The Pierre Auger Cosmic Ray Observatory

The successful installation, commissioning, and operation of the Pierre Auger Observatory would not have been possible without the strong commitment and effort from the technical and administrative staff in Malargüe. We are very grateful to the following agencies and organizations for financial support: Comisión Nacional de Energía Atómica, Fundación Antorchas, Gobierno De La Provincia de Mendoza, Municipalidad de Malargüe, NDM Holdings and Valle Las Leñas, in gratitude for their continuing cooperation over land access, Argentina; the Australian Research Council; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Financiadora de Estudos e Projetos (FINEP), Fundação de Amparo à Pesquisa do Estado de Rio de Janeiro (FAPERJ), São Paulo Research Foundation (FAPESP) Grants # 2010/07359-6 and # 1999/05404-3, Ministério de Ciência e Tecnologia (MCT), Brazil; MSMT-CR LG13007, 7AMB14AR005, CZ.1.05/2.1.00/03.0058 and the Czech Science Foundation Grant 14-17501S, Czech Republic; Centre de Calcul IN2P3/CNRS, Centre National de la Recherche Scientifique (CNRS), Conseil Régional Ile-de-France, Département Physique Nucléaire et Corpusculaire (PNC-IN2P3/CNRS), Département Sciences de l'Univers (SDU-INSU/CNRS), Institut Lagrange de Paris, ILP LABEX ANR-10-LABX-63, within the Investissements d'Avenir ProgrammeANR-11-IDEX-0004-02, France; Bundesministerium für Bildung und Forschung (BMBF), Deutsche Forschungsgemeinschaft (DFG), Finanzministerium Baden-Württemberg, Helmholtz Alliance for Astroparticle Physics (HAP), Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF), Ministerium für Wissenschaft und Forschung, Nordrhein Westfalen, Ministerium für Wissenschaft, Forschung und Kunst, Baden-Württemberg, Germany; Istituto Nazionale di Astrofisica (INAF), Istituto Nazionale di Fisica Nucleare (INFN), Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR), Gran Sasso Center for Astroparticle Physics (CFA), CETEMPS Center of Excellence, Italy; Consejo Nacional de Ciencia y Tecnología (CONACYT), Mexico; Ministerie van Onderwijs, Cultuur en Wetenschap, Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Stichting voor Fundamenteel Onderzoek der Materie (FOM), Netherlands; National Centre for Research and Development, Grant nos. ERA-NETASPERA/01/11 and ERA-NET-ASPERA/02/11, National Science Centre, Grant nos. 2013/08/M/ST9/00322, and 2013/08/M/ST9/00728 and HARMONIA 5 – 2013/10/M/ST9/00062, Poland; Portuguese national funds and FEDER funds within COMPETE – Programa Operacional Factores de Competitividade through Fundação para a Ciencia e a Tecnologia, Portugal; Romanian Authority for Scientific Research ANCS, CNDI-UEFISCDI partnership projects nos. 20/2012 and nr.194/2012, project nos. 1/ASPERA2/2012 ERA-NET, PN-II-RU-PD-2011-3-0145-17, and PN-II-RU-PD-2011- 3-0062, the Minister of National Education, Programme for research – Space Technology and Advanced Research – STAR, project number 83/2013, Romania; Slovenian Research Agency, Slovenia; Comunidad de Madrid, FEDER funds, Ministerio de Educación y Ciencia, Xunta de Galicia, European Community 7th Framework Program, Grant no. FP7-PEOPLE-2012-IEF-328826, Spain; Science and Technology Facilities Council, United Kingdom; Department of Energy, Contract no. DE-AC02-07CH11359, DE-FR02-04ER41300, DE-FG02-99ER41107 and DE-SC0011689, National Science Foundation, Grant no. 0450696, The Grainger Foundation, USA; NAFOSTED, Vietnam; Marie Curie-IRSES/EPLANET, European Particle Physics Latin American Network, European Union 7th Framework Program, Grant no. PIRSES-2009- GA-246806; and UNESCO.The Pierre Auger Observatory, located on a vast, high plain in western Argentina, is the world׳s largest cosmic ray observatory. The objectives of the Observatory are to probe the origin and characteristics of cosmic rays above 1017 eV and to study the interactions of these, the most energetic particles observed in nature. The Auger design features an array of 1660 water Cherenkov particle detector stations spread over 3000 km2 overlooked by 24 air fluorescence telescopes. In addition, three high elevation fluorescence telescopes overlook a 23.5 km2, 61-detector infilled array with 750 m spacing. The Observatory has been in successful operation since completion in 2008 and has recorded data from an exposure exceeding 40,000 km2 sr yr. This paper describes the design and performance of the detectors, related subsystems and infrastructure that make up the Observatory.Comision Nacional de Energia AtomicaFundacion AntorchasGobierno De La Provincia de MendozaMunicipalidad de MalargueNDM Holdings and Valle Las LenasAustralian Research CouncilNational Council for Scientific and Technological Development (CNPq)Ciencia Tecnologia e Inovacao (FINEP)Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (FAPERJ)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) 2010/07359-6 1999/05404-3Ministerio de Ciencia e Tecnologia (MCT), BrazilMinistry of Education, Youth & Sports - Czech Republic LG13007 7AMB14AR005 CZ.1.05/2.1.00/03.0058Grant Agency of the Czech Republic Czech Republic Government 14-17501SCentre National de la Recherche Scientifique (CNRS)Region Ile-de-FranceDepartement Physique Nucleaire et Corpusculaire PNC-IN2P3/CNRSDepartement Sciences de l'Univers (SDU-INSU/CNRS)Institut Lagrange de ParisFrench National Research Agency (ANR) ANR-11-IDEX-0004-02 ANR-10-LABX-63Federal Ministry of Education & Research (BMBF)German Research Foundation (DFG)Finanzministerium Baden-WurttembergHelmholtz Alliance for Astroparticle Physics (HAP)Helmholtz AssociationMinisterium fur Wissenschaft und ForschungNordrhein WestfalenMinisterium fur WissenschaftForschung und KunstBaden-Wurttemberg, GermanyIstituto Nazionale Astrofisica (INAF)Istituto Nazionale di Fisica Nucleare (INFN)Ministry of Education, Universities and Research (MIUR)Gran Sasso Center for Astroparticle Physics (CFA)CETEMPS Center of Excellence, ItalyConsejo Nacional de Ciencia y Tecnologia (CONACyT)Ministerie van OnderwijsCultuur en WetenschapNetherlands Organization for Scientific Research (NWO)FOM (The Netherlands) Netherlands GovernmentNational Centre for Research and Development ERA-NET-ASPERA/01/11 ERA-NET-ASPERA/02/11National Science Centre, Poland 2013/08/M/ST9/00322 2013/08/M/ST9/00728 HARMONIA 5 - 2013/10/M/ST9/00062Portuguese national fundsFEDER funds within COMPETE - Programa Operacional Factores de Competitividade through Fundacao para a Ciencia e a Tecnologia, PortugalRomanian Authority for Scientific Research ANCSCNDI-UEFISCDI 20/2012 194/2012 1/ASPERA2/2012 ERA-NET PN-II-RU-PD-2011-3-0145-17 PN-II-RU-PD-2011-3-0062Programme for research - Space Technology and Advanced Research - STAR, Romania 83/2013Slovenian Research Agency - SloveniaComunidad de Madrid Instituto de Salud Carlos IIIEuropean Union (EU)Spanish GovernmentXunta de GaliciaEuropean Community, Spain FP7-PEOPLE-2012-IEF-328826Science & Technology Facilities Council (STFC)United States Department of Energy (DOE) DE-AC02-07CH11359 DE-FR02-04ER41300 DE-FG02-99ER41107 DE-SC0011689National Science Foundation (NSF) 0450696Grainger Foundation, USANational Foundation for Science & Technology Development (NAFOSTED)Marie Curie-IRSES/EPLANETEuropean Particle Physics Latin American NetworkEuropean Union (EU) PIRSES-2009-GA-246806UNESC

