https://doi.org/10.1140/epjc/s10052-021-09700-w
Regular Article - Theoretical Physics
The energy spectrum of cosmic rays beyond the turn-down around
eV as measured with the surface detector of the Pierre Auger Observatory
1
Centro Atómico Bariloche and Instituto Balseiro (CNEA-UNCuyo-CONICET), San Carlos de Bariloche, Argentina
2
Centro de Investigaciones en Láseres y Aplicaciones, CITEDEF and CONICET, Villa Martelli, Argentina
3
Departamento de Física and Departamento de Ciencias de la Atmósfera y los Océanos, FCEyN, Universidad de Buenos Aires and CONICET, Buenos Aires, Argentina
4
IFLP, Universidad Nacional de La Plata and CONICET, La Plata, Argentina
5
Instituto de Astronomía y Física del Espacio (IAFE, CONICET-UBA), Buenos Aires, Argentina
6
Instituto de Física de Rosario (IFIR)-CONICET/U.N.R. and Facultad de Ciencias Bioquímicas y Farmacéuticas U.N.R., Rosario, Argentina
7
Instituto de Tecnologías en Detección y Astropartículas (CNEA, CONICET, UNSAM), Universidad Tecnológica Nacional-Facultad Regional Mendoza (CONICET/CNEA), Mendoza, Argentina
8
Instituto de Tecnologías en Detección y Astropartículas (CNEA, CONICET, UNSAM), Buenos Aires, Argentina
9
Observatorio Pierre Auger, Malargüe, Argentina
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Observatorio Pierre Auger and Comisión Nacional de Energía Atómica, Malargüe, Argentina
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Universidad Tecnológica Nacional-Facultad Regional Buenos Aires, Buenos Aires, Argentina
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University of Adelaide, Adelaide, SA, Australia
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Université Libre de Bruxelles (ULB), Brussels, Belgium
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Vrije Universiteit Brussels, Brussels, Belgium
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Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, RJ, Brazil
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Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, Nova Friburgo, Brazil
17
Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro (IFRJ), Rio de Janeiro, Brazil
18
Escola de Engenharia de Lorena, Universidade de São Paulo, Lorena, SP, Brazil
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Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
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Instituto de Física, Universidade de São Paulo, São Paulo, SP, Brazil
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Universidade Estadual de Campinas, IFGW, Campinas, SP, Brazil
22
Universidade Estadual de Feira de Santana, Feira de Santana, Brazil
23
Universidade Federal do ABC, Santo André, SP, Brazil
24
Universidade Federal do Paraná, Setor Palotina, Palotina, Brazil
25
Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
26
Observatório do Valongo, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil
27
Universidade Federal Fluminense, EEIMVR, Volta Redonda, RJ, Brazil
28
Universidad de Medellín, Medellín, Colombia
29
Universidad Industrial de Santander, Bucaramanga, Colombia
30
Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
31
Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic
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Palacky University, RCPTM, Olomouc, Czech Republic
33
CNRS/IN2P3, IJCLab, Université Paris-Saclay, Orsay, France
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Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Sorbonne Université, Université de Paris, CNRS-IN2P3, Paris, France
35
Univ. Grenoble Alpes, CNRS, Grenoble Institute of Engineering Univ. Grenoble Alpes, LPSC-IN2P3, 38000, Grenoble, France
36
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
37
Department of Physics, Bergische Universität Wuppertal, Wuppertal, Germany
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Institute for Experimental Particle Physics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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Institut für Prozessdatenverarbeitung und Elektronik, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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Institute for Astroparticle Physics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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III. Physikalisches Institut A, RWTH Aachen University, Aachen, Germany
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II. Institut für Theoretische Physik, Universität Hamburg, Hamburg, Germany
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Department Physik-Experimentelle Teilchenphysik, Universität Siegen, Siegen, Germany
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Gran Sasso Science Institute, L’Aquila, Italy
45
INFN Laboratori Nazionali del Gran Sasso, Assergi (L’Aquila), Italy
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INFN, Sezione di Catania, Catania, Italy
47
INFN, Sezione di Lecce, Lecce, Italy
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INFN, Sezione di Milano, Milan, Italy
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INFN, Sezione di Napoli, Naples, Italy
