiently detect the charged decay particles, in the high-density particle environment of the LHC. For this, the Outer Tracker (OT) was constructed, consisting of 54,000 straw tubes, covering in total an area of 360 m2 of double layers. The detector operated in 2011/2012 under large particle rates, up to 100 kHz/cm per straw in the region closest to the beam. The performance of the OT detector during Run-I of the LHC has been studied in detail, in terms of efficiency, resolution and noise rate. Particular attention is devoted to the radiation hardness of this sensitive gaseous detector, that has shown to suffer from gain loss after mild irradiation in laboratory conditions. During the shutdown period of the LHC, extensive studies have been performed on subtle spatial alignment effects, and real-time calibration procedures have been prepared for run-II. In addition, expect...

Distributed analysis at LHCb

International Nuclear Information System (INIS)

Williams, Mike; Egede, Ulrik; Paterson, Stuart

2011-01-01

The distributed analysis experience to date at LHCb has been positive: job success rates are high and wait times for high-priority jobs are low. LHCb users access the grid using the GANGA job-management package, while the LHCb virtual organization manages its resources using the DIRAC package. This clear division of labor has benefitted LHCb and its users greatly; it is a major reason why distributed analysis at LHCb has been so successful. The newly formed LHCb distributed analysis support team has also proved to be a success.

Automatised Data Quality Monitoring of the LHCb Vertex Locator

CERN Multimedia

Szumlak, Tomasz

2016-01-01

The LHCb Vertex Locator (VELO) is a silicon strip semiconductor detector operating at just 8mm distance to the LHC beams. Its 172,000 strips are read at a frequency of 1 MHz and processed by off-detector FPGAs followed by a PC cluster that reduces the event rate to about 10 kHz. During the second run of the LHC, which lasts from 2015 until 2018, the detector performance will undergo continued change due to radiation damage effects. This necessitates a detailed monitoring of the data quality to avoid adverse effects on the physics analysis performance. The VELO monitoring infrastructure has been re-designed compared to the first run of the LHC when it was based on manual checks. The new system is based around an automatic analysis framework, which monitors the performance of new data as well as long-term trends and flags issues whenever they arise. An unbiased subset of the detector data are processed about once per hour by monitoring algorithms. The new analysis framework then analyses the plots that are prod...

LHCb: The LHCb data bookkeeping system

CERN Multimedia

Lanciotti, E

2009-01-01

The LHCb Bookkeeping is a system for the storage and retrieval of meta data associated with LHCb datasets. e.g. whether it is real or simulated data, which running period it is associated with, how it was processed and all the other relevant characteristics of the files. etc. The meta data is stored in an oracle database which is interrogated using services provided by the LHCb DIRAC3 infrastructure, that provides security, data streaming, and multi threading connections. Users can browse the bookkeeping database through a command line interface or Graphical User Interface (GUI). The command line presents a view similar to a file system and the GUI is implemented on top of this.

$B_{d} \\to K^{*0}\\mu^{+}\\mu^{-}$ as a lab for discovering new physics at LHCb

CERN Document Server

Skottowe, Hugh

2010-01-01

The analysis of the penguin decay Bd->K*MuMu at LHCb can act as a laboratory for the discovery and understanding of new physics. Through the Operator Product Expansion, the decay kinematics are well understood in both the Standard Model and in a large range of new physics scenarios. The theoretical errors from QCD effects can be characterized and a set of observables have been derived which minimise their influence in measurements. We will describe how these measurements can be made in LHCb with special emphasis on what can be done with a first run of the LHC with a few hundred pb-1 of integrated luminosity.

LHC related projects and studies - Part (I)

International Nuclear Information System (INIS)

Garoby, R.; Ponce, L.

2012-01-01

This session was the first of the two sessions dealing with future projects and the associated studies. Starting with descriptions of the plans and needs of the LHCb and ALICE experiments which are less extensively documented than those of ATLAS and CMS, it addressed the plans for the High Luminosity LHC and for the upgrade of the injectors, both for protons and other ions. (authors)

Half way round the LHC

CERN Multimedia

CERN Bulletin

The LHC operations teams are preparing the machine for circulating beams and things are going very smoothly. ALICE and LHCb are getting used to observing particle tracks coming from the LHC beams. During the weekend of 7-8 November, CMS also  saw its first signals from beams dumped just upstream of  the experiment cavern.   Operators in the CMS control room observe the good performance of their detector. Particles are smoothly making their way around the 27 km circumference of the LHC. Last weekend (7-8 November), the first bunches of injection energy protons completed their journey (anti-clockwise) through three octants of the LHC’s circumference and were dumped in a collimator just before entering the CMS cavern. The particles produced by the impact of the protons on the tertiary collimators (used to stop the beam) left their tracks in the calorimeters and the muon chambers of the experiment. The more delicate inner detectors were switched off for protection reasons....

$CP$-violation studies with charm decays at LHCb

CERN Document Server

Gligorov, Vladimir V

2011-01-01

The LHCb detector [1] at the Large Hadron Collider (LHC) is a single arm spectrometer dedicated to studying the properties of charm ($D$) and beauty ($B$) hadrons. LHCb has two Ring Imaging Cherenkov (RICH) detectors, giving kaon-pion separation in the momentum range 2-100 GeV/$c$, a tracking system with a momentum resolution between 0.3% and 0.5% over the same range, and a silicon vertex detector able to measure $D$ and $B$ hadron lifetimes with a resolution of approximately 50 fs. The interest in studying $CP$-violation ($CPV$) in the charm sector stems from the fact that it is predicted to be small in the Standard Model. The arguments, summarized in [2], is that charm hadrons decay into quarks of the first two generations whose mixing matrix is real, and hence there is no $CPV$ possible in the dominant tree-level decays. $CPV$ can manifest itself through penguin or box diagrams, but since these are suppressed by $V_{cb}V_{ub}^*$ the allowed level of Standard Model $CPV$ does not exceed 1%. Although there ...

LHCb Silicon Tracker DAQ and DCS Online Systems

CERN Multimedia

Buechler, A; Rodriguez, P

2009-01-01

The LHCb experiment at the Large Hadron Collider (LHC) at CERN in Geneva Switzerland is specialized on precision measurements of b quark decays. The Silicon Tracker (ST) contributes a crucial part in tracking the particle trajectories and consists of two silicon micro-strip detectors, the Tracker Turicensis upstream of the LHCb magnet and the Inner Tracker downstream. The radiation and the magnetic field represent new challenges for the implementation of a Detector Control System (DCS) and the data acquisition (DAQ). The DAQ has to deal with more than 270K analog readout channels, 2K readout chips and real time DAQ at a rate of 1.1 MHz with data processing at TELL1 level. The TELL1 real time algorithms for clustering thresholds and other computations run on dedicated FPGAs that implement 13K configurable parameters per board, in total 1.17 K parameters for the ST. After data processing the total throughput amounts to about 6.4 Gbytes from an input data rate of around ~337 Gbytes per second. A finite state ma...

The LHCb vertex locator and level-1 trigger

CERN Document Server

Dijkstra, H

2000-01-01

LHCb will study CP violation and other rare phenomena in B-decays with a forward detector at the LHC. One of the challenges is to design a fast and efficient trigger. The design of the silicon Vertex Locator (VELO) has been driven by the requirements of one of the most selective triggers of the experiment. The VELO trigger is designed to work at an input rate of 1 MHz. The requirements and implementation of the VELO and the associated trigger are summarised, followed by a description of an upgrade which improves the trigger performance significantly. (3 refs).

Flavour physics at LHCb

Directory of Open Access Journals (Sweden)

Adeva B.

2016-01-01

Full Text Available Some selected results of the LHCb experiment, running at the LHC with ppcollisions at 7 TeV and 8 TeV, are reported here, after operation with a total integratedluminosity of 3.0 fb−1 (Run 1. We focus on the most recent analyses on flavour physics,that include measurements of the CKM invariant phases γ and β, precision determination of the quark coupling strength Vub, observation of the very rare decays B0(s→μ+μ−, search for new physics in the anomalous branching ratio of B→D*τv̄, and precision angular analysis of the rare decays B0→K*0μ+μ− and B0s→ϕμ+μ−. Detailed comparisons are performed in all cases with the predictions of the Standard Model, and a fewinteresting tensions are observed.

Confirmation of the Z(4430)- resonance and other exotic meson results from the LHCb experiment

CERN Multimedia

CERN. Geneva

2014-01-01

The LHCb experiment at CERN has recently confirmed the existence of the exotic Z(4430)- state first observed by the Belle experiment in 2008. Its quantum numbers have been measured and the resonant nature of this state has been demonstrated for the first time. As it is charged, the Z(4430)- cannot be classified as a conventional charmonium (ccbar) state, making it a candidate for an exotic resonance composed of four quarks (ccbar udbar). This talk will outline the history of the Z(4430)-, its possible interpretations and describe how the signature of this exotic state can be extracted from the large sample of B0 -> psi(2S) K+pi- decays that LHCb has collected during Run-1 of the LHC. I will also describe recent LHCb results that probe the nature of the exotic X(3872) particle and help to clarify our understanding of the f0(500) and f0(980) scalar mesons that have long thought to be four quark states.

Flavour tagging with baryons and a study of two body $\\Lambda_b$ decays with the LHCb experiment

CERN Document Server

Storey, James William

2008-01-01

The LHCb experiment will perform precision measurements of CP-violation and search for rare B decays at the Large Hadron Collider (LHC), which is due to begin operation in 2008. The LHCb Ring Imaging Cherenkov (RICH) system provides the particle identification crucial for these studies. The Multi-Anode photomultiplier tube (MaPMT)is a candidate photon detector for the LHCb RICH system. Performance studies of the MaPMT in a charged particle beam at CERN demonstrate that the pulse shape of the BeetleMA readout ASIC does not return to zero after 125ns, which will lead to ghost pixel hits and the possible drift of the pedestal outside the dynamic range of the amplifier. Measurement of key CP asymmetries at LHCb requires that the flavour of the B-meson at creation is known. Flavour tagging using protons is shown to have potentially useful tagging performance, but the implementation is found to be challenging. A correlation between b-quark and Lambda flavour is observed for a Lambda produced in the same fragmentati...

Physics Goals and Experimental Challenges of the Proton-Proton High-Luminosity Operation of the LHC

Science.gov (United States)

Campana, P.; Klute, M.; Wells, P. S.

2016-10-01

The completion of Run 1 of the Large Hadron Collider (LHC) at CERN has seen the discovery of the Higgs boson and an unprecedented number of precise measurements of the Standard Model, and Run 2 has begun to provide the first data at higher energy. The high-luminosity upgrade of the LHC (HL-LHC) and the four experiments (ATLAS, CMS, ALICE, and LHCb) will exploit the full potential of the collider to discover and explore new physics beyond the Standard Model. We review the experimental challenges and the physics opportunities in proton-proton collisions at the HL-LHC.

Direct search for Higgs boson in LHCb and contribution to the development of the Vertex Detector

CERN Document Server

Locatelli, L

2007-01-01

The LHCb experiment (Large Hadron Collider beauty) is one of the four experiments under construction at the LHC (Large Hadron Collider) at CERN near Geneva. It is planned to start in 2007 and its goal is the study of b-quark physics. The LHC is a circular accelerator in which collide protons-protons at a center-of-mass energy of sqrt{s} = 14 TeV. This generates a large number of high energy b-bbar pairs which are predominantly produced in the same forward cone. The LHCb detector is therefore a forward single arm spectrometer designed to exploit the large b-bbar production cross section (\\sigma b-bbar ~ 500 \\mu b) and to perform precise measurements of CP violation in b-hadrons decays. One of the actual greatest challenges in High Energy Physics is the discovery of the Higgs boson which is responsible for the Model Standard particles mass generation through the Spontaneous Symmetry Breaking process. The Higgs mass is not known and cannot be predicted by the theory. However the recent results of LEP at CERN hav...

Measurement of time dependent CP asymmetries in charged charmless hadronic two-body B decays at LHCb

CERN Document Server

Pennazzi, S

2008-01-01

The LHCb experiment is one of the four experiments that are installed at the protonproton Large Hadron Collider (LHC) at CERN, Geneva. The experiment is at the latest stage of its setting-up. The first collisions at high energy in LHC are planned to mid-2008, with the first results on the experiments soon after. The LHCb detector is a single-arm spectrometer conceived to pursue an extensive study of CP violation in the B meson system, over-constraining the Standard Model predictions and looking for any possible effect beyond this theory, and to look for rare phenomena in the b quark sector with very high precision. The subject of the present work is the study of the non-leptonic B meson decays into charged charmless two-body final states. This class of decays has been extensively studied and it is still matter of great interest at the B-factories and at Tevatron. In fact the current knowledge of this class of decays in the Bd/Bu sector starts to be quite constrained, but the Bs still remains a field where a r...

The Design and Production of the LHCb VELO High Voltage System and Analysis of the Bd ⇒ K*μ+μ- Rare Decay

CERN Document Server

Rakotomiaramanana, Barinjaka Mamitiana; Soler, P

2010-01-01

LHCb is the dedicated flavour physics experiment of the LHC. The experiment is designed for probing new physics through measurements of CP violation and rare decays. This thesis includes simulation studies of the Bd ⇒ K*μ+μ- decay. The LHCb vertex locator (VELO) is the highest precision tracking detector at the LHC and is used to identify primary and secondary vertices for the identification of the $b$ and $c$ hadrons. The VELO modules contain silicon strip detectors which must be operated under reverse bias voltage. This thesis presents the work performed on the design, production and characterisation of the VELO high voltage system. The VELO operates only 8\\mm~from the LHC beam in a high radiation environment. A future upgrade will require operation at up to 10$^{16}$ n_{eq}cm^{-2}.This thesis presents a characterisation of p-type silicon sensors before and after heavy irradiations. The design of the HV system and the substantial programme of quality assurance tests performed on both the hardware and so...

Lead ions and Coulomb’s Law at the LHC (CERN)

Science.gov (United States)

Cid-Vidal, Xabier; Cid, Ramon

2018-03-01

Although for most of the time the Large Hadron Collider (LHC) at CERN collides protons, for around one month every year lead ions are collided, to expand the diversity of the LHC research programme. Furthermore, in an effort not originally foreseen, proton-lead collisions are also taking place, with results of high interest to the physics community. All the large experiments of the LHC have now joined the heavy-ion programme, including the LHCb experiment, which was not at first expected to be part of it. The aim of this article is to introduce a few simple physical calculations relating to some electrical phenomena that occur when lead-ion bunches are running in the LHC, using Coulomb’s Law, to be taken to the secondary school classroom to help students understand some important physical concepts.

Tracking, Vertexing and data handling strategy for the LHCb upgrade

CERN Document Server

Seyfert, Paul

2017-01-01

For Run III (2021 onwards) of the LHC, LHCb will take data at an instantaneous luminosity of $2 \\times 10^{33} \\mathrm{cm}^{-2} \\mathrm{s}^{-1}$, five times higher than in Run II (2015-2018). To cope with the harsher data taking conditions, the LHCb collaboration will upgrade the DAQ system and install a purely software based trigger, in addition to various detector upgrades. The high readout rate contributes to the challenge of reconstructing and selecting events in real time. Special emphasis in this contribution will be put on the need for fast track reconstruction in the software trigger. The modified detector infrastructure will be able to face this challenge and the necessary changes to the reconstruction sequence are discussed. A novel strategy is presented which distributes and maximises the bandwidth among the different physics channels using a genetic algorithm. The data processing chain includes a re-design of the event scheduling, introduction of concurrent processing, optimisations in processor ...

"Big Science: the LHC in Pictures" in the Globe

CERN Multimedia

2008-01-01

An exhibition of spectacular photographs of the LHC and its experiments is about to open in the Globe. The LHC and its four experiments are not only huge in size but also uniquely beautiful, as the exhibition "Big Science: the LHC in Pictures" in the Globe of Science and Innovation will show. The exhibition features around thirty spectacular photographs measuring 4.5 metres high and 2.5 metres wide. These giant pictures reflecting the immense scale of the LHC and the mysteries of the Universe it is designed to uncover fill the Globe with shape and colour. The exhibition, which will open on 4 March, is divided into six different themes: CERN, the LHC and the four experiments ATLAS, LHCb, CMS and ALICE. Facts about all these subjects will be available at information points and in an explanatory booklet accompanying the exhibition (which visitors will be able to buy if they wish to take it home with them). Globe of Science and Innovatio...

The LHCb RICH system; detector description and operation

Energy Technology Data Exchange (ETDEWEB)

Papanestis, A., E-mail: antonis.papanestis@stfc.ac.uk

2014-12-01

Two RICH detectors provide positive charged hadron identification in the LHCb experiment at the Large Hadron Collider at CERN. RICH 1 covers the full acceptance of the spectrometer and contains two radiators: aerogel and C{sub 4}F{sub 10}. RICH 2 covers half the acceptance and uses CF{sub 4} as a Cherenkov radiator. Photon detection is performed by the Hybrid Photon Detectors (HPDs), with silicon pixel sensors and bump-bonded readout encapsulated in a vacuum tube for efficient, low-noise single photon detection. The LHCb RICH detectors form a complex system of three radiators, 120 mirrors and 484 photon detectors operating in the very challenging environment of the LHC. The high performance of the system in pion and kaon identification in the momentum range of 2–100 GeV/c is reached only after careful calibration of many parameters. Operational efficiency above 99% was achieved by a high level of automatization in the operation of the detectors, from switching-on to error recovery. The challenges of calibrating and operating such a system will be presented. - Highlights: • This paper describes the operation and calibration of the LHCb RICH detectors. • The scintillation of CF{sub 4} was successfully suppressed with CO{sub 2}. • The refractive index of the gas radiators was calibrated with data to an accuracy better than 0.1%. • The Hybrid Photons Detectors were calibrated for operation in a magnetic field without loss of resolution.

Measurement of particle multiplicity and energy flow in pp collisions at 13 TeV with the LHCb detector

CERN Document Server

AUTHOR|(CDS)2089888; Bowcock, Themis

The LHC is the world's largest and highest-energy particle collider. The LHCb experiment is one of four main experiments at the LHC. In July/August 2015, at the beginning of Run-II of the collider, the LHCb detector collected no-bias data during the so-called `Early Measurements' low intensity data taking run. The analysis described in this thesis, the measurement of particle multiplicity and energy flow in proton-proton collisions at a centre-of-mass energy of $\\sqrt{s}$ = 13 TeV, uses this dataset. This analysis is aimed at improving our understanding of the hadron-hadron interaction process in full and, more specifically, our knowledge of the contributions of the underlying event and multi-parton interactions to the observable final states. The data sample is split into the charged and neutral components and then further segregated into four event classes - inclusive minimum-bias, hard scattering, diffractive enriched and non-diffractive enriched. The measurement is carried out over a 2D $(e\\times\\eta)$ ...

The LHC at the AAAS

CERN Multimedia

CERN Bulletin

2011-01-01

The American Association for the Advancement of Science held its annual meeting in the Walter E. Washington Convention Center in Washington D.C. last week.   Veteran science writer Tim Radford introduces LHC scientists during a media briefing at the AAAS annual meeting. Left to right: Felicitas Pauss, Tom LeCompte, Yves Schutz and Nick Hadley. As the world’s largest popular science meeting, the AAAS meeting is a major event in the calendar of science journalists.  At this year’s LHC session, CERN’s coordinator for international relations, Felicitas Pauss, opened the discussion, paving the way for Tom LeCompte of ATLAS, Joe Incandela of CMS, Yves Schutz of ALICE and Monica Pepe-Altarelli of LHCb to report on the status of the first year’s analysis from their experiments.    

Integration of a neutral absorber for the LHC point 8

CERN Document Server

Santamaria, A; Alemany, R; Burkhardt, H; Cerutti, F

2014-01-01

The LHCb detector will be upgraded during the second long shutdown (LS2) of the LHC machine, in order to increase its statistical precision significantly. The upgraded LHCb foresees a peak luminosity of LHL = 1-21033cm-2s-11, with a pileup of ~5. This represents ten times more luminosity and five times more pile up than in the present LHC. With these conditions, the pp-collisions and beam losses will produce a non-negligeable beam-induced energy deposition in the interaction region. More precisely, studies [1] have shown that the energy deposition will especially increase on the D2 recombination dipole, which could bring them close to their safety thresholds. To avoid this, the placement of a minimal neutral absorber has been proposed. This absorber will have the same role as the TAN in the high luminosity Interaction Regions (IR) 1 and 5. This study shows the possible dimensions and location of this absorber, and how it would reduce both the peak power density and total heat load.

Highlights of LHCb Measurement in Rare Decays and Discovery of First Pentaquark States with Run 1 Data

CERN Document Server

Ukleja, Artur

2016-01-01

In pp collisions at the LHC, the LHCb experiment has collected the world’s largest sample of beauty and charmed hadrons. Very precise mea- surements obtained from these data provide tests of the Standard Model, which are indirect searches for new physics. The highlights obtained using data of an integrated luminosity of 3.0 fb

The LHCb VELO Status and Upgrade Developments

CERN Document Server

Bates, A G

2006-01-01

The LHCb VErtex LOcator (VELO) is a silicon based vertexing sub-detector which has active silicon positioned only 8~mm from the LHC beams and will operate in an extreme (up to 1.3~x~10$^{14}$~1~MeV neutron equivalents~/~cm$^2$~/~year) and non-uniform radiation environment. The complex design of the VELO silicon sensors exploits oxygenated silicon and n$^+$-on-n technology. Research has been carried out into new materials which could significantly extend the lifetime of silicon detectors at the LHC, these would have particular application in a VELO upgrade. Promising new results on the first test beam of a large, high resistivity Czochralski silicon detector with 50 $\\mu$m pitch and 40~MHz electronics will be presented. The performance was studied before and after irradiation with high energy protons. A signal to noise of over 20~:~1 was obtained from the detector and after a fluence of 4.3~x~10$^{14}$~1~MeV~n$_{eq}$ significant charge collection efficiencies were measured at relatively modest voltages. Studie...

Performance of the LHCb Outer Tracker

CERN Document Server

Arink, R; Bachmann, S.; Bagaturia, Y.; Band, H.; Bauer, Th.; Berkien, A.; Farber, Ch.; Bien, A.; Blouw, J.; Ceelie, L.; Coco, V.; Deckenhoff, M.; Deng, Z.; Dettori, F.; van Eijk, D.; Ekelhof, R.; Gersabeck, E.; Grillo, L.; Hulsbergen, W.D.; Karbach, T.M.; Koopman, R.; Kozlinskiy, A.; Langenbruch, Ch.; Lavrentyev, V.; Linn, Ch.; Merk, M.; Merkel, J.; Meissner, M.; Michalowski, J.; Morawski, P.; Nawrot, A.; Nedos, M.; Pellegrino, A.; Polok, G.; van Petten, O.; Rovekamp, J.; Schimmel, F.; Schuylenburg, H.; Schwemmer, R.; Seyfert, P.; Serra, N.; Sluijk, T.; Spaan, B.; Spelt, J.; Storaci, B.; Szczekowski, M.; Swientek, S.; Tolk, S.; Tuning, N.; Uwer, U.; Wiedner, D.; Witek, M.; Zeng, M.; Zwart, A.

2014-01-01

The LHCb Outer Tracker is a gaseous detector covering an area of 5x6 m2 with 12 double layers of straw tubes. The detector with its services are described together with the commissioning and calibration procedures. Based on data of the first LHC running period from 2010 to 2012, the performance of the readout electronics and the single hit resolution and efficiency are presented. The efficiency to detect a hit in the central half of the straw is estimated to be 99.2%, and the position resolution is determined to be approximately 200 um. The Outer Tracker received a dose in the hottest region corresponding to 0.12 C/cm, and no signs of gain deterioration or other ageing effects are observed.

Flavour tagging of $b$-mesons in $pp$ collisions at LHCb

CERN Document Server

Müller, Vanessa

2016-01-01

Flavour tagging, i.e. the inference of the production flavour of reconstructed B hadrons, is essen- tial for precision measurements of decay-time-dependent CP violation and of mixing parameters in the neutral B meson systems. At the LHC hadronic events create a challenging environment for flavour tagging and demand for new and improved strategies. We present recent progress and new developments in terms of the flavour tagging at the LHCb experiment, which will allow for a further improvement of CP violation measurements in neutral B meson decays.

Flavour tagging of $b$ mesons in $pp$ collisions at LHCb

CERN Multimedia

Mueller, Vanessa

2016-01-01

Flavour tagging, i.e. the inference of the production flavour of reconstructed $b$ hadrons, is essential for precision measurements of decay time-dependent $CP$ violation and of mixing parameters in the the neutral $B$ meson systems. LHC's $pp$ collisions with their high track multiplicities constitute a challenging environment for flavour tagging and demand for new and improved strategies. We present recent progress and new developments in flavour tagging at the LHCb experiment, which will allow for a further improvement of $CP$ violation measurements in decays of $B^0$ and $B_s^0$ mesons.

The LHCb front-end electronics and data acquisition system

CERN Document Server

Jost, B

2000-01-01

The LHCb experiment is the most recently approved of the four experiments under construction at CERN's LHC accelerator. It is a special purpose experiment designed to precisely measure the CP violation parameters in the B-B system and to study rare B-decays. Triggering poses special problems since the interesting events containing B-mesons are immersed in a large background of inelastic p-p reactions. We therefore decided to implement a four-level triggering scheme. The LHCb data acquisition (DAQ) system will have to cope with an average trigger rate of 40 kHz, after two levels of hardware triggers, and an average event size of 100 kB. Thus, an event-building network which can sustain an average bandwidth of 4 GB /s is required. A powerful software trigger farm will have to be installed to reduce the rate from 40 kHz to 100 Hz of events written for permanent storage. In this paper we will outline the general architectures of the front-end electronics and of the trigger and DAQ system and the readout protocols...

Track pattern-recognition on GPGPUs in the LHCb experiment

CERN Document Server

Gallorini, Stefano

2015-01-01

The LHCb experiment is entering in its upgrading phase, with its detector and read-out system re-designed to cope with the increased LHC energy after the long shutdown of 2018. In this upgrade, a trigger-less data acquisition is being developed to read-out the full detector at the bunch-crossing rate of 40 MHz. In particular, the High Level Trigger (HLT) system has to be heavily revised. Since the small LHCb event size (about 100 kB), many-core architectures such as General Purpose Graphics Processing Units (GPGPUs) and multi-core CPUs can be used to process many events in parallel for real-time selection, and may offer a solution for reducing the cost of the HLT farm. Track reconstruction and vertex finding are the more time-consuming applications running in HLT and therefore are the first to be ported on many-core. In this talk we present our implementation of the existing tracking algorithms on GPGPU, discussing in detail the case of the VErtex LOcator detector (VELO), and we show the achieved performances...