The ArDM Experiment

Presented at the Cracow Epiphany Conference on Physics in Underground Laboratories and Its Connection with LHC, Cracow, Poland, January 5–8, 2010.The aim of the ArDM project is the development and operation of a one ton double-phase liquid argon detector for direct Dark Matter searches. The detector measures both the scintillation light and the ionization charge from ionizing radiation using two independent readout systems. This paper briefly describes the detector concept and presents preliminary results from the ArDM R&D program, including a 3 l prototype developed to test the charge readout system

Depth of maximum of air-shower profiles at the Pierre Auger Observatory. I. Measurements at energies above 10(17.8) eV

The successful installation, commissioning, and operation of the Pierre Auger Observatory would not have been possible without the strong commitment and effort from the technical and administrative staff in Malargue. We are very grateful to the following agencies and organizations for financial support: Comision Nacional de Energia Atomica, Fundacion Antorchas, Gobierno De La Provincia de Mendoza, Municipalidad de Malargue, NDM Holdings and Valle Las Lenas, in gratitude for their continuing cooperation over land access, Argentina; the Australian Research Council; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Financiadora de Estudos e Projetos (FINEP), Fundacao de Amparo a Pesquisa do Estado de Rio de Janeiro (FAPERJ), Sao Paulo Research Foundation (FAPESP) Grants No. 2010/07359-6, No. 1999/05404-3, Ministerio de Ciencia e Tecnologia (MCT), Brazil; MSMT-CR LG13007, 7AMB14AR005, CZ.1.05/2.1.00/03.0058 and the Czech Science Foundation Grant No. 14-17501S, Czech Republic; Centre de Calcul IN2P3/CNRS, Centre National de la Recherche Scientifique (CNRS), Conseil Regional Ile-de-France, Departement Physique Nucleaire et Corpusculaire (PNC-IN2P3/CNRS), Departement Sciences de l'Univers (SDU-INSU/CNRS), Institut Lagrange de Paris, ILP LABEX ANR-10-LABX-63, within the Investissements d'Avenir Programme ANR-11-IDEX-0004-02, France; Bundesministerium fur Bildung und Forschung (BMBF), Deutsche Forschungsgemeinschaft (DFG), Finanzministerium Baden-Wurttemberg, Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF), Ministerium fur Wissenschaft und Forschung, Nordrhein Westfalen, Ministerium fur Wissenschaft, Forschung und Kunst, Baden-Wurttemberg, Germany; Istituto Nazionale di Fisica Nucleare (INFN), Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR), Gran Sasso Center for Astroparticle Physics (CFA), CETEMPS Center of Excellence, Italy; Consejo Nacional de Ciencia y Tecnologia (CONACYT), Mexico; Ministerie van Onderwijs, Cultuur en Wetenschap, Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO), Stichting voor Fundamenteel Onderzoek der Materie (FOM), Netherlands; National Centre for Research and Development, Grants No. ERA-NET-ASPERA/01/11 and No. ERA-NET-ASPERA/02/11, National Science Centre, Grants No. 2013/08/M/ST9/00322, No. 2013/08/M/ST9/00728 and No. HARMONIA 5 - 2013/10/M/ST9/00062, Poland; Portuguese national funds and FEDER funds within COMPETE - Programa Operacional Factores de Competitividade through Fundacao para a Ciencia e a Tecnologia, Portugal; Romanian Authority for Scientific Research ANCS, CNDI-UEFISCDI partnership projects nr. 20/2012 and nr. 194/2012, project nr. 1/ASPERA2/2012 ERA-NET, PN-II-RU-PD-2011-3-0145-17, and PN-II-RU-PD-2011-3-0062, the Minister of National Education, Programme for research - Space Technology and Advanced Research - STAR, project no. 83/2013, Romania; Slovenian Research Agency, Slovenia; Comunidad de Madrid, FEDER funds, Ministerio de Educacion y Ciencia, Xunta de Galicia, European Community 7th Framework Program, Grant No. FP7-PEOPLE-2012-IEF-328826, Spain; Science and Technology Facilities Council, U.K.; Department of Energy, Contracts