Production of pions, kaons and protons in pp collisionsat \sqrt{s} = 900 GeV with ALICE at the LHC

Production of pions, kaons and protons in pp collisions
at  = 900 GeV with ALICE at the LHC

ALICE collaboration
K. Aamodt Department of Physics, University of Oslo, Oslo, Norway    N. Abel Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    U. Abeysekara Physics Department, Creighton University, Omaha, NE, United States    A. Abrahantes Quintana Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba    A. Abramyan Yerevan Physics Institute, Yerevan, Armenia    D. Adamová Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež u Prahy, Czech Republic    M.M. Aggarwal Physics Department, Panjab University, Chandigarh, India    G. Aglieri Rinella European Organization for Nuclear Research (CERN), Geneva, Switzerland    A.G. Agocs KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    S. Aguilar Salazar Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    Z. Ahammed Variable Energy Cyclotron Centre, Kolkata, India    A. Ahmad Department of Physics Aligarh Muslim University, Aligarh, India    N. Ahmad Department of Physics Aligarh Muslim University, Aligarh, India    S.U. Ahn 11endnote: 1Also at Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France Gangneung-Wonju National University, Gangneung, South Korea    R. Akimoto University of Tokyo, Tokyo, Japan    A. Akindinov Institute for Theoretical and Experimental Physics, Moscow, Russia    D. Aleksandrov Russian Research Centre Kurchatov Institute, Moscow, Russia    B. Alessandro Sezione INFN, Turin, Italy    R. Alfaro Molina Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    A. Alici Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    E. Almaráz Aviña Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    J. Alme Department of Physics and Technology, University of Bergen, Bergen, Norway    T. Alt 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    V. Altini Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    S. Altinpinar Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    C. Andrei National Institute for Physics and Nuclear Engineering, Bucharest, Romania    A. Andronic Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    G. Anelli European Organization for Nuclear Research (CERN), Geneva, Switzerland    V. Angelov 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    C. Anson Department of Physics, Ohio State University, Columbus, OH, United States    T. Antičić Rudjer Bošković Institute, Zagreb, Croatia    F. Antinori 33endnote: 3Now at Sezione INFN, Padova, Italy European Organization for Nuclear Research (CERN), Geneva, Switzerland    S. Antinori Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    K. Antipin Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    D. Antończyk Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    P. Antonioli Sezione INFN, Bologna, Italy    A. Anzo Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    L. Aphecetche SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    H. Appelshäuser Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    S. Arcelli Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    R. Arceo Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    A. Arend Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    N. Armesto Departamento de Física de Partículas and IGFAE, Universidad de Santiago de Compostela, Santiago de Compostela, Spain    R. Arnaldi Sezione INFN, Turin, Italy    T. Aronsson Yale University, New Haven, CT, United States    I.C. Arsene 44endnote: 4Now at Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany Department of Physics, University of Oslo, Oslo, Norway    A. Asryan V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    A. Augustinus European Organization for Nuclear Research (CERN), Geneva, Switzerland    R. Averbeck Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    T.C. Awes Oak Ridge National Laboratory, Oak Ridge, TN, United States    J. Äystö Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    M.D. Azmi Department of Physics Aligarh Muslim University, Aligarh, India    S. Bablok Department of Physics and Technology, University of Bergen, Bergen, Norway    M. Bach Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    A. Badalà Sezione INFN, Catania, Italy    Y.W. Baek 11endnote: 1Also at Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France Gangneung-Wonju National University, Gangneung, South Korea    S. Bagnasco Sezione INFN, Turin, Italy    R. Bailhache 55endnote: 5Now at Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    R. Bala Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    A. Baldisseri Commissariat à l’Energie Atomique, IRFU, Saclay, France    A. Baldit Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    J. Bán Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia    R. Barbera Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy    G.G. Barnaföldi KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    L.S. Barnby School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    V. Barret Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    J. Bartke The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland    F. Barile Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    M. Basile Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    V. Basmanov Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    N. Bastid Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    B. Bathen Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    G. Batigne SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    B. Batyunya Joint Institute for Nuclear Research (JINR), Dubna, Russia    C. Baumann 55endnote: 5Now at Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    I.G. Bearden Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    B. Becker 66endnote: 6Now at Physics Department, University of Cape Town, iThemba Laboratories, Cape Town, South Africa Sezione INFN, Cagliari, Italy    I. Belikov Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France    R. Bellwied Wayne State University, Detroit, MI, United States    E. Belmont-Moreno Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    A. Belogianni Physics Department, University of Athens, Athens, Greece    L. Benhabib SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    S. Beole Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    I. Berceanu National Institute for Physics and Nuclear Engineering, Bucharest, Romania    A. Bercuci 77endnote: 7Now at National Institute for Physics and Nuclear Engineering, Bucharest, Romania Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    E. Berdermann Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    Y. Berdnikov Petersburg Nuclear Physics Institute, Gatchina, Russia    L. Betev European Organization for Nuclear Research (CERN), Geneva, Switzerland    A. Bhasin Physics Department, University of Jammu, Jammu, India    A.K. Bhati Physics Department, Panjab University, Chandigarh, India    L. Bianchi Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    N. Bianchi Laboratori Nazionali di Frascati, INFN, Frascati, Italy    C. Bianchin Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    J. Bielčík Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    J. Bielčíková Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež u Prahy, Czech Republic    A. Bilandzic Nikhef, National Institute for Subatomic Physics, Amsterdam, Netherlands    L. Bimbot Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    E. Biolcati Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    A. Blanc Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    F. Blanco 88endnote: 8Also at University of Houston, Houston, TX, United States Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy    F. Blanco Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain    D. Blau Russian Research Centre Kurchatov Institute, Moscow, Russia    C. Blume Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    M. Boccioli European Organization for Nuclear Research (CERN), Geneva, Switzerland    N. Bock Department of Physics, Ohio State University, Columbus, OH, United States    A. Bogdanov Moscow Engineering Physics Institute, Moscow, Russia    H. Bøggild Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    M. Bogolyubsky Institute for High Energy Physics, Protvino, Russia    J. Bohm Yonsei University, Seoul, South Korea    L. Boldizsár KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    M. Bombara Faculty of Science, P.J. Šafárik University, Košice, Slovakia    C. Bombonati 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    M. Bondila Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    H. Borel Commissariat à l’Energie Atomique, IRFU, Saclay, France    A. Borisov Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine    C. Bortolin 4040endnote: 40Also at Dipartimento di Fisica dell´Università, Udine, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    S. Bose Saha Institute of Nuclear Physics, Kolkata, India    L. Bosisio Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy    F. Bossú Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    M. Botje Nikhef, National Institute for Subatomic Physics, Amsterdam, Netherlands    S. Böttger Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    G. Bourdaud SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    B. Boyer Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    M. Braun V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    P. Braun-Munzinger 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany    L. Bravina Department of Physics, University of Oslo, Oslo, Norway    M. Bregant 1111endnote: 11Now at Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy    T. Breitner Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    G. Bruckner European Organization for Nuclear Research (CERN), Geneva, Switzerland    R. Brun European Organization for Nuclear Research (CERN), Geneva, Switzerland    E. Bruna Yale University, New Haven, CT, United States    G.E. Bruno Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    D. Budnikov Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    H. Buesching Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    P. Buncic European Organization for Nuclear Research (CERN), Geneva, Switzerland    O. Busch Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    Z. Buthelezi Physics Department, University of Cape Town, iThemba Laboratories, Cape Town, South Africa    D. Caffarri Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    X. Cai Hua-Zhong Normal University, Wuhan, China    H. Caines Yale University, New Haven, CT, United States    E. Calvo Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru    E. Camacho Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico    P. Camerini Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy    M. Campbell European Organization for Nuclear Research (CERN), Geneva, Switzerland    V. Canoa Roman European Organization for Nuclear Research (CERN), Geneva, Switzerland    G.P. Capitani Laboratori Nazionali di Frascati, INFN, Frascati, Italy    G. Cara Romeo Sezione INFN, Bologna, Italy    F. Carena European Organization for Nuclear Research (CERN), Geneva, Switzerland    W. Carena European Organization for Nuclear Research (CERN), Geneva, Switzerland    F. Carminati European Organization for Nuclear Research (CERN), Geneva, Switzerland    A. Casanova Díaz Laboratori Nazionali di Frascati, INFN, Frascati, Italy    M. Caselle European Organization for Nuclear Research (CERN), Geneva, Switzerland    J. Castillo Castellanos Commissariat à l’Energie Atomique, IRFU, Saclay, France    J.F. Castillo Hernandez Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    V. Catanescu National Institute for Physics and Nuclear Engineering, Bucharest, Romania    E. Cattaruzza Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy    C. Cavicchioli European Organization for Nuclear Research (CERN), Geneva, Switzerland    P. Cerello Sezione INFN, Turin, Italy    V. Chambert Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    B. Chang Yonsei University, Seoul, South Korea    S. Chapeland European Organization for Nuclear Research (CERN), Geneva, Switzerland    A. Charpy Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    J.L. Charvet Commissariat à l’Energie Atomique, IRFU, Saclay, France    S. Chattopadhyay Saha Institute of Nuclear Physics, Kolkata, India    S. Chattopadhyay Variable Energy Cyclotron Centre, Kolkata, India    M. Cherney Physics Department, Creighton University, Omaha, NE, United States    C. Cheshkov European Organization for Nuclear Research (CERN), Geneva, Switzerland    B. Cheynis Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France    E. Chiavassa Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    V. Chibante Barroso European Organization for Nuclear Research (CERN), Geneva, Switzerland    D.D. Chinellato Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil    P. Chochula European Organization for Nuclear Research (CERN), Geneva, Switzerland    K. Choi Pusan National University, Pusan, South Korea    M. Chojnacki Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    P. Christakoglou Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    C.H. Christensen Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    P. Christiansen Division of Experimental High Energy Physics, University of Lund, Lund, Sweden    T. Chujo University of Tsukuba, Tsukuba, Japan    F. Chuman Hiroshima University, Hiroshima, Japan    C. Cicalo Sezione INFN, Cagliari, Italy    L. Cifarelli Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    F. Cindolo Sezione INFN, Bologna, Italy    J. Cleymans Physics Department, University of Cape Town, iThemba Laboratories, Cape Town, South Africa    O. Cobanoglu Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    J.-P. Coffin Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France    S. Coli Sezione INFN, Turin, Italy    A. Colla European Organization for Nuclear Research (CERN), Geneva, Switzerland    G. Conesa Balbastre Laboratori Nazionali di Frascati, INFN, Frascati, Italy    Z. Conesa del Valle 1212endnote: 12Now at Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    E.S. Conner Zentrum für Technologietransfer und Telekommunikation (ZTT), Fachhochschule Worms, Worms, Germany    P. Constantin Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    G. Contin 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy    J.G. Contreras Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico    Y. Corrales Morales Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    T.M. Cormier Wayne State University, Detroit, MI, United States    P. Cortese Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy    I. Cortés Maldonado Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    M.R. Cosentino Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil    F. Costa European Organization for Nuclear Research (CERN), Geneva, Switzerland    M.E. Cotallo Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain    E. Crescio Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico    P. Crochet Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    E. Cuautle Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico    L. Cunqueiro Laboratori Nazionali di Frascati, INFN, Frascati, Italy    J. Cussonneau SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    A. Dainese Sezione INFN, Padova, Italy    H.H. Dalsgaard Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    A. Danu Institute of Space Sciences (ISS), Bucharest, Romania    I. Das Saha Institute of Nuclear Physics, Kolkata, India    A. Dash Institute of Physics, Bhubaneswar, India    S. Dash Institute of Physics, Bhubaneswar, India    G.O.V. de Barros Universidade de São Paulo (USP), São Paulo, Brazil    A. De Caro Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Sezione INFN, Salerno, Italy    G. de Cataldo Sezione INFN, Bari, Italy    J. de Cuveland 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    A. De Falco Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy    M. De Gaspari Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    J. de Groot European Organization for Nuclear Research (CERN), Geneva, Switzerland    D. De Gruttola Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Sezione INFN, Salerno, Italy    N. De Marco Sezione INFN, Turin, Italy    S. De Pasquale Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Sezione INFN, Salerno, Italy    R. De Remigis Sezione INFN, Turin, Italy    R. de Rooij Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    G. de Vaux Physics Department, University of Cape Town, iThemba Laboratories, Cape Town, South Africa    H. Delagrange SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    Y. Delgado Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru    G. Dellacasa Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy    A. Deloff Soltan Institute for Nuclear Studies, Warsaw, Poland    V. Demanov Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    E. Dénes KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    A. Deppman Universidade de São Paulo (USP), São Paulo, Brazil    G. D’Erasmo Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    D. Derkach V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    A. Devaux Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    D. Di Bari Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    C. Di Giglio 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    S. Di Liberto Sezione INFN, Rome, Italy    A. Di Mauro European Organization for Nuclear Research (CERN), Geneva, Switzerland    P. Di Nezza Laboratori Nazionali di Frascati, INFN, Frascati, Italy    M. Dialinas SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    L. Díaz Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico    R. Díaz Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    T. Dietel Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    R. Divià European Organization for Nuclear Research (CERN), Geneva, Switzerland    Ø. Djuvsland Department of Physics and Technology, University of Bergen, Bergen, Norway    V. Dobretsov Russian Research Centre Kurchatov Institute, Moscow, Russia    A. Dobrin Division of Experimental High Energy Physics, University of Lund, Lund, Sweden    T. Dobrowolski Soltan Institute for Nuclear Studies, Warsaw, Poland    B. Dönigus Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    I. Domínguez Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico    D.M.M. Don O. Dordic University of Houston, Houston, TX, United States Department of Physics, University of Oslo, Oslo, Norway    A.K. Dubey Variable Energy Cyclotron Centre, Kolkata, India    J. Dubuisson European Organization for Nuclear Research (CERN), Geneva, Switzerland    L. Ducroux Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France    P. Dupieux Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    A.K. Dutta Majumdar Saha Institute of Nuclear Physics, Kolkata, India    M.R. Dutta Majumdar Variable Energy Cyclotron Centre, Kolkata, India    D. Elia Sezione INFN, Bari, Italy    D. Emschermann 1414endnote: 14Now at Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany H. Engel Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    A. Enokizono Oak Ridge National Laboratory, Oak Ridge, TN, United States    B. Espagnon Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    M. Estienne SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    S. Esumi University of Tsukuba, Tsukuba, Japan    D. Evans School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    