Preliminary study for a measurement of the CKM angle $\\gamma$ using the tree $B^{\\pm} \\to D^{(*)0} K^{\\pm}$ decays with the LHCb detector at CERN

CERN Document Server

Anderlini, Lucio

2011-01-01

The Large Hadron Collider (LHC) offers the possibility to collect hints of New Physics (NP) in proton-proton collisions at high energy. The LHC experiments' collaborations are exploring direct and indirect techniques to reveal the existence of NP. General purpose detectors, as ATLAS and CMS, search for the decay of predicted particles to complete the Standard Model or its extensions. ALICE is dedicated to sudies of a high density and temperature environment, testing the theoretical predictions for quark gluon plasma state. LHCb tests the Standard Model (SM) in the sector of the Heavy Flavors and the global consistency of the description of the CP violation (CPV) phenomena. Since CPV manifestations involve in particular beauty mesons and because of the large b-antib production cross section at LHC, LHCb is already starting to contribute to world averages for B-meson physics and CPV parameters. The measurement of the gamma angle of the bd unitarity triangle of the Cabibbo-Kobayashi-Maskawa (CKM) matrix is ...

Measurement of the branching fraction of to D{sup +} {yields} K{sup -} K{sup +}K{sup +} in the LHCb experiment

Energy Technology Data Exchange (ETDEWEB)

Amato, Sandra; Cavalcante, Ana Barbara Rodrigues [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)

2012-07-01

Full text: The world's most powerful particle accelerator, Large Hadron Collider (LHC), is located near Geneva built around 100 m underground. For 2010 and 2011 it has collided opposing beams of 3.5 TeV protons and now the beam energy has increased to 4 TeV per beam. The LHCb experiment, one of the four main detectors in the LHC, is devoted to study CP violation and rare decays in the b and c-quark sectors. CP violation is one of the necessary ingredients to explain the difference between matter and anti-matter observed in the Universe, since they were created in equal amounts during the Big-Bang. According to the Standard Model, the CP violation in the charm sector is very small compared to the s and b systems. LHCb has the appropriate conditions to collect charm data with an outstanding statistics. So if it finds any asymmetry larger than the expected from the SM, it will open door to New Physics. We report a measurement of the branching fraction of the doubly Cabibbo suppressed mode D{sup +} {yields} K{sup -} K{sup +}K{sup +} relative to the Cabibbo-favored mode D{sup +} {yields} K{sup -} {pi}{sup +}{pi}- as a first step of a Dalitz plot analysis and CP violation measurement. Based on the signal signature, we choose the discriminating variables which distinguish between signal and background. We then select values (cuts) which allow us to not only select the signal but also maximize the statistical significance, so that, performing mass fits, we determine the yields. The efficiency was sub-divided into specific contributions, for instance, trigger and particle identification, because this way some of the contributions can be directly obtained from data and do not depend on the simulations. In this analysis we made use of 2011 LHCb data of about 1fb{sup -1} and due to the excellent performance of the LHC and LHCb we can improve the measurement of the branching fraction with respect to the previous experiments. (author)

Status of New Physics searches with $b \\to s \\ell^+ \\ell^-$ transitions @ LHCb

CERN Document Server

AUTHOR|(CDS)2069512

2017-01-01

Rare decays of heavy-flavoured particles provide an ideal laboratory to look for deviations from the Standard Model, and explore energy regimes beyond the LHC reach. Decays proceeding via electroweak penguin diagrams are excellent probes to search for New Physics, and $b \\to s \\ell^+ \\ell^-$processes are particularly interesting since they give access to many observables such as branching fractions, asymmetries and angular observables. Recent results from the LHCb experiment are reviewed.

Measurement of the Bs mixing phase at LHCb

CERN Multimedia

CERN. Geneva

2014-01-01

At scales that are not accessible by direct searches at the LHC, precision measurements of CP violating observables in the mixing and decay of B mesons  may reveal new physics through loop corrections. A good candidate for such indirect searches is the measurement of the CP violating phase phi_s which arises in the interference between the amplitudes of Bs meson decaying directly and after oscillation via b->ccs transitions. This talk will cover recent measurements of phi_s from Bs->J/psihh and DsDs decays at LHCb. Additionally, estimates of possible penguin contributions which are assumed to be zero in SM predictions will be discussed.  

Study on the performance of the Particle Identification Detectors at LHCb after the LHC First Long Shutdown (LS1)

CERN Document Server

Fontana, Marianna

2016-01-01

During the First Long Shutdown (LS1), the LHCb experiment has introduced major modification in the data-processing procedure and modified part of the detector to deal with the increased energy and the increased heavy-hadron production cross-section. In this contribution we review the performance of the particle identification detectors at LHCb, Rich, Calorimeters, and Muon system, after the LS1

LHCB Searches for long-lived heavy particles at LHCb

CERN Multimedia

Marin Benito, Carla

2014-01-01

Its forward acceptance and good resolution allow LHCb to perform competitive searches for heavy particles beyond the Standard Model. We report a search for the stau particle with the LHCb detector and give our prospects for searches of Hidden Valley particles.

Novel Real-time Calibration and Alignment Procedure for LHCb Run II

CERN Multimedia

Prouve, Claire

2016-01-01

In order to achieve optimal detector performance the LHCb experiment has introduced a novel real-time detector alignment and calibration strategy for Run II of the LHC. For the alignment tasks, data is collected and processed at the beginning of each fill while the calibrations are performed for each run. This real time alignment and calibration allows the same constants being used in both the online and offline reconstruction, thus improving the correlation between triggered and offline selected events. Additionally the newly computed alignment and calibration constants can be instantly used in the trigger, making it more efficient. The online alignment and calibration of the RICH detectors also enable the use of hadronic particle identification in the trigger. The computing time constraints are met through the use of a new dedicated framework using the multi-core farm infrastructure for the LHCb trigger. An overview of all alignment and calibration tasks is presented and their performance is shown.

Evaporative CO$_2$ microchannel cooling for the LHCb VELO pixel upgrade

CERN Document Server

de Aguiar Francisco, Oscar A; Collins, Paula; Dumps, Raphael; John, Malcolm; Mapelli, Alessandro; Romagnoli, Giulia

2015-01-01

The LHCb Vertex Detector (VELO) will be upgraded in 2018 to a lightweight pixel detector capable of 40 MHz readout and operation in very close proximity to the LHC beams. The thermal management of the system will be provided by evaporative CO$_2$ circulating in microchannels embedded within thin silicon plates. This solution has been selected due to the excellent thermal efficiency, the absence of thermal expansion mismatch with silicon ASICs and sensors, the radiation hardness of CO$_2$, and very low contribution to the material budget. Although microchannel cooling is gaining considerable attention for applications related to microelectronics, it is still a novel technology for particle physics experiments, in particular when combined with evaporative CO$_2$ cooling. The R&D effort for LHCb is focused on the design and layout of the channels together with a fluidic connector and its attachment which must withstand pressures up to 170 bar. Even distribution of the coolant is ensured by means of the use o...

Сharmonium production using decays to hadronic final states at LHCb

CERN Multimedia

Usachov, Andrii

2018-01-01

Non Relativistic QCD (NRQCD) provides so far the most successful framework to describe the production of the $J^{PC}=1^{--}$ quarkonium states. However, a comprehensive description of the production and polarisation of the $J/\\psi$ state at Tevatron and LHC in the complete $p_T$ and rapidity range remains a challenge. The heavy quark spin symmetry yields direct links between the long distance matrix elements describing hadroproduction of different charmonium states. The production of linked charmonium states - $\\eta_c$ and $J/\\psi$, $\\eta_c(2S)$ and $\\psi(2S)$, and the three $\\chi_c$ states - can thus be described simultaneously. Experimentally the production of non-$1^{--}$ charmonium states can be studied by reconstructing their decays to fully hadronic final states. The LHCb measurement of the $\\eta_c(1S)$ prompt production and production in inclusive b-hadron decays via the decay $\\eta_c(1S)\\to p\\bar{p}$ is discussed together with its strong impact on NRQCD-based theory models. Recent LHCb measurement of ...

A Future Vertex Locator with Precise Timing for the LHCb Experiment

CERN Multimedia

Mitreska, Biljana

2017-01-01

The LHCb experiment is designed to perform high precision measurements of matter-antimatter asymmetries and searches for rare and forbidden decays, with the aim of discovering new and unexpected particles and forces. In 2030 the LHC beam intensity will increase by a factor of 50 compared to current operations. This means increased samples of the particles we need to study, but it also presents experimental challenges. In particular, with current technology it becomes impossible to differentiate the many (>50) separate proton-proton collisions which occur for each bunch crossing. A Monte Carlo simulation was developed to model the operation of a silicon pixel vertex detector surrounding the collision region at LHCb, under the conditions expected after 2030, after the second upgrade of the Vertex Locator (VELO). The main goal was studying the effect of adding '4D' detectors which save high-precision timing information, in addition to the usual three spatial coordinates, as charged particles pass through them. W...

Fast simulation options in LHCb from ReDecay to fully parametrised

CERN Multimedia

Muller, Dominik

2017-01-01

With the steady increase in the precision of flavour physics measurements with data from Run 2 of the LHC, the LHCb experiment requires simulated data samples of ever increasing magnitude to study the detector response in detail. However, relying on an increase of computing resources available for the production of simulated samples will not suffice to achieve this goal. Therefore, multiple efforts are currently being investigated to reduce the time needed to simulate an event. This talk presents a summary of those efforts in LHCb, focusing on the newest developments: re-using parts of previously simulated events and a fully parametric detector description using the DELPHES framework. The former merges a simulation of an underlying event multiple times with signal decays simulated separately, achieving an order of magnitude increase in speed with identical precision. The latter provides a parametric solution replacing the full, GEANT4-based simulation, including the smearing of particles' energies, efficienci...

LHCb: The LHCb Muon detector commissioning and first running scenarios

CERN Multimedia

Furcas, S

2009-01-01

The LHCb Muon detector, being part of the first trigger level (L0), has been optimized in order to provide a fast and efficient identification of the muons produced in pp collisions at the LHC. The expected performances are: 95% L0 trigger efficiency within a 25ns time window and muon identification in L0 with a pT resolution of ~20%. The detector has been built, to met those stringent requirements, using Multi Wire Proportional Chambers and Gas Electron Multiplier (in the innermost region, closest to the IP) technology. The chambers (1368 MWPC + 12 GEM) are arranged in 5 detector stations, interspersed with iron filters placed along the beam pipe. While the installation of chambers in stations 2 to 5 has already been completed, the work on the first and most challenging station is still ongoing and expected to end by July 09. The results obtained in the commissioning of all the installed chambers as well as the performances measured by means of data acquired during cosmics runs since September 08 are reviewe...

New high resolution measurements of open and hidden charm production in proton-nucleus collisions at √{ s} = 110GeV with LHCb

Science.gov (United States)

Maurice, Émilie; LHCb Collaboration

2017-11-01

Open and hidden charm production in nucleus-nucleus collisions is considered as a key probe of Quark Gluon Plasma (QGP) formation. In the search of specific QGP effects, proton-nucleus collisions are used as the reference as they account for the corresponding Cold Nuclear Matter (CNM) effects. The LHCb experiment, thanks to its System for Measuring Overlap with Gas (SMOG) can be operated in a fixed target mode with the LHC beams, at an intermediate center-of-mass energy between nominal SPS and RHIC energies. In 2015, for the first time, reactions of incident LHC proton beams on noble gas targets have been recorded by the LHCb experiment at a center-of-mass energy of 110 GeV and within the center-of-mass rapidity range - 2.77

LHC Inner Triplet Powering Strategy

CERN Document Server

Bordry, Frederick

2001-01-01

In order to achieve a luminosity in excess of 10**34 cm**-2s**-1 at the Large Hadron Collider (LHC), special high gradient quadrupoles are required for the final focusing triplets. These low-b triplets, located in the four experimental insertions (ATLAS, CMS, ALICE, LHC-B), consist of four wide-aperture superconducting magnets: two outer quadrupoles, Q1 and Q3, with a maximum current of 7 kA and a central one divided into two identical magnets, Q2a and Q2b, with a maximum current of 11.5 kA. To optimise the powering of these mixed quadrupoles, it was decided to use two nested high-current power converters : [8kA, 8V] and [6kA, 8V]. This paper presents the consequence of the interaction between the two galvanically coupled circuits. A control strategy, using two independent, standard, LHC digital controllers, to decouple the two systems is proposed and described. The converter protection during the discharge of the magnet energy due to quenches or interlocks of the magnets are discussed. Simulation and experim...

Application of diamond based beam loss monitors at LHC

International Nuclear Information System (INIS)

Hempel, Maria

2013-04-01

The Large Hadron Collider (LHC) was conceived in the 1980s and started the operation in 2008. It needed more than 20 years to plan and construct this accelerator and its experiments. Four main experiments are located around the ring, Compact Muon Solenoid (CMS), A Toroidal LHC Apparatus(ATLAS), A Large Ion Collider Experiment (ALICE) and LHC beauty (LHCb). Two beams that traveling in opposite direction in the LHC tunnel, collide in each of the experiments to study the questions: ''What is mass?'', ''What is the universe made of?'' and ''Why is there no antimatter?''. The four experiments take data of the collision products and try to answer the fundamental questions of physics. The two larger detectors, CMS and ATLAS, are looking for the Higgs boson to study the electroweak symmetry breaking. Both detectors were built with contrasting concepts to exclude potential error sources and to rea rm the results. The smaller experiment LHCb studies the matter-antimatter asymmetry with a focus of the beauty quark. Another smaller experiment is ALICE that studies the conditions right after the Big Bang by colliding heavy ions. The navigation of the beams is done by over 10000 magnets and each beam has a stored energy of 362MJ which correspond to the kinetic energy of a train like the TGV travelling of 150 km/h. Only a small percentage of that energy can damage the material in the LHC ring or the magnets. This would mean a repair time of months or years, without taking any data. To avoid such a scenario, it is important to monitor the beam condition and measure the amount of losses of the beam. Such losses can for example happen due to dust particles in the vacuum chambers or due to deviations of the beam parameters. Several systems called beam loss monitors (BLMs) can measure beam losses. This thesis concentrates on two of them, ionization chambers and diamond detectors. Over 3600 ionization chambers are installed in the LHC, especially near each quadrupole and next to

Alignment of the LHCb Tracking Stations and Selection of $X(3872)$ and $Z(4430)^{\\pm}$ in $pp$ Collisions at 14TeV

CERN Document Server

Nicolas, L

2009-01-01

The LHCb experiment is one of the four large experiments located at the Large Hadron Collider (LHC) at CERN, close to Geneva, Switzerland. The LHCb detector is a single-arm forward spectrometer which is dedicated to precision measurements of CP violation, as well as to the study of rare $b$-hadron decays. Both the energy at which the proton-proton collisions will take place and the statistics of events that will be selected are unprecedented. The LHCb detector will start its measurements in November 2009 and operate for several years. Being an experiment for precision measurements, LHCb relies on excellent reconstruction and trigger efficiencies, outstanding proper-time and momentum resolutions, as well as on a reliable particle identification, both for the event selection and the flavour tagging of $B$-meson decays. These performances are however not possible without a precise construction and alignment of the detector. An extensive survey of the detector geometry has been performed. However these measuremen...

Study of the LHCb Muon Detector performance using 2010 beam data

CERN Document Server

Graziani, Giacomo; Satta, Alessia

2011-01-01

The LHCb muon detector is used online in level-0 (L0) and high-level (HLT) triggers and for the offline muon identification. All these applications require a very high efficiency in the very short LHC time gate. The most stringent requirement is dictated by the L0 trigger, which, in order to effectively reduce the background, asks the muon system to give a signal in all the five stations. To efficiently satisfy such requirement the muon chambers were designed to have a detection efficiency larger than 99% within the 25 ns LHC gate. Cosmic data and collision data acquired in 2009 were used for the first calibrations with physics signals and the first evaluation of performance, but the precisions was limited by statistical and systematic uncertaintites. The large p-p collisions data sample made available by the 2010 LHC run allowed for improving these results, and in particular for a precise determination of the chamber efficiency. In this note, after summarizing the main features of detector operations during ...

LHCb; Neutral Higgs $ \\to \\tau \\tau$ Limits at LHCb

CERN Multimedia

Ilten, P

2013-01-01

LHCb is fully instrumented in the forward region, $2 \\leq \\eta \\leq 5$, and provides compelentary results to the central measurements of ATLAS and CMS. Preliminary limits are presented on neutral Higgs production usint $\\tau \\tau$ final states in the forward region of LHCb.

SM+Top at the LHC

CERN Document Server

McCarthy, Tom; The ATLAS collaboration

2018-01-01

This overview talk highlights some of the latest results by the ATLAS, CMS & LHCb collaborations. A particular focus is placed on some of the rarer Standard Model processes which have recently become accessible with the large set of proton-proton collision data collected during the successful second run of the LHC at $\\sqrt{s}$ = 13 TeV. Searches and cross-section measurements involving top quark signatures are given prominence, as well as those targeting highly boosted objects such as SM W/Z and Higgs bosons, and which consequently feature large-R jets and substructure techniques.

Hard QCD Measurements at LHC

CERN Document Server

Pasztor, Gabriella

2018-01-01

The rich proton-proton collision data of the LHC allow to study QCD processes in a previously unexplored region with ever improving precision. This paper summarises recent results of the ATLAS, CMS and LHCb Collaborations using primarily multi-jet and vector boson plus jet data collected at $\\sqrt s$ = 8 and 13 TeV. Comparisons to higher-order theoretical calculations and sophisticated Monte Carlo predictions are presented, as well as the impact of the data on the determination of the parton distribution functions and the measurement of the strong coupling constant, $\\alpha_s$.

QCD probes at LHC

CERN Document Server

Da Silveira, G. Gil

2018-01-01

The LHC experiments have reported new results with respect to the dynamics of the strong interactions in $pp$, $p$A, and AA collisions over the past years. In proton-proton collisions, the data analyses have focused in exploring the nature of underlying events and double parton scattering at high energies. For large systems, the heavy-ion collisions have provided new insights on physics aspects related to azimuthal correlations, jet quenching, and particle production, such as antiprotons. This Letter reports the recent results from the ATLAS, CMS, and LHCb Collaborations on these various topics and highlights its relevant findings for the high-energy community.

VII Workshop Italiano sulla fisica pp a LHC

Science.gov (United States)

LHCpp2016 è la settima edizione dell'incontro nazionale sulla fisica p-p a LHC. Questa serie di incontri è nata a Pisa nel 2003 con lo scopo di stimolare lo scambio di idee tra le comunità sperimentali di ATLAS, CMS e LHCB e la comunità teorica. Caratteristica fondamentale di questi incontri è la preparazione di larga parte dei talk in collaborazione tra i vari esperimenti e la comunità teorica. Largo spazio nella preparazione e presentazione dei talk viene dato ai giovani ricercatori. In questa settima edizione, che si tiene di nuovo a Pisa, vogliamo concentrare l'attenzione sulle potenzialità di scoperta offerte dai dati raccolti durante il runII di LHC.

CORAL and COOL during the LHC long shutdown.

CERN Document Server

Valassi, Andrea; Dulstra, D; Goyal, N; Salnikov, A; Trentadue, R; Wache, M

2014-01-01

CORAL and COOL are two software packages used by the LHC experiments for managing detector conditions and other types of data using relational database technologies. They have been developed and maintained within the LCG Persistency Framework, a common project of the CERN IT department with ATLAS, CMS and LHCb. This presentation reports on the status of CORAL and COOL at the time of CHEP2013, covering the new features and enhancements in both packages, as well as the changes and improvements in the software process infrastructure. It also reviews the usage of the software in the experiments and the outlook for ongoing and future activities during the LHC long shutdown (LS1) and beyond.

CORAL and COOL during the LHC long shutdown

CERN Multimedia

Valassi, A; Dykstra, D; Goyal, N; Salnikov, A; Trentadue, R; Wache, M

2013-01-01

CORAL and COOL are two software packages used by the LHC experiments for managing detector conditions and other types of data using relational database technologies. They have been developed and maintained within the LCG Persistency Framework, a common project of the CERN IT department with ATLAS, CMS and LHCb. This presentation reports on the status of CORAL and COOL at the time of CHEP2013, covering the new features and enhancements in both packages, as well as the changes and improvements in the software process infrastructure. It also reviews the usage of the software in the experiments and the outlook for ongoing and future activities during the LHC long shutdown (LS1) and beyond.

Studies for Online Selection of Beam-Gas Events with the LHCb Vertex Locator

CERN Document Server

Hopchev, Plamen; Ferro-Luzzi, M

2008-01-01

The start of the Large Hadron Collider (LHC) is scheduled for the Summer 2008. The accelerator is going to provide unprecedented amount of proton-proton colli- sions with a record center-of-mass energy. The total number of collisions produced in an interaction point is directly connected to a collider characteristic called `absolute luminosity'. The luminosity depends on a number of quantities like the number of particles in a bunch, the bunch size and the number of bunches in a beam. For precise measurements of Standard Model parameters and for the search of New Physics the LHC experiments count on precise knowledge on its luminosity. The absolute luminosity of LHC is going to be measured using various meth- ods, including the recently proposed beam-gas luminosity method. This method counts on the reconstruction of beam-gas vertices for measuring the beam shapes and overlap integral. The beam-gas luminosity method is going to be first tried in the LHCb experiment, making use of its excellent vertex resolutio...

Physics Goals and Experimental Challenges of the Proton-Proton High-Luminosity Operation of the LHC

CERN Document Server

Campana, Pierluigi; Wells, Pippa

2016-01-01

The completion of Run 1 of the CERN Large Hadron Collider has seen the discovery of the Higgs boson and an unprecedented number of precise measurements of the Standard Model, while Run 2 operation has just started to provide first data at higher energy. Upgrades of the LHC to high luminosity (HL-LHC) and the experiments (ATLAS, CMS, ALICE and LHCb) will exploit the full potential of the collider to discover and explore new physics beyond the Standard Model. In this article, the experimental challenges and the physics opportunities in proton-proton collisions at the HL-LHC are reviewed.

Design of the interfaces for monitoring the Cooling Systems of Point 8 in the LHC

OpenAIRE

Caldés Llull, Maria Antonia

2009-01-01

El Cern es el Centro Europeo para la Investigación Nuclear donde se ha llevado a cabo la construcción y puesta en funcionamiento, en Septiembre de 2008, del LHC el mayor acelerador de partículas en el mundo. El LHC es un acelerador con forma anular de 27 km de perímetro situado a 100 metros bajo tierra en la frontera Franco-Suiza. A lo largo de él se localizan 4 grandes detectores de partículas: ATLAS, CMS, LHC-b y ALICE. Teóricamente se espera que, una vez en pleno funciona...

VETRA - offline analysis and monitoring software platform for the LHCb Vertex Locator

International Nuclear Information System (INIS)

Szumlak, Tomasz

2010-01-01

The LHCb experiment is dedicated to studying CP violation and rare decay phenomena. In order to achieve these physics goals precise tracking and vertexing around the interaction point is crucial. This is provided by the VELO (VErtex LOcator) silicon detector. After digitization, FPGAs are employed to run several algorithms to suppress noise and reconstruct clusters. This is performed by an FPGA based processing board. An off-line software project, VETRA, has been developed which performs a bit perfect emulation of this complex processing in the FPGAs. This is a novel development as this hardware emulation is not standalone but rather is fully integrated into the LHCb software to allow the reconstruction of full data from the detector. This software platform facilitates the development and understanding of the behaviour of the processing algorithms, the optimization of the parameters of the algorithms that will be loaded into the FPGA and monitoring of the detector performance. This framework has also been adopted by the Silicon Tracker detector of LHCb. This processing framework was successfully used with the first 1500 tracks of data in the VELO obtained from the first LHC beam in September 2008. The software architecture and utilisation of the VETRA project will be discussed in detail.

Search for gluon saturation at Bjorken-x $\\in [10^{−6}, 10^{−4}]$ with the LHCb detector(ID:39)

CERN Document Server

Da Silva, Cesar Luiz

2018-01-01

A new state of matter, where gluons have overlapping wave functions, has been in the minds of particle and nuclear physicists for decades. This gluon saturated state could explain several recent observations such as particle production and collectivity observed in p+p, p+A and A+A collisions at RHIC and LHC. The LHCb experiment is a forward spectrometer with vertexing, tracking, $p, K, \\pi, e, \\mu$ identification and calorimetry in the pseudorapidity region 2< $\\eta$ <5. LHCb is therefore well suited to study the gluon density of hadrons in at small Bjorken-x values $(x∼10^{−6}−10^{−5})$, down to two orders of magnitude smaller than HERA. The status of the analysis efforts aimed at finding the gluon saturation scale at LHCb using isolated photon yields and their correlations with hadrons and jets will be shown. In addition, the concept and R&D efforts of a new particle tracker inside the LHCb magnet to improve measurements of small Q2 processes, where gluon saturation is expected, will be pr...

LHC-GCS a model-driven approach for automatic PLC and SCADA code generation

CERN Document Server

Thomas, Geraldine; Barillère, Renaud; Cabaret, Sebastien; Kulman, Nikolay; Pons, Xavier; Rochez, Jacques

2005-01-01

The LHC experiments’ Gas Control System (LHC GCS) project [1] aims to provide the four LHC experiments (ALICE, ATLAS, CMS and LHCb) with control for their 23 gas systems. To ease the production and maintenance of 23 control systems, a model-driven approach has been adopted to generate automatically the code for the Programmable Logic Controllers (PLCs) and for the Supervision Control And Data Acquisition (SCADA) systems. The first milestones of the project have been achieved. The LHC GCS framework [4] and the generation tools have been produced. A first control application has actually been generated and is in production, and a second is in preparation. This paper describes the principle and the architecture of the model-driven solution. It will in particular detail how the model-driven solution fits with the LHC GCS framework and with the UNICOS [5] data-driven tools.

LHCb VELO Upgrade

CERN Document Server

Hennessy, Karol

2016-01-01

The upgrade of the LHCb experiment, scheduled for LHC Run-III, scheduled to start in 2021, will transform the experiment to a trigger-less system reading out the full detector at 40 MHz event rate. All data reduction algorithms will be executed in a high-level software farm enabling the detector to run at luminosities of $2\\times10^{33} \\mathrm{cm}^{-2}\\mathrm{s}^{-1}$. The Vertex Locator (VELO) is the silicon vertex detector surrounding the interaction region. The current detector will be replaced with a hybrid pixel system equipped with electronics capable of reading out at 40 MHz. The upgraded VELO will provide fast pattern recognition and track reconstruction to the software trigger. The silicon pixel sensors have $55\\times55 \\mu m^{2}$ pitch, and are read out by the VeloPix ASIC, from the Timepix/Medipix family. The hottest region will have pixel hit rates of 900 Mhits/s yielding a total data rate of more than 3 Tbit/s for the upgraded VELO. The detector modules are located in a separate vacuum, separate...