No. DE-AC02-07CH11359, No. DE-FR02-04ER41300, No. DE-FG02-99ER41107 and No. DE-SC0011689, National Science Foundation, Grant No. 0450696, The Grainger Foundation, USA; NAFOSTED, Vietnam; Marie Curie-IRSES/EPLANET, European Particle Physics Latin American Network, European Union 7th Framework Program, Grant No. PIRSES-2009-GA-246806; and UNESCO.We report a study of the distributions of the depth of maximum, Xmax, of extensive air-shower profiles with energies above 1017.8  eV as observed with the fluorescence telescopes of the Pierre Auger Observatory. The analysis method for selecting a data sample with minimal sampling bias is described in detail as well as the experimental cross-checks and systematic uncertainties. Furthermore, we discuss the detector acceptance and the resolution of the Xmax measurement and provide parametrizations thereof as a function of energy. The energy dependence of the mean and standard deviation of the Xmax distributions are compared to air-shower simulations for different nuclear primaries and interpreted in terms of the mean and variance of the logarithmic mass distribution at the top of the atmosphere.Comision Nacional de Energia AtomicaFundacion AntorchasGobierno De La Provincia de MendozaMunicipalidad de MalargueNDM HoldingsValle Las LenasAustralian Research CouncilNational Council for Scientific and Technological Development (CNPq)Ciencia Tecnologia e Inovacao (FINEP)Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (FAPERJ)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) 2010/07359-6 1999/05404-3Ministerio de Ciencia e Tecnologia (MCT), BrazilGrant Agency of the Czech Republic Czech Republic Government 14-17501SCentre National de la Recherche Scientifique (CNRS)Region Ile-de-FranceDepartement Sciences de l'Univers (SDU-INSU/CNRS)Institut Lagrange de ParisFrench National Research Agency (ANR) ANR-10-LABX-63 ANR-11-IDEX-0004-02Federal Ministry of Education & Research (BMBF)German Research Foundation (DFG)Finanzministerium Baden-WurttembergHelmholtz AssociationMinisterium fur Wissenschaft und ForschungNordrhein WestfalenMinisterium fur WissenschaftForschung und KunstBaden-Wurttemberg, GermanyIstituto Nazionale di Fisica Nucleare (INFN)Ministry of Education, Universities and Research (MIUR)Gran Sasso Center for Astroparticle Physics (CFA)CETEMPS Center of Excellence, ItalyConsejo Nacional de Ciencia y Tecnologia (CONACyT)Ministerie van Onderwijs, Cultuur en WetenschapNetherlands Organization for Scientific Research (NWO)FOM (The Netherlands) Netherlands GovernmentNational Centre for Research and Development ERA-NET-ASPERA/01/11 ERA-NET-ASPERA/02/11National Science Centre, Poland 2013/08/M/ST9/00322 2013/08/M/ST9/00728 HARMONIA 5 - 2013/10/M/ST9/00062Portuguese national funds within COMPETE - Programa Operacional Factores de Competitividade through Fundacao para a Ciencia e a Tecnologia, PortugalFEDER funds within COMPETE - Programa Operacional Factores de Competitividade through Fundacao para a Ciencia e a Tecnologia, PortugalRomanian Authority for Scientific Research ANCSCNDI-UEFISCDI 20/2012 194/2012 1/ASPERA2/2012 ERA-NET PN-II-RU-PD-2011-3-0145-17 PN-II-RU-PD-2011-3-0062Minister of National Education, Programme for research - Space Technology and Advanced Research - STAR, Romania 83/2013Slovenian Research Agency - SloveniaComunidad de Madrid Instituto de Salud Carlos IIIEuropean Union (EU)Spanish GovernmentXunta de GaliciaEuropean Community 7th Framework Program, Spain FP7-PEOPLE-2012-IEF-328826Science & Technology Facilities Council (STFC)United States Department of Energy (DOE) DE-AC02-07CH11359 DE-FR02-04ER41300 DE-FG02-99ER41107 DE-SC0011689National Science Foundation (NSF) 0450696Grainger Foundation, USANational Foundation for Science & Technology Development (NAFOSTED)European Union (EU) PIRSES-2009-GA-246806UNESCOMSMT-CR LG130077AMB14AR005CZ.1.05/2.1.00/03.005