S. Evrard European Organization for Nuclear Research (CERN), Geneva, Switzerland    G. Eyyubova Department of Physics, University of Oslo, Oslo, Norway    C.W. Fabjan 1515endnote: 15Now at: University of Technology and Austrian Academy of Sciences, Vienna, Austria European Organization for Nuclear Research (CERN), Geneva, Switzerland    D. Fabris Sezione INFN, Padova, Italy    J. Faivre Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, France    D. Falchieri Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    A. Fantoni Laboratori Nazionali di Frascati, INFN, Frascati, Italy    M. Fasel Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    O. Fateev Joint Institute for Nuclear Research (JINR), Dubna, Russia    R. Fearick Physics Department, University of Cape Town, iThemba Laboratories, Cape Town, South Africa    A. Fedunov Joint Institute for Nuclear Research (JINR), Dubna, Russia    D. Fehlker Department of Physics and Technology, University of Bergen, Bergen, Norway    V. Fekete Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia    D. Felea Institute of Space Sciences (ISS), Bucharest, Romania    B. Fenton-Olsen 1616endnote: 16Also at Lawrence Livermore National Laboratory, Livermore, CA, United States Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    G. Feofilov V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    A. Fernández Téllez Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    E.G. Ferreiro Departamento de Física de Partículas and IGFAE, Universidad de Santiago de Compostela, Santiago de Compostela, Spain    A. Ferretti Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    R. Ferretti 1717endnote: 17Also at European Organization for Nuclear Research (CERN), Geneva, Switzerland Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy    M.A.S. Figueredo Universidade de São Paulo (USP), São Paulo, Brazil    S. Filchagin Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    R. Fini Sezione INFN, Bari, Italy    F.M. Fionda Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    E.M. Fiore Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    M. Floris 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy    Z. Fodor KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    S. Foertsch Physics Department, University of Cape Town, iThemba Laboratories, Cape Town, South Africa    P. Foka Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    S. Fokin Russian Research Centre Kurchatov Institute, Moscow, Russia    F. Formenti European Organization for Nuclear Research (CERN), Geneva, Switzerland    E. Fragiacomo Sezione INFN, Trieste, Italy    M. Fragkiadakis Physics Department, University of Athens, Athens, Greece    U. Frankenfeld Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    A. Frolov Budker Institute for Nuclear Physics, Novosibirsk, Russia    U. Fuchs European Organization for Nuclear Research (CERN), Geneva, Switzerland    F. Furano European Organization for Nuclear Research (CERN), Geneva, Switzerland    C. Furget Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, France    M. Fusco Girard Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Sezione INFN, Salerno, Italy    J.J. Gaardhøje Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    S. Gadrat Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, France    M. Gagliardi Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    A. Gago Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru    M. Gallio Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    P. Ganoti Physics Department, University of Athens, Athens, Greece    M.S. Ganti Variable Energy Cyclotron Centre, Kolkata, India    C. Garabatos Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    C. García Trapaga Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    J. Gebelein Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    R. Gemme Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy    M. Germain SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    A. Gheata European Organization for Nuclear Research (CERN), Geneva, Switzerland    M. Gheata European Organization for Nuclear Research (CERN), Geneva, Switzerland    B. Ghidini Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    P. Ghosh Variable Energy Cyclotron Centre, Kolkata, India    G. Giraudo Sezione INFN, Turin, Italy    P. Giubellino Sezione INFN, Turin, Italy    E. Gladysz-Dziadus The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland    R. Glasow 1919endnote: 19Deceased Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    P. Glässel Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    A. Glenn Lawrence Livermore National Laboratory, Livermore, CA, United States    R. Gómez Jiménez Universidad Autónoma de Sinaloa, Culiacán, Mexico    H. González Santos Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    L.H. González-Trueba Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    P. González-Zamora Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain    S. Gorbunov 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    Y. Gorbunov Physics Department, Creighton University, Omaha, NE, United States    S. Gotovac Technical University of Split FESB, Split, Croatia    H. Gottschlag Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    V. Grabski Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    R. Grajcarek Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    A. Grelli Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    A. Grigoras European Organization for Nuclear Research (CERN), Geneva, Switzerland    C. Grigoras European Organization for Nuclear Research (CERN), Geneva, Switzerland    V. Grigoriev Moscow Engineering Physics Institute, Moscow, Russia    A. Grigoryan Yerevan Physics Institute, Yerevan, Armenia    S. Grigoryan Joint Institute for Nuclear Research (JINR), Dubna, Russia    B. Grinyov Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine    N. Grion Sezione INFN, Trieste, Italy    P. Gros Division of Experimental High Energy Physics, University of Lund, Lund, Sweden    J.F. Grosse-Oetringhaus European Organization for Nuclear Research (CERN), Geneva, Switzerland    J.-Y. Grossiord Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France    R. Grosso Sezione INFN, Padova, Italy    F. Guber Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    R. Guernane Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, France    C. Guerra Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru    B. Guerzoni Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    K. Gulbrandsen Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    H. Gulkanyan Yerevan Physics Institute, Yerevan, Armenia    T. Gunji University of Tokyo, Tokyo, Japan    A. Gupta Physics Department, University of Jammu, Jammu, India    R. Gupta Physics Department, University of Jammu, Jammu, India    H.-A. Gustafsson 1919endnote: 19Deceased Division of Experimental High Energy Physics, University of Lund, Lund, Sweden    H. Gutbrod Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    Ø. Haaland Department of Physics and Technology, University of Bergen, Bergen, Norway    C. Hadjidakis Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    M. Haiduc Institute of Space Sciences (ISS), Bucharest, Romania    H. Hamagaki University of Tokyo, Tokyo, Japan    G. Hamar KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    J. Hamblen University of Tennessee, Knoxville, TN, United States    B.H. Han Department of Physics, Sejong University, Seoul, South Korea    J.W. Harris Yale University, New Haven, CT, United States    M. Hartig Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    A. Harutyunyan Yerevan Physics Institute, Yerevan, Armenia    D. Hasch Laboratori Nazionali di Frascati, INFN, Frascati, Italy    D. Hasegan Institute of Space Sciences (ISS), Bucharest, Romania    D. Hatzifotiadou Sezione INFN, Bologna, Italy    A. Hayrapetyan Yerevan Physics Institute, Yerevan, Armenia    M. Heide Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    M. Heinz Yale University, New Haven, CT, United States    H. Helstrup Faculty of Engineering, Bergen University College, Bergen, Norway    A. Herghelegiu National Institute for Physics and Nuclear Engineering, Bucharest, Romania    C. Hernández Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    G. Herrera Corral Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico    N. Herrmann Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    K.F. Hetland Faculty of Engineering, Bergen University College, Bergen, Norway    B. Hicks Yale University, New Haven, CT, United States    A. Hiei Hiroshima University, Hiroshima, Japan    P.T. Hille 2020endnote: 20Now at Yale University, New Haven, CT, United States Department of Physics, University of Oslo, Oslo, Norway    B. Hippolyte Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France    T. Horaguchi 2121endnote: 21Now at University of Tsukuba, Tsukuba, Japan Hiroshima University, Hiroshima, Japan    Y. Hori University of Tokyo, Tokyo, Japan    P. Hristov European Organization for Nuclear Research (CERN), Geneva, Switzerland    I. Hřivnáčová Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    S. Hu China Institute of Atomic Energy, Beijing, China    M. Huang Department of Physics and Technology, University of Bergen, Bergen, Norway    S. Huber Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    T.J. Humanic Department of Physics, Ohio State University, Columbus, OH, United States    D. Hutter Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    D.S. Hwang Department of Physics, Sejong University, Seoul, South Korea    R. Ichou SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    R. Ilkaev Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    I. Ilkiv Soltan Institute for Nuclear Studies, Warsaw, Poland    M. Inaba University of Tsukuba, Tsukuba, Japan    P.G. Innocenti European Organization for Nuclear Research (CERN), Geneva, Switzerland    M. Ippolitov Russian Research Centre Kurchatov Institute, Moscow, Russia    M. Irfan Department of Physics Aligarh Muslim University, Aligarh, India    C. Ivan Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    A. Ivanov V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    M. Ivanov Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    V. Ivanov Petersburg Nuclear Physics Institute, Gatchina, Russia    T. Iwasaki Hiroshima University, Hiroshima, Japan    A. Jachołkowski European Organization for Nuclear Research (CERN), Geneva, Switzerland    P. Jacobs Lawrence Berkeley National Laboratory, Berkeley, CA, United States    L. Jančurová Joint Institute for Nuclear Research (JINR), Dubna, Russia    S. Jangal Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France    R. Janik Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia    C. Jena Institute of Physics, Bhubaneswar, India    S. Jena Indian Institute of Technology, Mumbai, India    L. Jirden European Organization for Nuclear Research (CERN), Geneva, Switzerland    G.T. Jones School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    P.G. Jones School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    P. Jovanović School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    H. Jung Gangneung-Wonju National University, Gangneung, South Korea    W. Jung Gangneung-Wonju National University, Gangneung, South Korea    A. Jusko School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    A.B. Kaidalov Institute for Theoretical and Experimental Physics, Moscow, Russia    S. Kalcher 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    P. Kaliňák Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia    M. Kalisky Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    T. Kalliokoski Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    A. Kalweit Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany    A. Kamal Department of Physics Aligarh Muslim University, Aligarh, India    R. Kamermans Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    K. Kanaki Department of Physics and Technology, University of Bergen, Bergen, Norway    E. Kang Gangneung-Wonju National University, Gangneung, South Korea    J.H. Kang Yonsei University, Seoul, South Korea    J. Kapitan Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež u Prahy, Czech Republic    V. Kaplin Moscow Engineering Physics Institute, Moscow, Russia    S. Kapusta European Organization for Nuclear Research (CERN), Geneva, Switzerland    O. Karavichev Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    T. Karavicheva Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    E. Karpechev Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    A. Kazantsev Russian Research Centre Kurchatov Institute, Moscow, Russia    U. Kebschull Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    R. Keidel Zentrum für Technologietransfer und Telekommunikation (ZTT), Fachhochschule Worms, Worms, Germany    M.M. Khan Department of Physics Aligarh Muslim University, Aligarh, India    S.A. Khan Variable Energy Cyclotron Centre, Kolkata, India    A. Khanzadeev Petersburg Nuclear Physics Institute, Gatchina, Russia    Y. Kharlov Institute for High Energy Physics, Protvino, Russia    D. Kikola Warsaw University of Technology, Warsaw, Poland    B. Kileng Faculty of Engineering, Bergen University College, Bergen, Norway    D.J. Kim Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    D.S. Kim Gangneung-Wonju National University, Gangneung, South Korea    D.W. Kim Gangneung-Wonju National University, Gangneung, South Korea    H.N. Kim Gangneung-Wonju National University, Gangneung, South Korea    J. Kim Institute for High Energy Physics, Protvino, Russia    J.H. Kim Department of Physics, Sejong University, Seoul, South Korea    J.S. Kim Gangneung-Wonju National University, Gangneung, South Korea    M. Kim Gangneung-Wonju National University, Gangneung, South Korea    M. Kim Yonsei University, Seoul, South Korea    S.H. Kim Gangneung-Wonju National University, Gangneung, South Korea    S. Kim Department of Physics, Sejong University, Seoul, South Korea    Y. Kim Yonsei University, Seoul, South Korea    S. Kirsch European Organization for Nuclear Research (CERN), Geneva, Switzerland    I. Kisel 44endnote: 4Now at Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    S. Kiselev Institute for Theoretical and Experimental Physics, Moscow, Russia    A. Kisiel 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Department of Physics, Ohio State University, Columbus, OH, United States    J.L. Klay California Polytechnic State University, San Luis Obispo, CA, United States    J. Klein Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    C. Klein-Bösing 1414endnote: 14Now at Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany European Organization for Nuclear Research (CERN), Geneva, Switzerland    M. Kliemant Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    A. Klovning Department of Physics and Technology, University of Bergen, Bergen, Norway    A. Kluge European Organization for Nuclear Research (CERN), Geneva, Switzerland    M.L. Knichel Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    S. Kniege Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    K. Koch Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    R. Kolevatov Department of Physics, University of Oslo, Oslo, Norway    A. Kolojvari V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    V. Kondratiev V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    N. Kondratyeva Moscow Engineering Physics Institute, Moscow, Russia    A. Konevskih Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    E. Kornaś The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland    R. Kour School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    M. Kowalski The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland    S. Kox Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, France    K. Kozlov Russian Research Centre Kurchatov Institute, Moscow, Russia    J. Kral 1111endnote: 11Now at Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    I. Králik Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia    F. Kramer Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    I. Kraus 44endnote: 4Now at Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany    A. Kravčáková Faculty of Science, P.J. Šafárik University, Košice, Slovakia    T. Krawutschke Fachhochschule Köln, Köln, Germany    M. Krivda School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    D. Krumbhorn Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    M. Krus Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    E. Kryshen Petersburg Nuclear Physics Institute, Gatchina, Russia    M. Krzewicki Nikhef, National Institute for Subatomic Physics, Amsterdam, Netherlands    Y. Kucheriaev Russian Research Centre Kurchatov Institute, Moscow, Russia    C. Kuhn Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France    P.G. Kuijer Nikhef, National Institute for Subatomic Physics, Amsterdam, Netherlands    L. Kumar Physics Department, Panjab University, Chandigarh, India    N. Kumar Physics Department, Panjab University, Chandigarh, India    R. Kupczak Warsaw University of Technology, Warsaw, Poland    P. Kurashvili Soltan Institute for Nuclear Studies, Warsaw, Poland    A. Kurepin Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    A.N. Kurepin Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    A. Kuryakin Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    S. Kushpil Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež u Prahy, Czech Republic    V. Kushpil Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež u Prahy, Czech Republic    M. Kutouski Joint Institute for Nuclear Research (JINR), Dubna, Russia    H. Kvaerno Department of Physics, University of Oslo, Oslo, Norway    M.J. Kweon Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    Y. Kwon Yonsei University, Seoul, South Korea    P. La Rocca 2222endnote: 22Also at Centro Fermi – Centro Studi e Ricerche e Museo Storico della Fisica “Enrico Fermi”, Rome, Italy Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy    F. Lackner European Organization for Nuclear Research (CERN), Geneva, Switzerland    P. Ladrón de Guevara Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain    V. Lafage Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    C. Lal Physics Department, University of Jammu, Jammu, India    C. Lara Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    D.T. Larsen Department of Physics and Technology, University of Bergen, Bergen, Norway    G. Laurenti Sezione INFN, Bologna, Italy    C. Lazzeroni School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    Y. Le Bornec Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    N. Le Bris SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    H. Lee Pusan National University, Pusan, South Korea    K.S. Lee Gangneung-Wonju National University, Gangneung, South Korea    S.C. Lee Gangneung-Wonju National University, Gangneung, South Korea    F. Lefèvre SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    M. Lenhardt SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    L. Leistam European Organization for Nuclear Research (CERN), Geneva, Switzerland    J. Lehnert Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    V. Lenti Sezione INFN, Bari, Italy    H. León Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    I. León Monzón Universidad Autónoma de Sinaloa, Culiacán, Mexico    H. León Vargas Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    P. Lévai KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    X. Li China Institute of Atomic Energy, Beijing, China    Y. Li China Institute of Atomic Energy, Beijing, China    R. Lietava School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    S. Lindal Department of Physics, University of Oslo, Oslo, Norway    V. Lindenstruth 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    C. Lippmann European Organization for Nuclear Research (CERN), Geneva, Switzerland    M.A. Lisa Department of Physics, Ohio State University, Columbus, OH, United States    L. Liu Department of Physics and Technology, University of Bergen, Bergen, Norway    V. Loginov Moscow Engineering Physics Institute, Moscow, Russia    S. Lohn European Organization for Nuclear Research (CERN), Geneva, Switzerland    X. Lopez Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    M. López Noriega Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    R. López-Ramírez Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    E. López Torres Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba    G. Løvhøiden Department of Physics, University of Oslo, Oslo, Norway    A. Lozea Feijo Soares Universidade de São Paulo (USP), São Paulo, Brazil    S. Lu China Institute of Atomic Energy, Beijing, China    M. Lunardon Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    G. Luparello Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    L. Luquin SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    J.