Instruments for calibration and monitoring of the LHCb Muon Detector

CERN Document Server

Deplano, C; Lai, A

2006-01-01

The subject of this Ph. D. thesis is the study and the development of the instruments needed to monitor and calibrate the Muon Detector of the LHCb (Large Hadron Collider beauty) experiment. LHCb is currently under installation at the CERN Large Hadron Collider (LHC) and will start to take data during 2007. The experiment will study B mesons decays to achieve a profound understanding of favour physics in the Standard Model framework and to search signs of new physics beyond. Muons can be found in the final states of many B-decays which are sensitive to CP violation. The Muon Detector has the crucial role to identify the muon particles generated by the b-hadron decays through a measurement of their transverse momentum, already at the first trigger level (Level-0). A 95% effciency in events selection is required for the Muon Trigger, which operates at the Level-0. 1380 detectors are used to equip the whole Muon System and the corresponding 122,112 readout channels must be time aligned and monitored with a resol...

A novel standalone track reconstruction algorithm for the LHCb upgrade

CERN Multimedia

Quagliani, Renato

2018-01-01

During the LHC Run III, starting in 2020, the instantaneous luminosity of LHCb will be increased up to 2×1033 cm−2 s−1, five times larger than in Run II. The LHCb detector will then have to be upgraded in 2019. In fact, a full software event reconstruction will be performed at the full bunch crossing rate by the trigger, in order to profit of the higher instantaneous luminosity provided by the accelerator. In addition, all the tracking devices will be replaced and, in particular, a scintillating fiber tracker (SciFi) will be installed after the magnet, allowing to cope with the higher occupancy. The new running conditions, and the tighter timing constraints in the software trigger, represent a big challenge for the track reconstruction. This talk presents the design and performance of a novel algorithm that has been developed to reconstruct track segments using solely hits from the SciFi. This algorithm is crucial for the reconstruction of tracks originating from long-lived particles such as KS and Λ. ...

LHCB: Non-POSIX File System for the LHCB Online Event Handling

CERN Multimedia

Garnier, J-C; Cherukuwada, S S

2010-01-01

LHCb aims to use its O(20000) CPU cores in the High Level Trigger (HLT) and its 120 TB Online storage system for data reprocessing during LHC shutdown periods. These periods can last between a few days and several weeks during the winter shutdown or even only a few hours during beam interfill gaps. These jobs run on files which are staged in from tape storage to the local storage buffer. The result are again one or more files. Efficient file writing and reading is essential for the performance of the system. Rather than using a traditional shared filesystem such as NFS or CIFS we have implemented a custom, light-weight, non-Posix file-system for the handling of these files. Streaming this filesystem for the data-access allows to obtain high performance, while at the same time keep the resource consumption low and add nice features not found in NFS such as high-availability, transparent failover of the read and write service. The writing part of this file-system is in successful use for the Online, real-time w...

The vacuum chamber in the interaction region of particle colliders a historical study and developments implementations in the LHCb experiment at CERN

CERN Document Server

Knaster, J R; Gamez-Mejias, L

2004-01-01

The history of particle colliders begins in the early 60's when an idea previously patented by R. Wideroe in 1953 is constructed. The design of the vacuum chamber in their experimental area became essential as it was the rst physical barrier that the particles to be detected needed to traverse. The interaction of the products of the collisions with the vacuum chamber structural materials, hindered the identification of the significative events. This Thesis analyses the historical evolution of the experimental vacuum chambers and summarizes the technical criteria that are to be fulfilled. The Large Hadron Collider (LHC) presently under construction at CERN is the last generation of particle colliders. Four big experiments will be in operation (ATLAS, CMS, ALICE and LHCb) in the LHC with diferent physics objectives. In particular, LHCb will be devoted to the study of CP violation and the design of its vacuum chamber is the scope of this Thesis. Physics simulations with an initial design consisting of a conical ...

Measurement of the CKM angle gamma and B meson lifetimes at the LHCb detector

CERN Document Server

Gligorov, Vladimir V; Rademacker, J

2008-01-01

LHCb is the dedicated B physics experiment at the Large Hadron Collider (LHC) at CERN. It will make precision measurements of CP violating effects in the Bd and Bs systems, as well as making precision measurements of the lifetimes of all flavours of B hadrons. In this thesis, two possible measurements of the CKM angle gamma are evaluated:from the decay mode B0d -> D- pi+, and from the combined analysis of the decay modes B0d -> D- pi+ and B0s -> D-s K+ under the conditions of U-spin symmetry. Also, a Monte Carlo independent method of measuring the lifetimes of B hadrons is described. The reconstruction of the decay mode B0d -> D- pi+ is studied using the LHCb simulation software, and a general method for categorising background at LHCb is developed. The decay mode B0d -> D- pi+ is found to have a yearly yield of 1340k events, and a signal to background ratio of ~5. It is shown that the analysis of time dependent decay rate asymmetries in B0d -> D- pi+ can result in a ...

CKM angle $\\gamma$ from LHCb

CERN Multimedia

Smith, Jackson

2015-01-01

Results of the latest $\\gamma$ combination from LHCb are presented, along with the six LHCb measurements used as inputs. In addition, the anticipated precision attainable for measuring $\\gamma$ after the LHCb Upgrade is outlined

LHC France 2013: French Meeting on High Energy Physics at the LHC

CERN Document Server

2013-01-01

Cette 1ère édition des rencontres françaises sur la physique des hautes énergies au Large Hadron Collider réunira près de 300 physiciens membres des laboratoires IN2P3-CNRS et IRFU-CEA, participants aux collaborations Atlas, CMS, LHCb et Alice. La rencontre LHC France, aura lieu à une période particulièrement cruciale pour la discipline, les derniers résultats des expériences LHC, basés sur toutes les données collectées en 2011 et 2012 y seront présentés et discutés. Elle sera l'occasion de faire le point et le bilan des avancées des diverses thématiques de recherche: boson de Higgs, les interactions électrofaibles, le quark top, la Supersymétrie, les saveurs lourdes, la violation de CP et le Plasma de Quarks et de Gluons. Elle sera aussi l'occasion de discuter des plans d'amélioration des détecteurs en vue des futures phases de fonctionnement du LHC ainsi que les perspectives pour la physique. Cette rencontre se veut un moment d'échange privilégié pour la communauté française des ...

Summary of Session 8 'LHC-related Projects and Studies (I)'

Energy Technology Data Exchange (ETDEWEB)

Garoby, R; Ponce, Laurette [European Organization for Nuclear Research, Geneva (Switzerland)

2012-07-01

This session was the first of the two sessions dealing with future projects and the associated studies. Starting with descriptions of the plans and needs of the LHCb and ALICE experiments which are less extensively documented than those of ATLAS and CMS, it addressed the plans for the High Luminosity LHC and for the upgrade of the injectors, both for protons and other ions. (author)

Application of diamond based beam loss monitors at LHC

Energy Technology Data Exchange (ETDEWEB)

Hempel, Maria

2013-04-15

The Large Hadron Collider (LHC) was conceived in the 1980s and started the operation in 2008. It needed more than 20 years to plan and construct this accelerator and its experiments. Four main experiments are located around the ring, Compact Muon Solenoid (CMS), A Toroidal LHC Apparatus(ATLAS), A Large Ion Collider Experiment (ALICE) and LHC beauty (LHCb). Two beams that traveling in opposite direction in the LHC tunnel, collide in each of the experiments to study the questions: ''What is mass?'', ''What is the universe made of?'' and ''Why is there no antimatter?''. The four experiments take data of the collision products and try to answer the fundamental questions of physics. The two larger detectors, CMS and ATLAS, are looking for the Higgs boson to study the electroweak symmetry breaking. Both detectors were built with contrasting concepts to exclude potential error sources and to rea rm the results. The smaller experiment LHCb studies the matter-antimatter asymmetry with a focus of the beauty quark. Another smaller experiment is ALICE that studies the conditions right after the Big Bang by colliding heavy ions. The navigation of the beams is done by over 10000 magnets and each beam has a stored energy of 362MJ which correspond to the kinetic energy of a train like the TGV travelling of 150 km/h. Only a small percentage of that energy can damage the material in the LHC ring or the magnets. This would mean a repair time of months or years, without taking any data. To avoid such a scenario, it is important to monitor the beam condition and measure the amount of losses of the beam. Such losses can for example happen due to dust particles in the vacuum chambers or due to deviations of the beam parameters. Several systems called beam loss monitors (BLMs) can measure beam losses. This thesis concentrates on two of them, ionization chambers and diamond detectors. Over 3600 ionization chambers are installed in

LHCb on track

CERN Document Server

2006-01-01

On 7 and 8 June 2006, the last large component of the LHCb experiment was lowered into the cavern. This 10-tonne, 18-metre long metal structure known as 'the bridge' will support the LHCb tracking system.

Rare leptonic and semileptonic $b$-hadron decays and tests of lepton flavour universality at LHCb

CERN Document Server

AUTHOR|(CDS)2069512

2016-01-01

Rare decays of heavy-flavoured particles provide an ideal laboratory to look for deviations from the Standard Model, and explore energy regimes beyond the LHC reach. Decays proceeding via electroweak penguin diagrams are excellent probes to search for New Physics, and $b \\to s \\ell^+ \\ell^-$ processes are particularly interesting since they give access to many observables such as branching fractions, asymmetries and angular observables. Recent results from the LHCb experiment are reviewed.

Performance Studies of Pixel Hybrid Photon Detectors for the LHCb RICH Counters

CERN Document Server

Aglieri Rinella, G; Piedigrossi, D; Van Lysebetten, A

2004-01-01

The Pixel Hybrid Photon Detector is a vacuum tube with a multi-alkali photo cathode, high voltage cross-focused electron optics and an anode consisting of a silicon pixel detector bump-bonded to a readout CMOS electronic chip fully encapsulated in the device. The Pixel HPD fulfils the requirements of the Ring Imaging Cherenkov counters of the LHCb experiment at LHC. The performances of the Pixel HPD will be discussed with reference to laboratory measurements, Cherenkov light imaging in recent beam tests, image distortions due to a magnetic field.

LHCb : Novel real-time alignment and calibration of the LHCb Detector in Run2

CERN Multimedia

Tobin, Mark

2015-01-01

LHCb has introduced a novel real-time detector alignment and calibration strategy for LHC Run 2. Data collected at the start of the fill will be processed in a few minutes and used to update the alignment, while the calibration constants will be evaluated for each run. This procedure will improve the quality of the online alignment. For example, the vertex locator is retracted and reinserted for stable beam collisions in each fill to be centred on the primary vertex position in the transverse plane. Consequently its position changes on a fill-by-fill basis. Critically, this new realtime alignment and calibration procedure allows identical constants to be used in the online and offline reconstruction, thus improving the correlation between triggered and offline selected events. This offers the opportunity to optimise the event selection in the trigger by applying stronger constraints. The online calibration facilitates the use of hadronic particle identification using the RICH detectors at the trigger level. T...

Proceedings of the second workshop of LHC Computing Grid, LCG-France; ACTES, 2e colloque LCG-France

Energy Technology Data Exchange (ETDEWEB)

Chollet, Frederique; Hernandez, Fabio; Malek, Fairouz; Gaelle, Shifrin (eds.) [Laboratoire de Physique Corpusculaire Clermont-Ferrand, Campus des Cezeaux, 24, avenue des Landais, Clermont-Ferrand (France)

2007-03-15

The second LCG-France Workshop was held in Clermont-Ferrand on 14-15 March 2007. These sessions organized by IN2P3 and DAPNIA were attended by around 70 participants working with the Computing Grid of LHC in France. The workshop was a opportunity of exchanges of information between the French and foreign site representatives on one side and delegates of experiments on the other side. The event allowed enlightening the place of LHC Computing Task within the frame of W-LCG world project, the undergoing actions and the prospects in 2007 and beyond. The following communications were presented: 1. The current status of the LHC computation in France; 2.The LHC Grid infrastructure in France and associated resources; 3.Commissioning of Tier 1; 4.The sites of Tier-2s and Tier-3s; 5.Computing in ALICE experiment; 6.Computing in ATLAS experiment; 7.Computing in the CMS experiments; 8.Computing in the LHCb experiments; 9.Management and operation of computing grids; 10.'The VOs talk to sites'; 11.Peculiarities of ATLAS; 12.Peculiarities of CMS and ALICE; 13.Peculiarities of LHCb; 14.'The sites talk to VOs'; 15. Worldwide operation of Grid; 16.Following-up the Grid jobs; 17.Surveillance and managing the failures; 18. Job scheduling and tuning; 19.Managing the site infrastructure; 20.LCG-France communications; 21.Managing the Grid data; 22.Pointing the net infrastructure and site storage. 23.ALICE bulk transfers; 24.ATLAS bulk transfers; 25.CMS bulk transfers; 26. LHCb bulk transfers; 27.Access to LHCb data; 28.Access to CMS data; 29.Access to ATLAS data; 30.Access to ALICE data; 31.Data analysis centers; 32.D0 Analysis Farm; 33.Some CMS grid analyses; 34.PROOF; 35.Distributed analysis using GANGA; 36.T2 set-up for end-users. In their concluding remarks Fairouz Malek and Dominique Pallin stressed that the current workshop was more close to users while the tasks for tightening the links between the sites and the experiments were definitely achieved. The IN2P3

arXiv Architecture of the LHCb muon Frontend control system upgrade

CERN Document Server

Bocci, Valerio

2016-10-06

The LHCb experiment(Fig. 1), that is presently taking data at CERN (European Center for Nuclear Research) Large Hadron Collider (LHC), aims at the study of CP violation in the B meson sector. Its key elements is the Muon detector [1], which allows triggering, and muon identification from inclusive b decays. The electronic system (Fig. 2) of the whole detector is very complex and its Muon detector Experiment Control System (ECS) allows monitoring and control of a number of Front-End boards in excess of 7000. The present system in charge of controlling Muon detector Front-End (FE) Electronics consists of 10 Crates of equipment; each crate contains two kinds of modules: a Pulse Distribution Module (PDM) and up to 20 Service Boards (SB) connected via a custom Backplane for a total amount of about 800 microcontrollers[2]. LHCb upgrade is planned for 2018/19, which will allow the detector to exploit higher luminosity running. This upgrade will allow the experiment to accumulate more luminosity to allow measurements...

LHCb computing in Run II and its evolution towards Run III

CERN Document Server

Falabella, Antonio

2016-01-01

his contribution reports on the experience of the LHCb computing team during LHC Run 2 and its preparation for Run 3. Furthermore a brief introduction on LHCbDIRAC, i.e. the tool to interface to the experiment distributed computing resources for its data processing and data management operations, is given. Run 2, which started in 2015, has already seen several changes in the data processing workflows of the experiment. Most notably the ability to align and calibrate the detector between two different stages of the data processing in the high level trigger farm, eliminating the need for a second pass processing of the data offline. In addition a fraction of the data is immediately reconstructed to its final physics format in the high level trigger and only this format is exported from the experiment site to the physics analysis. This concept have successfully been tested and will continue to be used for the rest of Run 2. Furthermore the distributed data processing has been improved with new concepts and techn...

Searches for Dark Matter in events with long-lived particles at the LHC

CERN Document Server

Schioppa, Marco; The ATLAS collaboration

2017-01-01

The ATLAS, CMS and LHCb collaborations searched for Dark Matter (DM) in events with long-lived particles. Many theories of physics beyond the Standard Model predict the existence of stable, neutral, weakly-interacting and massive particles that are putative Dark Matter candidates. The observation of such matter at a collider could only establish that it is neutral, weakly-interactive, massive and stable on the distance-scales of tens of meters. The searches are performed using the LHC Run-I and Run-II datasets recorded with the ATLAS, CMS and LHCb detectors in proton-proton collisions at a center-of-mass energy of 7, 8 and 13 TeV. Signatures include both long-lived particles produced in association with DM and long-lived DM particles (e.g. dark photons decay in lepton-jets). This presentation covers only some of the many researches carried out with the LHC experiments in recent years. No deviation from SM background expectation was found up to now and exclusion limits on DM production cross section were set.

Silicon Detectors for the sLHC - an Overview of Recent RD50 Results

CERN Document Server

Pellegrini, Giulio

2009-01-01

It is foreseen to significantly increase the luminosity of the Large Hadron Collider(LHC) at CERN around 2018 by upgrading the LHC towards the sLHC (Super-LHC). Due to the radiation damage to the silicon detectors used, the physics experiment will require new tracking detectors for sLHC operation. All-silicon central trackers are being studied in ATLAS, CMS and LHCb, with extremely radiation hard silicon sensors on the innermost layers. The radiation hardness of these new sensors must surpass the one of LHC detectors by roughly an order of magnitude. Within the CERN RD50 collaboration, a massive R&D programme is underway to develop silicon sensors with sufficient radiation tolerance. Among the R&D topics are the development of new sensor types like 3D silicon detectors designed for the extreme radiation levels of the sLHC. We will report on the recent results obtained by RD50 from tests of several detector technologies and silicon materials at radiation levels corresponding to SLHC fluences. Based on ...

Exclusive ϒ photoproduction in hadronic collisions at CERN LHC energies

Energy Technology Data Exchange (ETDEWEB)

Gonçalves, V.P., E-mail: barros@ufpel.edu.br [High and Medium Energy Group, Instituto de Física e Matemática, Universidade Federal de Pelotas, Caixa Postal 354, CEP 96010-900, Pelotas, RS (Brazil); Moreira, B.D.; Navarra, F.S. [Instituto de Física, Universidade de São Paulo, C.P. 66318, 05315-970 São Paulo, SP (Brazil)

2015-03-06

The exclusive ϒ photoproduction in proton–proton and proton–nucleus collisions at LHC energies is investigated using the color dipole formalism and considering different models for the ϒ wave function and forward dipole–target scattering amplitude. Our goal is to update the color dipole predictions and estimate the theoretical uncertainty present in these predictions. We present predictions for the kinematical ranges probed by the ALICE, CMS and LHCb Collaborations.

Commissioning of the LHCb Inner Tracker and measurement of $V^0$-particle production in $pp$ collisions at 0.9 TeV

CERN Document Server

Knecht, Mathias

2011-01-01

The Large Hadron Collider (LHC) at CERN near Geneva is an accelerator designed to collide protons at a centre-of-mass energy of $\\sqrt{s}$ = 14 TeV. It is operational since November 2009 and has delivered collisions up to an energy of $\\sqrt{s}$ = 7 TeV in 2010. The LHCb experiment is one of the four major LHC experiments, together with ATLAS, CMS and ALICE. It is a single-arm forward spectrometer designed to study CP-violation and rare decays in the $b$-quark sector. The tracking system of the LHCb experiment is composed of the silicon Vertex Locator (VELO), the silicon Tracker Turicensis (TT), the dipole magnet, the silicon Inner Tracker (IT) and the straw-tube Outer Tracker (OT). The IT is covering the innermost acceptance region close to the beam-pipe, where the track multiplicity is highest (20% of the tracks for 1.5% of the acceptance). Two topics have been addressed in this doctoral thesis. The first part is dedicated to the IT commissioning phase. In particular the first version of the data-quality o...

Studies of $\\mathrm{D}^0\\to\\mathrm{K}^0_{\\scriptscriptstyle\\rm S}\\mathrm{h}^{+}\\mathrm{h}'^{-}$ decays at the LHCb experiment

CERN Document Server

Lupton, Oliver

This thesis documents two studies of the neutral charm meson system using the LHCb detector, and gives an overview of the numerous changes made to the LHCb software trigger in advance of Run~2 of the LHC. In the first analysis, amplitude models are applied to studies of the resonance structure in $\\mathrm{D}^0\\to\\mathrm{K}^0_{\\scriptscriptstyle\\rm S}\\mathrm{K}^{-}\\pi^{+}$ and $\\mathrm{D}^0\\to\\mathrm{K}^0_{\\scriptscriptstyle\\rm S}\\mathrm{K}^{+}\\pi^{-}$ decays using proton-proton collision data, corresponding to an integrated luminosity of $3.0\\mbox{ fb}^{-1}$, collected during Run~1 of the LHC. Relative magnitude and phase information is determined, and coherence factors and related observables are computed for both the whole phase space and a restricted region of $100\\mathrm{\\,Me\\kern -0.1em V\\!/}c^2$ around the $\\mathrm{K}^{*}(892)^{\\pm}$ resonance. Two formulations for the $\\mbox{$\\mathrm{K}\\pi$ $S$-wave}$ are used, both of which give a good description of the data. The ratio of branching fractions $\\mathca...

LHCb launches new website

CERN Multimedia

2008-01-01

A new public website for the LHCb experiment was launched last Friday to coincide with CERN’s Open Day weekend. Designed to provide accessible information on all aspects of the experiment, the website contains images and key facts about the LHCb detector, its design and installation and the international team behind the project. "LHCb is going to be one of the most important b-physics experiments in the world when it starts taking data later this year", explains Roger Forty, the experiment’s deputy spokesperson. "We hope the website will be a valuable resource, enabling people to learn about this fascinating area of research." The new website can be found at: http://cern.ch/lhcb-public

Behind the scenes at LHCb

CERN Multimedia

Katarina Anthony

2010-01-01

A new book chronicling the journey of LHCb has just been published: “LHCb: the collaboration in photos”. It takes readers through the creation of the detector, from the project's inception to the construction of the site and final operation.   Cover of the new book, "LHCb: the collaboration in photos". “LHCb: the collaboration in photos” presents a stunning collection of images and information about the experiment and its staff. Part photo journal of the experiment’s creation, part introduction to the physics and engineering of the detector, it provides a complete overview of the LHCb project. The many faces of the LHCb collaboration are reflected in the 77 glossy pages of the new book: from technical staff to computer scientists, physicists to secretaries, and Nobel Prize winners to post-docs. For all of its members, the book represents a well-earned celebration of their 15 years of effort. “We are very pleased to ha...

LHCb: Optimization and Calibration of Flavour Tagging Algorithms for the LHCb experiment

CERN Multimedia

Falabella, A

2013-01-01

The LHCb purposes are to make precise measurements of $B$ and $D$ meson decays. In particular in time-dependent CP violation studies the determination of $B$ flavour at production is fundamental. This is known as "flavour tagging" and at LHCb it is performed with several algorithms. The performances and calibration of the flavour tagging algorithms with 2011 data collected by LHCb are reported. Also the performances of the flavour tagging algorithms in the relevant CP violation and asymmetry studies are also reported.

A symphony of data at LHCb

CERN Multimedia

2008-01-01

Like musical instruments in an orchestra, the main difficulty with the many detectors of LHCb is coaxing them into playing in harmony. On 8 February 2008, for the first time, the LHCb control room team managed to extract a symphony of data from an almost complete ensemble of LHCb detectors. The LHCb control room team examining the data read out from the LHCb detectors. General view of the LHCb detector components.Now that all the detectors of LHCb are installed in the cavern they can begin to play a tune. The week of 4 February was commissioning week for the LHCb control room, when, for the first time, data from the majority of the sub-detectors (VELO, RICH 1, RICH 2, ECAL, HCAL, MUON, L0Calo and L0DU) was read out, controlled from a single window on the main computer. Sixty electronic boards, which read out the fragments of triggered events, were used during the readout at a frequency of 100 Hz. As not all of the boards ...

LHCb: LHCb Software and Conditions Database Cross-Compatibility Tracking: a Graph-Theory Approach

CERN Multimedia

Cattaneo, M; Shapoval, I

2012-01-01

The Conditions Database (CondDB) of the LHCb experiment provides versioned, time dependent geometry and conditions data or all LHCb data processing applications (simulation, high level trigger, reconstruction, analysis). The evolution of CondDB and of the LHCb applications is a weakly-homomorphic process. It means that compatibility between a CondDB state and LHCb application state may not be preserved across different database and application generations. More over, a CondDB state by itself belongs to a complex three-dimensional phase space which evolves according to certain CondDB self-compatibility criteria, so it is sometimes difficult even to determine a self-consistent CondDB state. These compatibility issues may lead to various kinds of problems in the LHCb production, varying from unexpected application crashes to incorrect data processing results. Thus, there is a need for defining a well-established set of compatibility criteria between mentioned above entities, together with developing a compatibil...

LHCb VELO Upgrade

CERN Document Server

van Beuzekom, Martin; Ketel, Tjeerd; Gershon, Timothy; Parkes, Christopher; Reid, Matthew

2011-01-01

The VErtex LOcator (VELO) is a vital piece of apparatus for allowing precision measurements in hadronic physics. It provides not only superb impact parameter resolutions but also excellent momentum resolution, both important discriminating tools for precision high energy physics. This poster focuses on the R&D going into the future LHCb VELO detector. At present there are two proposed options for the upgrade; pixel chips or strip detectors. The LHCb upgrade is designed with higher luminosities and increased yields in mind. In order to get more out of the LHCb detector changes to the front end electronics will have to be made. At present, the first level hardware trigger is sets a limiting factor on the maximum efficiency for hadronic channels. As the VELO is positioned so close the proton-proton interaction region, whatever the choice of sensor, we will require efficient cooling and some proposed solutions are outlined. The LHCb TimePix telescope has had a very successful years running, with various devic...

LHCb: A GPU offloading mechanism for LHCb

CERN Multimedia

Badalov, A; Zvyagin, A; Neufeld, N; Vilasis Cardona, X

2013-01-01

The LHCb Software Infrastructure is built around a flexible, extensible, single-process, single-threaded framework named Gaudi. One way to optimise the overall usage of a multi-core server, which is used for example in the Online world, is running multiple instances of Gaudi-based applications concurrently. For LHCb, this solution has been shown to work well up to 32 cores and is expected to scale up a bit further. The appearance of many-core architectures such as GPGPUs and the Intel Xeon/Phi poses a new challenge for LHCb. Since the individual data sets are so small (about 60 kB raw event size), many events must be processed in parallel for optimum efficiency. This is, however, not possible with the current framework, which allows only a single event at a time. Exploiting the fact that we always have many instances of the same application running, we have developed an offloading mechanism, based on a client-server design. The server runs outside the Gaudi framework and thus imposes no additional dependencie...

The LHCb trigger

CERN Document Server

Hernando Morata, Jose Angel

2006-01-01

The LHCb experiment relies on an efficient trigger to select a rate up to 2 kHz of events useful for physics analysis from an initial rate of 10 MHz of visible collisions. In this contribution, we describe the different LHCb trigger algorithms and present their expected performance.

