Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum

Autores
Dova, María Teresa; Hansen, Patricia María; Mariazzi, Analisa Gabriela; Sciutto, Sergio Juan; Wahlberg, Hernán Pablo; The Pierre Auger Collaboration
Año de publicación
2016
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
We report a first measurement for ultrahigh energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncer- tainties in hadronic event generators. The observed correlation in the energy range around the ‘ankle’ at lg(E/eV) = 18.5–19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A > 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavored as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.
Facultad de Ciencias Exactas
Materia
Ciencias Exactas
Pierre Auger Observatory
Cosmic rays
Mass composition
Ankle
Física
Nivel de accesibilidad
acceso abierto
Condiciones de uso
http://creativecommons.org/licenses/by/4.0/
Repositorio
SEDICI (UNLP)
Institución
Universidad Nacional de La Plata
OAI Identificador
oai:sedici.unlp.edu.ar:10915/77681

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network_name_str SEDICI (UNLP)
spelling Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrumDova, María TeresaHansen, Patricia MaríaMariazzi, Analisa GabrielaSciutto, Sergio JuanWahlberg, Hernán PabloThe Pierre Auger CollaborationCiencias ExactasPierre Auger ObservatoryCosmic raysMass compositionAnkleFísicaWe report a first measurement for ultrahigh energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncer- tainties in hadronic event generators. The observed correlation in the energy range around the ‘ankle’ at lg(E/eV) = 18.5–19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A > 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavored as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.Facultad de Ciencias Exactas2016-11-10info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdf288-295http://sedici.unlp.edu.ar/handle/10915/77681enginfo:eu-repo/semantics/altIdentifier/issn/0370-2693info:eu-repo/semantics/altIdentifier/doi/10.1016/j.physletb.2016.09.039info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/4.0/Creative Commons Attribution 4.0 International (CC BY 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-09-29T11:12:21Zoai:sedici.unlp.edu.ar:10915/77681Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-09-29 11:12:22.167SEDICI (UNLP) - Universidad Nacional de La Platafalse
dc.title.none.fl_str_mv Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
title Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
spellingShingle Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
Dova, María Teresa
Ciencias Exactas
Pierre Auger Observatory
Cosmic rays
Mass composition
Ankle
Física
title_short Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
title_full Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
title_fullStr Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
title_full_unstemmed Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
title_sort Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
dc.creator.none.fl_str_mv Dova, María Teresa
Hansen, Patricia María
Mariazzi, Analisa Gabriela
Sciutto, Sergio Juan
Wahlberg, Hernán Pablo
The Pierre Auger Collaboration
author Dova, María Teresa
author_facet Dova, María Teresa
Hansen, Patricia María
Mariazzi, Analisa Gabriela
Sciutto, Sergio Juan
Wahlberg, Hernán Pablo
The Pierre Auger Collaboration
author_role author
author2 Hansen, Patricia María
Mariazzi, Analisa Gabriela
Sciutto, Sergio Juan
Wahlberg, Hernán Pablo
The Pierre Auger Collaboration
author2_role author
author
author
author
author
dc.subject.none.fl_str_mv Ciencias Exactas
Pierre Auger Observatory
Cosmic rays
Mass composition
Ankle
Física
topic Ciencias Exactas
Pierre Auger Observatory
Cosmic rays
Mass composition
Ankle
Física
dc.description.none.fl_txt_mv We report a first measurement for ultrahigh energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncer- tainties in hadronic event generators. The observed correlation in the energy range around the ‘ankle’ at lg(E/eV) = 18.5–19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A > 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavored as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.
Facultad de Ciencias Exactas
description We report a first measurement for ultrahigh energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncer- tainties in hadronic event generators. The observed correlation in the energy range around the ‘ankle’ at lg(E/eV) = 18.5–19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A > 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavored as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.
publishDate 2016
dc.date.none.fl_str_mv 2016-11-10
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
Articulo
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://sedici.unlp.edu.ar/handle/10915/77681
url http://sedici.unlp.edu.ar/handle/10915/77681
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/issn/0370-2693
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.physletb.2016.09.039
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International (CC BY 4.0)
eu_rights_str_mv openAccess
rights_invalid_str_mv http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International (CC BY 4.0)
dc.format.none.fl_str_mv application/pdf
288-295
dc.source.none.fl_str_mv reponame:SEDICI (UNLP)
instname:Universidad Nacional de La Plata
instacron:UNLP
reponame_str SEDICI (UNLP)
collection SEDICI (UNLP)
instname_str Universidad Nacional de La Plata
instacron_str UNLP
institution UNLP
repository.name.fl_str_mv SEDICI (UNLP) - Universidad Nacional de La Plata
repository.mail.fl_str_mv alira@sedici.unlp.edu.ar
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