-R. Lutz Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France    K. Ma Hua-Zhong Normal University, Wuhan, China    R. Ma Yale University, New Haven, CT, United States    D.M. Madagodahettige-Don University of Houston, Houston, TX, United States    A. Maevskaya Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    M. Mager 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany    D.P. Mahapatra Institute of Physics, Bhubaneswar, India    A. Maire Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France    I. Makhlyueva European Organization for Nuclear Research (CERN), Geneva, Switzerland    D. Mal’Kevich Institute for Theoretical and Experimental Physics, Moscow, Russia    M. Malaev Petersburg Nuclear Physics Institute, Gatchina, Russia    K.J. Malagalage Physics Department, Creighton University, Omaha, NE, United States    I. Maldonado Cervantes Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico    M. Malek Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    T. Malkiewicz Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    P. Malzacher Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    A. Mamonov Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    L. Manceau Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    L. Mangotra Physics Department, University of Jammu, Jammu, India    V. Manko Russian Research Centre Kurchatov Institute, Moscow, Russia    F. Manso Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    V. Manzari Sezione INFN, Bari, Italy    Y. Mao 2424endnote: 24Also at Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, France Hua-Zhong Normal University, Wuhan, China    J. Mareš Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic    G.V. Margagliotti Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy    A. Margotti Sezione INFN, Bologna, Italy    A. Marín Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    I. Martashvili University of Tennessee, Knoxville, TN, United States    P. Martinengo European Organization for Nuclear Research (CERN), Geneva, Switzerland    M.I. Martínez Hernández Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    A. Martínez Davalos Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    G. Martínez García SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    Y. Maruyama Hiroshima University, Hiroshima, Japan    A. Marzari Chiesa Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    S. Masciocchi Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    M. Masera Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    M. Masetti Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    A. Masoni Sezione INFN, Cagliari, Italy    L. Massacrier Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France    M. Mastromarco Sezione INFN, Bari, Italy    A. Mastroserio 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    Z.L. Matthews School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    A. Matyja 3434endnote: 34Now at SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland    D. Mayani Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico    G. Mazza Sezione INFN, Turin, Italy    M.A. Mazzoni Sezione INFN, Rome, Italy    F. Meddi Dipartimento di Fisica dell’Università ‘La Sapienza’ and Sezione INFN, Rome, Italy    A. Menchaca-Rocha Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    P. Mendez Lorenzo European Organization for Nuclear Research (CERN), Geneva, Switzerland    M. Meoni European Organization for Nuclear Research (CERN), Geneva, Switzerland    J. Mercado Pérez Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    P. Mereu Sezione INFN, Turin, Italy    Y. Miake University of Tsukuba, Tsukuba, Japan    A. Michalon Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France    N. Miftakhov Petersburg Nuclear Physics Institute, Gatchina, Russia    L. Milano Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    J. Milosevic Department of Physics, University of Oslo, Oslo, Norway    F. Minafra Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    A. Mischke Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    D. Miśkowiec Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    C. Mitu Institute of Space Sciences (ISS), Bucharest, Romania    K. Mizoguchi Hiroshima University, Hiroshima, Japan    J. Mlynarz Wayne State University, Detroit, MI, United States    B. Mohanty Variable Energy Cyclotron Centre, Kolkata, India    L. Molnar 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    M.M. Mondal Variable Energy Cyclotron Centre, Kolkata, India    L. Montaño Zetina 2525endnote: 25Now at Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico    M. Monteno Sezione INFN, Turin, Italy    E. Montes Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain    M. Morando Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    S. Moretto Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    A. Morsch European Organization for Nuclear Research (CERN), Geneva, Switzerland    T. Moukhanova Russian Research Centre Kurchatov Institute, Moscow, Russia    V. Muccifora Laboratori Nazionali di Frascati, INFN, Frascati, Italy    E. Mudnic Technical University of Split FESB, Split, Croatia    S. Muhuri Variable Energy Cyclotron Centre, Kolkata, India    H. Müller European Organization for Nuclear Research (CERN), Geneva, Switzerland    M.G. Munhoz Universidade de São Paulo (USP), São Paulo, Brazil    J. Munoz Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    L. Musa European Organization for Nuclear Research (CERN), Geneva, Switzerland    A. Musso Sezione INFN, Turin, Italy    B.K. Nandi Indian Institute of Technology, Mumbai, India    R. Nania Sezione INFN, Bologna, Italy    E. Nappi Sezione INFN, Bari, Italy    F. Navach Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    S. Navin School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    T.K. Nayak Variable Energy Cyclotron Centre, Kolkata, India    S. Nazarenko Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    G. Nazarov Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    A. Nedosekin Institute for Theoretical and Experimental Physics, Moscow, Russia    F. Nendaz Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France    J. Newby Lawrence Livermore National Laboratory, Livermore, CA, United States    A. Nianine Russian Research Centre Kurchatov Institute, Moscow, Russia    M. Nicassio 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Sezione INFN, Bari, Italy    B.S. Nielsen Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    S. Nikolaev Russian Research Centre Kurchatov Institute, Moscow, Russia    V. Nikolic Rudjer Bošković Institute, Zagreb, Croatia    S. Nikulin Russian Research Centre Kurchatov Institute, Moscow, Russia    V. Nikulin Petersburg Nuclear Physics Institute, Gatchina, Russia    B.S. Nilsen  Physics Department, Creighton University, Omaha, NE, United States    M.S. Nilsson Department of Physics, University of Oslo, Oslo, Norway    F. Noferini Sezione INFN, Bologna, Italy    P. Nomokonov Joint Institute for Nuclear Research (JINR), Dubna, Russia    G. Nooren Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    N. Novitzky Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    A. Nyatha Indian Institute of Technology, Mumbai, India    C. Nygaard Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    A. Nyiri Department of Physics, University of Oslo, Oslo, Norway    J. Nystrand Department of Physics and Technology, University of Bergen, Bergen, Norway    A. Ochirov V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    G. Odyniec Lawrence Berkeley National Laboratory, Berkeley, CA, United States    H. Oeschler Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany    M. Oinonen Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    K. Okada University of Tokyo, Tokyo, Japan    Y. Okada Hiroshima University, Hiroshima, Japan    M. Oldenburg European Organization for Nuclear Research (CERN), Geneva, Switzerland    J. Oleniacz Warsaw University of Technology, Warsaw, Poland    C. Oppedisano Sezione INFN, Turin, Italy    F. Orsini Commissariat à l’Energie Atomique, IRFU, Saclay, France    A. Ortiz Velasquez Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico    G. Ortona Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    A. Oskarsson Division of Experimental High Energy Physics, University of Lund, Lund, Sweden    F. Osmic European Organization for Nuclear Research (CERN), Geneva, Switzerland    L. Österman Division of Experimental High Energy Physics, University of Lund, Lund, Sweden    P. Ostrowski Warsaw University of Technology, Warsaw, Poland    I. Otterlund Division of Experimental High Energy Physics, University of Lund, Lund, Sweden    J. Otwinowski Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    G. Øvrebekk Department of Physics and Technology, University of Bergen, Bergen, Norway    K. Oyama Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    K. Ozawa University of Tokyo, Tokyo, Japan    Y. Pachmayer Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    M. Pachr Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    F. Padilla Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    P. Pagano Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Sezione INFN, Salerno, Italy    G. Paić Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico    F. Painke Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    C. Pajares Departamento de Física de Partículas and IGFAE, Universidad de Santiago de Compostela, Santiago de Compostela, Spain    S. Pal 2727endnote: 27Now at Commissariat à l’Energie Atomique, IRFU, Saclay, France Saha Institute of Nuclear Physics, Kolkata, India    S.K. Pal Variable Energy Cyclotron Centre, Kolkata, India    A. Palaha School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    A. Palmeri Sezione INFN, Catania, Italy    R. Panse Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    V. Papikyan Yerevan Physics Institute, Yerevan, Armenia    G.S. Pappalardo Sezione INFN, Catania, Italy    W.J. Park Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    B. Pastirčák Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia    C. Pastore Sezione INFN, Bari, Italy    V. Paticchio Sezione INFN, Bari, Italy    A. Pavlinov Wayne State University, Detroit, MI, United States    T. Pawlak Warsaw University of Technology, Warsaw, Poland    T. Peitzmann Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    A. Pepato Sezione INFN, Padova, Italy    H. Pereira Commissariat à l’Energie Atomique, IRFU, Saclay, France    D. Peressounko Russian Research Centre Kurchatov Institute, Moscow, Russia    C. Pérez Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru    D. Perini European Organization for Nuclear Research (CERN), Geneva, Switzerland    D. Perrino 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    W. Peryt Warsaw University of Technology, Warsaw, Poland    J. Peschek 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    A. Pesci Sezione INFN, Bologna, Italy    V. Peskov 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico    Y. Pestov Budker Institute for Nuclear Physics, Novosibirsk, Russia    A.J. Peters European Organization for Nuclear Research (CERN), Geneva, Switzerland    V. Petráček Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    A. Petridis 1919endnote: 19Deceased Physics Department, University of Athens, Athens, Greece    M. Petris National Institute for Physics and Nuclear Engineering, Bucharest, Romania    P. Petrov School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    M. Petrovici National Institute for Physics and Nuclear Engineering, Bucharest, Romania    C. Petta Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy    J. Peyré Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    S. Piano Sezione INFN, Trieste, Italy    A. Piccotti Sezione INFN, Turin, Italy    M. Pikna Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia    P. Pillot SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    O. Pinazza 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Sezione INFN, Bologna, Italy    L. Pinsky University of Houston, Houston, TX, United States    N. Pitz Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    F. Piuz European Organization for Nuclear Research (CERN), Geneva, Switzerland    R. Platt School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    M. Płoskoń Lawrence Berkeley National Laboratory, Berkeley, CA, United States    J. Pluta Warsaw University of Technology, Warsaw, Poland    T. Pocheptsov 2828endnote: 28Also at Department of Physics, University of Oslo, Oslo, Norway Joint Institute for Nuclear Research (JINR), Dubna, Russia    S. Pochybova KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    P.L.M. Podesta Lerma Universidad Autónoma de Sinaloa, Culiacán, Mexico    F. Poggio Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    M.G. Poghosyan Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    K. Polák Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic    B. Polichtchouk Institute for High Energy Physics, Protvino, Russia    P. Polozov Institute for Theoretical and Experimental Physics, Moscow, Russia    V. Polyakov Petersburg Nuclear Physics Institute, Gatchina, Russia    B. Pommeresch Department of Physics and Technology, University of Bergen, Bergen, Norway    A. Pop National Institute for Physics and Nuclear Engineering, Bucharest, Romania    F. Posa Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    V. Pospíšil Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    B. Potukuchi Physics Department, University of Jammu, Jammu, India    J. Pouthas Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    S.K. Prasad Variable Energy Cyclotron Centre, Kolkata, India    R. Preghenella 2222endnote: 22Also at Centro Fermi – Centro Studi e Ricerche e Museo Storico della Fisica “Enrico Fermi”, Rome, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    F. Prino Sezione INFN, Turin, Italy    C.A. Pruneau Wayne State University, Detroit, MI, United States    I. Pshenichnov Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    G. Puddu Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy    P. Pujahari Indian Institute of Technology, Mumbai, India    A. Pulvirenti Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy    A. Punin Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    V. Punin Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    M. Putiš Faculty of Science, P.J. Šafárik University, Košice, Slovakia    J. Putschke Yale University, New Haven, CT, United States    E. Quercigh European Organization for Nuclear Research (CERN), Geneva, Switzerland    A. Rachevski Sezione INFN, Trieste, Italy    A. Rademakers European Organization for Nuclear Research (CERN), Geneva, Switzerland    S. Radomski Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    T.S. Räihä Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    J. Rak Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    A. Rakotozafindrabe Commissariat à l’Energie Atomique, IRFU, Saclay, France    L. Ramello Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy    A. Ramírez Reyes Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico    M. Rammler Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    R. Raniwala Physics Department, University of Rajasthan, Jaipur, India    S. Raniwala Physics Department, University of Rajasthan, Jaipur, India    S.S. Räsänen Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    I. Rashevskaya Sezione INFN, Trieste, Italy    S. Rath Institute of Physics, Bhubaneswar, India    K.F. Read University of Tennessee, Knoxville, TN, United States    J.S. Real Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier, CNRS-IN2P3, Institut Polytechnique de Grenoble, Grenoble, France    K. Redlich 4141endnote: 41Also at Wrocław University, Wrocław, Poland Soltan Institute for Nuclear Studies, Warsaw, Poland    R. Renfordt Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    A.R. Reolon Laboratori Nazionali di Frascati, INFN, Frascati, Italy    A. Reshetin Institute for Nuclear Research, Academy of Sciences, Moscow, Russia    F. Rettig 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    J.