LHCb VErtex LOcator module characterisation and long term quality assurance tests

CERN Document Server

Bates, A; Doherty, F; Dumps, R; Dwyer, L; Gersabeck, M; Marinho, 1, F; Melone, J; Parkes, C; Saavedra, A; Tobin, M; Viret, S

2009-01-01

LHCb is the dedicated b-physics experiment of the LHC. Its vertex detector, the VErtex LOcator (VELO), will operate in a harsh radiation environment with limited access due to its proximity to the LHC beam. To ensure the long term operation and performance, every module was required to pass a set of quality assurance tests. These were specifically developed for the VELO modules to take into account their operational environment and assembly steps. Each VELO module was rigorously inspected, tested and thermally cycled in the Glasgow module burn-in procedures. This paper provides details of the burn-in procedures and summarises the main results that were found. Some of the major results presented in this paper are: the full characterisation of the leakage currents; identification of bad channels; and signal to noise measurements. A few minor problems were identified through visual inspections of the modules and the feedback into the production process proved critical. As a result of the electrical and thermal t...

The LHCb VELO Upgrade

CERN Document Server

de Capua, Stefano

2016-01-01

The upgrade of the LHCb experiment, scheduled for LHC Run-3, will transform the experiment to a triggerless system reading out the full detector at 40 MHz event rate. All data reduction algorithms will be executed in a high-level software farm, enabling the detector to run at luminosities of 2×1033 cm−2 s −1 . The Vertex Locator (VELO) is the silicon vertex detector surrounding the interaction region. The current strip detector will be replaced with a hybrid pixel system equipped with electronics capable of reading out at 40 MHz. The upgraded VELO will allow for fast pattern recognition and track reconstruction in the software trigger. The silicon pixel sensors have 55×55 µm2 pitch, and are read out by the VeloPix ASIC. The VeloPix builds on the currently available Timepix3, modified to deliver a radiation hard design capable of an order of magnitude increase in output rate. The hottest regions will have pixel hit rates of 900 Mhits/s, yielding a total data rate more than 3 Tbit/s for the upgraded VELO...

LHCb: Alignment of the LHCb Detector with Kalman Filter Fitted Tracks

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Amoraal, J; Hulsbergen, W; Needham, M; Nicolas, L; Pozzi, S; Raven, G; Vecchi, S

2009-01-01

We report on an implementation of a global chisquare algorithm for the simultaneous alignment of all tracking systems in the LHCb detector. Our algorithm uses hit residuals from the standard LHCb track fit which is based on a Kalman filter. The algorithm is implemented in the LHCb reconstruction framework and exploits the fact that all sensitive detector elements have the same geometry interface. A vertex constraint is implemented by fitting tracks to a common point and propagating the change in track parameters to the hit residuals. To remove unconstrained or poorly constrained degrees of freedom (so-called weak modes) the average movements of (subsets of) alignable detector elements can be fixed with Lagrange constraints. Alternatively, weak modes can be removed with a cutoff in the eigenvalue spectrum of the second derivative of the chisquare. As for all LHCb reconstruction and analysis software the configuration of the algorithm is done in python and gives detailed control over the selection of alignable ...

Optimisation of the LHCb detector

CERN Document Server

Hierck, R H

2003-01-01

This thesis describes a comparison of the LHCb classic and LHCb light concept from a tracking perspective. The comparison includes the detector occupancies, the various pattern recognition algorithms and the reconstruction performance. The final optimised LHCb setup is used to study the physics performance of LHCb for the Bs->DsK and Bs->DsPi decay channels. This includes both the event selection and a study of the sensitivity for the Bs oscillation frequency, delta m_s, the Bs lifetime difference, DGamma_s, and the CP parameter gamma-2delta gamma.

The 40 MHz trigger-less DAQ for the LHCb Upgrade

Energy Technology Data Exchange (ETDEWEB)

Campora Perez, D.H. [INFN CNAF, Bologna (Italy); Falabella, A., E-mail: antonio.falabella@cnaf.infn.it [CERN, Geneva (Switzerland); Galli, D. [INFN Sezione di Bologna, Bologna (Italy); Università Bologna, Bologna (Italy); Giacomini, F. [CERN, Geneva (Switzerland); Gligorov, V. [INFN CNAF, Bologna (Italy); Manzali, M. [Università Bologna, Bologna (Italy); Università Ferrara, Ferrara (Italy); Marconi, U. [INFN Sezione di Bologna, Bologna (Italy); Neufeld, N.; Otto, A. [INFN CNAF, Bologna (Italy); Pisani, F. [INFN CNAF, Bologna (Italy); Università la Sapienza, Roma (Italy); Vagnoni, V.M. [INFN Sezione di Bologna, Bologna (Italy)

2016-07-11

The LHCb experiment will undergo a major upgrade during the second long shutdown (2018–2019), aiming to let LHCb collect an order of magnitude more data with respect to Run 1 and Run 2. The maximum readout rate of 1 MHz is the main limitation of the present LHCb trigger. The upgraded detector, apart from major detector upgrades, foresees a full read-out, running at the LHC bunch crossing frequency of 40 MHz, using an entirely software based trigger. A new high-throughput PCIe Generation 3 based read-out board, named PCIe40, has been designed for this purpose. The read-out board will allow an efficient and cost-effective implementation of the DAQ system by means of high-speed PC networks. The network-based DAQ system reads data fragments, performs the event building, and transports events to the High-Level Trigger at an estimated aggregate rate of about 32 Tbit/s. Different architecture for the DAQ can be implemented, such as push, pull and traffic shaping with barrel-shifter. Possible technology candidates for the foreseen event-builder under study are InfiniBand and Gigabit Ethernet. In order to define the best implementation of the event-builder we are performing tests of the event-builder on different platforms with different technologies. For testing we are using an event-builder evaluator, which consists of a flexible software implementation, to be used on small size test beds as well as on HPC scale facilities. The architecture of DAQ system and up to date performance results will be presented.

LHCb: LHCb High Level Trigger design issues for post Long Stop 1 running

CERN Multimedia

Albrecht, J; Raven, G; Sokoloff, M D; Williams, M

2013-01-01

The LHCb High Level Trigger uses two stages of software running on an Event Filter Farm (EFF) to select events for offline reconstruction and analysis. The first stage (Hlt1) processes approximately 1 MHz of events accepted by a hardware trigger. In 2012, the second stage (Hlt2) wrote 5 kHz to permanent storage for later processing. Following the LHC's Long Stop 1 (anticipated for 2015), the machine energy will increase from 8 TeV in the center-of-mass to 13 TeV and the cross sections for beauty and charm are expected to grow proportionately. We plan to increase the Hlt2 output to 12 kHz, some for immediate offline processing, some for later offline processing, and some ready for immediate analysis. By increasing the absolute computing power of the EFF, and buffering data for processing between machine fills, we should be able to significantly increase the efficiency for signal while improving signal-to-background ratios. In this poster we will present several strategies under consideration and some of th...

LHCb Computing Resource usage in 2017

CERN Document Server

Bozzi, Concezio

2018-01-01

This document reports the usage of computing resources by the LHCb collaboration during the period January 1st – December 31st 2017. The data in the following sections have been compiled from the EGI Accounting portal: https://accounting.egi.eu. For LHCb specific information, the data is taken from the DIRAC Accounting at the LHCb DIRAC Web portal: http://lhcb-portal-dirac.cern.ch.

Triple-GEM detectors for the innermost region of the muon apparatus at the LHCb experiment

CERN Document Server

Poli-Lener, M; Bencivenni, G

2005-01-01

The LHCb experiment will take place at the future LHC accelerator at CERN and will start in 2007. It is a single arm spectrometer to precision measurements of CP violation and rare decays in the b quark sector. Recent experimental results have shown that CP violation is large in this sector. LHCb is designed with a robust and flexible trigger in order to extensively gain access to a wide spread of different physical processes involving the beauty particles. This will allow to over-constrain the Standard Model predictions about $\\mathcal{CP}$ violation, and to discover any possible inconsistency, which would reveal the presence of ''New Physics''. The work presented in this thesis has two main parts: the development of a charged particle detector based on Gas Electron Multiplication (GEM) and the study of luminosity measurements with the physical channels $Z^{0} \\rightarrow \\mu^{+} \\mu^{-}$ and $W^{\\pm} \\rightarrow \\mu^{\\pm} \

A stand-alone track reconstruction algorithm for the scintillating fibre tracker at the LHCb upgrade

CERN Multimedia

Quagliani, Renato

2017-01-01

The LHCb upgrade detector project foresees the presence of a scintillating fiber tracker (SciFi) to be used during the LHC Run III, starting in 2020. The instantaneous luminosity will be increased up to $2\\times10^{33}$, five times larger than in Run II and a full software event reconstruction will be performed at the full bunch crossing rate by the trigger. The new running conditions, and the tighter timing constraints in the software trigger, represent a big challenge for track reconstruction. This poster presents the design and performance of a novel algorithm that has been developed to reconstruct track segments using solely hits from the SciFi. This algorithm is crucial for the reconstruction of tracks originating from long-lived particles such as $K_{S}^{0}$ and $\\Lambda$ and allows to greatly enhance the physics potential and capabilities of the LHCb upgrade when compared to its previous implementation.

COOL, LCG Conditions Database for the LHC Experiments Development and Deployment Status

CERN Document Server

Valassi, A; Clemencic, M; Pucciani, G; Schmidt, S A; Wache, M; CERN. Geneva. IT Department, DM

2009-01-01

The COOL project provides common software components and tools for the handling of the conditions data of the LHC experiments. It is part of the LCG Persistency Framework (PF), a broader project set up within the context of the LCG Application Area (AA) to devise common persistency solutions for the LHC experiments. COOL software development is the result of the collaboration between the CERN IT Department and ATLAS and LHCb, the two experiments that have chosen it as the basis of their conditions database infrastructure. COOL supports conditions data persistency using several relational technologies (Oracle, MySQL, SQLite and FroNTier), based on the CORAL Common Relational Abstraction Layer. For both experiments, Oracle is the backend used for the deployment of COOL database services at Tier0 and Tier1 sites of the LHC Computing Grid. While the development of new software functionalities is being frozen as LHC operations are ramping up, the main focus for the project in 2008 has shifted to performance optimi...

LHCb: Recent results on B and D decays from LHCb

CERN Multimedia

Obłakowska-Mucha, A

2014-01-01

The LHCb experiment has collected more than 3 fb$^{-1}$ of integrated luminosity in 2011 and 2012 and is producing a large amount of excellent results in beauty and charmed meson physics. An overview of the most recent results on rare B decays, CP violation, and charm physics will be given along with an outlook to the physics perspectives and to the LHCb upgrade.

Studies for the LHCb SciFi Tracker - Development of Modules from Scintillating Fibres and Tests of their Radiation Hardness

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00341158

The LHCb detector will see a major upgrade in the LHC long shutdown 2, which is planned for 2019/20. Among others, the tracking stations, currently realised as silicon strip and drift tube detectors, will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker is based on scintillating fibres with a diameter of $\\text 250 \\mu m$, read out by multichannel silicon photomultipliers. The two major challenges related to the fibres are the radiation damage of the light guidance and the production of precise multi-layer fibre mats. This thesis presents radiation hardness studies performed with protons at the tandem accelerator at Forschungszentrum Garching and in situ in the LHCb cavern. The obtained results are combined with additional data of the LHCb SciFi group and two different wavelength dependent models of the radiation induced attenuation are determined. These are used to simulate the relative light yield, for both models it drops to $83 \\%$ on average at the end of the nominal lifetime of ...

Contribution to the Inner Tracker design and penguin sensitivity studies for the measurement of sin 2 $\\beta$ in LHCb

CERN Document Server

Perrin, A

2008-01-01

LHCb is one of the four large experiments hosted at the Large Hadron Collider (LHC) at CERN in Geneva. It will start taking data in september 2008, and will then operate for several years. It consists of a single-arm forward spectrometer dedicated to precise measurements of CP violation and rare decays in the $B$ sector, with the aim of testing the Standard Model and possibly of discovering the first signatures of New Physics.Building such a large experiment as LHCb is a challenge, and many contributions are needed. The Lausanne lab is responsible for the design and the production of the Silicon Inner Tracker (IT) of LHCb. This detector is made of Silicon sensors which need to be cooled to avoid thermal runaway. We present here a contribution to the design of this sub-detector and a description of the production steps. In particular, a study of the cooling of the Inner Tracker is described. It is shown that the cooling abilities of the IT can avoid thermal runaway. CP violation in B meson decays was first obs...

Prospects for time-dependent asymmetries at LHCb

CERN Document Server

INSPIRE-00260500

2012-01-01

LHCb is already providing leading measurements of time-dependent CP asymmetries with 1 fb$^{-1}$ of data. With the LHCb detector, and further one with the LHCb upgrade, very high-precision time-dependent CP measurements are expected to stringently test the CKM paradigm and to the search for possible small NP effects. A review of the current precision and the prospects for these time-dependent quantities with the LHCb and LHCb upgraded detectors are summarised in this paper.

LHCb: W and Z production at LHCb

CERN Multimedia

Barter, W

2011-01-01

Preliminary results are presented for the production cross-sections of $Z^0$ and $W^{\\pm}$ production at the LHCb experiment. Also shown is the $W$ charge asymmetry as a function of lepton pseudo-rapidity. These measurements have particular interest because of the forward acceptance of the LHCb experiment, which covers pseudo-rapidities between approximately 2 and 5. The results may be interpreted as tests of the Standard Model, or can be used to constrain better the parton density functions. Prospects are given for improving these measurements in the forthcoming run, and for making complementary studies of Drell-Yan production to lower mass dilepton final states.

LHC Report: a very productive hiatus

CERN Document Server

Mike Lamont for the LHC team

2015-01-01

On Monday, 24 August, the LHC transitioned from nascent 25 ns operation to a two-week hiatus devoted to luminosity calibration (two days), machine development (five days) and a technical stop (five days).   No stopping for Sunday at the CERN Control Centre. (Image: Rogelio Tomás García) Accurate calibration of the luminosity is vital input for many of an experiment’s measurements. The luminosity is calibrated using separation scans pioneered in 1968 by Simon van der Meer at the ISR. In these scans, carefully prepared beams are stepped across each other, horizontally and vertically, one plane at a time. Accurate measurements of the interaction rates, beam intensity, beam movement during the scan and other factors allow determination of the absolute luminosity. ATLAS, ALICE, CMS and LHCb all had dedicated time for Van der Meer scans. TOTEM and ALFA also took advantage of the special conditions to take data. The LHC machine development (MD) period that followed consis...

LHCb: Statistical Comparison of CPU performance for LHCb applications on the Grid

CERN Multimedia

Graciani, R

2009-01-01

The usage of CPU resources by LHCb on the Grid id dominated by two different applications: Gauss and Brunel. Gauss the application doing the Monte Carlo simulation of proton-proton collisions. Brunel is the application responsible for the reconstruction of the signals recorded by the detector converting them into objects that can be used for later physics analysis of the data (tracks, clusters,…) Both applications are based on the Gaudi and LHCb software frameworks. Gauss uses Pythia and Geant as underlying libraries for the simulation of the collision and the later passage of the generated particles through the LHCb detector. While Brunel makes use of LHCb specific code to process the data from each sub-detector. Both applications are CPU bound. Large Monte Carlo productions or data reconstructions running on the Grid are an ideal benchmark to compare the performance of the different CPU models for each case. Since the processed events are only statistically comparable, only statistical comparison of the...

Optimization of the muon reconstruction algorithms for LHCb Run 2

CERN Document Server

Aaij, Roel; Dettori, Francesco; Dungs, Kevin; Lopes, Helder; Martinez Santos, Diego; Prisciandaro, Jessica; Sciascia, Barbara; Syropoulos, Vasileios; Stahl, Sascha; Vazquez Gomez, Ricardo

2017-01-01

The muon identification algorithm in the LHCb HLT software trigger and offline reconstruction has been revisited in view of the LHC Run 2. This software has undergone a significant refactorisation, resulting in a modularized common code base between the HLT and offline event processing. Because of the latter, the muon identification is now identical in HLT and offline. The HLT1 algorithm sequence has been updated given the new rate and timing constraints. Also, information from the TT subdetector is used in order to reduce ghost tracks and optimize for low $p_T$ muons. The current software is presented here together with performance studies showing improved efficiencies and reduced timing.

The LHCb magnet

CERN Multimedia

Maximilien Brice

2004-01-01

The LHCb magnet consists of two huge 27 tonne coils mounted inside a 1450 tonne iron yoke. As charged particles pass through the magnet's field their trajectories will be bent according to their momentum, allowing their momentum to be measured as they pass through the detector walls. LHCb will study bottom quarks, which will be produced close to the two colliding proton beams.

DIRAC reliable data management for LHCb

CERN Document Server

Smith, A C

2008-01-01

DIRAC, LHCb's Grid Workload and Data Management System, utilizes WLCG resources and middleware components to perform distributed computing tasks satisfying LHCb's Computing Model. The Data Management System (DMS) handles data transfer and data access within LHCb. Its scope ranges from the output of the LHCb Online system to Grid-enabled storage for all data types. It supports metadata for these files in replica and bookkeeping catalogues, allowing dataset selection and localization. The DMS controls the movement of files in a redundant fashion whilst providing utilities for accessing all metadata. To do these tasks effectively the DMS requires complete self integrity between its components and external physical storage. The DMS provides highly redundant management of all LHCb data to leverage available storage resources and to manage transient errors in underlying services. It provides data driven and reliable distribution of files as well as reliable job output upload, utilizing VO Boxes at LHCb Tier1 sites ...

Scintillating Fibre Tracker Front-End Electronics for LHCb upgrade

CERN Multimedia

Comerma, A

2014-01-01

The LHCb detector will be upgraded during the next LHC shutdown in 2018/19. The tracker system will undergo major changes. Its components will be replaced by new technologies in order to cope with the increased hit occupancy and the higher radiation dose. A detector made of scintillating fibres read out by silicon photomultipliers (SiPM) is envisaged for this upgrade. Even if this technology has proven to achieve high efficiency and spatial resolution, its integration within a LHC experiment bears new challenges. The detector will consist of 12 planes of 5 to 6 layers of 250μm fibres stacked covering a total area of 5x6m^2 . The desired spacial resolution on the reconstructed hit is 100μm. SiPMs have been adapted to the detector geometry reducing the dead area between channels. A total of 64 channels are arranged in a single die with common cathode connection and channel size of 0.23x1.32mm^2 . Two dies are packaged together with only 0.25mm of dead area between them. Radiation tolerance of such devices is ...

LHCb: LHCb Upstream Tracker

CERN Multimedia

Manning Jr, P; Stone, S

2014-01-01

The LHCb upgrade requires replacing the silicon strip tracker between the vertex locator and the magnet. A new design has been developed and tested based on the "stave" concept planned for the ATLAS upgrade. We will describe the new detector being constructed and show its improved performance in charged particle tracking and triggering.

LHCb: Parameterization of the LHCb magnetic field map

CERN Multimedia

Conti, G

2007-01-01

The LHCb warm magnet has been designed to provide an integrated field of 4 Tm for tracks coming from the primary vertex. To insure good momentum resolution of a few per mil, an accurate description of the magnetic field map is needed. This is achieved by combining the information from a TOSCA-based simulation and data from measurements. The paper presents the fit method applied to both the simulation and data to achieve the requirements. It also explains how the corresponding software tool is integrated in the LHCb Gaudi software and shows the relation with the environment in which it is used.

Electromagnetic dipole moments of charged baryons with bent crystals at the LHC

Energy Technology Data Exchange (ETDEWEB)

Bagli, E.; Bandiera, L.; Guidi, V.; Mazzolari, A. [Universita di Ferrara, Ferrara (Italy); INFN, Sezione di Ferrara (Italy); Cavoto, G. [' ' Sapienza' ' Universita di Roma, Rome (Italy); INFN, Sezione di Roma (Italy); Henry, L.; Martinez Vidal, F.; Ruiz Vidal, J. [IFIC, Universitat de Valencia-CSIC, Valencia (Spain); Marangotto, D. [Universita di Milano, Milan (Italy); INFN, Sezione di Milano (Italy); Merli, A.; Neri, N. [Universita di Milano, Milan (Italy); CERN, Geneva (Switzerland); INFN, Sezione di Milano (Italy)

2017-12-15

We propose a unique program of measurements of electric and magnetic dipole moments of charm, beauty and strange charged baryons at the LHC, based on the phenomenon of spin precession of channeled particles in bent crystals. Studies of crystal channeling and spin precession of positively- and negatively-charged particles are presented, along with feasibility studies and expected sensitivities for the proposed experiment using a layout based on the LHCb detector. (orig.)

LHCb: Fast Readout Control for the upgraded readout architecture of the LHCb experiment at CERN

CERN Multimedia

Alessio, F

2013-01-01

The LHCb experiment at CERN has proposed an upgrade towards a full 40 MHz readout system in order to run between five and ten times its initial design luminosity with an upgraded LHCb detector. As a consequence, the various LHCb sub-systems in the readout architecture will be upgraded to cope with higher sub-detector occupancies, higher rate, and higher readout load. The new architecture, new functionalities, and the first hardware implementation of a new LHCb Readout Control system (commonly referred to as S-TFC) for the upgraded LHCb experiment is here presented. Our attention is focused in describing solutions for the distribution of clock and timing information to control the entire upgraded readout architecture by profiting of a bidirectional optical network and powerful FPGAs, including a real-time mechanism to synchronize the entire system. Solutions and implementations are presented, together with first results on the simulation and the validation of the system.

The LHCb Starterkit initiative

CERN Document Server

Puig Navarro, Albert

2017-01-01

The vast majority of high-energy physicists use and produce software every day. Software skills are usually acquired on the go and dedicated training courses are rare. The LHCb Starterkit is a new training format for getting LHCb collaborators started in effectively using software to perform their research. The initiative, combining courses and online tutorials, focuses on teaching basic skills for research computing, as well as LHCb software specifics. Unlike traditional tutorials we focus on starting with basics, performing all the material live, with a high degree of interactivity, giving priority to understanding the tools as opposed to handing out recipes that work “as if by magic”. The LHCb Starterkit was started by young members of the collaboration inspired by the principles of Software Carpentry, and the material is created in a collaborative fashion using the tools we teach. Three successful entry-level workshops, as well as two advanced ones, have taken place since the start of the initiative i...

The LHCb Grid Simulation

CERN Multimedia

Baranov, Alexander

2016-01-01

The LHCb Grid access if based on the LHCbDirac system. It provides access to data and computational resources to researchers with different geographical locations. The Grid has a hierarchical topology with multiple sites distributed over the world. The sites differ from each other by their number of CPUs, amount of disk storage and connection bandwidth. These parameters are essential for the Grid work. Moreover, job scheduling and data distribution strategy have a great impact on the grid performance. However, it is hard to choose an appropriate algorithm and strategies as they need a lot of time to be tested on the real grid. In this study, we describe the LHCb Grid simulator. The simulator reproduces the LHCb Grid structure with its sites and their number of CPUs, amount of disk storage and bandwidth connection. We demonstrate how well the simulator reproduces the grid work, show its advantages and limitations. We show how well the simulator reproduces job scheduling and network anomalies, consider methods ...

LHCb: Study of a solution with COTS for the LHCb calorimeter upgrade

CERN Multimedia

Abellan Beteta, C

2011-01-01

Since the end of the commissioning of LHCb in 2009 the detector has proven to work nicely even in high pile-up conditions and by the end of 2010 nominal instantaneous luminosity was reached. Data taking is expected to continue for 5 more years, aiming to accumulate an integrated luminosity of 5fb-1. Even if new physics is discovered at that time, it will be difficult to characterize it and it would be more profitable to upgrade the detector. The foreseen long shutdown offers an opportunity to upgrade the detector . As expressed in the Letter of Intend for the LHCb upgrade [1] the main objective of this enhancement is to have a 40MHz readout electronics to allow the use of a more flexible and efficient software-based triggering system. Moreover, after the shutdown, the instantaneous luminosity at the LHCb interaction point is expected to be multiplied by 5. From the point of view of the LHCb calorimeter changing the readout implies a change of the electronic boards. Also because of the luminosity increase and ...

Charm production and QCD analysis at HERA and LHC

International Nuclear Information System (INIS)

Zenaiev, O.

2017-02-01

This review is devoted to the study of charm production in ep and pp collisions. The total set of measurements obtained by the two collaborations H1 and ZEUS from HERA and their combination is outlined, as well as complementary data obtained by the LHCb collaboration at the LHC. After fitting the parton distribution functions the charm production cross sections are predicted within perturbative QCD at next-to-leading order using the fixed-flavour-number scheme. Agreement with the data is found. The combined HERA charm data are sensitive to the c-quark mass and enabled its accurate determination. The predictions crucially depend upon the knowledge of the gluon distribution function. It is shown that the shape of the gluon distribution based on the HERA data is considerably improved by adding the measurements from LHCb and applicable down to values x of about 10"-"6, where x is the proton momentum fraction carried by a parton.

Charm production and QCD analysis at HERA and LHC

Energy Technology Data Exchange (ETDEWEB)

Zenaiev, O.

2017-02-15

This review is devoted to the study of charm production in ep and pp collisions. The total set of measurements obtained by the two collaborations H1 and ZEUS from HERA and their combination is outlined, as well as complementary data obtained by the LHCb collaboration at the LHC. After fitting the parton distribution functions the charm production cross sections are predicted within perturbative QCD at next-to-leading order using the fixed-flavour-number scheme. Agreement with the data is found. The combined HERA charm data are sensitive to the c-quark mass and enabled its accurate determination. The predictions crucially depend upon the knowledge of the gluon distribution function. It is shown that the shape of the gluon distribution based on the HERA data is considerably improved by adding the measurements from LHCb and applicable down to values x of about 10{sup -6}, where x is the proton momentum fraction carried by a parton.

Charm production and QCD analysis at HERA and LHC

Energy Technology Data Exchange (ETDEWEB)

Zenaiev, O. [DESY, Hamburg (Germany)

2017-03-15

This review is devoted to the study of charm production in ep and pp collisions. The total set of measurements obtained by the two collaborations H1 and ZEUS from HERA and their combination is outlined, as well as complementary data obtained by the LHCb Collaboration at the LHC. After fitting the parton distribution functions the charm-production cross sections are predicted within perturbative QCD at next-to-leading order using the fixed-flavour-number scheme. Agreement with the data is found. The combined HERA charm data are sensitive to the c-quark mass and enabled its accurate determination. The predictions crucially depend upon the knowledge of the gluon distribution function. It is shown that the shape of the gluon distribution based on the HERA data is considerably improved by adding the measurements from LHCb and applicable down to values x of about 10{sup -6}, where x is the proton momentum fraction carried by a parton. (orig.)

