606 research outputs found
Evidence for a mixed mass composition at the ‘ankle’ in the cosmic-ray spectrum
No full textWe 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 uncertainties in hadronic event generators. The observed correlation in the energy range around the ‘ankle’ at lg(E/eV)=18.5–19.0lg(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>4A>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
Erratum: Search for photons with energies above 1018 eV using the hybrid detector of the Pierre Auger Observatory (Journal of Cosmology and Astroparticle Physics (2017) 4 (9) DOI: 10.1088/1475-7516/2017/04/009)
No full text1 Exposure calculation Due to a mistake in the numerical integration following eq. (6.2) of the original article [1], the exposure shown in figure 5 of the original article was incorrect. The correct exposure is shown in figure 1. 2 Upper limits on the integral photon flux and fraction The incorrect exposure affects the calculation of the upper limits on the integral photon flux following eq. (6.1) of the original article. The correct values for the upper limits are 0.038, 0.010, 0.009, 0.008 and 0.007 km−2 sr−1 yr−1 for threshold energies of 1, 2, 3, 5 and 10 EeV. The correct values for the upper limits on the integral photon fraction subsequently derived are 0.14 %, 0.17 %, 0.42 %, 0.86 % and 2.9 % for the same threshold energies. 3 Author list The author list of this erratum also corrects a mistake made in the original article, where F. Zuccarello was missing and Z. Zong was listed twice
Erratum: Search for photons with energies above 1018 eV using the hybrid detector of the Pierre Auger Observatory
No full textExposure calculation Due to a mistake in the numerical integration following eq. (6.2) of the original article [1], the exposure shown in figure 5 of the original article was incorrect. The correct exposure is shown in figure 1. 2 Upper limits on the integral photon flux and fraction The incorrect exposure affects the calculation of the upper limits on the integral photon flux following eq. (6.1) of the original article. The correct values for the upper limits are 0.038, 0.010, 0.009, 0.008 and 0.007 km−2 sr−1 yr−1 for threshold energies of 1, 2, 3, 5 and 10 EeV. The correct values for the upper limits on the integral photon fraction subsequently derived are 0.14 %, 0.17 %, 0.42 %, 0.86 % and 2.9 % for the same threshold energies. 3 Author list The author list of this erratum also corrects a mistake made in the original article, where F. Zuccarello was missing and Z. Zong was listed twice
A 3-Year Sample of Almost 1,600 Elves Recorded Above South America by the Pierre Auger Cosmic-Ray Observatory
No full textElves are a class of transient luminous events, with a radial extent typically greater than 250 km, that occur in the lower ionosphere above strong electrical storms.We report the observation of 1,598 elves, from 2014 to 2016, recorded with unprecedented time resolution (100 ns) using the fluorescence detector (FD) of the Pierre Auger Cosmic-Ray Observatory. The Auger Observatory is located in the Mendoza province of Argentina with a viewing footprint for elve observations of 3 · 106 km2, reaching areas above the Pacific and Atlantic Oceans, as well as the Córdoba region, which is known for severe convective thunderstorms. Primarily designed for ultrahigh energy cosmic-ray observations, the Auger FD turns out to be very sensitive to the ultraviolet emission in elves. The detector features modified Schmidt optics with large apertures resulting in a field of view that spans the horizon, and year-round operation on dark nights with low moonlight background, when the local weather is favorable. The measured light profiles of 18% of the elve events have more than one peak, compatible with intracloud activity. Within the 3-year sample, 72% of the elves correlate with the far-field radiation measurements of the World Wide Lightning Location Network. The Auger Observatory plans to continue operations until at least 2025, including elve observations and analysis. To the best of our knowledge, this observatory is the only facility on Earth that measures elves with year-round operation and full horizon coverage.