-P. Revol European Organization for Nuclear Research (CERN), Geneva, Switzerland    K. Reygers 2929endnote: 29Now at Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    H. Ricaud Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany    L. Riccati Sezione INFN, Turin, Italy    R.A. Ricci Laboratori Nazionali di Legnaro, INFN, Legnaro, Italy    M. Richter Department of Physics and Technology, University of Bergen, Bergen, Norway    P. Riedler European Organization for Nuclear Research (CERN), Geneva, Switzerland    W. Riegler European Organization for Nuclear Research (CERN), Geneva, Switzerland    F. Riggi Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy    A. Rivetti Sezione INFN, Turin, Italy    M. Rodriguez Cahuantzi Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    K. Røed Faculty of Engineering, Bergen University College, Bergen, Norway    D. Röhrich 3131endnote: 31Now at Department of Physics and Technology, University of Bergen, Bergen, Norway European Organization for Nuclear Research (CERN), Geneva, Switzerland    S. Román López Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    R. Romita 44endnote: 4Now at Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    F. Ronchetti Laboratori Nazionali di Frascati, INFN, Frascati, Italy    P. Rosinský European Organization for Nuclear Research (CERN), Geneva, Switzerland    P. Rosnet Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    S. Rossegger European Organization for Nuclear Research (CERN), Geneva, Switzerland    A. Rossi 4242endnote: 42Now at Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy    F. Roukoutakis 3232endnote: 32Now at Physics Department, University of Athens, Athens, Greece European Organization for Nuclear Research (CERN), Geneva, Switzerland    S. Rousseau Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    C. Roy 1212endnote: 12Now at Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    P. Roy Saha Institute of Nuclear Physics, Kolkata, India    A.J. Rubio-Montero Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain    R. Rui Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy    I. Rusanov Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    G. Russo Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Sezione INFN, Salerno, Italy    E. Ryabinkin Russian Research Centre Kurchatov Institute, Moscow, Russia    A. Rybicki The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland    S. Sadovsky Institute for High Energy Physics, Protvino, Russia    K. Šafařík European Organization for Nuclear Research (CERN), Geneva, Switzerland    R. Sahoo Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    J. Saini Variable Energy Cyclotron Centre, Kolkata, India    P. Saiz European Organization for Nuclear Research (CERN), Geneva, Switzerland    D. Sakata University of Tsukuba, Tsukuba, Japan    C.A. Salgado Departamento de Física de Partículas and IGFAE, Universidad de Santiago de Compostela, Santiago de Compostela, Spain    R. Salgueiro Domingues da Silva European Organization for Nuclear Research (CERN), Geneva, Switzerland    S. Salur Lawrence Berkeley National Laboratory, Berkeley, CA, United States    T. Samanta Variable Energy Cyclotron Centre, Kolkata, India    S. Sambyal Physics Department, University of Jammu, Jammu, India    V. Samsonov Petersburg Nuclear Physics Institute, Gatchina, Russia    L. Šándor Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovakia    A. Sandoval Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    M. Sano University of Tsukuba, Tsukuba, Japan    S. Sano University of Tokyo, Tokyo, Japan    R. Santo Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    R. Santoro Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    J. Sarkamo Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    P. Saturnini Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    E. Scapparone Sezione INFN, Bologna, Italy    F. Scarlassara Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    R.P. Scharenberg Purdue University, West Lafayette, IN, United States    C. Schiaua National Institute for Physics and Nuclear Engineering, Bucharest, Romania    R. Schicker Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    H. Schindler European Organization for Nuclear Research (CERN), Geneva, Switzerland    C. Schmidt Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    H.R. Schmidt Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    K. Schossmaier European Organization for Nuclear Research (CERN), Geneva, Switzerland    S. Schreiner European Organization for Nuclear Research (CERN), Geneva, Switzerland    S. Schuchmann Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    J. Schukraft European Organization for Nuclear Research (CERN), Geneva, Switzerland    Y. Schutz SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    K. Schwarz Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    K. Schweda Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    G. Scioli Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    E. Scomparin Sezione INFN, Turin, Italy    P.A. Scott School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    G. Segato Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    D. Semenov V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    S. Senyukov Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy    J. Seo Gangneung-Wonju National University, Gangneung, South Korea    S. Serci Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy    L. Serkin Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico City, Mexico    E. Serradilla Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain    A. Sevcenco Institute of Space Sciences (ISS), Bucharest, Romania    I. Sgura Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    G. Shabratova Joint Institute for Nuclear Research (JINR), Dubna, Russia    R. Shahoyan European Organization for Nuclear Research (CERN), Geneva, Switzerland    G. Sharkov Institute for Theoretical and Experimental Physics, Moscow, Russia    N. Sharma Physics Department, Panjab University, Chandigarh, India    S. Sharma Physics Department, University of Jammu, Jammu, India    K. Shigaki Hiroshima University, Hiroshima, Japan    M. Shimomura University of Tsukuba, Tsukuba, Japan    K. Shtejer Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Havana, Cuba    Y. Sibiriak Russian Research Centre Kurchatov Institute, Moscow, Russia    M. Siciliano Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    E. Sicking 3333endnote: 33Also at Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany European Organization for Nuclear Research (CERN), Geneva, Switzerland    E. Siddi Sezione INFN, Cagliari, Italy    T. Siemiarczuk Soltan Institute for Nuclear Studies, Warsaw, Poland    A. Silenzi Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    D. Silvermyr Oak Ridge National Laboratory, Oak Ridge, TN, United States    E. Simili Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    G. Simonetti 1010endnote: 10Now at European Organization for Nuclear Research (CERN), Geneva, Switzerland Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    R. Singaraju Variable Energy Cyclotron Centre, Kolkata, India    R. Singh Physics Department, University of Jammu, Jammu, India    V. Singhal Variable Energy Cyclotron Centre, Kolkata, India    B.C. Sinha Variable Energy Cyclotron Centre, Kolkata, India    T. Sinha Saha Institute of Nuclear Physics, Kolkata, India    B. Sitar Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia    M. Sitta Dipartimento di Scienze e Tecnologie Avanzate dell’Università del Piemonte Orientale and Gruppo Collegato INFN, Alessandria, Italy    T.B. Skaali Department of Physics, University of Oslo, Oslo, Norway    K. Skjerdal Department of Physics and Technology, University of Bergen, Bergen, Norway    R. Smakal Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    N. Smirnov Yale University, New Haven, CT, United States    R. Snellings Nikhef, National Institute for Subatomic Physics, Amsterdam, Netherlands    H. Snow School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    C. Søgaard Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark    A. Soloviev Institute for High Energy Physics, Protvino, Russia    H.K. Soltveit Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    R. Soltz Lawrence Livermore National Laboratory, Livermore, CA, United States    W. Sommer Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    C.W. Son Pusan National University, Pusan, South Korea    H. Son Department of Physics, Sejong University, Seoul, South Korea    M. Song Yonsei University, Seoul, South Korea    C. Soos European Organization for Nuclear Research (CERN), Geneva, Switzerland    F. Soramel Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    D. Soyk Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    M. Spyropoulou-Stassinaki Physics Department, University of Athens, Athens, Greece    B.K. Srivastava Purdue University, West Lafayette, IN, United States    J. Stachel Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    F. Staley Commissariat à l’Energie Atomique, IRFU, Saclay, France    E. Stan Institute of Space Sciences (ISS), Bucharest, Romania    G. Stefanek Soltan Institute for Nuclear Studies, Warsaw, Poland    G. Stefanini European Organization for Nuclear Research (CERN), Geneva, Switzerland    T. Steinbeck 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    E. Stenlund Division of Experimental High Energy Physics, University of Lund, Lund, Sweden    G. Steyn Physics Department, University of Cape Town, iThemba Laboratories, Cape Town, South Africa    D. Stocco 3434endnote: 34Now at SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    R. Stock Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    P. Stolpovsky Institute for High Energy Physics, Protvino, Russia    P. Strmen Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia    A.A.P. Suaide Universidade de São Paulo (USP), São Paulo, Brazil    M.A. Subieta Vásquez Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    T. Sugitate Hiroshima University, Hiroshima, Japan    C. Suire Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    M. Šumbera Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Řež u Prahy, Czech Republic    T. Susa Rudjer Bošković Institute, Zagreb, Croatia    D. Swoboda European Organization for Nuclear Research (CERN), Geneva, Switzerland    J. Symons Lawrence Berkeley National Laboratory, Berkeley, CA, United States    A. Szanto de Toledo Universidade de São Paulo (USP), São Paulo, Brazil    I. Szarka Faculty of Mathematics, Physics and Informatics, Comenius University, Bratislava, Slovakia    A. Szostak Sezione INFN, Cagliari, Italy    M. Szuba Warsaw University of Technology, Warsaw, Poland    M. Tadel European Organization for Nuclear Research (CERN), Geneva, Switzerland    C. Tagridis Physics Department, University of Athens, Athens, Greece    A. Takahara University of Tokyo, Tokyo, Japan    J. Takahashi Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil    R. Tanabe University of Tsukuba, Tsukuba, Japan    J.D. Tapia Takaki Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    H. Taureg European Organization for Nuclear Research (CERN), Geneva, Switzerland    A. Tauro European Organization for Nuclear Research (CERN), Geneva, Switzerland    M. Tavlet European Organization for Nuclear Research (CERN), Geneva, Switzerland    G. Tejeda Muñoz Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    A. Telesca European Organization for Nuclear Research (CERN), Geneva, Switzerland    C. Terrevoli Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    J. Thäder 22endnote: 2Also at Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    R. Tieulent Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France    D. Tlusty Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    A. Toia European Organization for Nuclear Research (CERN), Geneva, Switzerland    T. Tolyhy KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academy of Sciences, Budapest, Hungary    C. Torcato de Matos European Organization for Nuclear Research (CERN), Geneva, Switzerland    H. Torii Hiroshima University, Hiroshima, Japan    G. Torralba Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    L. Toscano Sezione INFN, Turin, Italy    F. Tosello Sezione INFN, Turin, Italy    A. Tournaire 3535endnote: 35Now at Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    T. Traczyk Warsaw University of Technology, Warsaw, Poland    P. Tribedy Variable Energy Cyclotron Centre, Kolkata, India    G. Tröger Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    D. Truesdale Department of Physics, Ohio State University, Columbus, OH, United States    W.H. Trzaska Helsinki Institute of Physics (HIP) and University of Jyväskylä, Jyväskylä, Finland    G. Tsiledakis Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    E. Tsilis Physics Department, University of Athens, Athens, Greece    T. Tsuji University of Tokyo, Tokyo, Japan    A. Tumkin Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    R. Turrisi Sezione INFN, Padova, Italy    A. Turvey Physics Department, Creighton University, Omaha, NE, United States    T.S. Tveter Department of Physics, University of Oslo, Oslo, Norway    H. Tydesjö European Organization for Nuclear Research (CERN), Geneva, Switzerland    K. Tywoniuk Department of Physics, University of Oslo, Oslo, Norway    J. Ulery Institut für Kernphysik, Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt, Germany    K. Ullaland Department of Physics and Technology, University of Bergen, Bergen, Norway    A. Uras Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy    J. Urbán Faculty of Science, P.J. Šafárik University, Košice, Slovakia    G.M. Urciuoli Sezione INFN, Rome, Italy    G.L. Usai Dipartimento di Fisica dell’Università and Sezione INFN, Cagliari, Italy    A. Vacchi Sezione INFN, Trieste, Italy    M. Vala 99endnote: 9Now at Faculty of Science, P.J. Šafárik University, Košice, Slovakia Joint Institute for Nuclear Research (JINR), Dubna, Russia    L. Valencia Palomo Instituto de Física, Universidad Nacional Autónoma de México, Mexico City, Mexico    S. Vallero Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    N. van der Kolk Nikhef, National Institute for Subatomic Physics, Amsterdam, Netherlands    P. Vande Vyvre European Organization for Nuclear Research (CERN), Geneva, Switzerland    M. van Leeuwen Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    L. Vannucci Laboratori Nazionali di Legnaro, INFN, Legnaro, Italy    A. Vargas Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    R. Varma Indian Institute of Technology, Mumbai, India    A. Vasiliev Russian Research Centre Kurchatov Institute, Moscow, Russia    I. Vassiliev 3232endnote: 32Now at Physics Department, University of Athens, Athens, Greece Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    M. Vasileiou Physics Department, University of Athens, Athens, Greece    V. Vechernin V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    M. Venaruzzo Dipartimento di Fisica dell’Università and Sezione INFN, Trieste, Italy    E. Vercellin Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Turin, Italy    S. Vergara Benemérita Universidad Autónoma de Puebla, Puebla, Mexico    R. Vernet 3636endnote: 36Now at: Centre de Calcul IN2P3, Lyon, France Dipartimento di Fisica e Astronomia dell’Università and Sezione INFN, Catania, Italy    M. Verweij Nikhef and Institute for Subatomic Physics of Utrecht University, Utrecht, Netherlands    I. Vetlitskiy Institute for Theoretical and Experimental Physics, Moscow, Russia    L. Vickovic Technical University of Split FESB, Split, Croatia    G. Viesti Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy    O. Vikhlyantsev Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    Z. Vilakazi Physics Department, University of Cape Town, iThemba Laboratories, Cape Town, South Africa    O. Villalobos Baillie School of Physics and Astronomy, University of Birmingham, Birmingham, United Kingdom    A. Vinogradov Russian Research Centre Kurchatov Institute, Moscow, Russia    L. Vinogradov V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    Y. Vinogradov Russian Federal Nuclear Center (VNIIEF), Sarov, Russia    T. Virgili Dipartimento di Fisica ‘E.R. Caianiello’ dell’Università and Sezione INFN, Salerno, Italy    Y.P. Viyogi Variable Energy Cyclotron Centre, Kolkata, India    A. Vodopianov Joint Institute for Nuclear Research (JINR), Dubna, Russia    K. Voloshin Institute for Theoretical and Experimental Physics, Moscow, Russia    S. Voloshin Wayne State University, Detroit, MI, United States    G. Volpe Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy    B. von Haller European Organization for Nuclear Research (CERN), Geneva, Switzerland    D. Vranic Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany    J. Vrláková Faculty of Science, P.J. Šafárik University, Košice, Slovakia    B. Vulpescu Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France    B. Wagner Department of Physics and Technology, University of Bergen, Bergen, Norway    V. Wagner Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    L. Wallet European Organization for Nuclear Research (CERN), Geneva, Switzerland    R. Wan 1212endnote: 12Now at Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg, CNRS-IN2P3, Strasbourg, France Hua-Zhong Normal University, Wuhan, China    D. Wang Hua-Zhong Normal University, Wuhan, China    Y. Wang Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    Y. Wang Hua-Zhong Normal University, Wuhan, China    K. Watanabe University of Tsukuba, Tsukuba, Japan    Q. Wen China Institute of Atomic Energy, Beijing, China    J. Wessels Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    U. Westerhoff Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    J. Wiechula Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    J. Wikne Department of Physics, University of Oslo, Oslo, Norway    A. Wilk Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Münster, Germany    G. Wilk Soltan Institute for Nuclear Studies, Warsaw, Poland    M.C.S. Williams Sezione INFN, Bologna, Italy    N. Willis Institut de Physique Nucléaire d’Orsay (IPNO), Université Paris-Sud, CNRS-IN2P3, Orsay, France    B. Windelband Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    C. Xu Hua-Zhong Normal University, Wuhan, China    C. Yang Hua-Zhong Normal University, Wuhan, China    H. Yang Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    S. Yasnopolskiy Russian Research Centre Kurchatov Institute, Moscow, Russia    F. Yermia SUBATECH, Ecole des Mines de Nantes, Université de Nantes, CNRS-IN2P3, Nantes, France    J. Yi Pusan National University, Pusan, South Korea    Z. Yin Hua-Zhong Normal University, Wuhan, China    H. Yokoyama University of Tsukuba, Tsukuba, Japan    I-K. Yoo Pusan National University, Pusan, South Korea    X. Yuan 3838endnote: 38Also at Dipartimento di Fisica dell’Università and Sezione INFN, Padova, Italy Hua-Zhong Normal University, Wuhan, China    V. Yurevich Joint Institute for Nuclear Research (JINR), Dubna, Russia    I. Yushmanov Russian Research Centre Kurchatov Institute, Moscow, Russia    E. Zabrodin Department of Physics, University of Oslo, Oslo, Norway    B. Zagreev Institute for Theoretical and Experimental Physics, Moscow, Russia    A. Zalite Petersburg Nuclear Physics Institute, Gatchina, Russia    C. Zampolli 3939endnote: 39Also at Sezione INFN, Bologna, Italy European Organization for Nuclear Research (CERN), Geneva, Switzerland    Yu. Zanevsky Joint Institute for Nuclear Research (JINR), Dubna, Russia    S. Zaporozhets Joint Institute for Nuclear Research (JINR), Dubna, Russia    A. Zarochentsev V. Fock Institute for Physics, St. Petersburg State University, St. Petersburg, Russia    P. Závada Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic    H. Zbroszczyk Warsaw University of Technology, Warsaw, Poland    P. Zelnicek Kirchhoff-Institut für Physik, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany    A. Zenin Institute for High Energy Physics, Protvino, Russia    A. Zepeda Centro de Investigación y de Estudios Avanzados (CINVESTAV), Mexico City and Mérida, Mexico    I. Zgura Institute of Space Sciences (ISS), Bucharest, Romania    M. Zhalov Petersburg Nuclear Physics Institute, Gatchina, Russia    X. Zhang 11endnote: 1Also at Laboratoire de Physique Corpusculaire (LPC), Clermont Université, Université Blaise Pascal, CNRS–IN2P3, Clermont-Ferrand, France Hua-Zhong Normal University, Wuhan, China    D. Zhou Hua-Zhong Normal University, Wuhan, China    S. Zhou China Institute of Atomic Energy, Beijing, China    J. Zhu Hua-Zhong Normal University, Wuhan, China    A. Zichichi 2222endnote: 22Also at Centro Fermi – Centro Studi e Ricerche e Museo Storico della Fisica “Enrico Fermi”, Rome, Italy Dipartimento di Fisica dell’Università and Sezione INFN, Bologna, Italy    A. Zinchenko Joint Institute for Nuclear Research (JINR), Dubna, Russia    G. Zinovjev Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine    Y. Zoccarato Université de Lyon, Université Lyon 1, CNRS/IN2P3, IPN-Lyon, Villeurbanne, France    V. Zycháček Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic    M. Zynovyev 1313endnotetext: Now at Sezione INFN, Bari, Italy 1818endnotetext: Now at Sección Física, Departamento de Ciencias, Pontificia Universidad Católica del Perú, Lima, Peru 2323endnotetext: Now at Dipartimento Interateneo di Fisica ‘M. Merlin’ and Sezione INFN, Bari, Italy 2626endnotetext: Now at Physics Department, Creighton University, Omaha, NE, United States 3030endnotetext: Now at Institut für Kernphysik, Technische Universität Darmstadt, Darmstadt, Germany 3737endnotetext: Now at Variable Energy Cyclotron Centre, Kolkata, India
\theendnotes