DIRAC: reliable data management for LHCb

International Nuclear Information System (INIS)

Smith, A C; Tsaregorodtsev, A

2008-01-01

DIRAC, LHCb's Grid Workload and Data Management System, utilizes WLCG resources and middleware components to perform distributed computing tasks satisfying LHCb's Computing Model. The Data Management System (DMS) handles data transfer and data access within LHCb. Its scope ranges from the output of the LHCb Online system to Grid-enabled storage for all data types. It supports metadata for these files in replica and bookkeeping catalogues, allowing dataset selection and localization. The DMS controls the movement of files in a redundant fashion whilst providing utilities for accessing all metadata. To do these tasks effectively the DMS requires complete self integrity between its components and external physical storage. The DMS provides highly redundant management of all LHCb data to leverage available storage resources and to manage transient errors in underlying services. It provides data driven and reliable distribution of files as well as reliable job output upload, utilizing VO Boxes at LHCb Tier1 sites to prevent data loss. This paper presents several examples of mechanisms implemented in the DMS to increase reliability, availability and integrity, highlighting successful design choices and limitations discovered

LS1 Report: LHCb's early Christmas

CERN Multimedia

Katarina Anthony

2014-01-01

Accelerator chain up and running... CCC Operators back at their desks... all telltale signs of the start of Run 2! For the experiments, that means there are just a few short weeks left for them to prepare for beams. Over at LHCb, teams have kept ahead of the curve by focusing on new installations and improvements.   A delicate task: re-connecting the beam pipe in LHCb. From the primary detector services to the DAQ system to the high level trigger, November's injector test beams saw their way through a well-prepared LHCb experiment. “We set the transfer line tests as our deadline for the restart - the entire experiment had to be at nominal position and conditions,” says Eric Thomas, LHCb deputy Technical Coordinator and LHCb LS1 Project Coordinator. “Achieving this was a major milestone for the collaboration. If beam were to come tomorrow, we would be ready.” The injector tests gave the LHCb team a chance to synchronise their detectors, and to al...

LHCb: LHCb Distributed Computing Operations

CERN Multimedia

Stagni, F

2011-01-01

The proliferation of tools for monitoring both activities and infrastructure, together with the pressing need for prompt reaction in case of problems impacting data taking, data reconstruction, data reprocessing and user analysis brought to the need of better organizing the huge amount of information available. The monitoring system for the LHCb Grid Computing relies on many heterogeneous and independent sources of information offering different views for a better understanding of problems while an operations team and defined procedures have been put in place to handle them. This work summarizes the state-of-the-art of LHCb Grid operations emphasizing the reasons that brought to various choices and what are the tools currently in use to run our daily activities. We highlight the most common problems experienced across years of activities on the WLCG infrastructure, the services with their criticality, the procedures in place, the relevant metrics and the tools available and the ones still missing.

LHCb: A New Nightly Build System for LHCb

CERN Multimedia

Clemencic, M

2013-01-01

The nightly build system used so far by LHCb has been implemented as an extension on the system developed by CERN PH/SFT group (as presented at CHEP2010). Although this version has been working for many years, it has several limitations in terms of extensibility, management and ease of use, so that it was decided to develop a new version based on a continuous integration system. In this paper we describe a new implementation of the LHCb Nightly Build System based on the open source continuous integration system Jenkins and report on the experience on the configuration of a complex build workflow in Jenkins.

Detailed Performance of the Outer Tracker at LHCb

CERN Document Server

Tuning, N

2014-01-01

The LHCb Outer Tracker is a gaseous detector covering an area of 5x6m2 with 12 double layers of straw tubes. Based on data of the first LHC running period from 2010 to 2012, the performance in terms of the single hit resolution and efficiency are presented. Details on the ionization length and subtle effects regarding signal reflections and the subsequent time-walk correction are given. The efficiency to detect a hit in the central half of the straw is estimated to be 99.2%, and the position resolution is determined to be approximately 200 um, depending on the detailed implementation of the internal alignment of individual detector modules. The Outer Tracker received a dose in the hottest region corresponding to 0.12 C/cm, and no signs of gain deterioration or other ageing effects are observed.

Commissioning and Performance of the LHCb Silicon Tracker

CERN Multimedia

van Tilburg, J; Buechler, A; Bursche , A; Chiapolini, N; Elsaesser, C; Hangartner, V; Salzmann, C; Steiner, S; Steinkamp, O; Staumann, U; Tobin, M; Vollhardt, A; Bay, A; Bettler, M O; Blanc, F; Bressieux, J; Conti, G; Fave, V; Frei, R; Gauvin, N; Gonzalez, R; Haefeli, G; Hicheur, A; Keune, A; Luisier, J; Muresan, R; Nakada, T; Needham, M; Nicolas, L; Knecht, M; Perrin, A; Potterat, C; Schneider, O; Tran, M; Aquines Gutierrez, O; Bauer, C; Britsch, M; Hofmann, W; Maciuc, F; Schmelling, M; Voss, H; Adeva, B; Esperante, D; Fungueiriño Pazos, J; Gallas, A; Pazos-Alvarez, A; Pérez-Trigo, E; Pló Casasús, M; Rogríguez Pérez, P; Saborido, J; Vázquez, P; Iakovenko, V; Okhrimenko, O; Pugatch, V

2010-01-01

The LHCb Silicon Tracker is a silicon micro-strip detector with a sensitive area of 12 m$^2$ and a total of 272k readout channels. The Silicon Tracker consists of two parts that use different detector modules. The detector installation was completed by early summer 2008 and the commissioning without beam has reached its finals stage, successfully overcoming most of the encountered problems. Currently, the detector has more than 99% of the channels fully functioning. Commissioning with particles has started using beam-induced events from the LHC injection tests in 2008 and 2009. These events allowed initial studies of the detector performance. Especially, the detector modules could be aligned with an accuracy of about 20 $\\mu$m. Furthermore, with the first beam collisions that took place end of 2009 we could further study the performance and improve the alignment of the detector.

LHC Detector Vacuum System Consolidation for Long Shutdown 1 (LS1) in 2013-2014

CERN Document Server

Gallilee, M; Cruikshank, P; Gallagher, J; Garion, C; Jimenez, J M; Kersevan, R; Kos, H; Leduc, L; Lepeule, P; Provot, N; Rambeau, H; Veness, R

2012-01-01

The LHC has ventured into unchartered territory for Particle Physics accelerators. A dedicated consolidation program is required between 2013 and 2014 to ensure optimal physics performance. The experiments, ALICE, ATLAS, CMS, and LHCb, will utilise this shutdown, along with the gained experience of three years of physics running, to make optimisations to their detectors. New vacuum technologies have been developed for the experimental areas, to be integrated during this first phase shutdown. These technologies include bellows, vacuum chambers and ion pumps in aluminium, new beryllium vacuum chambers, and composite mechanical supports. An overview of this first phase consolidation program for the LHC experiments is presented.

Upstream Tracking and the Decay $B^{0} \\to K^{+}\\pi^{-}\\mu^{+}\\mu^{-}$ at the LHCb Experiment

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00388407; Serra, Nicola; Steinkamp, Olaf; Storaci, Barbara

The LHCb detector is a single-arm forward spectrometer covering the pseudorapidity range $2 < \\eta < 5$, designed to search for indirect evidence of New Physics in $C\\!P$ violation and rare decays of beauty and charm hadrons. The unique geometry takes advantage of the large $b$ and $c$ quark production in the forward region at the LHC. The detector includes a high granularity silicon-strip vertex detector, a silicon-strip detector upstream of the magnet and three stations of silicon-strip detectors and straw drift tubes downstream of the magnet. This thesis is divided into two main parts. The first part details the development of improved algorithms to perform track reconstruction using the sub-detectors upstream of the LHCb magnet. A novel idea to perform upstream tracking as an intermediate step of the track reconstruction sequence was investigated. The vast gains in tracking performance obtained when using upstream tracks led to the algorithm being adopted into the default reconstruction sequence for...

J/ψ production study at the LHCb experiment

International Nuclear Information System (INIS)

Qian, Wenbin

2010-09-01

The LHCb experiment is one of the four main experiments at the LHC. Dedicated to b physics studies, the primary goal of the LHCb experiment is to explore possible New Physics beyond the Standard Model through the studies of rare decays of charm and beauty-flavored hadrons and precision measurements of CP-violating observables. In this thesis, studies of J/ψ production at LHCb are presented based on fully-simulated Monte Carlo events generated at a center-of-mass energy of 14 TeV and a luminosity of 2*10 32 cm -2 s -1 . The study shows that 6.5*10 6 J/ψ events can be reconstructed in every pb -1 of data, with a mass resolution of 11 MeV/c 2 and a S/B ∼ 18 in a ±3σ mass window. With 0.79 pb -1 of data, we can achieve a 10% precision for majority of the bins. Possible systematic errors are estimated to be at the same level. The study also shows that the polarization of the J/ψ plays an important role in the cross-section determinations. It may contribute to a systematic uncertainty up to 30% in some p T and η bins. Such an effect can be well reduced once an analysis on the J/ψ polarization is performed simultaneously. The measurement of the polarization parameters will also help in the understanding of the J/ψ production mechanism. In order to reduce the amount of simulated data needed for the efficiency estimations, a method is developed to describe the 2-D efficiency by three parameters and all the errors except statistic errors from data will depend on the three parameters. As the real LHCb experiment has already collected 14 nb -1 of data, part of the J/ψ analysis can be performed. Around 3,000 J/ψ candidates are reconstructed with a mass resolution of 16 MeV/c 2 and a S/B ∼ 1 in a 3σ mass window. Based on the above sample, the cross sections as a function of p T are obtained. The preliminary cross section for J/ψ in the region p T belonging to [0, 9] GeV/c and y belonging to [2.5, 4] is (7.6 ± 0.3) μb where only the statistical error is quoted

Successful beam test of the SPS-to-LHC transfer line TI2

CERN Multimedia

2007-01-01

Image of the first beam spot on the last BTV screen traversed by the beam during the TI 2 test.At 12:03:47 on 28 October a beam passed down the 2.7 km of the new SPS-to-LHC transfer line TI 2 at the first attempt, to within some 50 m of the LHC tunnel. After initial tuning, a range of measurements was carried out with a low intensity proton beam and preliminary analyses look good. After the test, no increase in radiation levels was found in either the LHC or ALICE, and the zones were rapidly opened again for access. As from next year TI 2 will regularly transport a beam from the SPS to the LHC injection point of Ring 1, near Point 2 (ALICE). The TI 8 transfer line, which will bring particles from the SPS to the injection point in Ring 2, near Point 8 (LHCb), was commissioned successfully with low intensity beam in 2004. The two LHC injection lines have a combined length of 5.6 km and comprise some seven hundred warm magnets. While a...

Fast polycrystalline CdTe detectors for bunch-by-bunch luminosity monitoring in the LHC

CERN Document Server

Brambilla, A; Jolliot, M; Bravin, E

2008-01-01

The luminosity at the four interaction points of the Large Hadron Collider (LHC) must be continuously monitored in order to provide an adequate tool for the control and optimisation of beam parameters. Polycrystalline cadmium telluride (CdTe) detectors have previously been tested, showing their high potential to fulfil the requirements of luminosity measurement in the severe environment of the LHC interaction regions. Further, the large signal yield and the fast response time should allow bunch-by-bunch measurement of the luminosity at 40 MHz with high accuracy. Four luminosity monitors with two rows of five polycrystalline CdTe detectors each have been fabricated and will be installed at both sides of the low-luminosity interaction points ALICE and LHC-b. A detector housing was specially designed to meet the mechanical constraints in the LHC. A series of elementary CdTe detectors were fabricated and tested, of which 40 were selected for the luminosity monitors. A sensitivity of 104 electrons per minimum ioni...

A 40 MHz Bunch by Bunch Intensity Measurement for the CERN SPS and LHC

CERN Document Server

Jakob, H; Jones, R; Jensen, L

2003-01-01

A new acquisition system has been developed to allow the measurement of the individual intensity of each bunch in a 40MHz bunch train. Such a system will be used for the measurement of LHC type beams after extraction from the CERN-PS right through to the dump lines of the CERN-LHC. The method is based on integrating the analogue signal supplied by a Fast Beam Current Transformer at a frequency of 40MHz. This has been made possible with the use of a fast integration ASIC developed by the University of Clermont-Ferrand, France, for the LHC-b pre-shower detector. The output of the integrator is digitised using a 12-bit ADC and fed into a Digital Acquisition Board (DAB) that was originally developed by TRIUMF, Canada, for use in the LHC orbit system. A full system set-up was commissioned during 2002 in the CERN-SPS, and following its success will now be extended in 2003 to cover the PS to SPS transfer lines and the new TT40 LHC extraction channel.

LHCb: Exotic meson studies at LHCb

CERN Multimedia

Bressieux, Joël

2012-01-01

In this poster, we present the narrow $J/\\psi\\phi$ resonances X(4140) and X(4274) search as well as the X(3872) mass and productions cross-section measurements. These analysis have been done using pp collisions data collected at LHCb.

First Results of the LHC Collision Rate Monitors

CERN Document Server

Burger, S; Bart Pedersen, S; Boccardi, A; Dutriat, C; Miyamoto, R; Doolittle, L; Matis, H S; Placidi, M; Ratti, A; Stezelberger, T; Yaver, H

2011-01-01

The aim of CERN large hadron collider (LHC) is to collide protons and heavy ions with centre of mass energies up to 14 zTeV. In order to monitor and optimize the collision rates special detectors have been developed and installed around the four luminous interaction regions. Due to the different conditions at the high luminosity experiments (ATLAS and CMS) and the low luminosity experiments (ALICE and LHC-b) two very different types of monitors are used: a fast ionisation chamber (BRAN-A) and a Cd-Te solid state detector (BRAN-B respectively. Moreover, in order to cope with the low collision rates foreseen for the initial run, a third type of monitor, based on a simple scintillating pad, was installed in parallel with the BRAN-A (BRAN-P). This contribution illustrates the results obtained during the 2010 run with an outlook for 2011 and beyond.

Feasibility Studies for Quarkonium Production at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC)

International Nuclear Information System (INIS)

Hadjidakis, C.; Kikola, D.; Massacrier, L.; Trzeciak, B.; Lansberg, J. P.; Fleuret, F.; Shao, H.-S.

2015-01-01

Being used in the fixed-target mode, the multi-TeV LHC proton and lead beams allow for studies of heavy-flavour hadroproduction with unprecedented precision at backward rapidities, far negative Feynman-x, using conventional detection techniques. At the nominal LHC energies, quarkonia can be studied in detail in p+p, p+d, and p+A collisions at √(s_N_N)≃115 GeV and in Pb + p and Pb + A collisions at √(s_N_N)≃72 GeV with luminosities roughly equivalent to that of the collider mode that is up to 20 fb"−"1 yr"−"1 in p+p and p+d collisions, up to 0.6 fb"−"1 yr"−"1 in p+A collisions, and up to 10 nb"−"1 yr"−"1 in Pb + A collisions. In this paper, we assess the feasibility of such studies by performing fast simulations using the performance of a LHCb-like detector.

Feasibility studies for quarkonium production at a fixed-target experiment using the LHC proton and lead beams (AFTER@LHC)

CERN Document Server

Massacrier, L; Fleuret, F; Hadjidakis, C; Kikola, D; Lansberg, J P; Shao, H -S

2015-01-01

Used in the fixed-target mode, the multi-TeV LHC proton and lead beams allow for studies of heavy-flavour hadroproduction with unprecedented precision at backward rapidities - far negative Feyman-x - using conventional detection techniques. At the nominal LHC energies, quarkonia can be studies in detail in p+p, p+d and p+A collisions at sqrt(s_NN) ~ 115 GeV as well as in Pb+p and Pb+A collisions at sqrt(s_NN) ~ 72 GeV with luminosities roughly equivalent to that of the collider mode, i.e. up to 20 fb-1 yr-1 in p+p and p+d collisions, up to 0.6 fb-1 yr-1 in p+A collisions and up to 10 nb-1 yr-1 in Pb+A collisions. In this paper, we assess the feasibility of such studies by performing fast simulations using the performance of a LHCb-like detector.

LHCb: Hardware Data Injector

CERN Multimedia

Delord, V; Neufeld, N

2009-01-01

The LHCb High Level Trigger and Data Acquisition system selects about 2 kHz of events out of the 1 MHz of events, which have been selected previously by the first-level hardware trigger. The selected events are consolidated into files and then sent to permanent storage for subsequent analysis on the Grid. The goal of the upgrade of the LHCb readout is to lift the limitation to 1 MHz. This means speeding up the DAQ to 40 MHz. Such a DAQ system will certainly employ 10 Gigabit or technologies and might also need new networking protocols: a customized TCP or proprietary solutions. A test module is being presented, which integrates in the existing LHCb infrastructure. It is a 10-Gigabit traffic generator, flexible enough to generate LHCb's raw data packets using dummy data or simulated data. These data are seen as real data coming from sub-detectors by the DAQ. The implementation is based on an FPGA using 10 Gigabit Ethernet interface. This module is integrated in the experiment control system. The architecture, ...

The Front-End electronics for the LHCb scintillating fibres detector

CERN Document Server

Chanal, Hervé; Pillet, Nicolas

2014-01-01

The LHCb detector will be upgraded during the next LHC shutdown in 2018/19 [ 1 ]. The tracker system will have a major overhaul. Its components will be replaced with new technologies in order to cope with the increased hit occupancy and radiation environment. A detector made of scintillating fibres read out by silicon photomultipliers (SiPM) is studied for this upgrade. Even if this technology has proven to achieve high efficiency and spatial resolution, its integration within a LHC experiment bears new challenges. This detector will consist of 12 planes of 5 to 6 layers of 250 m m fibres with an area of 5 6 m 2 . It leads to a total of 500k SiPM channels which need to be read out at 40 MHz. This article gives an overview of the R&D; status of the readout board and the PACIFIC chip. The readout board is connected to the SiPM on one side and to the experiment data-acquisition, experimental control system and services on the other side. The PACIFIC chip is a 128-channels ASIC which can be connected to one 1...

LHCB : Exotic hadrons at LHCb

CERN Multimedia

Salazar De Paula, Leandro

2015-01-01

The latest years have seen a resurrection of interest in searches for exotic states motivated by tantalising observations by Belle and CDF. Using the data collected at pp collisions at 7 and 8 TeV by the LHCb experiment we present the unambiguous new observation of exotic charmonia hadrons produced in B decays.

The performance of SCT128A ASICs when reading out silicon sensors and a study of $B^{0}_{s}\\to D^{+-}_{s} \\pi^{-+}$ at LHCb

CERN Document Server

Charles, M J; Harnew, N

2003-01-01

LHCb is a future detector which will take data at the CERN Large Hadron Collider proton-proton collider. It is optimized for B physics and will make precision measurements of CP violation parameters and flavour mixing. Measurements of time-dependent asymmetries and decay rates require accurate reconstruction of the B meson production and decay vertices; this is achieved with a silicon microstrip VErtex LOcator (VELO). In this thesis, an overview of silicon strip detectors (SSDs) is given and the choice of sensor technology at LHCb justified. Data from beam tests in which prototype VELO SSDs were read out using SCT128A electronics are presented and analysed. The time response of the system is measured and the implications for LHC-speed readout are discussed. The effect of detector input capacitance is investigated. Measurements of the mass and width differences of the Bs mass eigenstates, Delta M_s and Delta Gamma_s, will be possible at LHCb. Recent theoretical predictions for these parameters are given and it...

LHCb-The LHCb trigger in Run II

CERN Multimedia

Michielin, Emanuele

2016-01-01

The LHCb trigger system has been upgraded to exploit the real-time alignment, calibration and analysis capabilities of LHCb in Run-II. An increase in the CPU and disk capacity of the event filter farm, combined with improvements to the reconstruction software, mean that efficient, exclusive selections can be made in the first stage of the High Level Trigger (HLT1). The output of HLT1 is buffered to the 5 PB of disk on the event filter farm, while the detector is aligned and calibrated in real time. The second stage, HLT2, performs complete, offline quality, event reconstruction. Physics analyses can be performed directly on this information, and for the majority of charm physics selections, a reduced event format can be written out, which permits higher event rates.

LHCb: Measurement of the polarization amplitudes of the decay $B^0 \\rightarrow J/\\psi K^\\ast$

CERN Multimedia

Linn, C

2011-01-01

Using the data sample recorded with the LHCb detector in 2010 we perform a combined angular and lifetime analysis of the decay $B^0 \\rightarrow J/\\psi K^\\ast$. The data corresponds to an integrated luminosity of about 36 pb$^{-1}$ and was taken at the LHC at an centre-of-mass energy of $\\sqrt{s}$= 7 TeV. A total of 3909 $J/\\psi K^*$ candidates are found and are used to extract the polarisation amplitudes and the corresponding strong phases for the decays $B_d \\rightarrow J/\\psi K^\\ast$.

Monitoring the LHCb data quality system

CERN Multimedia

Baranov, Alexander

2016-01-01

Monitoring the quality of the data, DQM, is crucial in a high-energy physics experiment to ensure the correct functioning of the apparatus during the data taking. DQM at LHCb is carried out in two phase. The first one is performed on-site, in real time, using unprocessed data directly from the LHCb detector, while the second, also performed on-site, requires the reconstruction of the data selected by the LHCb trigger system and occurs with some delay. For the Run II data taking the LHCb collaboration has re-engineered the DQM protocols and the DQM graphical interface, moving the latter to a web-based monitoring system, called Monet, thus allowing researchers to perform the second phase off-site. In order to support the operator's task, Monet is also equipped with an automated, fully configurable, alarm system, thus allowing its use not only for DQM purposes, but also to track and assess the quality of LHCb software and simulation.

Build your own tiny Lego LHC

CERN Multimedia

Abha Eli Phoboo

2015-01-01

A PhD student working on the ATLAS experiment has created a replica of the Large Hadron Collider using Lego building blocks. Nathan Readioff, from the University of Liverpool (see here), submitted his design to Lego Ideas (see here) this week and is now awaiting the 10,000 votes needed for it to qualify for the Lego Review, which decides if projects become new Lego products. You can help this project, vote online now!   A computer simulation of the miniature Lego LHC, complete with four detectors connected with blue dipole magnets. His Lego design is a stylised model of the LHC, showcasing the four main detectors ALICE, ATLAS, CMS and LHCb at the micro scale. Each detector is small enough to fit in the palm of your hand, yet the details of the internal systems are intricate, revealed by cutaway walls. Every major detector component is represented by a Lego piece. The models are not strictly to scale with one another, but the same size base is used for each one to maximise the detail that can...

ReDecay, a method to re-use the underlying events to speed up the simulation in LHCb

CERN Multimedia

Muller, Dominik

2017-01-01

With the steady increase in the precision of flavour physics measurements collected during LHC Run 2, the LHCb experiment requires simulated data samples of ever increasing magnitude to study the detector response in detail. However, relying on an increase of available computing power for the production of simulated events will not suffice to achieve this goal. The simulation of the detector response is the main contribution to the time needed to generate a sample, that scales linearly with the particles multiplicity of the event. Of the dozens of particles present in the simulation only a few, namely those participating in the studied signal decay, are of particular interest, while all remaining ones, the so-called underlying event, mainly affect the resolution and efficiencies of the detector. This talk presents a novel development for the LHCb simulation software which re-uses the underlying event from previously simulated events. This approach achieves an order of magnitude increase in speed and the same ...

Implementing database system for LHCb publications page

CERN Document Server

Abdullayev, Fakhriddin

2017-01-01

The LHCb is one of the main detectors of Large Hadron Collider, where physicists and scientists work together on high precision measurements of matter-antimatter asymmetries and searches for rare and forbidden decays, with the aim of discovering new and unexpected forces. The work does not only consist of analyzing data collected from experiments but also in publishing the results of those analyses. The LHCb publications are gathered on LHCb publications page to maximize their availability to both LHCb members and to the high energy community. In this project a new database system was implemented for LHCb publications page. This will help to improve access to research papers for scientists and better integration with current CERN library website and others.

Characterisation of the Photon Detection System for the LHCb RICH Detector Upgrade

CERN Document Server

AUTHOR|(CDS)2097582; D'Ambrosio, Carmelo; Easo, Sajan

The LHCb Experiment will be upgraded during Long Shutdown II of the Large Hadron Collider (LHC) in 2019 and 2020. The goal of the upgrade is to efficiently use the increased instantaneous luminosity in LHC Run 3 and to collect data at the proton collision rate of 40 MHz. The Ring Imaging Cherenkov (RICH) particle identification detectors will be upgraded to perform in the new operating conditions with continuing reliability. The photon detection system will be replaced using multi-anode photomultiplier tubes (MaPMTs) and associated read-out electronics. The photon detection chain was studied at CERN using a pulsed laser to test the system under high event rates and high photon intensities. The behaviour of two types of MaPMTs which are foreseen for the upgrade is presented for varying rates and intensities, and different applied bias voltages. A simulation was created to model the photon detection chain using the Geant4 simulation toolkit. The RICH Upgrade test beam using 180 GeV positive hadrons from CERN SP...

arXiv Electromagnetic dipole moments of charged baryons with bent crystals at the LHC

CERN Document Server

Bagli, E.; Cavoto, G.; Guidi, V.; Henry, L.; Marangotto, D.; Martinez Vidal, F.; Mazzolari, A.; Merli, A.; Neri, N.; Ruiz Vidal, J.

2017-12-05

We propose a unique program of measurements of electric and magnetic dipole moments of charm, beauty and strange charged baryons at the LHC, based on the phenomenon of spin precession of channeled particles in bent crystals. Studies of crystal channeling and spin precession of positively- and negatively-charged particles are presented, along with feasibility studies and expected sensitivities for the proposed experiment using a layout based on the LHCb detector.

The LHCb Starterkit

Science.gov (United States)

Puig, Albert; LHCb Starterkit Team

2017-10-01

The vast majority of high-energy physicists use and produce software every day. Software skills are usually acquired “on the go” and dedicated training courses are rare. The LHCb Starterkit is a new training format for getting LHCb collaborators started in effectively using software to perform their research. The course focuses on teaching basic skills for research computing. Unlike traditional tutorials we focus on starting with basics, performing all the material live, with a high degree of interactivity, giving priority to understanding the tools as opposed to handing out recipes that work “as if by magic”. The LHCb Starterkit was started by two young members of the collaboration inspired by the principles of Software Carpentry, and the material is created in a collaborative fashion using the tools we teach. Three successful entry-level workshops, as well as an advance one, have taken place since the start of the initiative in 2015, and were taught largely by PhD students to other PhD students.