Co-authors: A. Aab, P. Abreu,M. Aglietta, I. F.M. Albuquerque, J.M. Albury, I. Allekotte, A. Almela, J. Alvarez Castillo, J. Alvarez-Muniz, G. A. Anastasi,L. Anchordoqui, B. Andrada, S. Andringa, C. Aramo, H. Asorey, P. Assis, G. Avila, A.M. Badescu, A. Bakalova, A. Balaceanu,F. Barbato, R. J. Barreira Luz, S. Baur, K. H. Becker, J.A. Bellido, C. Berat,M. E. Bertaina, X. Bertou, P. L. Biermann, J. Biteau, S. G. Blaess, A. Blanco, J. Blazek, C. Bleve,M. Bohaˇcova, D. Boncioli, C. Bonifazi, N. Borodai, A. M. Botti, J. Brack,T. Bretz, A. Bridgeman, F. L. Briechle, P. Buchholz, A. Bueno, S. Buitink,M. Buscemi, K. S. Caballero-Mora, L. Caccianiga, L. Calcagni, A. Cancio, F. Canfora, J.M. Carceller, R. Caruso, A. Castellina, F. Catalani, G. Cataldi, L. Cazon,M. Cerda, J. A. Chinellato,J. Chudoba, L. Chytka, R.W. Clay, A. C. Cobos Cerutti, R. Colalillo, A. Coleman,M. R. Coluccia, R. Conceicao, A. Condorelli, G. Consolati,F. Contreras,M. J. Cooper, S. Coutu, C. E. Covault, B. Daniel, S. Dasso, K. Daumiller, B. R. Dawson, J. A. Day, R.M. de Almeida,S. J. de Jong, G. Mauro, J. R. T. de Mello Neto, I. Mitri, J. de Oliveira, F. O. de Oliveira Salles, V. de Souza, J. Debatin,M. del Rio, O. Deligny,N. Dhital,M. L. Diaz Castro, F. Diogo, C. Dobrigkeit, J. C. D\u27Olivo, Q. Dorosti, R. C. dos Anjos, M. T. Dova, A. Dundovic, J. Ebr, R. Engel,M. Erdmann, C. O. Escobar, A. Etchegoyen, H. Falcke, J. Farmer, G. Farrar, A. C. Fauth, N. Fazzini, F. Feldbusch,F. Fenu, L. P. Ferreyro, J.M. Figueira, A. Filipˇciˇc, M. M. Freire, T. Fujii, A. Fuster, B. Garcia, H. Gemmeke, A. Gherghel-Lascu,P. L. Ghia, U. Giaccari,M. Giammarchi,M. Giller, D. Głas, J. Glombitza, F. Gobbi, G. Golup,M. Gomez Berisso, P. F. Gomez Vitale,J. P. Gongora, N. Gonzalez, I. Goos, D. Gora, A. Gorgi,M. Gottowik, T. D. Grubb, F. Guarino, G. P. Guedes, E. Guido,R. Halliday, M. R. Hampel, P. Hansen, D. Harari, T. A. Harrison, V. M. Harvey, A. Haungs, T. Hebbeker, D. Heck, P. Heimann,G. C. Hill, C. Hojvat, E. M. Holt, P. Homola, J. R. Horandel, P. Horvath,M. Hrabovsky, T. Huege, J. Hulsman, A. Insolia,P. G. Isar, I. Jandt, J. A. Johnsen,M. Josebachuili, J. Jurysek, A. Kaapa, K. H. Kampert, B. Keilhauer, N. Kemmerich, J. Kemp,H. O. Klages, M. Kleifges, J. Kleinfeller, R. Krause, D. Kuempel, G. Kukec Mezek, A. Kuotb Awad, B. L. Lago, D. LaHurd, R. G. Lang,R. Legumina,M. A. Leigui de Oliveira, V. Lenok, A. Letessier-Selvon, I. Lhenry-Yvon, O. C. Lippmann, D. Lo Presti, L. Lopes, R. Lopez, A. Lopez Casado,R. Lorek, Q. Luce, A. Lucero,M. Malacari, G. Mancarella, D. Mandat, B. C. Manning, P. Mantsch, A. G. Mariazzi, I. C. Mari，s, G. Marsella, D. Martello, H. Martinez, O. Martinez Bravo,M. Mastrodicasa, H. J. Mathes, S. Mathys, J. Matthews, G. Matthiae, E. Mayotte,P. O. Mazur, G. Medina-Tanco, D. Melo, A. Menshikov, K.-D. Merenda, S. Michal,M. I. Micheletti, L. Middendorf, L. Miramonti, B. Mitrica,D. Mockler, S. Mollerach, F. Montanet, C. Morello, G. Morlino,M. Mostafa, A. L. Muller,M. A. Muller, S. Muller, R. Mussa,L. Nellen, P. H. Nguyen,M. Niculescu-Oglinzanu,M. Niechciol, D. Nitz, D. Nosek, V. Novotny, L. Noža, A Nucita, L.A. Nunez,A. Olinto,M. Palatka, J. Pallotta,M. P. Panetta, P. Papenbreer, G. Parente, A. Parra, M. Pech, F. Pedreira, J. Pe，kala,R. Pelayo, J. Pena-Rodriguez, L. A. S. Pereira,M. Perlin, L. Perrone, C. Peters, S. Petrera, J. Phuntsok, T. Pierog,M. Pimenta,V. Pirronello,M. Platino, J. Poh, B. Pont, C. Porowski, R. R. Prado, P. Privitera,M. Prouza, A. Puyleart, S. Querchfeld,S. Quinn, R. Ramos-Pollan, J. Rautenberg, D. Ravignani, M. Reininghaus, J. Ridky, F. Riehn,M. Risse, P. Ristori, V. Rizi, W. Rodrigues