Collaboration institutes

Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine
Received: July 12, 2019/ Revised version: date
Abstract

The production of , , K, K, p, and  at mid-rapidity has been measured in proton-proton collisions at   = 900 GeV with the ALICE detector. Particle identification is performed using the specific energy loss in the inner tracking silicon detector and the time projection chamber. In addition, time-of-flight information is used to identify hadrons at higher momenta. Finally, the distinctive kink topology of the weak decay of charged kaons is used for an alternative measurement of the kaon transverse momentum () spectra. Since these various particle identification tools give the best separation capabilities over different momentum ranges, the results are combined to extract spectra from MeV/ to 2.5 GeV/. The measured spectra are further compared with QCD-inspired models which yield a poor description. The total yields and the mean  are compared with previous measurements, and the trends as a function of collision energy are discussed.

pacs:
25.75.DwParticle and resonance production and 13.85.NiInclusive production with identified hadrons
\shipout
EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN) CERN-PH-EP-2010-085 Submitted to: EPJC   Production of pions, kaons and protons in pp collisions at  = 900 GeV with ALICE at the LHC ALICE Collaboration Abstract The production of , , K, K, p, and  at mid-rapidity has been measured in proton-proton collisions at   = 900 GeV with the ALICE detector. Particle identification is performed using the specific energy loss in the inner tracking silicon detector and the time projection chamber. In addition, time-of-flight information is used to identify hadrons at higher momenta. Finally, the distinctive kink topology of the weak decay of charged kaons is used for an alternative measurement of the kaon transverse momentum () spectra. Since these various particle identification tools give the best separation capabilities over different momentum ranges, the results are combined to extract spectra from MeV/ to 2.5 GeV/. The measured spectra are further compared with QCD-inspired models which yield a poor description. The total yields and the mean  are compared with previous measurements, and the trends as a function of collision energy are discussed. \hugehead

1 Introduction

In pp collisions at ultra-relativistic energies the bulk of the particles produced at mid-rapidity have transverse momenta, , below 1 GeV/. Their production is not calculable from first principles via perturbative Quantum Chromodynamics, and is not well modelled at lower collision energies. This low  particle production, and species composition, must therefore be measured, providing crucial input for the modelling of hadronic interactions and the hadronization process. It is important to study the bulk production of particles as a function of both  and particle species. With the advent of pp collisions at the Large Hadron Collider (LHC) at CERN a new energy regime is being explored, where particle production from hard interactions which are predominantly gluonic in nature, is expected to play an increasing role. Such data will provide extra constraints on the modelling of fragmentation functions. The data will also serve as a reference for the heavy-ion measurements.

The ALICE detector Alessandro:2006yt (); Carminati:2004fp () is designed to perform measurements in the high-multiplicity environment expected in central lead-lead collisions at = 5.5 TeV at the LHC and to identify particles over a wide range of momenta. As such, it is ideally suited to perform these measurements also in pp collisions.

This paper presents the transverse momentum spectra and yields of identified particles at mid-rapidity from the first pp collisions collected in the autumn of 2009, during the commissioning of the LHC, at  = 900 GeV. The evolution of particle production in pp collisions with collision energy is studied by comparing to data from previous experiments.

We report , , K, K, p, and  distributions, identified via several independent techniques utilizing specific energy loss, d/d, information from the Inner Tracking System (ITS) and the Time Projection Chamber (TPC), and velocity measurements in the Time-Of-Flight array (TOF). The combination of these methods provides particle identification over the transverse momentum range . Charged kaons, identified via kink topology of their weak decays in the TPC, provide a complementary measurement over a similar  range. All reported particle yields are for primary particles, namely those directly produced in the collision including the products of strong and electromagnetic decays but excluding weak decays of strange particles.

The paper is organized as follows: In Section 2, the ALICE detectors relevant for these studies, the experimental conditions, and the corresponding analysis techniques are described. Details of the event and particle selection are presented. In Section 3, the , , K, K, p, and  inclusive spectra and yields, obtained by combining the various techniques described in Section 2, are presented. The results are compared with calculations from QCD-inspired models and the -dependence of ratios of particle yields, e.g. K/ and p/, are discussed. Comparisons with data from other experiments at different  are made and the evolution of the ratio of strange to non-strange hadrons with collision energy is discussed. Finally, in Section 4 the results are summarized.

2 Experimental setup and data analysis

2.1 The ALICE detector

The ALICE detector and its expected performance are described in detail in Alessandro:2006yt (); Carminati:2004fp (); ALICE-JINST (). For the analyses described in this paper the following detectors are used: the ITS, the TPC and the TOF detector. These detectors are positioned in a solenoidal magnetic field of  = 0.5 T and have a common pseudo-rapidity coverage of . Two forward scintillator hodoscopes (VZERO) are used for triggering purposes. They are placed on either side of the interaction region, covering regions and .

2.1.1 The Inner Tracking System

The ITS is the closest of the central barrel detectors to the beam axis. It is composed of six cylindrical layers of silicon detectors. The two innermost layers are equipped with pixel detectors (SPD), followed by two layers of drift detectors (SDD) and two layers of double-sided silicon strip detectors (SSD). The innermost layer is at 3.9 cm from the beam axis, while the outer layer is at 43.0 cm.

The ITS provides high-resolution space points that allow the extension of tracks reconstructed in the TPC towards the interaction vertex, thus improving momentum and angular resolution. The four layers equipped with SDD and SSD also provide a measurement of the specific energy loss d/d. The SPD yields an on-line measure of the multiplicity by counting the number of chips that have one or more hits (fast-OR), which is included in the minimum-bias trigger logic ALICE-JINST (); AglieriRinella:2007hm (). The ITS is also used as a stand-alone tracker to reconstruct charged particles with momenta below 200 MeV/ that are deflected or decay before reaching the TPC, and to recover tracks crossing dead regions of the TPC. A detailed description of the three sub-systems can be found in ALICE-JINST (). The d/d measurement in the SDD and SSD has been calibrated using cosmic ray data and pp events Alessandro:2010rq (). The 2198 ITS modules have been aligned using survey information, cosmic-ray tracks and pp data with the methods described in :2010ys (). The fraction of active modules per layer in the present setup is around 80% in the SPD and 90% - 95% both in SDD and SSD.

2.1.2 The Time Projection Chamber

The TPC is the main tracking device. It is a large volume, high granularity, cylindrical detector with an outer radius of 2.78 m and a length of 5.1 m. The active volume extends from 0.85 m to 2.47 m in radius. It covers 2 in azimuth and in polar angle for the full radial track length. Accepting one third of the full radial track length extends the range to 1.5. The 90 m drift volume is filled with a Ne (85.7%), CO (9.5%), and N (4.8%) gas mixture. A high voltage central membrane splits the drift region in two halves, resulting in a maximal drift time of 94 s. Each of the two read-out planes is composed of 18 inner and 18 outer chambers with a total of 159 pad rows, resulting in a total of 557 568 pads which are read out separately. The position resolution in direction varies from 1100 m to 800 m when going from the inner to the outer radius. Along the beam axis (, also the drift direction) the resolution ranges between 1250 m and 1100 m. A maximum of 159 clusters can be measured along a track in the TPC. For a detailed description see Alme:2010ke ().