Energy Reconstruction of Electromagnetic Showers from π0 Decays with the ICARUS T600 Liquid Argon TPC

We discuss the ICARUS T600 detector capabilities in electromagnetic shower reconstruction through the analysis of a sample of 212 events, coming from the 2001 Pavia surface test run, of hadronic interactions leading to the production of π0 mesons. Methods of shower energy and shower direction measurements were developed and the invariant mass of the photon pairs was reconstructed. The (γ,γ) invariant mass was found to be consistent with the value of the π0 mass. The resolution of the reconstructed π0 mass was found to be equal to 27.3%. An improved analysis, carried out in order to clean the full event sample from the events measured in the crowded environment, mostly due to the trigger conditions, gave a π0 mass resolution of 16.1%, significantly better than the one evaluated for the full event sample. The trigger requirement of the coincidence of at least four photo-multiplier signals favored the selection of events with a strong pile up of cosmic ray tracks and interactions. Hence a number of candidate π0 events were heavily contaminated by other tracks and had to be rejected. Monte Carlo simulations of events with π0 production in hadronic and neutrino interactions confirmed the validity of the shower energy and shower direction reconstruction methods applied to the real data.We are glad of the financial and technical support of our funding agencies and in particular of the Istituto Nazionale di Fisica Nucleare (INFN). The Polish groups acknowledge the support of the Ministry of Science and Higher Education in Poland, 105,160,620,621/E-344,E-340,E-77,E-78/SPB/ICARUS/ P-03/DZ211-214/2003-2008, 1P03B04130 and N N202 0299 33