LHCb: Optimization and Calibration of Flavour Tagging Algorithms for the LHCb experiment

CERN Multimedia

Falabella, A

2013-01-01

The LHCb purposes are to make precise measurements in $B$ and $D$ meson decays. In particular in time-dependent CP violation studies the determination of $B$ flavour at production ("Flavour Tagging") is fundamental. The performances and calibration of the flavour tagging algorithms with 2011 data collected by LHCb are reported. The performances of the flavour tagging algorithms on the relevant CP violation and asymmetry studies are also reported.

Système de PLC pour la supervision de la distribution basse tension des expériences ALICE et LHCb

CERN Document Server

Burdet, G

2004-01-01

Le groupe TS/EL étudie et réalise la distribution électrique basse tension pour alimenter les racks contenant l'électronique associée aux détecteurs dans les zones expérimentales du LHC. La distribution basse tension utilisera des tableaux récupérés des expériences du LEP pour ALICE et LHCb et un système basé sur des gaines CANALIS pour ATLAS et CMS. L'ensemble de la distribution électrique basse tension sera surveillée et contrôlée par l'intermédiaire de systèmes à base de PLC. Ce papier décrit l'infrastructure de supervision proposée pour ALICE et LHCb et son intégration au CERN Electrical Network Supervisor (ENS) et au Detector Control System (DCS).

Test of lepton flavour universality using hadronic tau decays with the LHCb detector

CERN Document Server

Arbouch, Emmanuel

The goal of this internship was to realize a preliminary study on the measurement of the R(D ∗ ) parameter, defined as the ratio between the two branching frac- tions R(D ∗ ) ≡ B(B 0 → D ∗− τ + ν τ )/B(B 0 → D ∗− μ + ν μ ), using the τ + → π + π − π + ν τ hadronic decays recorded by the LHCb detector. The world average on the mea- surements done so far shows a discrepancy of 3.4 standard deviations with respect to the Standard Model prediction. This points towards Lepton Flavor Universality Violation and needs to be investigated further. So far, the Run 2 (2015-2018) data had never been exploited for the measurement of R(D ∗ ) and a first look was made during this internship. Between Run 1 (2011-2012) and Run 2, the LHC center-of- mass energy increased and the LHCb trigger was improved. Lower statistical error is expected on measurements performed on Run 2 data. The gain in performance due to the improved trigger is evaluated to be 15.3%. Finally, the gain factor...

The LHC experiment control system: on the path to full automation

International Nuclear Information System (INIS)

Gaspar, C.; Alessio, F.; Cardoso, L.; Frank, M.; Garnier, J.C.; Herwijnen, E.V.; Jacobsson, R.; Jost, B.; Neufeld, N.; Schwemmer, R.; Callot, O.; Franek, B.

2012-01-01

LHCb is a large experiment at the LHC accelerator. The experiment control system is in charge of the configuration, control and monitoring of the different sub-detectors and of all areas of the online system. The building blocks of the control system are based on the PVSS SCADA System complemented by a control Framework developed in common for the 4 LHC experiments. This framework includes an 'expert system' like tool called SMI++ which is used for the system automation. The experiment's operations are now almost completely automated, driven by a top-level object called Big-Brother, which pilots all the experiment's standard procedures and the most common error-recovery procedures. The architecture, tools and mechanisms used for the implementation as well as some operational examples will be described. (authors)

Status and prospects for strange physics at LHCb

CERN Multimedia

CERN. Geneva

2016-01-01

Rare decays are fundamental probes of physics beyond the Standard Model. We present the current status of rare decays studies at the LHCb experiment and discuss a possible picture emerging from these measurements. The expanding LHCb program of strange physics, in particular of their rare decays, provides a unique and complementary probe to test the SM with respect to the beauty and charm. We present recent results on rare strange hadrons decays exploiting the LHCb Run I data. We then present prospects for strange physics with the LHCb Run II data and after the improvements in the trigger for the LHCb Upgrade.

Supersymmetry and Dark Matter in Light of LHC 2010 and Xenon100 Data

CERN Document Server

Buchmueller, O.; Colling, D.; De Roeck, A.; Dolan, M.J.; Ellis, J.R.; Flacher, H.; Heinemeyer, S.; Isidori, G.; Santos, D.Martinez; Olive, K.A.; Rogerson, S.; Ronga, F.J.; Weiglein, G.

2011-01-01

We make frequentist analyses of the CMSSM, NUHM1, VCMSSM and mSUGRA parameter spaces taking into account all the public results of searches for supersymmetry using data from the 2010 LHC run and the Xenon100 direct search for dark matter scattering. The LHC data set includes ATLAS and CMS searches for jets + ETslash events (with or without leptons) and for the heavier MSSM Higgs bosons, and the upper limit on bs to mu mu including data from LHCb as well as CDF and D0. The absences of signals in the LHC data favour somewhat heavier mass spectra than in our previous analyses of the CMSSM, NUHM1 and VCMSSM, and somewhat smaller dark matter scattering cross sections, all close to or within the pre-LHC 68% CL ranges, but do not impact significantly the favoured regions of the mSUGRA parameter space. We also discuss the impact of the Xenon100 constraint on spin-independent dark matter scattering, stressing the importance of taking into account the uncertainty in the pi-nucleon sigma term, that affects the spin-inde...

LHC Report: the machine - on the level

CERN Multimedia

Mike Lamont for the LHC Team

2011-01-01

The LHC has held the number of bunches per beam at 1092 over the last couple of weeks and has been delivering luminosity to the experiments at a healthy rate. The integrated luminosity total has already passed 1 inverse femtobarn (fb-1), which was the overall goal for the year. There was a modest celebration in the CCC to mark the occasion. Modest celebrations are now on hold until the end of this year's run or the delivery of 5 fb-1.   LHCb is designed to perform different types of physics searches from those at ATLAS and CMS, and is limited to a peak luminosity of about 3x1032 cm-2s-1. If the beams were to be collided head-on in the LHCb detector, this figure would be exceeded. Therefore the beams are initially separated by a few microns in the vertical plane and then, as the beam intensity decays during a fill, this separation is gently reduced to keep the luminosity constant at the acceptable maximum. This technique is known as 'luminosity levelling' and has been used successfully to deliver ...

The Fire Brigade is training for the LHC

CERN Multimedia

2007-01-01

Rescue exercise at Point 8: the CERN Fire Brigade works to save a virtual victim trapped under scaffolding in the LHCb cavern.The CERN Fire Brigade really is unique. Its mission is made even more difficult by the fact that it must be capable of responding to situations underground, in many kilometres of tunnels and dozens of shafts. These specialist skills have to be honed in preparation for LHC commissioning. With a view to meeting these requirements, the "Preparing for the LHC" training course was held for the second time on 23 and 24 May. "The aim of the course is to allow the Fire Brigade to familiarise itself with and use all the resources available in the event of a problem in the tunnel", explains Gilles Colin, who is in charge of training for the CERN Fire Brigade. The two-day programme is designed to train fire Brigade members in the techniques used to free and release trapped victims. Through a series of theoretical sess...

Performance of the LHCb Vertex Locator

CERN Document Server

Aaij, R.; Akiba, K.; Alexander, M.; Ali, S.; Appleby, R.B.; Artuso, M.; Bates, A.; Bay, A.; Behrendt, O.; Benton, J.; van Beuzekom, M.; Bjornstad, P.M.; Bogdanova, G.; Borghi, S.; Borgia, A.; Bowcock, T.J.V.; van den Brand, J.; Brown, H.; Buytaert, J.; Callot, O.; Carroll, J.; Casse, G.; Collins, P.; De Capua, S.; Doets, M.; Donleavy, S.; Dossett, D.; Dumps, R.; Eckstein, D.; Eklund, L.; Farinelli, C.; Farry, S.; Ferro-Luzzi, M.; Frei, R.; Garofoli, J.; Gersabeck, M.; Gershon, T.; Gong, A.; Gong, H.; Gordon, H.; Haefeli, G.; Harrison, J.; Heijne, V.; Hennessy, K.; Hulsbergen, W.; Huse, T.; Hutchcroft, D.; Jaeger, A.; Jalocha, P.; Jans, E.; John, M.; Keaveney, J.; Ketel, T.; Korolev, M.; Kraan, M.; Lastovicka, T.; Lafferty, G.; Latham, T.; Lefeuvre, G.; Leflat, A.; Liles, M.; van Lysebetten, A.; MacGregor, G.; Marinho, F.; McNulty, R.; Merkin, M.; Moran, D.; Mountain, R.; Mous, I.; Mylroie-Smith, J.; Needham, M.; Nikitin, N.; Noor, A.; Oblakowska-Mucha, A.; Papadelis, A.; Pappagallo, M.; Parkes, C.; Patel, G.D.; Rakotomiaramanana, B.; Redford, S.; Reid, M.; Rinnert, K.; Rodrigues, E.; Saavedra, A.F.; Schiller, M.; Schneider, O.; Shears, T.; Silva Coutinho, R.; Smith, N.A.; Szumlak, T.; Thomas, C.; van Tilburg, J.; Tobin, M.; Velthuis, J.; Verlaat, B.; Viret, S.; Volkov, V.; Wallace, C.; Wang, J.; Webber, A.; Whitehead, M.; Zverev, E.

2014-01-01

The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stability of these characteristic features of the detector are described, and details of the material budget are given. The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described. The system performance is fully characterised. The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 microns is achieved at the optimal track angle. The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 0.5%, and the detector has less than 1% of faulty strips. The proximity of the detector to the beam means ...

User analysis of LHCb data with Ganga

International Nuclear Information System (INIS)

Maier, Andrew; Gaidioz, Benjamin; Moscicki, Jakub; Muraru, Adrian; Ster, Daniel van der; Brochu, Frederic; Cowan, Greg; Egede, Ulrik; Reece, Will; Williams, Mike; Elmsheuser, Johannes; Harrison, Karl; Slater, Mark; Tan, Chun Lik; Lee, Hurng-Chun; Liko, Dietrich; Pajchel, Katarina; Samset, Bjoern; Soroko, Alexander

2010-01-01

GANGA (http://cern.ch/ganga) is a job-management tool that offers a simple, efficient and consistent user analysis tool in a variety of heterogeneous environments: from local clusters to global Grid systems. Experiment specific plug-ins allow GANGA to be customised for each experiment. For LHCb users GANGA is the officially supported and advertised tool for job submission to the Grid. The LHCb specific plug-ins allow support for end-to-end analysis helping the user to perform his complete analysis with the help of GANGA. This starts with the support for data selection, where a user can select data sets from the LHCb Bookkeeping system. Next comes the set up for large analysis jobs: with tailored plug-ins for the LHCb core software, jobs can be managed by the splitting of these analysis jobs with the subsequent merging of the resulting files. Furthermore, GANGA offers support for Toy Monte-Carlos to help the user tune their analysis. In addition to describing the GANGA architecture, typical usage patterns within LHCb and experience with the updated LHCb DIRAC workload management system are presented.

Etude des désintégrations $\\boldsymbol{B^0_{(s)}\\to\\bar{D}^0 K^+ K^-}$ et des sous-modes $\\boldsymbol{B^0_{(s)}\\to \\bar{D}^{(*)0}\\phi}$ avec le détecteur LHCb

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00389141; T'Jampens, Stéphane

L'expérience LHCb a été conçue pour étudier la physique des saveurs, dont entre autre la violation de CP, sur le collisioneur proton-proton LHC. La première phase de fonctionnement du LHC a durée de 2011 à 2012, ce qui a permis à LHCb de collecter $3.19~\\mathrm{fb}^{-1}$ de données à une énergie dans le centre de masse des collisions de $\\sqrt{s} = 7~TeV$ et $\\sqrt{s} = 8~TeV$. L'analyse présentée dans cette thèse est basée sur l'ensemble des données collectées par LHCb lors de la première phase de fonctionnement (2011-2012). Le mécanisme de Cabibbo-Kobayashi-Maskawa (CKM) est le mécanisme décrivant les transitions entre les différentes familles de quarks et la violation de CP dans le cadre du Modèle Standard. Les expériences de la décennie précédente dédiées à la physique des saveurs, BaBar et Belle, ont permis de démontrer le fonctionnement du mécanisme CKM et qu'il est majoritairement standard. A présent LHCb a pour objectif de mesurer avec précision les paramètres de ce...

LHCbDIRAC as Apache Mesos microservices

OpenAIRE

Haen, Christophe; Couturier, Benjamin

2017-01-01

The LHCb experiment relies on LHCbDIRAC, an extension of DIRAC, to drive its offline computing. This middleware provides a development framework and a complete set of components for building distributed computing systems. These components are currently installed and run on virtual machines (VM) or bare metal hardware. Due to the increased workload, high availability is becoming more and more important for the LHCbDIRAC services, and the current installation model is showing its limitations. A...

LHCb: A new Readout Control system for the LHCb Upgrade

CERN Multimedia

Alessio, F

2012-01-01

The LHCb experiment has proposed an upgrade towards a full 40 MHz readout system in order to run between five and ten times its initial design luminosity. The entire readout architecture will be upgraded in order to cope with higher sub-detector occupancies, higher rate and higher network load. In this paper, we describe the architecture, functionalities and the first hardware implementation of a new Readout Control system for the LHCb upgrade. The system is based on FPGAs and bi-directional links for the control of the entire readout architecture. First results on the validation of the system are also given.

Precision luminosity measurement at LHCb with beam-gas imaging

International Nuclear Information System (INIS)

Barschel, Colin

2014-01-01

The luminosity is the physical quantity which relates the cross-section to the production rate in collider experiments. The cross-section being the particle physics observable of interest, a precise determination of the luminosity is required. This work presents the absolute luminosity calibration results performed at the Large Hadron Collider beauty (LHCb) experiment at CERN using a novel method based on beam-gas interactions with data acquired at a center of mass energy √(s)=8 TeV and √(s)=2.76 TeV. Reconstructed beam-gas interaction vertices in LHCb are used to measure the beam profiles, thus making it possible to determine the beams overlap integral. An important element of this work was to install and use a neon gas injection system to increase the beam-gas interaction rate. The precision reached with the beam-gas imaging method relies on the two-dimensional beam shape determination developed in this work. For such precision, the interaction vertex resolution is an important ingredient. Therefore, a new method has been developed using all reconstructed vertices in order to improve the understanding of the vertex resolution. In addition to the overlap integral, the knowledge of the colliding bunch populations is required to measure the luminosity. The determination of the bunch populations relies on LHC instruments to measure the bunch population fractions and the total beam intensity. Studies performed as part of this work resulted in a reduction of the bunch current normalization uncertainty from ±2.7% to ±0.2% and making it possible to achieve precision luminosity measurements at all LHC experiments. Furthermore, information on beam-gas interactions not originating from nominally filled bunches was analyzed to determine the charge fraction not participating in bunch collisions. The knowledge of this fraction is required to correct the total beam intensity. The reference cross-section of pp interactions with at least two tracks in the vertex detector

LHCb : Behaviour of Multi-anode Photomultipliers in Magnetic Fields for the LHCb RICH Upgrde

CERN Multimedia

Gambetta, Silvia

2015-01-01

A key feature of the LHCb upgrade, scheduled for 2019, is to remove the first level trigger and its data reduction from 40MHz to 1MHz, which is implemented in the on-detector readout electronics. The consequence for the LHCb Ring Imaging Cherenkov (RICH) detectors is that the Hybrid Photon Detectors need to be replaced as the readout chip is inside the detector vacuum. The baseline for replacement are Multianode Photomultiplier tubes (MaPMT) and new readout electronics. The MaPMTs will be located in the fringe field of the LHCb dipole magnet with residual fields up to 25 G. Therefore, their behaviour in magnetic fields is critical. Here we report about studies of the Hamamatsu models R11265 and H12700 in a magnetic field in an effort to qualify them for use in the LHCb RICH upgrade. Comparisons to the known model R7600 are also made. Measurements of the collection efficiency and gain were performed for all three space directions as a function of the magnetic field strength. In addition to measurements with ba...

Measurement of antiproton production in $p$–He collisions at LHCb to constrain the secondary cosmic antiproton flux

CERN Document Server

Graziani, Giacomo

2018-01-01

The flux of cosmic ray antiprotons is a powerful tool for indirect detection of dark matter. The sensitivity is limited by the uncertainty on the predicted antiproton flux from scattering of primary rays on the interstellar medium. This is, in turn, limited by the knowledge of production cross-sections, notably in p–He scattering. Thanks to its internal gas target, the LHCb experiment performed the first measurement of antiproton production from collisions of LHC proton beams on He nuclei at rest. The results and prospects are presented.

Exclusive photoproduction of Upsilon in pPb collisions at LHC energies

International Nuclear Information System (INIS)

Dutta, Dipanwita; Chudasama, Ruchi; Mohanty, A.K.

2014-01-01

Recent results of exclusive photoproduction of heavy vector mesons at LHC energies by ALICE and LHCb in pp, pPb and PbPb Ultraperipheral collisions (UPC) confirmed the expectations that UPCs are a very promising probe to study the gluon distributions in nucleons and in nuclei at small x. In this work, we have estimated the photoproduction of γ in pPb collisions at √s NN = 5.02 TeV in the framework of perturbative two-gluon exchange formalism employing various parametrization of gluon distributions functions

LHCb: Electroweak studies at LHCb

CERN Multimedia

Salustino Guimaraes, V

2012-01-01

Results on the measurement of the $W^{\\pm}$ and $Z^{0}$ cross-sections are presented using final state leptons with pseudorapidities between 2 and 4.5. Due to its acceptance, LHCb can probe a regime of low low-x electroweak boson production, where parton distribution functions are not well constrained. We summarize the $W^{\\pm}$ measurements performed in the decay $\\mu^{\\pm}\

Pancake day comes early for LHCb

CERN Multimedia

2003-01-01

The assembly of LHCb has begun! The two coils of the LHCb magnet arrived and were lowered into the underground experimental area during the arctic conditions of Epiphany week. Deliveries for the yoke continue.

The GEM detectors for the innermost region of the forward muon station of the LHCb experiment

CERN Document Server

Alfonsi, M

The LHCb experiment will take place at the LHC accelerator at CERN and will start in 2008. It is dedicated to precision measurements of CP violation and rare decays in the b quark sec- tor. The apparatus is a single arm spectrometer and it is designed with a robust and flexible trigger in order to extensively gain access to a wide spread of differ ent physical processes involving beauty particles. This will allow to over-constrain the Standard M odel predictions about CP violation, and to discover any possible inconsistency, whi ch would reveal the presence of “New Physics” beyond the Standard Model. This thesis reports the work performed on two aspects of the L HCb experiment: the main contribution is the development and the construction of a de tector based on Gas Electron Multiplier (GEM) technology for the instrumentation of the high irradiated region around the beam pipe of the forward Muon Station; in the second part t he possibility of the search of the rare D 0 → + − decay at the LHCb exper...

A measurement of $\\sigma \\left( Z \\rightarrow \\mu \\mu \\right)$ using the LHCb detector at CERN

CERN Document Server

Hicks, Emma; Shears, Tara

LHCb is one of four main experiments at the LHC in CERN. This thesis analyses 1.03 fb$^{-1}$ of $\\sqrt{s} = 7$ TeV data collected in 2011. Measurements of the $Z\\rightarrow\\mu\\mu$ cross-section and a differential measurement with respect to $Z$ boson rapidity are presented. The primary motivations for making these measurements are to probe the accuracy of the Standard Model and constrain theoretical parton distribution functions. Final state radiation causes a downward shift in the reconstructed dimuon invariant mass and broadening in the peak. Reconstructing the radiated photon means the invariant mass distribution shift can be corrected for. Here final state radiation is implemented in LHCb simulation for the first time. It is used to study the effect on the reconstructed $Z$ mass distribution. Selections are placed on the distance between the photon and muon, and the photon $P_T$. The distribution is fitted to be 12% narrower than the non-reconstructed sample. The measured mass of the $Z$ boson is increase...

Studies for the LHCb SciFi tracker. Development of modules from scintillating fibres and tests of their radiation hardness

Energy Technology Data Exchange (ETDEWEB)

Ekelhof, Robert Jan

2016-05-18

The LHCb detector will see a major upgrade in the LHC long shutdown 2, which is planned for 2019/20. Among others, the tracking stations, currently realised as silicon strip and drift tube detectors, will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker is based on scintillating fibres with a diameter of 250 μm, read out by multichannel silicon photomultipliers. The two major challenges related to the fibres are the radiation damage of the light guidance and the production of precise multi-layer fibre mats. This thesis presents radiation hardness studies performed with protons at the tandem accelerator at Forschungszentrum Garching and in situ in the LHCb cavern. The obtained results are combined with additional data of the LHCb SciFi group and two different wavelength dependent models of the radiation induced attenuation are determined. These are used to simulate the relative light yield, for both models it drops to 83% on average at the end of the nominal lifetime of the SciFi Tracker. A machine and techniques to produce multi-layer fibre mats were developed and optimised. Procedures for the production and alignment are described. These are implemented in the serial production of the SciFi modules which will start in the second quarter 2016.

Constraints on Mixing and CP-Violation in the Neutral Charmed Meson System at LHCb

CERN Document Server

Alexander, Michael Thomas; Soler, P

This thesis presents measurements of the charm sector mixing and CP-violation parameters yCP and AGamma, made using data collected in 2010 by the LHCb experiment at the LHC at a centre of mass energy of 7 TeV. yCP is defined as the difference from unity of the ratio of the effective lifetime of the D0 meson decaying to a CP-undefined final state to its lifetime when decaying to a CP-eigenstate. AGamma is the CP-asymmetry of the effective lifetimes of the D0 and D0bar when decaying to a CP-eigenstate. In the absence of CPV yCP will be consistent with the mixing parameter y, and AGamma will be consistent with zero. CP-violation in the charm sector is predicted to be very small in the SM, though first evidence for direct CP-violation in D0 decays has recently been observed by LHCb. Observation of significantly more CP-violation than is allowed in the SM would be a strong indication of new physics. The current world best measurements of yCP and AGamma show no evidence of CP-violation. The methods used to measure ...

LHC Report: Summertime and the living is ZZ (and WW etc.)

CERN Document Server

Mike Lamont for the LHC Team

2012-01-01

The LHC had a rocky recovery from the extended luminosity calibration runs, and on Saturday 21 July a number of fills were lost due to beam instabilities. The situation was stabilised by temporarily backing off increasing bunch intensity and, in fact, the next 24 hours saw a record delivery of around 260 pb-1 to each of the ATLAS and CMS experiments.   This good performance continued the following week with around 55% of the time spent in "stable beams". Over 1 fb-1 was delivered to ATLAS and CMS. This was despite some timeouts for access and operational development. Peak luminosity is down about 10% from the highs earlier in the year, but the LHC is regularly enjoying long fills in the 12 to 15 hour range. Here we are seeing the benefits of the extensive consolidation work to mitigate the effects of radiation to electronics in the LHC tunnel and the continuing efforts to improve overall reliability. Combining data runs from 2011 and 2012, LHCb crossed the 2 fb-1 mark last Mond...

LHCbDIRAC as Apache Mesos microservices

Science.gov (United States)

Haen, Christophe; Couturier, Benjamin

2017-10-01

The LHCb experiment relies on LHCbDIRAC, an extension of DIRAC, to drive its offline computing. This middleware provides a development framework and a complete set of components for building distributed computing systems. These components are currently installed and run on virtual machines (VM) or bare metal hardware. Due to the increased workload, high availability is becoming more and more important for the LHCbDIRAC services, and the current installation model is showing its limitations. Apache Mesos is a cluster manager which aims at abstracting heterogeneous physical resources on which various tasks can be distributed thanks to so called “frameworks” The Marathon framework is suitable for long running tasks such as the DIRAC services, while the Chronos framework meets the needs of cron-like tasks like the DIRAC agents. A combination of the service discovery tool Consul together with HAProxy allows to expose the running containers to the outside world while hiding their dynamic placements. Such an architecture brings a greater flexibility in the deployment of LHCbDirac services, allowing for easier deployment maintenance and scaling of services on demand (e..g LHCbDirac relies on 138 services and 116 agents). Higher reliability is also easier, as clustering is part of the toolset, which allows constraints on the location of the services. This paper describes the investigations carried out to package the LHCbDIRAC and DIRAC components into Docker containers and orchestrate them using the previously described set of tools.

LHCb: Physics with the LHCb calorimeter

CERN Multimedia

Barsuk, S

2007-01-01

The LHCb calorimeter comprises the scintillator pad detector (SPD), preshower (PS), electromagnetic Shashlyk type (ECAL) and hadronichadronic Tile (HCAL) calorimeters, arranged in pseudo-projective geometry. All the four detectors follow the general principle of reading the light from scintillator tiles with wave length shifting fibers, and transporting the light towards photomultipliers (25 ns R/O).

Data acquisition system for LHCb calorimeter

International Nuclear Information System (INIS)

Dai Gang; Gong Guanghua; Shao Beibei

2007-01-01

LHCb Calorimeter system is mainly used to identify and measure the energy of the photon, electron, hadron produced by the collision of proton. TELL1 is a common data acquisition platform based on FPGA for LHCb experiment. It is used to adopt custom data acquisition and process method for every detector and provide the data standard for the CPU matrix. This paper provides a novel DAQ and data process model in VHDL for Calorimeter. According to this model. We have built an effective Calorimeter DAQ system, which would be used in LHCb Experiment. (authors)

A search for heavy long-lived staus in the LHCb detector at $\\sqrt{s}$ = 7 and 8 TeV

CERN Document Server

La, Viet Nga Thi

The Large Hadron Collider (LHC) has been producing $pp$ collisions at 7 and 8 TeV since 2010 and promises a new era of discoveries in particle physics. One of its experiments, the Large Hadron Collider beauty (LHCb) experiment, was constructed to study CP violation in the B meson system. In addition to B physics, new Physics beyond the Standard Model can also be searched for at this single-arm forward spectrometer. With the different sub-detectors and the high resolution of the tracking system, the LHCb detector has the ability to search for heavy, long-lived and charged particles, which are predicted by extensions of the Standard Model. One of these extensions, the $minimal$ $Gauge$ $Mediated$ $Supersymmetry$ $Breaking$ (mGMSB), proposes such a particle, named $stau$ ($\\widetilde{\\tau}$) - the SUSY bosonic counterpart of the heavy lepton tau ($\\tau$). The theory proposes that the staus may be pair-produced in $pp$ collisions or in the decays of heavier particles, and have only electromagnetic...