2.1.3 The Time-Of-Flight Detector

The TOF detector consists of 18 azimuthal sectors, each containing 91 Multi-gap Resistive Plate Chambers (MRPCs) distributed in five gas-tight modules. It is positioned at 370-399 cm from the beam axis. The region at is not covered in order to minimize the material in front of the Photon Spectrometer, which is not used in this analysis. The MRPC detectors are installed with a projective geometry along the beam direction, minimizing the variation of the flight path of particles across the sensitive area of the detector. Each MRPC is segmented into 96 read-out pads (2.5 3.5 size), resulting in a total of 152928 channels. Test beam results demonstrated that the intrinsic time resolution of the detector is better than 50 , dominated by electronic effects and the time resolution of the time-to-digital converters Akindinov:2009zz (). Results from the TOF commissioning with cosmic rays are described in references  Akindinov:2006hs (); Akindinov:2010zza (); Akindinov:2010zz (). In the present setup, 9.6% of the readout channels were inactive due to failures in the high- or low-voltage systems or in the readout electronics. The fraction of noisy channels, identified during data taking by online monitoring and excluded from the subsequent reconstruction, was below 0.1%.

2.2 Event selection and normalization

The data presented in this paper were collected during the commissioning of the LHC at CERN in the autumn of 2009, with pp collisions at  GeV. The collider was run with four bunches per beam, resulting in two bunch crossings per beam circulation period (89 s) at the ALICE interaction point. The remaining two bunches per beam were not collided at ALICE, and served to estimate the contribution of beam-gas interactions. The average event rate was a few Hz, so the fraction of pile-up events was negligible.

The analysis is based on a sample of k inelastic pp collisions. The online trigger selection requires a signal in either of the VZERO counters or at least one hit in either of the SPD layers. The selection was improved offline with recomputed trigger input quantities using the time average over all VZERO hits and a suppression of noisy channels. The contamination from beam-induced background is rejected offline using the timing information of the VZERO and by cutting on the correlation between the number of clusters and track segments (tracklets) in the SPD detector Aamodt:2010ft (); Aamodt:2010my (). Selected events are further required to contain a reconstructed primary vertex. The vertex reconstruction efficiency calculated via Monte-Carlo simulations is 96.5% for events with one reconstructed track and approaches unity for events with more than two tracks.

The results presented in this paper are normalized to inelastic pp collisions, employing the strategy described in Aamodt:2010ft (); Aamodt:2010my (). In order to reduce the extrapolation and thus the systematic uncertainty on the normalization, the sample of selected events used for normalization includes triggered events without reconstructed tracks or vertices. Those events still contain a small contamination from very low multiplicity beam-induced background or accidentals from the trigger, which are not rejected by the selections described above. This contamination is of the order of 4% and is subtracted using the control triggers. From the analysis of empty bunch events the random contribution from cosmic rays is found to be negligible. The number of selected events is then converted to the number of inelastic collisions after correcting for the trigger efficiency, which is determined from the Monte-Carlo simulation, scaling the cross section for diffractive processes to the measurements of UA5 Ansorge:1986xq (). The subtraction of beam-gas events and the efficiency correction partially compensate each other: the overall correction factor is about 5% with a systematic uncertainty of about 2%, coming mainly from the uncertainties in the modelling of diffraction in the event generators.

In order to compare to previous experimental results, which are only published for the  non-single-diffractive (NSD) class, in Section 3, we scale our spectra for the measured ratio  Aamodt:2010ft (). PYTHIA and PHOJET simulations indicate that the -dependence of the ratio of spectra for NSD and inelastic collisions is less than 5% in the reported range. Particle ratios are found to be insensitive to the conversion from inelastic to non-single-diffractive events.

2.3 Track selection

The identified particle spectra were measured independently with the ITS, TPC and TOF, and combined in the final stage of the analysis. The rapidity range was used for all analyses except for the kink analysis ().

For the TPC and TOF analyses, tracks reconstructed in the TPC are used. The TPC has full acceptance for tracks with . However, shorter tracks at higher can still be used for physics analysis, in particular protons with a transverse momentum of = 400 MeV/ and which correspond to . To ensure high tracking efficiency and d/d-resolution, while keeping the contamination from secondaries and fakes low, tracks are required to have at least 80 clusters, and a of the momentum fit that is smaller than 4 per cluster. Since each cluster in the TPC provides two degrees of freedom and the number of parameters of the track fit is much smaller than the number of clusters, the cut is approximately 2 per degree of freedom. In addition, at least two clusters in the ITS must be associated to the track, out of which at least one is from the SPD. Tracks are further rejected based on their distance-of-closest approach (DCA) to the reconstructed event vertex. The cut is implemented as a function of  to correspond to about seven (five) standard deviations in the transverse (longitudinal) coordinate, taking into account the -dependence of the impact parameter resolution. These selection criteria are tuned to select primary charged particles with high efficiency while minimizing the contributions from weak decays, conversions and secondary hadronic interactions in the detector material. The DCA resolution in the data is found to be in good agreement with the Monte-Carlo simulations that are used for efficiency corrections (see next Section).

Tracks reconstructed in the TPC are extrapolated to the sensitive layer of the TOF and a corresponding signal is searched for. The channel with the center closest to the track extrapolation point is selected if the distance is less than 10 cm. This rather weak criterion results in a high matching efficiency while keeping the fraction of wrongly associated tracks below 1% in the low-density environment presented by pp collisions.

The d/d measurements in the ITS are used to identify hadrons in two independent analyses, based on different tracking algorithms. One analysis uses the ITS-TPC combined tracking, while the other is based on ITS stand-alone tracks. The combined ITS-TPC tracking result serves as a cross-check of both the ITS stand-alone and the TPC results in the overlap region. The ITS stand-alone analysis extends the acceptance to lower  than the TPC or ITS-TPC analyses.

The combined ITS-TPC analysis uses the same track selection criteria as the TPC only analysis, with the additional requirement of at least four clusters in the ITS, out of which at least one must be in the SPD and at least three in SSD+SDD. This further reduces the contamination of secondaries and provides high resolution on track impact parameter and optimal resolution on the d/d. The ITS stand-alone tracking uses a similar selection, with a different selection and a different DCA selection. In the current tracking algorithm, ITS clusters are assigned a larger position error to account for residual misalignment of the detector. As a result, the values are not properly normalized, but the selection was adjusted to be equivalent to the TPC selection by inspecting the distributions. The DCA cut in the ITS analysis uses the same -dependent parametrization as for TPC tracks, but with different parameters to account for the different resolution.

2.4 Monte-Carlo Calculations

The efficiency and other correction factors including acceptance (jointly called efficiency in the following discussion) used in this paper are calculated from a Monte-Carlo simulation, based on over two million events produced with the PYTHIA 6.4 event generator Sjostrand:2006za () (tune D6T D6T ()), propagated through the detector with the GEANT3 :1994zzo () transport code. Dead and noisy channels as well as beam position and spread have been taken into account. A simulation based on the PHOJET event generator Engel:1995sb () is also used as a cross check.

GEANT3 is known to reproduce the absorption cross sections of hadrons incorrectly. The transport code FLUKA contains a more accurate description of these cross sections Bendiscioli:1994uv (); Zhang:1996ev (); Klempt:2002ap (), and a dedicated simulation is used to calculate a correction to the GEANT3 efficiency calculation Aamodt:2010dx (). This is relevant mainly for antiprotons at low , where the correction is on the order of 10%. For other particles and at higher , the difference between GEANT and FLUKA calculations is negligible.

2.5 Particle Identification

The d/d and TOF signals are used for particle identification as a function of the momentum , whereas the final spectra are given as a function of the transverse momentum .

In the case of the TPC and ITS analyses, particles were identified via the specific energy loss d/d. Unique identification on a track-by-track basis is possible in regions of momentum where the bands are clearly separated from each other. In overlapping areas, particle identification is still possible on a statistical basis using fits to the energy loss distribution in each -bin. The fits are performed on the distribution of the difference between the measured and the expected energy deposition for tracks within the selected rapidity range 0.5. This compensates for the very steep slope of the Bethe-Bloch in the region which would make the d/d-distribution in a simple  or -slice non-Gaussian. The calculated expected energy loss depends on the measured track momentum and the assumed mass for the particle. The procedure is therefore repeated three times for the entire set of tracks, assuming the pion, kaon, and proton mass.

In the TPC analysis, the difference
[d/d][d/d is used. For the ITS the difference of the logarithm of the measured and calculated energy deposit d/dd/d(, is taken to suppress the non-gaussian tails originating from the smaller number of d/d measurements.

In the case of the TOF, the identification is based on the time-of-flight information. The procedure for the extraction of the raw yields differs slightly from the one used for TPC and ITS, and is described in Section 2.5.3.

2.5.1 Particle identification in the ITS

In both the ITS stand-alone and in the ITS-TPC analyses, the d/d measurement from the SDD and the SSD is used to identify particles. The stand-alone tracking result extends the momentum range to lower than can be measured in the TPC, while the combined tracking provides a better momentum resolution.

The energy loss measurement in each layer of the ITS is corrected for the track length in the sensitive volume using tracking information. In the case of SDD clusters, a linear correction for the dependence of the reconstructed raw charge as a function of drift time due to the combined effect of charge diffusion and zero suppression is also applied Alessandro:2010rq (). For each track, d/d is calculated using a truncated mean: the average of the lowest two points in case four points are measured, or a weighted sum of the lowest (weight 1) and the second lowest point (weight 1/2), in case only three points are measured.

Figure 1: (Color online) Specific energy loss d/d vs. momentum for tracks measured with the ITS. The solid lines are a parametrization (from Back:2006tt ()) of the detector response based on the Bethe-Bloch formula.

Figure 1 shows the truncated mean d/d for the sample of ITS stand-alone tracks along with the PHOBOS parametrization of the most probable value Back:2006tt ().

Figure 2: (Color online) Distribution of ln[d/d]ln[d/d(K)] measured with the ITS in the two -ranges, 300–350 MeV/ (upper panels) and 400-450 MeV/ (lower panels), using the kaon mass hypothesis. The left panels show the result for ITS-TPC combined tracks, while the right panels show the ITS stand-alone result. The lines indicate fits as described in the text.

For the ITS stand-alone track sample, the histograms are fitted with three Gaussians and the integral of the Gaussian centered at zero is used as the raw yield of the corresponding hadron species. In a first step, the peak widths of the peaks are extracted as a function of  for pions and protons in the region where their d/d distributions do not overlap with the kaon (and electron) distribution. For kaons, the same procedure is used at low , where they are well separated. The -dependence of the peak width is then extrapolated to higher  with the same functional form used to describe the pions and protons. The resulting parametrizations of the  dependence of are used to constrain the fits of the ln[d/d] distributions to extract the raw yields.

For the ITS-TPC combined track sample, a non-Gau-ssian tail is visible. This tail is a remnant of the tail of the Landau distribution for energy loss. It was verified using simulations that the shape and size of the tail are compatible with the expectations for a truncated mean using two out of four samples. The tail is not as pronounced for the ITS stand-alone track sample, due to the limited momentum resolution. The distribution is fitted with a combination of a Gaussian and an exponential function for the main peak and another exponential function to describe the tail of a background peak. This functional form provides an accurate description of the peak shape in the detector simulation, as well as the measured shape.

Examples of d/d distributions are shown in Fig. 2 for negative tracks using the kaon mass hypothesis in two different  intervals for both ITS stand-alone tracks (right panels) and ITS-TPC combined tracks (left panels).

Efficiency correction

The raw hadron yields extracted from the fits to the d/d distributions are corrected for the reconstruction efficiency determined from Monte-Carlo simulations, applying the same analysis criteria to the simulated events as to the data. Secondary particles from interactions in the detector material and strange particle decays have been subtracted from the yield of both simulated and real data. The fraction of secondaries after applying the track impact-parameter cut depends on the hadron species and amounts to 1-3% for pions and 5-10% for protons depending on . The secondary-to-primary ratio has been estimated by fitting the measured track impact-parameter distributions with three components, prompt particles, secondaries from strange particle decays and secondaries produced in the detector material for each hadron species. Alternatively, the contamination from secondaries have been determined using Monte-Carlo samples, after rescaling the yield to the measured values strange (). The difference between these two procedures is about 3% for protons and is negligible for other particles.

Figure 3 shows the total reconstruction efficiency for primary tracks in the ITS stand-alone, including the effects of detector and tracking efficiency, the track selection cuts and residual contamination in the fitting procedure, as determined from the Monte-Carlo simulation. This efficiency is used to correct the measured raw yields after subtraction of the contributions from secondary hadrons. The measured spectra are corrected for the efficiency of the primary vertex reconstruction with the SPD using the ratio between generated primary spectra in simulated events with a reconstructed vertex and events passing the trigger conditions.

Figure 3: (Color online) Efficiency for pions, kaons and protons for the ITS stand-alone analysis as obtained from Monte-Carlo simulations.

Systematic errors are summarized in Table 1. The systematic uncertainty from secondary contamination has been estimated by repeating the full analysis chain with different cuts on the track impact parameter and by comparing the two alternative estimates outlined above. The effect of the uncertainty in the material budget has been estimated by modifying the material budget in the Monte-Carlo simulations by %, which is the present uncertainty of the ITS material budget. The systematic contribution from the fitting procedure to the ln[d/d]ln[d/d(i)] distributions has been estimated by varying the fit condition and by comparing to an independent analysis using a track-by-track identification approach based on the distance between the measured and expected d/d values normalized to its resolution. The residual imperfections in the description of the ITS detector modules and dead areas in the simulation introduce another uncertainty in the ITS tracking efficiency. This is estimated by varying the cuts on the number of clusters and on the track both in data and in Monte-Carlo simulations.

