The energy spectrum of cosmic rays beyond the turn-down around 1017 eV as measured with the surface detector of the Pierre Auger 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: Argentina – Comisión Nacional de Energía Atómica; Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET); Gobierno de la Provincia de Mendoza; Municipalidad de Malargüe; NDM Holdings and Valle Las Leñas; in gratitude for their continuing cooperation over land access; Australia – the Australian Research Council; Belgium – Fonds de la Recherche Scientifique (FNRS); Research Foundation Flanders (FWO); Brazil – 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 No. 2019/10151-2, No. 2010/07359-6 and No. 1999/05404-3; Ministério da Ciência, Tecnologia, Inovações e Comunicações (MCTIC); Czech Republic – Grant No. MSMT CR LTT18004, LM2015038, LM2018102, CZ.02.1.01/0.0/0.0/16_013/0001402, CZ.02.1.01/0.0/0.0/18_046/0016010 and CZ.02.1.01/0.0/0.0/17_049/0008422; France – 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) Grant No. LABEX ANR-10-LABX-63 within the Investissements d’Avenir Programme Grant No. ANR-11-IDEX-0004-02; Germany – 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 Innovation, Wissenschaft und Forschung des Landes Nordrhein-Westfalen; Ministerium für Wissenschaft, Forschung und Kunst des Landes Baden-Württemberg; Italy – Istituto Nazionale di Fisica Nucleare (INFN); Istituto Nazionale di Astrofisica (INAF); Ministero dell’Istruzione, dell’Universitá e della Ricerca (MIUR); CETEMPS Center of Excellence; Ministero degli Affari Esteri (MAE); México – Consejo Nacional de Ciencia y Tecnología (CONACYT) No. 167733; Universidad Nacional Autónoma de México (UNAM); PAPIIT DGAPA-UNAM; The Netherlands – Ministry of Education, Culture and Science; Netherlands Organisation for Scientific Research (NWO); Dutch national e-infrastructure with the support of SURF Cooperative; Poland -Ministry of Science and Higher Education, grant No. DIR/WK/2018/11; National Science Centre, Grants No. 2013/08/M/ST9/00322, No. 2016/23/B/ST9/01635 and No. HARMONIA 5–2013/10/M/ST9/00062, UMO-2016/22/M/ST9/00198; Portugal – Portuguese national funds and FEDER funds within Programa Operacional Factores de Competitividade through Fundação para a Ciência e a Tecnologia (COMPETE); Romania – Romanian Ministry of Education and Research, the Program Nucleu within MCI (PN19150201/16N/2019 and PN19060102) and project PN-III-P1-1.2-PCCDI-2017-0839/19PCCDI/2018 within PNCDI III; Slovenia – Slovenian Research Agency, grants P1-0031, P1-0385, I0-0033, N1-0111; Spain – Ministerio de Economía, Industria y Competitividad (FPA2017-85114-P and PID2019-104676GB-C32), Xunta de Galicia (ED431C 2017/07), Junta de Andalucía (SOMM17/6104/UGR, P18-FR-4314) Feder Funds, RENATA Red Nacional Temática de Astropartículas (FPA2015-68783-REDT) and María de Maeztu Unit of Excellence (MDM-2016-0692); USA – 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; Marie Curie-IRSES/EPLANET; European Particle Physics Latin American Network; University of Delaware Research Foundation (UDRF) – 2019; and UNESCO.
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.
ANR-10-LABX-63 ANR-11-IDEX-0004-02
Belgium – Fonds de la Recherche Scientifique
Comisión Nacional de Energía Atómica
Département Physique Nucléaire et Corpusculaire PNC-IN2P3/CNRS
Département Sciences de l’Univers
Feder Funds
María de Maeztu Unit of Excellence MDM-2016-0692
Ministero degli Affari Esteri
RENATA Red Nacional Temática de Astropartículas FPA2015-68783-REDT
SURF
National Science Foundation 0450696
U.S. Department of Energy DE-AC02-07CH11359, DE-FG02-99ER41107, DE-FR02-04ER41300, DE-SC0011689
University of Delaware Research Foundation
United Nations Educational, Scientific and Cultural Organization
Australian Research Council
Helmholtz-Gemeinschaft
Deutsche Forschungsgemeinschaft
Fundação de Amparo à Pesquisa do Estado de São Paulo 1999/05404-3, 2010/07359-6, 2019/10151-2
Fundação para a Ciência e a Tecnologia
Bundesministerium für Bildung und Forschung
Fonds De La Recherche Scientifique - FNRS
Consejo Nacional de Investigaciones Científicas y Técnicas
Agencia Nacional de Promoción Científica y Tecnológica
Fonds Wetenschappelijk Onderzoek
Consejo Nacional de Ciencia y Tecnología 167733
Ministerie van Onderwijs, Cultuur en Wetenschap
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Ministero dell’Istruzione, dell’Università e della Ricerca
Ministerium für Wissenschaft, Forschung und Kunst Baden-Württemberg
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Conseil Régional, Île-de-France
Instituto Nazionale di Fisica Nucleare
Narodowe Centrum Nauki 2013/08/M/ST9/00322, 2013/10/M/ST9/00062, 2016/23/B/ST9/01635, UMO-2016/22/M/ST9/00198
Javna Agencija za Raziskovalno Dejavnost RS I0-0033, N1-0111, P1-0031, P1-0385
Ministerstwo Edukacji i Nauki DIR/WK/2018/11
Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
Centre National de la Recherche Scientifique
Financiadora de Estudos e Projetos
Istituto Nazionale di Astrofisica
Universidad Nacional Autónoma de México
Ministry of Education and Research, Romania PN-III-P1-1.2-PCCDI-2017-0839/19PCCDI/2018, PN19060102, PN19150201/16N/2019
European Regional Development Fund
Ministerium für Innovation, Wissenschaft und Forschung des Landes Nordrhein-Westfalen
Ministerio de Economía, Industria y Competitividad, Gobierno de España FPA2017-85114-P, PID2019-104676GB-C32
Xunta de Galicia ED431C 2017/07
Junta de Andalucía P18-FR-4314
Ministério da Ciência, Tecnologia, Inovações e Comunicações CZ.02.1.01/0.0/0.0/16_013/0001402, CZ.02.1.01/0.0/0.0/17_049/0008422, CZ.02.1.01/0.0/0.0/18_046/0016010, LM2015038, LM2018102, MSMT CR LTT18004
Programa Operacional Temático Factores de Competitividade
Institut Lagrange de Paris