A true real-time success story: the case of collecting beauty-ful data at the LHCb experiment arXiv

CERN Document Server

Alessio, Federico

The LHCb experiment at CERN is currently completing its first big data taking campaign at the LHC started in 2009. It has been collecting data at more than 2.5 times its nominal design luminosity value and with a global efficiency of ~92%. Even more striking, the efficiency between online and offline recorded luminosity, obtained by comparing the data quality output, is close to 99%, which highlights how well the detector, its data acquisition system and its control system have been performing despite much harsher and more variable conditions than initially foreseen. In this paper, the excellent performance of the LHCb experiment will be described, by transversally tying together the timing and data acquisition system, the software trigger, the real-time calibration and the shifters interaction with the control system. Particular attention will be given to their real-time aspects, which allow performing an online reconstruction that is at the same performance level as the offline one through a real-time calib...

Operational aspects of the VELO cooling system of LHCb

CERN Document Server

Jans, E

2014-01-01

The VELO is a silicon strip detector that is positioned around the interaction region of LHCb. It is placed inside a secondary vacuum with respect to that of the LHC. The cooling system of the VELO is based on the bi-phase accumulator controlled method, using CO$_2$ as coolant. The main objective is the removal of the heat produced by the front-end electronics. Moreover, the leakage currents of the sensors are strongly reduced and thermal runaway is prevented. Since the sensors have been irradiated in Run 1 they should always be cooled to below $^-$5 $^{\\rm{o}}$C. The operational principle and main characteristics of the system are described, as well as the warning and safety systems that guarantee the safe operation of the detector. The few problems that have been encountered during the four years of continuous operation are discussed together with the solutions that have been implemented.

LHCb: Determination of $f_s / f_d$ for 7 TeV $pp$ collisions and a measurement of the branching ratio of the decay $B^{0} \\to D^{⁻} K^{+}$

CERN Multimedia

David, P N Y

2011-01-01

This poster presents an analysis measuring the relative abundance of the three decay modes $B^{0} \\to D^{-} K^{+}$, $B^{0} \\to D^{-} \\pi^{+}$ and $B^{0}_{s} \\to D^{-}_{s} \\pi^{+}$ produced in 7 TeV $pp$ collisions at the LHC, from data corresponding to an integrated luminosity of 35 pb$^{-1}$. The branching fraction of $B^{0} \\to D^{-} K^{+}$ is found to be $BR(B^{0}\\to D^{-} K^{+}) = (2.01\\pm 0.18^{stat}\\pm 0.14^{syst}) 10^{-4}$. The ratio of fragmentation fractions $f_s/f_d$ is determined through the relative abundance of $B^{0}_{s} \\to D^{-}_{s} \\pi^{+}$ to $B^{0} \\to D^{-} K^{+}$ and $B^{0} \\to D^{-} \\pi^{+}$, leading to $f_s/f_d = 0.253\\pm 0.017\\pm 0.017\\pm 0.020$, where the uncertainties are statistical, systematic and theoretical respectively. A detailed presentation can be found in the paper, conference note and analysis note (LHCb-ANA-2010-010; LHCb-CONF-2011-013; CERN-LHCb-CONF-2011-013; latest paper draft: LHCB-B2DH-004; CERN-PH-EP-2011-075).

A flavor dependent gauge symmetry, predictive radiative seesaw and LHCb anomalies

Directory of Open Access Journals (Sweden)

P. Ko

2017-09-01

Full Text Available We propose a predictive radiative seesaw model at one-loop level with a flavor dependent gauge symmetry U(1xB3−xe−μ+τ and Majorana fermion dark matter. For the neutrino mass matrix, we obtain an A1 type texture (with two zeros that provides us several predictions such as the normal ordering for the neutrino masses. We analyze the constraints from lepton flavor violations, relic density of dark matter, and collider physics for the new U(1xB3−xe−μ+τ gauge boson. Within the allowed region, the LHCb anomalies in B→K⁎μ+μ− and B→Kℓ+ℓ− with ℓ=e or μ can be resolved, and such Z′ could be also observed at the LHC.

Machine learning based global particle indentification algorithms at LHCb experiment

CERN Multimedia

Derkach, Denis; Likhomanenko, Tatiana; Rogozhnikov, Aleksei; Ratnikov, Fedor

2017-01-01

One of the most important aspects of data processing at LHC experiments is the particle identification (PID) algorithm. In LHCb, several different sub-detector systems provide PID information: the Ring Imaging CHerenkov (RICH) detector, the hadronic and electromagnetic calorimeters, and the muon chambers. To improve charged particle identification, several neural networks including a deep architecture and gradient boosting have been applied to data. These new approaches provide higher identification efficiencies than existing implementations for all charged particle types. It is also necessary to achieve a flat dependency between efficiencies and spectator variables such as particle momentum, in order to reduce systematic uncertainties during later stages of data analysis. For this purpose, "flat” algorithms that guarantee the flatness property for efficiencies have also been developed. This talk presents this new approach based on machine learning and its performance.

Study of Pentaquark States at LHCb

CERN Document Server

Yang, Zhenwei

2016-01-01

The observation of the two resonances consistent with charmonium-like pentaquark states, Pc(4380)+ and Pc(4450)+, by the LHCb collaboration inspires enthusiasm in particle physics. This article briefly reports about the observation and the experimental study of the pentaquark states by the LHCb collaboration

Novel real-time alignment and calibration of LHCb detector for Run II and tracking for the upgrade.

CERN Document Server

AUTHOR|(CDS)2091576

2016-01-01

LHCb has introduced a novel real-time detector alignment and calibration strategy for LHC Run II. Data collected at the start of the fill is processed in a few minutes and used to update the alignment, while the calibration constants are evaluated for each run. The procedure aims to improve the quality of the online selection and performance stability. The required computing time constraints are met thanks to a new dedicated framework using the multi-core farm infrastructure for the trigger. A similar scheme is planned to be used for Run III foreseen to start in 2020. At that time LHCb will run at an instantaneous luminosity of $2 \\times 10^{33}$ cm$^2$ s$^1$ and a fully software based trigger strategy will be used. The new running conditions and the tighter timing constraints in the software trigger (only 13 ms per event are available) represent a big challenge for track reconstruction. The new software based trigger strategy implies a full detector read-out at the collision rate of 40 MHz. High performance ...

Novel Real-time Alignment and Calibration of the LHCb detector in Run2

Science.gov (United States)

Martinelli, Maurizio; LHCb Collaboration

2017-10-01

LHCb has introduced a novel real-time detector alignment and calibration strategy for LHC Run2. Data collected at the start of the fill are processed in a few minutes and used to update the alignment parameters, while the calibration constants are evaluated for each run. This procedure improves the quality of the online reconstruction. For example, the vertex locator is retracted and reinserted for stable beam conditions in each fill to be centred on the primary vertex position in the transverse plane. Consequently its position changes on a fill-by-fill basis. Critically, this new real-time alignment and calibration procedure allows identical constants to be used in the online and offline reconstruction, thus improving the correlation between triggered and offline-selected events. This offers the opportunity to optimise the event selection in the trigger by applying stronger constraints. The required computing time constraints are met thanks to a new dedicated framework using the multi-core farm infrastructure for the trigger. The motivation for a real-time alignment and calibration of the LHCb detector is discussed from both the operational and physics performance points of view. Specific challenges of this novel configuration are discussed, as well as the working procedures of the framework and its performance.

Radiative decays of B mesons at LHCb

CERN Document Server

Soomro, Fatima; Golutvin, Andrei

2011-01-01

This thesis is dedicated to the study of radiative decays of $B$ mesons at LHC$b$. At quark level, such decays are a $b\\to s\\gamma$ transition and take place via a penguin loop and are sensitive to virtual contribution of New Physics, which can be indicated by an increase in the decay rates. These decays also offer the possibility to test the V-A structure of the Standard Model coupling in the processes mediated by loop penguin diagrams. In the decay $B_s \\to \\phi\\gamma$, New Physics contribution can be probed by measuring the polarization of the photon in this decay. Systematic effects in the proper time reconstruction of the $B_s$ in $B_s \\to \\phi\\gamma$ can bias the photon polarization measurement in this decay, which will reduce the sensitivity on the relevant New Physics parameter. The author studied those effects and developed ideas to calibrate them using $B_d\\to K^{*}\\gamma$ and $B_s\\to J/\\psi\\phi$ decays as control channels. These studies are mostly Monte Carlo based due to a relatively small data ...

Resolving the SELEX--LHCb Double-Charm Baryon Conflict: The Impact of Intrinsic Heavy-Quark Hadroproduction and Supersymmetric Light-Front Holographic QCD

Energy Technology Data Exchange (ETDEWEB)

Brodsky, Stanley [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2017-01-01

In this paper we show that the intrinsic heavy-quark QCD mechanism for the hadroproduction of heavy hadrons at large $x_F$ can resolve the apparent conflict between measurements of double-charm baryons by the SELEX fixed-target experiment and the LHCb experiment at the LHC collider. We show that both experiments are compatible, and that both results can be correct. The observed spectroscopy of double-charm hadrons is in agreement with the predictions of supersymmetric light front holographic QCD.

LHCb: Improvements in the LHCb DAQ

CERN Multimedia

Campora, D; Schwemmer, R

2014-01-01

The LHCb data acquisition system is realized as a Gigabit Ethernet local area network with more than 330 FPGA driven data-sources, two core-routers, 56 fan-out switches and more than 1400 servers (will be upgraded to about 1800 soon). In total there are almost 3000 switch-ports. Data are pushed top-down, quasi-synchronously using n unreliable datagram protocol (like UDP).

Measurement of antiproton production in p-He collisions and prospects for other inputs to cosmic rays physics from the fixed target program of the LHCb experiment

CERN Document Server

Graziani, Giacomo

2018-01-01

The LHCb experiment has the unique possibility, among the LHC experiments, to be operated in fixed target mode, using its internal gas target SMOG. The energy scale achievable at the LHC and the excellent detector capabilities for vertexing, tracking and particle identification allow a wealth of measurements of great interest for cosmic ray physics. We present the first measurement of antiproton production in proton-helium collisions at $\\sqrt s_{NN} = 110$ GeV, which allows to improve the accuracy of the prediction for secondary antiproton production in cosmic rays. Prospects for other measurements achievable in the fixed target program are also discussed.

Observation of the $B^0_s \\to \\eta_c \\phi$ decay with the LHCb experiment

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00536869

The interference between $B^0_s$ meson decay amplitudes to CP final state directly or via mixing gives rise to a measurable CP-violating phase $\\phi_s$, which is predicted to be $\\phi_s^{SM} = (-0.0370\\pm0.0006)~\\mathrm{rad}$ in the Standard Model. However, such process may receive contributions from New Physics and change the value of $\\phi_s$. At present, the most precise measurement of $\\phi_s$ is given by the LHCb experiment and the world average is $\\phi_s^{\\rm{exp}} = (-0.021\\pm 0.032)~\\mathrm{rad}$, with uncertainty still dominated by the statistics. In this context, a study of $B^0_s \\to \\eta_c \\phi$ decays is performed using $pp$ collision data corresponding to an integrated luminosity of~3.0\\,fb$^{-1}$, collected with the LHCb detector during the Run~1 of the LHC. The observation of the decay $B^0_s \\to \\eta_c \\phi$ is reported, where the $\\eta_c$ meson is reconstructed in the $p\\bar{p}$, $K^+K^-\\pi^+\\pi^-$, $\\pi^+\\pi^-\\pi^+\\pi^-$ and $K^+K^-K^+K^-$ decay modes and the $\\phi(1020)$ in t...

$CPT$ violation searches and prospects for LHCb

CERN Document Server

van Tilburg, Jeroen

2015-03-06

An overview of current experimental bounds on $CPT$ violation in neutral meson mixing is given. New values for the $CPT$ asymmetry in the $B^0$ and $B_s^0$ systems are deduced from BaBar, Belle and LHCb data. With dedicated analyses, LHCb will be able to further improve the bounds on $CPT$ violation in the $D^0$, $B^0$ and $B_s^0$ systems. Since $CPT$ violation implies violation of Lorentz invariance, the observed $CPT$ asymmetry will exhibit sidereal- and boost-dependent variations. Such $CPT$-violating and Lorentz-violating effects are accommodated in the framework of the Standard-Model Extension (SME). The large boost of the neutral mesons produced at LHCb results in a high sensitivity to the corresponding SME coefficients. For the $B^0$ and $B_s^0$ systems, using existing LHCb data, we determine with high precision the SME coefficients that are not varying with sidereal time. With a full sidereal analysis, LHCb will be able to improve the existing SME bounds in the $D^0$, $B^0$ and $B_s^0$ systems by up t...

ARIADNE: a Tracking System for Relationships in LHCb Metadata

CERN Document Server

Shapoval, I; Cattaneo, M

2014-01-01

The data processing model of the LHCb experiment implies handling of an evolving set of heterogeneous metadata entities and relationships between them. The entities range from software and databases states to architecture specificators and software/data deployment locations. For instance, there is an important relationship between the LHCb Conditions Database (CondDB), which provides versioned, time dependent geometry and conditions data, and the LHCb software, which is the data processing applications (used for simulation, high level triggering, reconstruction and analysis of physics data). The evolution of CondDB and of the LHCb applications is a weakly-homomorphic process. It means that relationships between a CondDB state and LHCb application state may not be preserved across different database and application generations. These issues may lead to various kinds of problems in the LHCb production, varying from unexpected application crashes to incorrect data processing results. In this paper we present Ari...

The LHCb Silicon Inner Tracker

International Nuclear Information System (INIS)

Sievers, P.

2002-01-01

A silicon strip detector has been adopted as baseline technology for the LHCb Inner Tracker system. It consists of nine planar stations covering a cross-shaped area around the LHCb beam pipe. Depending on the final layout of the stations the sensitive surface of the Inner Tracker will be of the order of 14 m 2 . Ladders have to be 22 cm long and the pitch of the sensors should be as large as possible in order to reduce costs of the readout electronics. Major design criteria are material budget, short shaping time and a moderate spatial resolution of about 80 μm. After an introduction on the requirements of the LHCb Inner Tracker we present a description and characterization of silicon prototype sensors. First, laboratory and test beam results are discussed

The LHCb Data Management System

International Nuclear Information System (INIS)

Baud, J P; Charpentier, Ph; Ciba, K; Lanciotti, E; Màthè, Z; Graciani, R; Remenska, D; Santana, R

2012-01-01

The LHCb Data Management System is based on the DIRAC Grid Community Solution. LHCbDirac provides extensions to the basic DMS such as a Bookkeeping System. Datasets are defined as sets of files corresponding to a given query in the Bookkeeping system. Datasets can be manipulated by CLI tools as well as by automatic transformations (removal, replication, processing). A dynamic handling of dataset replication is performed, based on disk space usage at the sites and dataset popularity. For custodial storage, an on-demand recall of files from tape is performed, driven by the requests of the jobs, including disk cache handling. We shall describe the tools that are available for Data Management, from handling of large datasets to basic tools for users as well as for monitoring the dynamic behavior of LHCb Storage capacity.

Measurement of $CP$ asymmetries in $\\Lambda_{b}^{0} \\to pK^{-}$ and $\\Lambda_{b}^{0} \\to p\\pi^-$ decays at LHCb

CERN Document Server

Ferrari, F

2016-01-01

The LHCb experiment has been designed to perform precision measurements in the flavour physics sector at the Large Hadron Collider (LHC). The measurement of the CP-violating observable defined as ΔACP = ACP (Λ0b → pK − ) − ACP (Λ0b → pπ − ), where ACP (Λ0b → pK − ) and ACP (Λ0b → pπ − ) are the direct CP asymmetries in Λ0b → pK − and Λ0b → pπ − decays, is presented for the first time using LHCb data. Using the full 2011 and 2012 data sets of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of about 3 fb −1, the value ΔACP = (0.8 ± 2.1 ± 0.2)% is obtained. The first uncertainty is statistical and the second corresponds to one of the dominant systematic effects. As the result is compatible with zero, no evidence of CP violation is found. This is the most precise measurement of CP violation in the decays of baryons containing the b quark to date. Once the analysis will be completed with an exhaustive study of systematic uncertainti...

LHCb; DAQ Architecture for the LHCb Upgrade

CERN Multimedia

Neufeld, N

2013-01-01

LHCb will have an upgrade of its detector in 2018. After the upgrade, the LHCb experiment will run at a high luminosity of 2x 10$^{33}$ cm$^{-2}$ . s$^{-1}$. The upgraded detector will be read out at 40 MHz with a highly flexible software-based triggering strategy. The Data Acquisition (DAQ) system of HCb reads out the data fragments from the Front-End Electronics and transports them to the High-Lever Trigger farm at an aggregate throughput of 32 Tbit/s. The DAQ system will be based on high speed network technologies such as InfiniBand and/or 10/40/100 Gigabit Ethernet. Independent of the network technology, there are different possible architectures for the DAQ system. In this paper, we present our studies on the DAQ architecture, where we analyze size, complexity and (relative) cost. We evaluate and compare several data-flow schemes for a network-based DAQ: push, pull and push with barrel-shifter traffic shaping. We also discuss the requirements and overall implications of the data-flow schemes on the DAQ ...

Test beam results of LHCb scintillating fibre tracker prototypes

Energy Technology Data Exchange (ETDEWEB)

Bachmann, Sebastian; Comerma, Albert; Gerick, David; Hansmann-Menzemer, Stephanie; Kecke, Matthieu; Leverington, Blake; Mazorra de Cos, Jose; Mitzel, Dominik; Neuner, Max; Uwer, Ulrich; Han, Xiaoxue [Physikalisches Institut, Universitaet Heidelberg (Germany); Collaboration: LHCb-Collaboration

2016-07-01

During the Long Shutdown 2 of the LHC, the LHCb detector will undergo a major upgrade to meet the challenges of running at a higher luminosity. The current Inner and Outer Tracking system will not be sufficient to deal with the envisaged increased detector occupancy and higher radiation levels and will be replaced by a single tracking detector based on 0.250 mm diameter plastic scintillating fibres. The fibres are wound to multilayer ribbons 2.4 m long and read out by 128 channel silicon photomultiplier arrays. The Scintillating Fibre (SciFi) tracker will cover a total active area of 360 m{sup 2}, arranged in 12 layers. The performances of prototype modules having 6 and 8 layers of fibre have been tested at the SPS at CERN. This talk focuses on basic properties of the prototype modules such as spatial resolution, single hit efficiency and light yield measured during the test beam campaigns in 2015.

Characterization of Silica Aerogel for the LHCb RICH Detector and Measurement of the Oscillation Parameter $\\Delta m_{s}$

CERN Document Server

Perego, D L; Matteuzzi, C

2005-01-01

LHCb is the Large Hadron Collider experiment to precise measurements of CP violation and rare decays in the B meson sector. It is presently under construction at CERN, and it will start operations in 2007. In the Standard Model picture, CP violation naturally arises by the complex phase in the unitary 3x3 Cabibbo-Kobayashi-Maskawa (CKM) matrix which accounts for the quark mixing. Thanks both to the high bb cross section and to the high luminosity, the LHC collider will be by far the most copious source of B mesons. A large amount of data will be available and the consistency of the Standard Model will be definitively tested by measuring in several ways all the angles and all the sides of the Unitarity Triangle. These measurements will over-constrain the model and look for inconsistencies due to New Physics. The design of the detector has been optimized to match the kinematical structure of bb events produced in a proton-proton collision. One of the key aspects of LHCb is the identification of the particles pr...

Study of the decay B+ → K+π0 at LHCb and mechanical development for the design of the Upstream Tracker

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00387304

The LHCb experiment at the Large Hadron Collider (LHC) is designed to measure the properties of particles containing charm ($c$) and bottom ($b$) quarks. This dissertation documents two major studies I have completed, one analyzing data collected by the LHCb detector, and another contributing to the design and development of an extensive upgrade to the detector. The pattern of CP asymmetry measurements of the \\mbox{$B\\rightarrow K\\pi$} family of decays deviates from expectations derived from the standard model (SM), a contradiction known as the ``$\\text{K}\\pi$ puzzle.'' The present size of the experimental errors are such that more precise measurements in the $B^{+}\\rightarrow K^{+}\\pi^0$ decay channel are especially important. An analysis of the $B^{+}\\rightarrow K^{+}\\pi^0$ decay using data collected during Run 1 is performed. Despite low reconstruction and trigger efficiencies and enormous combinatorial backgrounds, a signal is found with a statistical significance of $3.7\\sigma$. This achievement has led...

ARIADNE: a tracking system for relationships in LHCb metadata

International Nuclear Information System (INIS)

Shapoval, I; Clemencic, M; Cattaneo, M

2014-01-01

The data processing model of the LHCb experiment implies handling of an evolving set of heterogeneous metadata entities and relationships between them. The entities range from software and databases states to architecture specificators and software/data deployment locations. For instance, there is an important relationship between the LHCb Conditions Database (CondDB), which provides versioned, time dependent geometry and conditions data, and the LHCb software, which is the data processing applications (used for simulation, high level triggering, reconstruction and analysis of physics data). The evolution of CondDB and of the LHCb applications is a weakly-homomorphic process. It means that relationships between a CondDB state and LHCb application state may not be preserved across different database and application generations. These issues may lead to various kinds of problems in the LHCb production, varying from unexpected application crashes to incorrect data processing results. In this paper we present Ariadne – a generic metadata relationships tracking system based on the novel NoSQL Neo4j graph database. Its aim is to track and analyze many thousands of evolving relationships for cases such as the one described above, and several others, which would otherwise remain unmanaged and potentially harmful. The highlights of the paper include the system's implementation and management details, infrastructure needed for running it, security issues, first experience of usage in the LHCb production and potential of the system to be applied to a wider set of LHCb tasks.

ARIADNE: a Tracking System for Relationships in LHCb Metadata

Science.gov (United States)

Shapoval, I.; Clemencic, M.; Cattaneo, M.

2014-06-01

The data processing model of the LHCb experiment implies handling of an evolving set of heterogeneous metadata entities and relationships between them. The entities range from software and databases states to architecture specificators and software/data deployment locations. For instance, there is an important relationship between the LHCb Conditions Database (CondDB), which provides versioned, time dependent geometry and conditions data, and the LHCb software, which is the data processing applications (used for simulation, high level triggering, reconstruction and analysis of physics data). The evolution of CondDB and of the LHCb applications is a weakly-homomorphic process. It means that relationships between a CondDB state and LHCb application state may not be preserved across different database and application generations. These issues may lead to various kinds of problems in the LHCb production, varying from unexpected application crashes to incorrect data processing results. In this paper we present Ariadne - a generic metadata relationships tracking system based on the novel NoSQL Neo4j graph database. Its aim is to track and analyze many thousands of evolving relationships for cases such as the one described above, and several others, which would otherwise remain unmanaged and potentially harmful. The highlights of the paper include the system's implementation and management details, infrastructure needed for running it, security issues, first experience of usage in the LHCb production and potential of the system to be applied to a wider set of LHCb tasks.

Identification of light-harvesting chlorophyll a/b-binding protein genes of Zostera marina L. and their expression under different environmental conditions

Science.gov (United States)

Kong, Fanna; Zhou, Yang; Sun, Peipei; Cao, Min; Li, Hong; Mao, Yunxiang

2016-02-01

Photosynthesis includes the collection of light and the transfer of solar energy using light-harvesting chlorophyll a/b-binding (LHC) proteins. In high plants, the LHC gene family includes LHCA and LHCB sub-families, which encode proteins constituting the light-harvesting complex of photosystems I and II. Zostera marina L. is a monocotyledonous angiosperm and inhabits submerged marine environments rather than land environments. We characterized the Lhca and Lhcb gene families of Z. marina from the expressed sequence tags (EST) database. In total, 13 unigenes were annotated as ZmLhc, 6 in Lhca family and 7 in ZmLhcb family. ZmLHCA and ZmLHCB contained the conservative LHC motifs and amino acid residues binding chlorophyll. The average similarity among mature ZmLHCA and ZmLHCB was 48.91% and 48.66%, respectively, which indicated a high degree of divergence within ZmLHChc gene family. The reconstructed phylogenetic tree showed that the tree topology and phylogenetic relationship were similar to those reported in other high plants, suggesting that the Lhc genes were highly conservative and the classification of ZmLhc genes was consistent with the evolutionary position of Z. marina. Real-time reverse transcription (RT) PCR analysis showed that different members of ZmLhca and ZmLhcb responded to a stress in different expression patterns. Salinity, temperature, light intensity and light quality may affect the expression of most ZmLhca and ZmLhcb genes. Inorganic carbon concentration and acidity had no obvious effect on ZmLhca and ZmLhcb gene expression, except for ZmLhca6.

Design and implementation of the decision unit of the first level trigger system of the LHCb detector at the Large Hadron Collider (LHC); Conception et realisation de l'unite de decision du systeme de declenchement de premier niveau du detecteur LHCb au LHC

Energy Technology Data Exchange (ETDEWEB)

Laubser, J

2007-11-15

The LHCb experiment is one of the four particle physic detector installed at the new Large Hadron Collider (LHC) at CERN in Geneva. In order to reduce the amount of data storage for offline analysis, an online trigger system of interesting event according to the studied physic is implemented in parallel of the Data Acquisition system. The trigger system is composed by a first level (Level-0) made by a complex electronic system and a second level made by a computing system called the High Level Trigger. The Level-0 Decision Unit is the central part of the first trigger level that takes the decision to accept or to reject the event by using a fraction of information coming from the fastest sub-triggers (432 bits at 80 MHz). It is a full custom 16 layers board using advanced FPGA (Field Programmable Gate Array) in BGA (Bill Grid Array) package. Each sub-trigger transmit their data via high speed optical links running at 1.6 Gbit/s. The processing is implemented using a 40 MHz synchronous pipelined architecture. It performs a simple physical algorithm to compute the Level-0 trigger decision in order to reduce the data flow from 40 MHz down to 1 MHz for the next trigger level. The internal design of the processing FPGA is mainly composed by a Partial Data Processing (PDP) and a Trigger Definition Unit (TDU). The aim of the PDP is to adjust the clock phase, perform the time alignment, prepare the data for the TDU and monitor the data processing. The TDU is flexible and allows to fully re-configure all the trigger conditions through the Experiment Control System without any FPGA re-programming. (author)

LHCb Kalman Filter cross architecture studies

Science.gov (United States)

Hugo, Daniel; Pérez, Cámpora

2017-10-01

The 2020 upgrade of the LHCb detector will vastly increase the rate of collisions the Online system needs to process in software, in order to filter events in real time. 30 million collisions per second will pass through a selection chain, where each step is executed conditional to its prior acceptance. The Kalman Filter is a fit applied to all reconstructed tracks which, due to its time characteristics and early execution in the selection chain, consumes 40% of the whole reconstruction time in the current trigger software. This makes the Kalman Filter a time-critical component as the LHCb trigger evolves into a full software trigger in the Upgrade. I present a new Kalman Filter algorithm for LHCb that can efficiently make use of any kind of SIMD processor, and its design is explained in depth. Performance benchmarks are compared between a variety of hardware architectures, including x86_64 and Power8, and the Intel Xeon Phi accelerator, and the suitability of said architectures to efficiently perform the LHCb Reconstruction process is determined.