In the lowest -bins, a larger systematic error has been assigned to account for the steep slope of the tracking efficiency as a function of the particle transverse momentum (see Fig. 3).

systematic errors K p and
secondary contamination negl. negl. negl.
from material
secondary contamination % negl. 3%
from weak decay
material budget
highest  bin % % 1%
lowest  bin 5% 2% 3%
ITS efficiency
all  bins 2% 2% 2%
lowest  bin 12% 13% 11%
ln(d/d) distr. 1% 5% 3.5%
fitting procedure
Table 1: Summary of systematic errors in the efficiency correction of the ITS analysis.

2.5.2 Particle identification in the TPC

Particle identification is based on the specific energy deposit of each particle in the drift gas of the TPC, shown in Fig. 4 as a function of momentum separately for positive and negative charges. The solid curves show the calibration curves obtained by fitting the ALEPH parametrization of the Bethe-Bloch curve ALEPH () to the data points in regions of clear separation.

The calibration parameters have mostly been determined and tested via the analysis of cosmic rays. The pad-gain factors have been measured using the decay of radioactive Kr gas released into the TPC volume (for a detailed description see Alme:2010ke ()).

Figure 4: (Color online) Specific energy loss d/d vs. momentum for tracks measured with the ALICE TPC. The solid lines are a parametrization of the Bethe-Bloch curve ALEPH ().

As in the case of the ITS, a truncated-mean procedure is used to determine d/d (60% of the points are kept). This reduces the Landau tail of the d/d distribution to the extent that it is very close to a Gaussian distribution.

Examples of the d/d distribution in some  bins are shown in Fig. 5. The peak centered at zero is from kaons and the other peaks are from other particle species. As the background in all momentum bins is negligible, the integrals of the Gaussian give the raw yields.

Figure 5: (Color online) Distribution of ([d/d][d/d(kaon)])/[d/d(kaon)] measured with the TPC for several -bins showing the separation power. The solid lines are Gaussian fits to the distributions.
Efficiency correction

The raw hadron spectra are corrected for the reconstruction efficiency, shown in Fig. 6, determined by doing the same analysis on Monte-Carlo events. The efficiency is calculated by comparing the number of reconstructed particles to the number of charged primary particles from PYTHIA in the chosen rapidity range. For transverse momenta above 800 MeV/ the efficiency saturates at roughly 80%. For kaons, the decay reduces the efficiency by about 30% at 250 MeV/ and 12% at 1.5 GeV/. The range with a reconstruction efficiency lower than 60% (for pions and protons) is omitted for the analysis corresponding to a low- cut-off of 200 MeV/ for pions, 250 MeV/ for kaons, and 400 MeV/ for protons.

Protons are corrected for the contamination of secondaries from material and of feed down from weak decays. The feed down was determined by two independent methods. Firstly, the contamination obtained from Monte-Carlo simulation was scaled such that it corresponds to the measured yield of s in the data strange (). Secondly, the shape of the impact parameter distribution was compared to the Monte-Carlo simulation. Weak decays produce a non-Gaussian tail in the distribution of primary particles whereas secondaries from material generate a flat background Aamodt:2010dx (). The remaining difference between the methods is included in the systematic error. The correction for weak decays amounts to up to 14% and the correction for secondaries from material up to 4% for protons with 400 MeV/   MeV/. For other particle species and other transverse momenta the contamination is negligible.

Figure 6: (Color online) Efficiency of charged pions, kaons, and protons for the spectra extracted with the TPC.

The systematic errors in the track reconstruction and in the removal of secondary particles have been estimated by varying the number of standard deviations in the distance-to-vertex cut, using a fixed cut of 3 cm instead of the variable one, and varying the SPD-TPC matching cut. Their impact on the corrected spectra is less than 5%. The influence of the uncertainty in the material budget has been examined by varying it by 7%. This resulted in the systematic errors given in Table 2. The uncertainty due to a possible deviation from a Gaussian shape has been established by comparing the multi-Gauss fit with a 3- band in well separated regions. The precision of the kink rejection is estimated to be within 3%.

The correction for the event selection bias has been tested with two event generators, PYTHIA Sjostrand:2006za (); D6T () and PHOJET Engel:1995sb () and the corresponding uncertainty is less than 1%.

systematic errors K p and
secondary contamination negl. negl. 2%
from material
secondary contamination 4% - 10%
from weak decay
energy loss and 1% 1% 2%
absorption in material
kink rejection negl. 3% -
non-Gaussianity of negl. negl. negl.
dE/dx signal
matching to ITS 3%
Table 2: Summary of systematic errors in the efficiency correction in the TPC analysis.

2.5.3 Particle identification with the TOF

Particles reaching the TOF system are identified by measuring their momentum and velocity simultaneously.

The velocity is obtained from the measured time of flight and the reconstructed flight path along the track trajectory between the point of closest approach to the event vertex and the TOF sensitive surface. The measured velocities are shown as a function of the momentum at the vertex in Fig. 7. The bands corresponding to charged pions, kaons and protons are clearly visible. The width of the bands reflects the overall time-of-flight resolution of about 180 ps, which depends on the TOF timing signal resolution, the accuracy of the reconstructed flight path and the uncertainty of the event start time, . This last contribution is related to the uncertainty in establishing the absolute time of the collision. In the present sample this fluctuated with respect to the nominal time signal from the LHC with a of about 140 ps due to the finite size of the bunches.

Figure 7: (Color online) of tracks of particles measured by TOF vs. their momentum.

To improve the overall time-of-flight resolution, the TOF information itself is used to determine in events having at least three tracks with an associated TOF signal. This is done with a combinatorial algorithm which compares the TOF times with the calculated times of the tracks for each event for different mass hypotheses. Using this procedure, the start-time has been improved for 44% of the tracks having an associated TOF signal and is rather independent on the momentum of the tracks. In this way the precision on the event start-time is about 85 ps on average.

Finally, tracks whose particle identity as determined from the TOF information is not compatible with the one inferred from the d/d signal in the TPC within five have been removed. This TOF-TPC compatibility criterion rejects about 0.6% of the tracks and further reduces the small contamination coming from tracks incorrectly associated with a TOF signal.

Figure 8: (Color online) Distribution of the time difference between the measured TOF signal and the average of the calculated times for pions and kaons for several -bins for positively charged particles. The fits are performed using Gaussian shapes.

For each particle species , the expected time of flight is calculated by summing up the time-of-flight increments at each tracking step, with being the local value of the track momentum, the mass of the particle, and the track-length increment along its trajectory. The yields of , K and p are obtained from the simultaneous fit of the distribution of the time difference between measured and the average between the calculated time for pions and kaons

(1)

The symmetric treatment of kaons and pions in the definition of ensures that the kaon and pion peak are both Gaussian. Extracting the yield for different species in a simultaneous fit guarantees that the resulting number of pions, kaons and protons matches the total number of tracks in the given momentum bin.

The distribution of the variable is shown in Fig. 8 for three different transverse momentum bins for positive particles. The curves show the results of the three-Gaussian fit used to extract the raw yields. The integral of the fit result has been constrained to the number of entries in the distribution, and the means and the widths are allowed to vary within 5% and 10%, respectively, of their nominal values. The only free parameters in the fit are therefore the relative normalizations between the Gaussians.

The raw yields are extracted in different -bins using a rapidity selection , where is the rapidity calculated with the proton mass. For pions and kaons, this condition results in a larger -acceptance and in both cases, the fraction outside of has been subtracted in each -bin taking into account the -distribution of the yields within the pions and kaons peaks.

Efficiency correction

Since the track selection used in the TOF analysis is the same as the one described in the TPC analysis (subsection 2.5.2), the same tracking and feed-down corrections are applied. In the case of the TOF analysis, an additional correction is needed in order to take into account the fraction of the particles reconstructed by the TPC with an associated signal in TOF. This matching efficiency includes all sources of track losses in the propagation from the TPC to the TOF (geometry, decays and interactions with the material) and its matching with a TOF signal (the TOF intrinsic detector efficiency, the effect of dead channels and the efficiency of the track-TOF signal matching procedure). The TOF matching efficiency has been derived from Monte-Carlo events as the fraction of TPC reconstructed tracks having an associated TOF signal and is shown in Fig. 9 for each hadron species. The main factors limiting the TOF matching efficiency are the loss due to geometrical acceptance ( 15%), the number of dead or noisy channels ( 10%) and the absorption of particles in the material of the transition radiation detector ( 8%).

Figure 9: (Color online) The TOF matching efficiency is shown for the three particles, separately, for (top) positive and (bottom) negative particles.

The TOF matching efficiency has been tested with data, using d/d in the TPC to identify the particles. Good agreement between the efficiencies obtained from the data and from Monte-Carlo simulations is observed in case of pions and kaons, with deviations at the level of, at most, 3% and 6% respectively, over the full transverse-momentum range. The observed differences are assigned as systematic errors, see Table 3. In the case of protons and antiprotons, larger differences are observed at  below 0.7 GeV/, where the efficiency varies very rapidly with momentum. This region is therefore not considered in the final results (see Table 3).

Other sources of systematic errors related to the TOF PID procedure have been estimated from Monte-Carlo simulations and cross-checked with data. They include the effect of the residual contribution from tracks wrongly associated with TOF signals, and the quality and stability of the fit procedure used for extracting the yields. Table 3 summarizes the maximal value of the systematic errors observed over the full transverse momentum range relevant in the analysis, for each of the sources mentioned above.

systematic errors K p and
TOF 3% 6% 4%
matching ()
efficiency 7.5%
()
PID procedure 2% 7% 3%
Table 3: Summary of systematic errors in the TOF analysis.

2.6 Kaon Identification using their decay within the TPC

In this section, the determination of the yields of charged kaons identified by their weak decay (kink topology) inside the TPC detector is described. These tracks are rejected in the previously described TPC analysis. This procedure allows an extension of the study of kaons to intermediate momenta, on a track-by-track level, although in this analysis the  reach is limited by statistics.

The kinematics of the kink topology, measured as a secondary vertex with one mother and one daughter track of the same charge, allows the separation of kaon decays from the main source of background kinks coming from charged pion decays. The decay channels with the highest branching ratio (B.R.) for kaons are the two-body decays

  • , (B.R. 63.55%)

  • , (B.R. 20.66%).

Three-body decays with one charged daughter track (B.R. 9.87%) as well as three-body decays into three charged pions (B.R. 5.6%) are also detected.

The algorithm for reconstructing kinks as secondary vertices is applied inside a fiducial volume of the TPC with radius 120 cm 210 cm in order to have a minimum number of clusters for reconstructing both the mother and daughter tracks. Inside this volume a sufficient number of kinks can be found since the of kaon and pion decays are 3.7 m and 7.8 m, respectively. The mother track of the kink has been selected with similar criteria to those of the TPC tracks used for the d/d analysis, except that the minimum required number of clusters per track is 30, because the kink mother track does not traverse the entire TPC. The relation between the number of clusters per mother track and the radius of the kink is used as a quality check of the kink reconstruction procedure.

Figure 10: (Color online) (a) distribution of the daughter tracks with respect to mother momentum for all reconstructed kinks inside the analyzed sample. The dashed(solid) histograms show the distribution before (after) applying the  MeV/ cut. (b) Invariant mass of the two-body decays for candidate kaon kinks. Solid curve: after applying 40 MeV/; dashed curve: without this selection (hence also showing the pion decays). (c) d/d of kinks as a function of the mother momentum, after applying the full list of selection criteria for their identification.

The identification of kaons from kink topology and its separation from pion decay is based on the decay kinematics. The transverse momentum of the daughter with respect to the mother’s direction, , has an upper limit of 236 MeV/ for kaons and 30 MeV/ for pions for the two-body decay to . The corresponding upper limit for the two-body decay (2) is 205 MeV/. All three limits can be seen as peaks in Fig. 10 (a), which shows the distribution of all measured kinks inside the selected volume and rapidity range 0.7. Selecting kinks with MeV/ removes the majority of -decays as shown by the dashed (before) and solid (after) histograms.

The invariant mass for the decay into is calculated from the measured difference between the mother and daughter momentum, their decay angle, assuming zero mass for the neutrino. Figure 10 (b) shows the invariant mass for the full sample of kinks (dashed line) and for the sample after applying the preceding cuts (full line). The masses of pions and kaons are reconstructed at their nominal values. The third peak at 0.43 GeV/ originates from the decay for which the invariant mass is calculated with wrong mass assumptions for the daughter tracks. The broad structure originates from three-body decays of kaons.

At this stage, we have a rather clean sample of kaons as demonstrated in Fig. 10 (c) showing the d/d vs. the mother momentum. Most of the tracks are within a band with respect to the corresponding Bethe-Bloch curve of kaons. The few tracks outside these limits are at momenta below 600 MeV/ (less than 5%) and they have been removed in the last analysis step.

Efficiency and acceptance

The total correction factor includes both the acceptance of kinks and their efficiency (reconstruction and identification). The study has been performed for the rapidity interval 0.7, larger than the corresponding rapidity interval for the other studies in order to reduce the statistical errors.

Figure 11: (Color online) Upper panel: The acceptance of kaons decaying in the fiducial volume of the TPC as a function of the kaon for (full-triangles) and (open-squares). Lower panel: The efficiency of reconstructed kaons from kinks as a function of the  (mother), separately for (full-triangles) and (open-squares). The contamination from wrongly associated kinks is also plotted for both charges (lower set of points).

The acceptance is defined as the ratio of weak decays (two- and three-body decays) whose daughters are inside the fiducial volume of the TPC to all kaons inside the same rapidity window (Fig. 11, upper part). It essentially reflects the decay probability. However, the acceptance is not the same in the low-momentum region for both charges of kaons, since the interaction cross section of the negative kaons with the ITS material is higher than that of the positive kaons. As a result, the acceptance of positive kaons is larger at low momenta.