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INFN, Sezione di Roma “Tor Vergata”, Rome, Italy
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INFN, Sezione di Torino, Turin, Italy
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Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo (INAF), Palermo, Italy
53
Osservatorio Astrofisico di Torino (INAF), Turin, Italy
54
Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano, Milan, Italy
55
Dipartimento di Matematica e Fisica “E. De Giorgi”, Università del Salento, Lecce, Italy
56
Dipartimento di Scienze Fisiche e Chimiche, Università dell’Aquila, L’Aquila, Italy
57
Dipartimento di Fisica e Astronomia, Università di Catania, Catania, Italy
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Dipartimento di Fisica, Università di Milano, Milan, Italy
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Dipartimento di Fisica “Ettore Pancini”, Università di Napoli “Federico II”, Naples, Italy
60
Dipartimento di Fisica e Chimica ”E. Segrè”, Università di Palermo, Palermo, Italy
61
Dipartimento di Fisica, Università di Roma “Tor Vergata”, Rome, Italy
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Dipartimento di Fisica, Università Torino, Turin, Italy
63
Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
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Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas del Instituto Politécnico Nacional (UPIITA-IPN), Mexico, D.F., Mexico
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Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas, Mexico
66
Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, México
67
Universidad Nacional Autónoma de México, Mexico, D.F., Mexico
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Facultad de Ciencias Naturales y Formales, Universidad Nacional de San Agustin de Arequipa, Arequipa, Peru
69
Institute of Nuclear Physics PAN, Krakow, Poland
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Faculty of High-Energy Astrophysics, University of Łódź, Łódź, Poland
71
Laboratório de Instrumentação e Física Experimental de Partículas – LIP and Instituto Superior Técnico-IST, Universidade de Lisboa-UL, Lisbon, Portugal
72
“Horia Hulubei” National Institute for Physics and Nuclear Engineering, Bucharest-Magurele, Romania
73
Institute of Space Science, Bucharest-Magurele, Romania
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University Politehnica of Bucharest, Bucharest, Romania
75
Center for Astrophysics and Cosmology (CAC), University of Nova Gorica, Nova Gorica, Slovenia
76
Experimental Particle Physics Department, J. Stefan Institute, Ljubljana, Slovenia
77
Universidad de Granada and C.A.F.P.E., Granada, Spain
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Instituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela, Santiago de Compostela, Spain
79
IMAPP, Radboud University Nijmegen, Nijmegen, The Netherlands
80
Nationaal Instituut voor Kernfysica en Hoge Energie Fysica (NIKHEF), Science Park, Amsterdam, The Netherlands
81
Stichting Astronomisch Onderzoek in Nederland (ASTRON), Dwingeloo, The Netherlands
82
Faculty of Science, Universiteit van Amsterdam, Amsterdam, The Netherlands
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Kapteyn Astronomical Institute, University of Groningen, Groningen, The Netherlands
84
Case Western Reserve University, Cleveland, OH, USA
85
Colorado School of Mines, Golden, CO, USA
86
Department of Physics and Astronomy, Lehman College, City University of New York, Bronx, NY, USA
87
Louisiana State University, Baton Rouge, LA, USA
88
Michigan Technological University, Houghton, MI, USA
89
New York University, New York, NY, USA
90
Pennsylvania State University, University Park, PA, USA
91
University of Chicago, Enrico Fermi Institute, Chicago, IL, USA
92
Department of Physics and Astronomy, Bartol Research Institute, University of Delaware, Newark, DE, USA
93
Department of Physics and WIPAC, University of Wisconsin-Madison, Madison, WI, USA
94
Fermi National Accelerator Laboratory, Fermilab, Batavia, IL, USA
95
Max-Planck-Institut für Radioastronomie, Bonn, Germany
96
School of Physics and Astronomy, University of Leeds, Leeds, UK
97
Colorado State University, Fort Collins, CO, USA
98
Hakubi Center for Advanced Research and Graduate School of Science, Kyoto University, Kyoto, Japan
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University of Bucharest, Physics Department, Bucharest, Romania
100
The Pierre Auger Observatory, Av. San Martín Norte 306, 5613, Malargüe, Mendoza, Argentina
sj
spokespersons@auger.org
http://www.auger.org
Received:
10
May
2021
Accepted:
29
September
2021
Published online:
2
November
2021
We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the spectrum is observed, confirming the presence of the so-called second-knee feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays.
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epjc/s10052-021-09700-w.
© The Author(s) 2021
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