LHCb Online event processing and filtering

CERN Document Server

Alessio, F; Brarda, L; Frank, M; Franek, B; Galli, D; Gaspar, C; Van Herwijnen, E; Jacobsson, R; Jost, B; Köstner, S; Moine, G; Neufeld, N; Somogyi, P; Stoica, R; Suman, S

2008-01-01

The first level trigger of LHCb accepts one million events per second. After preprocessing in custom FPGA-based boards these events are distributed to a large farm of PC-servers using a high-speed Gigabit Ethernet network. Synchronisation and event management is achieved by the Timing and Trigger system of LHCb. Due to the complex nature of the selection of B-events, which are the main interest of LHCb, a full event-readout is required. Event processing on the servers is parallelised on an event basis. The reduction factor is typically 1/500. The remaining events are forwarded to a formatting layer, where the raw data files are formed and temporarily stored. A small part of the events is also forwarded to a dedicated farm for calibration and monitoring. The files are subsequently shipped to the CERN Tier0 facility for permanent storage and from there to the various Tier1 sites for reconstruction. In parallel files are used by various monitoring and calibration processes running within the LHCb Online system. ...

LHCb distributed conditions database

International Nuclear Information System (INIS)

Clemencic, M

2008-01-01

The LHCb Conditions Database project provides the necessary tools to handle non-event time-varying data. The main users of conditions are reconstruction and analysis processes, which are running on the Grid. To allow efficient access to the data, we need to use a synchronized replica of the content of the database located at the same site as the event data file, i.e. the LHCb Tier1. The replica to be accessed is selected from information stored on LFC (LCG File Catalog) and managed with the interface provided by the LCG developed library CORAL. The plan to limit the submission of jobs to those sites where the required conditions are available will also be presented. LHCb applications are using the Conditions Database framework on a production basis since March 2007. We have been able to collect statistics on the performance and effectiveness of both the LCG library COOL (the library providing conditions handling functionalities) and the distribution framework itself. Stress tests on the CNAF hosted replica of the Conditions Database have been performed and the results will be summarized here

Conception et réalisation de l'unité de décision du système de déclenchement de premier niveau du détecteur LHCb au LHC

CERN Document Server

Laubser, Julien

2007-01-01

Le detecteur LHCb est l'une des quatre experiences de physique des particules installees sur la nouvelle chaine d'acceleration LHC (Large Hadron Collider) du CERN a Geneve. Afin de reduire la quantite de donnees destinees au stockage pour les analyses hors ligne, un dispositif de selection en ligne des collisions interessantes selon la physique a etudier est mis en place en parallele de la chaine d'acquisition des donnees. Ce dispositif est compose d'un premier niveau(niveau 0) realise par un systeme electronique complexe et d'un second niveau de selection realise par informatique HLT (High Level Trigger). L'unite de decision de niveau 0 (L0DU) est le systeme central du niveau 0 de declenchement. L0DU prend la decision d'accepter ou de rejeter la collision pour ce premier niveau a partir d'une fraction d'informations issues des sous-detecteurs les plus rapides (432 bits a 80 MHz). L'unite de decision est un circuit imprime 16 couches integrant des composants de haute technologie de type FPGA (Field Programmab...

LHCb Conditions database operation assistance systems

International Nuclear Information System (INIS)

Clemencic, M; Shapoval, I; Cattaneo, M; Degaudenzi, H; Santinelli, R

2012-01-01

The Conditions Database (CondDB) of the LHCb experiment provides versioned, time dependent geometry and conditions data for all LHCb data processing applications (simulation, high level trigger (HLT), reconstruction, analysis) in a heterogeneous computing environment ranging from user laptops to the HLT farm and the Grid. These different use cases impose front-end support for multiple database technologies (Oracle and SQLite are used). Sophisticated distribution tools are required to ensure timely and robust delivery of updates to all environments. The content of the database has to be managed to ensure that updates are internally consistent and externally compatible with multiple versions of the physics application software. In this paper we describe three systems that we have developed to address these issues. The first system is a CondDB state tracking extension to the Oracle 3D Streams replication technology, to trap cases when the CondDB replication was corrupted. Second, an automated distribution system for the SQLite-based CondDB, providing also smart backup and checkout mechanisms for the CondDB managers and LHCb users respectively. And, finally, a system to verify and monitor the internal (CondDB self-consistency) and external (LHCb physics software vs. CondDB) compatibility. The former two systems are used in production in the LHCb experiment and have achieved the desired goal of higher flexibility and robustness for the management and operation of the CondDB. The latter one has been fully designed and is passing currently to the implementation stage.

LHCb VELO upgrade

Energy Technology Data Exchange (ETDEWEB)

Hennessy, Karol

2017-02-11

The upgrade of the LHCb experiment, scheduled for LHC Run-III, scheduled to start in 2021, will transform the experiment to a trigger-less system reading out the full detector at 40 MHz event rate. All data reduction algorithms will be executed in a high-level software farm enabling the detector to run at luminosities of 2×10{sup 33} cm{sup −2} s{sup −1}. The Vertex Locator (VELO) is the silicon vertex detector surrounding the interaction region. The current detector will be replaced with a hybrid pixel system equipped with electronics capable of reading out at 40 MHz. The upgraded VELO will provide fast pattern recognition and track reconstruction to the software trigger. The silicon pixel sensors have 55×55 μm{sup 2} pitch, and are read out by the VeloPix ASIC, from the Timepix/Medipix family. The hottest region will have pixel hit rates of 900 Mhits/s yielding a total data rate of more than 3 Tbit/s for the upgraded VELO. The detector modules are located in a separate vacuum, separated from the beam vacuum by a thin custom made foil. The foil will be manufactured through milling and possibly thinned further by chemical etching. The material budget will be minimised by the use of evaporative CO{sub 2} coolant circulating in microchannels within 400 μm thick silicon substrates. The current status of the VELO upgrade is described and latest results from operation of irradiated sensor assemblies are presented.

Measurement of $sin2\\beta$ from $B^{0}_{d} \\rightarrow J/\\Psi K^{0}_{S}$ with the LHCb detector

CERN Document Server

Mangiafave, N; Calvi, M; Matteuzzi, C

2008-01-01

The LHCb experiment will study CP violation and rare B meson decays at the LHC accelerator, in the CERN laboratories of Geneva. The CP violation in the $b$ quark mesons was observed for the first time measuring the $\\sin2\\beta$ parameter. In the first year of data taking at LHCb the $\\sin2\\beta$ measurement will be performed in the channel $B_d ^0 \\rightarrow J/\\psi K_S ^0$ (called golden channel). The comparison with results obtained in previous experiments will show possible systematic errors. Once the systematic errors will be understood, the possible discrepancies with the expected results will be the sign of a new physics beyond the Standard Model. $\\sin2\\beta$ is extracted from the asymmetry in the decay $B_d ^0 \\rightarrow J/\\psi(\\mu^+\\mu^-) K_S ^0 (\\pi^+\\pi^-)$ and its CP conjugated $\\overline{B}_d ^0 \\rightarrow J/\\psi(\\mu^-\\mu^+) K_S ^0(\\pi^-\\pi^+)$. To distinguish between $B_d ^0$ and $\\overline{B}_d$ flavour tagging algorithms are used. These introduce an additional parameter: the wrong tag fracti...

Study of J/$\\psi$ production with the LHCb experiment in proton-proton collisions at $\\sqrt{s} = 7$ TeV

CERN Document Server

Frosini, Maddalena

The LHCb detector is one of the four main experiments installed at the proton-proton Large Hadron Collider (LHC) at CERN, Geneva. The first beams circulated in the collider in September 2008 and the data taking started in April 2010. The LHCb detector is a single-arm forward spectrometer conceived to extensively study the CP violation in the $B$ meson system, looking for constraints of the Standard Model predictions, for possible effects of new physics beyond this theory and generally for rare phenomena in the $b$ and $c$ quark sectors with high precision. Already in the first data recorded by the experiment, a huge amount of J/$\\psi$ mesons have been collected, which allow to make an extensive study of the charmonia production. This is a very interesting sector in particle physics. From the experimental point of view, the measurement of the charmonium production cross section and polarization has been carried on by several experiments. At Tevatron, CDF measured the $J/\\psi$ and $\\psi (2S)$ cross section and ...

Implications of LHCb measurements and future prospects

CERN Multimedia

Ordan, Julien Marius

2017-01-01

This is the 2017 edition of a series of workshops between the LHCb collaboration and the theory community. It follows similar meetings held on 10-11 Nov. 2011, 16-18 April 2012 (which resulted in a paper published in EPJ C 73 (2013) 2373), 14-16 Oct. 2013, 15-17 Oct. 2014, 3-5 Nov. 2015 and 12-14 Oct. 2016. The purpose of the meeting is to consider the latest results from LHCb, discuss possible interpretations and identify important channels and observables to test leading theoretical frameworks in the near future of LHCb data-taking.

Past Experiences and Future Trends on Vertex Detector Cooling at LHC

CERN Document Server

Petagna, Paolo

2014-01-01

Substantially different approaches have been ad opted for the refrigeration plants of the first generation of vertex detectors at LHC: those of ALICE, ATLAS and CMS use PFC fluids, either in single phase or in a traditional Joule-Thomson cycle, while carbon dioxide in a pumped two-phase loop has been selected for the LHCb VELO. For what concerns the on-board thermal management of the sensors and related electronics, a traditional design has been followed, based on a common general approach and only differing in the specific choices related to the local configuration. Although the global performance of the detectors in this first phase of LHC operation can be claimed as fully satisfactory, it appears that the additional challenges posed by the coming upgrade phases can only be tackled through an effort on technology innovation and, in particular on much stronger and earlier integration of all the cooling-related aspects in the detector conception. Carbon dioxide seems to be the preferred choice for the refrige...

Supersymmetry in light of 1/fb of LHC data

International Nuclear Information System (INIS)

Buchmueller, O.

2011-11-01

We update previous frequentist analyses of the CMSSM and NUHM1 parameter spaces to include the public results of searches for supersymmetric signals using ∝1 /fb of LHC data recorded by ATLAS and CMS and ∝0.3/fb of data recorded by LHCb in addition to electroweak precision and B-physics observables. We also include the constraints imposed by the cosmological dark matter density and the XENON100 search for spin-independent dark matter scattering. The LHC data set includes ATLAS and CMS searches for jets + is not an element of T events and for the heavier MSSM Higgs bosons, and the upper limits on BR(B s → μ + μ - ) from LHCb and CMS. The absences of jets + is not an element of T signals in the LHC data favour heavier mass spectra than in our previous analyses of the CMSSM and NUHM1, which may be reconciled with (g-2) μ if tan β ∝ 40, a possibility that is however under pressure from heavy Higgs searches and the upper limits on BR(B s → μ + μ - ). As a result, the p-value for the CMSSM fit is reduced to ∝ 15 (38)%, and that for the NUHM1 to ∝ 16 (38)%, to be compared with ∝ 9 (49)% for the Standard Model limit of the CMSSM for the same set of observables (dropping (g-2) μ ), ignoring the dark matter relic density in both cases. We discuss the sensitivities of the fits to the (g-2) μ and BR(b → sγ) constraints, contrasting fits with and without the (g-2) μ constraint, and combining the theoretical and experimental errors for BR(b → sγ) linearly or in quadrature. We present predictions for m anti g , BR(B s → μ + μ - ), M h and M A , and update predictions for spin-independent dark matter scattering, stressing again the importance of taking into account the uncertainty in the π-nucleon σ term Σ πN . Finally, we present predictions based on our fits for the likely thresholds for sparticle pair production in e + e - collisions in the CMSSM and NUHM1. (orig.)

LHCb: $2\\beta_s$ measurement at LHCb

CERN Multimedia

Conti, G

2009-01-01

A measurement of $2\\beta_s$, the phase of the $B_s-\\bar{B_s}$ oscillation amplitude with respect to that of the ${\\rm b} \\rightarrow {\\rm c^{+}}{\\rm W^{-}}$ tree decay amplitude, is one of the key goals of the LHCb experiment with first data. In the Standard Model (SM), $2\\beta_s$ is predicted to be $0.0360^{+0.0020}_{-0.0016} \\rm rad$. The current constraints from the Tevatron are: $2\\beta_{s}\\in[0.32 ; 2.82]$ at 68$\\%$CL from the CDF experiment and $2\\beta_{s}=0.57^{+0.24}_{-0.30}$ from the D$\\oslash$ experiment. Although the statistical uncertainties are large, these results hint at the possible contribution of New Physics in the $B_s-\\bar{B_s}$ box diagram. After one year of data taking at LHCb at an average luminosity of $\\mathcal{L}\\sim2\\cdot10^{32}\\rm cm^{-2} \\rm s^{-1}$ (integrated luminosity $\\mathcal{L}_{\\rm int}\\sim 2 \\rm fb^{-1}$), the expected statistical uncertainty on the measurement is $\\sigma(2\\beta_s)\\simeq 0.03$. This uncertainty is similar to the $2\\beta_s$ value predicted by the SM.

Federating LHCb datasets using the DIRAC File catalog

CERN Document Server

Haen, Christophe; Frank, Markus; Tsaregorodtsev, Andrei

2015-01-01

In the distributed computing model of LHCb the File Catalog (FC) is a central component that keeps track of each file and replica stored on the Grid. It is federating the LHCb data files in a logical namespace used by all LHCb applications. As a replica catalog, it is used for brokering jobs to sites where their input data is meant to be present, but also by jobs for finding alternative replicas if necessary. The LCG File Catalog (LFC) used originally by LHCb and other experiments is now being retired and needs to be replaced. The DIRAC File Catalog (DFC) was developed within the framework of the DIRAC Project and presented during CHEP 2012. From the technical point of view, the code powering the DFC follows an Aspect oriented programming (AOP): each type of entity that is manipulated by the DFC (Users, Files, Replicas, etc) is treated as a separate 'concern' in the AOP terminology. Hence, the database schema can also be adapted to the needs of a Virtual Organization. LHCb opted for a highly tuned MySQL datab...

LHCb: Fabric Management with Diskless Servers and Quattor on LHCb

CERN Multimedia

Schweitzer, P; Brarda, L; Neufeld, N

2011-01-01

Large scientific experiments nowadays very often are using large computer farms to process the events acquired from the detectors. In LHCb a small sysadmin team manages 1400 servers of the LHCb Event Filter Farm, but also a wide variety of control servers for the detector electronics and infrastructure computers: file servers, gateways, DNS, DHCP and others. This variety of servers could not be handled without a solid fabric management system. We choose the Quattor toolkit for this task. We will present our use of this toolkit, with an emphasis on how we handle our diskless nodes (Event filter farm nodes and computers embedded in the acquisition electronic cards). We will show our current tests to replace the standard (RedHat/Scientific Linux) way of handling diskless nodes to fusion filesystems and how it improves fabric management.

LHCb: The LHCb off-Site HLT Farm Demonstration

CERN Multimedia

Liu, Guoming

2012-01-01

The LHCb High Level Trigger (HLT) farm consists of about 1300 nodes, which are housed in the underground server room of the experiment point. Due to the constraints of the power supply and cooling system, it is difficult to install more servers in this room for the future. Off-site computing farm is a solution to enlarge the computing capacity. In this paper, we will demonstrate the LHCb off-site HLT farm which locate in the CERN computing center. Since we use private IP addresses for the HLT farm, we would need virtual private network (VPN) to bridge both sites. There are two kinds of traffic in the event builder: control traffic for the control and monitoring of the farm and the Data Acquisition (DAQ) traffic. We adopt IP tunnel for the control traffic and Network Address Translate (NAT) for the DAQ traffic. The performance of the off-site farm have been tested and compared with the on-site farm. The effect of the network latency has been studied. To employ a large off-site farm, one of the potential bottle...

LHCb - Novel Muon Identification Algorithms for the LHCb Upgrade

CERN Multimedia

Cogoni, Violetta

2016-01-01

The present LHCb Muon Identification procedure was optimised to guarantee high muon detection efficiency at the istantaneous luminosity $\\mathcal{L}$ of $2\\cdot10^{32}$~cm$^{-2}$~s$^{-1}$. In the current data taking conditions, the luminosity is higher than foreseen and the low energy background contribution to the visible rate in the muon system is larger than expected. A worse situation is expected for Run III when LHCb will operate at $\\mathcal{L} = 2\\cdot10^{33}$~cm$^{-2}$~s$^{-1}$ causing the high particle fluxes to deteriorate the muon detection efficiency, because of the increased dead time of the electronics, and in particular to worsen the muon identification capabilities, due to the increased contribution of the background, with deleterious consequences especially for the analyses requiring high purity signal. In this context, possible new algorithms for the muon identification will be illustrated. In particular, the performance on combinatorial background rejection will be shown, together with the ...

LHCb: Time structure analysis of the LHCb Online network

CERN Multimedia

Antichi, G; Campora Perez, D H; Liu, G; Neufeld, N; Giordano, S; Owezarski, P; Moore, A

2013-01-01

The LHCb Online Network is a real time high performance network, in which 350 data sources send data over a Gigabit Ethernet LAN to more than 1500 receiving nodes. The aggregated throughput of the application, called Event Building, is more than 60 GB/s. The protocol employed by LHCb makes the sending nodes transmit simultaneously portions of events to one receiving node at a time, which is selected using a credit-token scheme. The resulting traffic is very bursty and sensitive to irregularities in the temporal distribution of packet-bursts to the same destination or region of the network. In order to study the relevant properties of such a dataflow, a non-disruptive monitoring setup based on a networking capable FPGA (NetFPGA) has been deployed. The NetFPGA allows order of hundred nano-second precise time-stamping of packets. We study in detail the timing structure of the Event Building communication, and we identify potential effects of micro-bursts like buffer packet drops or jitter.

New Physics perspectives with the upgraded LHCb detector

International Nuclear Information System (INIS)

Cavallero, G.

2017-01-01

First encouraging deviations from Standard Model have been observed by the LHCb Collaboration in the first phase of data taking. The LHCb upgrade will be crucial to conclude if New Physics exists up to ∼ O(100 TeV), thanks to the collection of a very large data sample of ∼ 50 fb"−"1 and to an innovative flexible software based trigger system. An overview of the main observables accessible to LHCb that could reveal New Physics effects is reported.

Considerations on Xi- reconstruction in LHCb

CERN Document Server

Brochu, F.M.

2016-01-01

This paper describes an alternative method of charged hyperon reconstruction applicable to the LHCb experiment. It extends the seminal work of the FOCUS collaboration to the specific detector layout of LHCb and addresses the reconstruction ambiguities reported in their earlier work, leading to improvements in the reconstruction efficiency for the specific cases of Xi- and Omega- baryon decays to a charged meson and a Lambda baryon.

Timing and Readout Contorl in the LHCb Upgraded Readout System

CERN Document Server

Alessio, Federico

2016-01-01

In 2019, the LHCb experiment at CERN will undergo a major upgrade where its detectors electronics and entire readout system will be changed to read-out events at the full LHC rate of 40 MHz. In this paper, the new timing, trigger and readout control system for such upgrade is reviewed. Particular attention is given to the distribution of the clock, timing and synchronization information across the entire readout system using generic FTTH technology like Passive Optical Networks. Moreover the system will be responsible to generically control the Front-End electronics by transmitting configuration data and receiving monitoring data, offloading the software control system from the heavy task of manipulating complex protocols of thousands of Front-End electronics devices. The way in which this was implemented is here reviewed with a description of results from first implementations of the system, including usages in test-benches, implementation of techniques for timing distribution and latency control."

Optimisation of LHCb Applications for Multi- and Manycore Job Submission

CERN Document Server

Rauschmayr, Nathalie; Graciani Diaz, Ricardo; Charpentier, Philippe

The Worldwide LHC Computing Grid (WLCG) is the largest Computing Grid and is used by all Large Hadron Collider experiments in order to process their recorded data. It provides approximately 400k cores and storages. Nowadays, most of the resources consist of multi- and manycore processors. Conditions at the Large Hadron Collider experiments will change and much larger workloads and jobs consuming more memory are expected in future. This has lead to a shift of paradigm which focuses on executing jobs as multiprocessor tasks in order to use multi- and manycore processors more efficiently. All experiments at CERN are currently investigating how such computing resources can be used more efficiently in terms of memory requirements and handling of concurrency. Until now, there are still many unsolved issues regarding software, scheduling, CPU accounting, task queues, which need to be solved by grid sites and experiments. This thesis develops a systematic approach to optimise the software of the LHCb experiment fo...

LHCb Upstream Tracker

CERN Multimedia

Gandini, Paolo

2014-01-01

The LHCb upgrade requires replacing the silicon strip tracker between the vertex locator (VELO) and the magnet. A new design has been developed and tested based on the "stave" concept planned for the ATLAS upgrade.

LHCb Upstream Tracker

CERN Multimedia

Gandini, P

2014-01-01

The LHCb upgrade requires replacing the silicon strip tracker between the vertex locator (VELO) and the magnet. A new design has been developed and tested based on the "stave" concept planned for the ATLAS upgrade

Selection of Doubly Cabibbo suppressed $D^{*+} \\rightarrow D^0 (K^+ \\pi^-) \\pi^+$ decays and measurement of the $D^0$ lifetime in $D^0 \\rightarrow K^- \\pi^+$ at the LHCb experiment

CERN Document Server

AUTHOR|(SzGeCERN)704283

The LHC beauty (LHCb) experiment is one of the four main experiments at the Large Hadron Collider, colliding protons since March 2010 with a center-of-mass energy of 7 TeV. This thesis investigates the current status towards a mixing analysis in the $D$ system in LHCb data. First, a selection of Doubly Cabibbo Suppressed (DCS) $D^0 \\rightarrow K^+ \\pi^-$ decays in the presently largest LHCb data set is presented. The self tagging decay chain $D^{*+} \\rightarrow D^0 \\pi^+$ is used. A signal of $1966 \\pm 28$ decays is measured in $37 \\textrm{pb}^{-1}$ of data. The ratio of DCS decays to Cabibbo Favored (CF) $D^0 \\rightarrow K^- \\pi^+$ decays, using the same $D^*$ decay chain, is measured with $(4.89 \\pm 0.07) \\times 10^{-3}$. Second, the $D^0$ lifetime is measured in the CF decay mode. In hadronic interactions the proper time distribution of heavy mesons is distorted due to trigger cuts on the final state hadrons' impact parameters. In this thesis an average proper time acceptance function is evaluated in the M...

Production and test of the LHCb Muon Chamber

CERN Multimedia

2005-01-01

- The Muon System of LHCb - The Multi-Wire Proportional Chambers for LHCb - Wire tension meter - Wire pitch measurement - Gas leakage test - Test with cosmic rays - Production and test summary - Gap gain uniformity - Production and test summary

Study of double charm B decays with the LHCb experiment at CERN and track reconstruction for the LHCb upgrade

CERN Document Server

AUTHOR|(CDS)2091576; Rademacker, Jonas

Double charmed $B$ meson decays are dominated by the Cabibbo favoured $b\\rightarrow c (W^{-} \\rightarrow \\overline{c}s)$ transition. This thesis presents the study of $B^{0}\\rightarrow D^{0}\\overline{D}^{0}K^{\\ast 0}$ decay which has never been observed so far. The branching ratio is quoted with respect to the $B^{0}\\rightarrow D^{\\ast -} D^{0} K^{+}$ decay mode. No $K^{\\ast0}$ mass window selection is applied in sigmode, reconstructing the $K\\pi$ system as a $K^{\\ast0}$. The invariant mass of the $K\\pi$ system is selected to be in full allowed phase space: $ m(K) + m(\\pi) < m(K\\pi) < m(B)-2 m(D^{0})$. $D^{0}$ mesons are reconstructed through the Cabibbo favoured $D^{0}\\rightarrow K^{-}\\pi^{+}$ mode and the $K^{\\ast 0}$ as $K^{+}\\pi^{-}$. The integrated luminosity of 3fb$^{-1}$ collected by LHCb during LHC Run 1 are used to select and reconstruct $B{0}\\rightarrow D^{0}\\overline{D}^{0} K^{\\ast 0}$ leading to a preliminary branching ratio corresponding to: $$\\dfrac{\\mathcal{B}(B{0}\\rightarrow D^{0}\\over...

Study of the B0→K*0μ+μ- decay with the LHCb experiment : angular analysis and measurement of the ratio RK

CERN Document Server

Coquereau, Samuel; Ben-Haïm, Eli

Rare beauty decays proceed mostly through the Flavor Changing Neutral Current, which is possible only at loop level in the Standard Model. These FCNC processes are subject to GIM suppression leading to a rare decay. Therefore the [Math Processing Error] processes are good tools to look for New Physics phenomenon beyond the Standard Model. New Physics particle could become detectable by causing deviation from the Standard Model predictions for observables such as angular observables, branching ratio or CP asymmetries. This thesis present the angular analysis of the [Math Processing Error] decay with the whole dataset collected by lhcb during the first run of the lhc. The full set of the angular observables has been measured through a maximum likelihood fit, thanks to an improved selection and the 3 fb[Math Processing Error] of data collected in 2011 and 2012 by lhcb. In addition, the analysis on the measurement of the ratio [Math Processing Error] has also been presented and the results are expected by the end...

Identificazione di particelle e studio del decadimento $B^{\\pm} \\rightarrow K^{\\pm} \\pi^{0}$ con il rivelatore RICH di LHCb

CERN Document Server

Cardinale, Roberta; D’Ambrosio, C

2009-01-01

The violation of the CP symmetry is one of the still open issues in the physics of fundamental interactions. Moreover, CP violation is important to understand the asymmetry between matter and anti-matter in the universe. LHCb is one of the experiments installed at the Large Hadron Collider (LHC) at CERN, and it is dedicated to precise measurements of CP violation and rare decays in the B hadron sector to test flavour physics in the Standard Model and to point out possible New Physics beyond the Standard Model. One of the key aspects of LHCb is the identification of the B decay products. The capability to distinguish between a pion and a kaon in the final state is fundamental to measure CP violation. This identification is provided by two RICH (Ring Imaging CHerenkov) detectors covering the particle momentum range 1 $\\div$ 100 GeV/$c$. Cherenkov photons are detected using Hybrid Photon Detector (HPD). My thesis deals with three topics: characterization and correction of the magnetic distortion effects on the H...