The efficiency is the ratio of reconstructed and identified kaons divided by the number of kaon decays within the acceptance as shown in Fig. 11 (lower part), as a function of the kaon . It reaches about 60% at 0.7 GeV/ and decreases gradually at higher transverse momenta, as the angle between mother and daughter tracks becomes smaller. The decay angle of kaon kinks allows their identification up to high momenta, e.g. at  of 5 GeV/ the values are between and .

The contamination due to random associations of primary and secondary charged tracks has been established using Monte-Carlo simulations and it is systematically smaller than 5% in the studied -range as also shown in Fig. 11. Hadronic interactions are the main source of these fake kinks (65%).

The systematic error due to the uncertainty in the material budget is about 1% as for the TPC analysis. The quality cuts remove about 8% of all real kaon kinks, which leads to a systematic error of less than 1%. The main uncertainty originates from the efficiency of the kink finding algorithm which has an uncertainty of 5%.

3 Results

Figure 12: (Color online) Transverse momentum spectra for 0.5 of positive (upper part) and negative (lower part) hadrons from the various analyses. Only systematic errors are plotted.

Figure 12 shows a comparison between the results from the different analyses. The spectra are normalized to inelastic collisions, as explained in Sec. 2.2. The kaon spectra obtained with various techniques, including K spectra strange (), are compared in Fig. 13. The very good agreement demonstrates that all the relevant efficiencies are well reproduced by the detector simulation.

The spectra from ITS stand-alone, TPC and TOF are combined in order to cover the full momentum range. The analyses from the different detectors use a slightly different sample of tracks and have largely independent systematics (mainly coming from the PID method and the contamination from secondaries). The spectra have been averaged, using the systematic errors as weights. From this weighted average, the combined, -dependent, systematic error is derived. The combined spectra have an additional overall normalization error, coming primarily from the uncertainty on the material budget (3%, Sec. 2.5) and from the normalization procedure (2%, Sec. 2.2).

Figure 13: (Color online) Comparison of charged kaon spectra, obtained from the combined ITS stand-alone, TPC, TOF analysis, from the kink topology and K spectra from Ref. strange ()

. Only statistical errors are shown.

The combined spectra shown in Fig. 14 are fitted with the Lévy (or Tsallis) function (see e.g. Tsallis:1987eu (); Abelev:2006cs ())

(2)
Figure 14: (Color online) Transverse momentum spectra of positive (top) and negative (bottom) hadrons from pp collisions at = 900 GeV. Grey bands: total -dependent error (systematic plus statistical); normalization systematic error (3.6%) not shown. The curves represent fits using a Lévy function.

with the fit parameters , and the yield . This function gives a good description of the spectra and has been used to extract the total yields and the , summarized in Table 4. The /degree-of-freedom is calculated using the total error. Due to residual correlations in the point-by-point systematic error, the values are less than 1. Also listed are the lowest measured -bin and the fraction of the yield contained in the extrapolation of the spectra to zero momentum. The extrapolation to infinite momentum gives a negligible contribution. The systematic errors take into account the contributions from the individual detectors, propagated to the combined spectra, the overall normalization error and the uncertainty in the extrapolation. The latter is evaluated using different fit functions (modified Hagedorn Hagedorn:1983wk () and the UA1 parametrization Albajar:1989an ()) or using a Monte-Carlo generator, matched to the data for (PYTHIA Sjostrand:2006za (), with tunes D6T D6T (), CSC and Perugia0 perugia (), or PHOJET Engel:1995sb ()). While none of these alternative extrapolations provides a description as good as the one from the Lévy fit, we estimate from this procedure an uncertainty of about 25% of the extrapolated part of the yield.

The ratios of /and K/K as a function of  are close to unity within the errors, allowing the combination of both spectra in the Lévy fits. The /p ratio as a function of  has been studied with high precision in our previous publication Aamodt:2010dx (). It is -independent with a mean value of . Also here we used the sum of both charges. Table LABEL:tab:levy_values summarizes the fit parameters along with the yields and mean . The errors have been determined as for the individual fits.

Particle d/d   (GeV/) Lowest  (GeV/) Extrapolation /ndf
0.02 10% 14.23/30
0.02 10% 12.46/30
K 0.05 13% 12.71/24
K 0.05 13% 6.23/24
p 0.06 21% 13.79/21
0.06 21% 13.46/21
Table 4: Integrated yield d/d () with statistical and systematic errors, and , as obtained from the fit with the Lévy function together with the lowest  experimentally accessible, the fraction of extrapolated yield and the /ndf of the fit (see text). The systematic error of d/d and of the includes the contributions from the systematic errors of the individual detectors, from the choice of the functional form for extrapolation and from the absolute normalization.
Particle d/d (GeV)   (GeV/) /ndf
+ 19.69/30
K + K 8.46/24
p + 15.70/21
Table 5: Results of the Lévy fits to combined positive and negative spectra. See text and the caption of Table 4 for details on the systematic errors.
Figure 15: (Color online) Mean  as a function of the mass of the emitted particle in pp collisions at 900 GeV (ALICE, red solid circles, statistical and systematic errors) compared to results at  = 200 GeV (star markers, average values of the results from the STAR and the PHENIX Collaborations :2008ez (); Adare:2010fe ()) and p reactions at  = 900 GeV Ansorge:1987cj () (open squares). Some data points are displaced for clarity.
Figure 16: (Color online) Ratios (K+K)/(+) and K as a function of . Data (full symbols) are from pp collisions, (at  = 17.9 GeV by NA49 Alt:2005zq (); Anticic:2010yg (), at  = 200 GeV by STAR :2008ez () and at  = 900 ALICE, present work) and (open symbols) from p interaction (at  = 560 GeV by UA5 Alner:1985ra () and at the TEVATRON by E735 Alexopoulos:1993wt (); Alexopoulos:1992ut ()).
Figure 17: (Color online) Comparison of measured pion, kaon and proton spectra at  = 900 GeV (both charges combined) with various tunes of event generators. Statistical errors only. See text for details.

Our values on yield and given in Table 4 and LABEL:tab:levy_values agree well with the results from p collisions at the same  Ansorge:1987cj (). Figure 15 compares the with measurements in pp collisions at  = 200 GeV :2008ez (); Adare:2010fe () and in p reactions at  = 900 GeV Ansorge:1987cj (). The mean  rises very little with increasing  despite the fact that the spectral shape clearly shows an increasing contribution from hard processes. It was already observed at RHIC that the increase in mean  at = 200 GeV compared to studies at = 25 GeV is small. The values obtained in pp collisions are lower than those for central Au+Au reactions at = 200 GeV :2008ez ().

The spectra presented in this paper are normalized to inelastic events. In a similar study by the STAR Collaboration the yields have been normalized to NSD collisions :2008ez (). In order to compare these two results, the yields in Table 4 have been scaled to NSD events, multiplying by 1.185 (see Section 2.2). The yields of pions increase from = 200 GeV to 900 GeV by 23%, while K rises by 45% and K by 48%.

Figure 16 shows the K/ ratio as a function of  both in pp (full symbols, :2008ez (); Alt:2005zq (); Anticic:2010yg ()) and in p (open symbols, Alexopoulos:1993wt (); Alner:1985ra (); Alexopoulos:1992ut ()) collisions. For most energies, (K+K)/(+) is plotted, but for some cases only neutral mesons were measured and K is used instead. The -integrated (K+K)/(+) ratio shows a slight increase from = 200 GeV (K/ = ) to = 900 GeV (K/=:2008ez (), yet consistent within the error bars. The results at 7 TeV will show whether the K/ ratio keeps rising slowly as a function of or saturates.

Figure 18: (Color online) Ratios of (K+ K)/(+ ) (upper panel) and (p + ) / (+ ) (lower panel) as a function of  from pp collisions at = 900 GeV (statistical errors only). Values from the E735 Collaboration Alexopoulos:1993wt () and the STAR Collaboration :2008ez ()(upper part) and from the PHENIX Collaboration Adler:2006xd () (lower part) also are given. The dashed and dotted curves refer to calculations using PYTHIA and PHOJET at = 900 GeV.

Protons and antiprotons in Table 4 have been corrected for feed down (mainly from ), while the results from the STAR Collaboration are not. The proton spectra measured by PHENIX, on the other hand, have a lower -cut of 0.6 GeV/. This makes a direct comparison with RHIC data difficult.

Figure 17 shows a comparison of the measured pion, kaon and proton spectra with several tunes of the PYTHIA event generator Sjostrand:2006za () and with PHOJET Engel:1995sb (). The PYTHIA CSC 306 Moraes:306AIN () tune provides a very poor description of the particle spectra for all species. Similar deviations were already seen for the unidentified charged hadron spectra Aamodt:2010my (). The other PYTHIA tunes, Perugia0 perugia () and D6T D6T (), and PHOJET give a reasonable description of the charged pion spectra, but show large deviations in the kaon and proton spectra. The measured kaon -spectrum falls more slowly with increasing  than the event generators predict. A similar trend is seen for the proton spectra, except for PYTHIA tune D6T, which describes the proton spectra reasonably well.

The upper panel of Figure 18 shows the -dependence of the K/ and also the measurements by the E735 Alexopoulos:1993wt () and STAR Collaborations :2008ez (). It can be seen that the observed increase of K/ with  does not depend strongly on collision energy.

A comparison with event generators shows that at 1.2 GeV/, the measured K/ ratio is larger than any of the model predictions. It is interesting to note that while the spectra in the CSC tune are much steeper than the other tunes, the -dependence of the K/ ratio is very similar. In the models, the amount of strangeness production depends on the production ratios of gluons and the different quark flavours in the hard scattering and on the strangeness suppression in the string breaking. The latter could probably be tuned to better describe the data. A similar disagreement between measured strangeness production and PYTHIA predictions was found at RHIC energies Heinz:2007ci ().

In the bottom panel of Figure 18, the measured p/ ratio is compared to results at = 200 GeV from the PHENIX Collaboration Adler:2006xd (). Both measurements are feed-down corrected. At low , there is no energy-dependence of the p ratio visible, while at higher GeV/, the p/ ratio is larger at = 900 GeV than at = 200 GeV energy.

Event generators seem to separate into two groups, one with high p/ ratio (PYTHIA CSC and D6T), which agree better with the data and one group with a lower p/ ratio (PHOJET and PYTHIA Perugia0), which are clearly below the measured values. These comparisons can be used for future tunes of baryon production in the event generators.

4 Summary

We present the first analysis of transverse momentum spectra of identified hadrons, , , K, K, p, and  in pp collisions at  = 900 GeV with the ALICE detector. The identification has been performed using the d/d of the inner silicon tracker, the d/d in the gas of the TPC, the kink topology of the decaying kaons inside the TPC and the time-of-flight information from TOF. The combination of these techniques allows us to cover a broad range of momentum.

Agreement in the K/ ratio is seen when comparing to p collisions at the Tevatron and SpS. Comparing our results with a similar measurement from the STAR Collaboration using pp collisions at = 200 GeV the shape of the spectra shows an increase of the hard component, but we observe only a slight increase of the mean -values. Whether the fraction of strange to non-strange particles rises with increasing  remains open until data at 7 TeV become available.

Acknowledgements

The ALICE collaboration would like to thank all its engineers and technicians for their invaluable contributions to the construction of the experiment and the CERN accelerator teams for the outstanding performance of the LHC complex.
The ALICE collaboration acknowledges the following funding agencies for their support in building and running the ALICE detector:
Department of Science and Technology, South Africa;
Calouste Gulbenkian Foundation from Lisbon and Swiss Fonds Kidagan, Armenia;
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Financiadora de Estudos e Projetos (FINEP), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP);
National Natural Science Foundation of China (NSFC), the Chinese Ministry of Education (CMOE) and the Ministry of Science and Technology of China (MSTC);
Ministry of Education and Youth of the Czech Republic;
Danish Natural Science Research Council, the Carlsberg Foundation and the Danish National Research Foundation;
The European Research Council under the European Community’s Seventh Framework Programme;
Helsinki Institute of Physics and the Academy of Finland;
French CNRS-IN2P3, the ‘Region Pays de Loire’, ‘Region Alsace’, ‘Region Auvergne’ and CEA, France;
German BMBF and the Helmholtz Association;
Hungarian OTKA and National Office for Research and Technology (NKTH);
Department of Atomic Energy and Department of Science and Technology of the Government of India;
Istituto Nazionale di Fisica Nucleare (INFN) of Italy;
MEXT Grant-in-Aid for Specially Promoted Research, Japan;
Joint Institute for Nuclear Research, Dubna;
National Research Foundation of Korea (NRF);
CONACYT, DGAPA, México, ALFA-EC and the HELEN Program (High-Energy physics Latin-American–European Network);
Stichting voor Fundamenteel Onderzoek der Materie (FOM) and the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Netherlands;
Research Council of Norway (NFR);
Polish Ministry of Science and Higher Education;
National Authority for Scientific Research - NASR (Autoritatea Naţională pentru Cercetare Ştiinţifică - ANCS);
Federal Agency of Science of the Ministry of Education and Science of Russian Federation, International Science and Technology Center, Russian Academy of Sciences, Russian Federal Agency of Atomic Energy, Russian Federal Agency for Science and Innovations and CERN-INTAS;
Ministry of Education of Slovakia;
CIEMAT, EELA, Ministerio de Educación y Ciencia of Spain, Xunta de Galicia (Consellería de Educación), CEADEN, Cubaenergía, Cuba, and IAEA (International Atomic Energy Agency);
Swedish Reseach Council (VR) and Knut Alice Wallenberg Foundation (KAW);
Ukraine Ministry of Education and Science;
United Kingdom Science and Technology Facilities Council (STFC);
The United States Department of Energy, the United States National Science Foundation, the State of Texas, and the State of Ohio.

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