de Carvalho, J. Rodriguez Rojo,M. J. Roncoroni, M. Roth, E. Roulet, A. C. Rovero, P. Ruehl, S. J. Saffi, A. Saftoiu, F. Salamida,H. Salazar, G. Salina,J. D. Sanabria Gomez, F. Sanchez, E.M. Santos, E. Santos, F. Sarazin, R. Sarmento, C. Sarmiento-Cano, R. Sato,P. Savina,M. Schauer, V. Scherini, H. Schieler, M. Schimassek,M. Schimp, F. Schluter, D. Schmidt, O. Scholten, P. Schovanek, F. G. Schroder, S. Schroder, J. Schumacher, S. J. Sciutto,M. Scornavacche, R. C. Shellard, G. Sigl, G. Silli, O. Sima, R. Šmida,G.R. Snow, P. Sommers, J. F. Soriano, J. Souchard, R. Squartini, D. Stanca, S. Staniˇc, J. Stasielak, P. Stassi, M. Stolpovskiy,A. Streich, F. Suarez,M. Suarez-Duran, T. Sudholz, T. Suomijarvi, A.D. Supanitsky, J. Šupik, Z. Szadkowski, A. Taboada, O. A. Taborda, A. Tapia, C. Timmermans, C. J. Todero Peixoto, B. Tome, G. Torralba Elipe, A. Travaini, P. Travnicek,M. Trini, M. Tueros, R. Ulrich,M. Unger,M. Urban, J. F. Valdes Galicia, I. Valino, L. Valore, P. van Bodegom, A.M. van den Berg, A. van Vliet, E. Varela, B. Vargas Cardenas,D. Veberiˇc, C. Ventura, I. D. Vergara Quispe, V. Verzi, J. Vicha, L. Villasenor, J. Vink, S. Vorobiov, H. Wahlberg, A. A. Watson, M. Weber, A. Weindl,M.Wieden´ ski, L. Wiencke, H. Wilczyn´ ski, T.Winchen, M. Wirtz, D. Wittkowski, B. Wundheiler, L. Yang, A. Yushkov, E. Zas, D. Zavrtanik, M. Zavrtanik, L. Zehrer, A. Zepeda, B. Zimmermann,M. Ziolkowski, Z. Zongand F. Zuccarello
Data set attached as supplementary file
Ultrahigh energy neutrinos at the pierre auger observatory
No full textThe observation of ultrahigh energy neutrinos (UHE nu s) has become a priority in experimental astroparticle physics. UHE nu s can be detected with a variety of techniques. In particular, neutrinos can interact in the atmosphere (downward-going nu) or in the Earth crust (Earth-skimming nu), producing air showers that can be observed with arrays of detectors at the ground. With the surface detector array of the Pierre Auger Observatory we can detect these types of cascades. The distinguishing signature for neutrino events is the presence of very inclined showers produced close to the ground (i.e., after having traversed a large amount of atmosphere). In this work we review the procedure and criteria established to search for UHE nu s in the data collected with the ground array of the Pierre Auger Observatory. This includes Earth-skimming as well as downward-going neutrinos. No neutrino candidates have been found, which allows us to place competitive limits to the diffuse flux of UHE nu s in the EeV range and above
Measurement of the Proton-Air Cross Section at root s=57 TeV with the Pierre Auger Observatory
No full textA SEARCH FOR POINT SOURCES OF EeV PHOTONS
No full textMeasurements of air showers made using the hybrid technique developed with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for point sources of EeV photons anywhere in the exposed sky. A multivariate analysis reduces the background of hadronic cosmic rays. The search is sensitive to a declination band from
−85◦ to +20◦, in an energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been detected.
An upper limit on the photon flux has been derived for every direction. The mean value of the energy flux limit
that results from this, assuming a photon spectral index of −2, is 0.06 eV cm^−2 s^−1, and no celestial direction exceeds 0.25 eV cm^−2 s^−1. These upper limits constrain scenarios in which EeV cosmic ray protons are emitted by non-transient sources in the Galaxy
Measurement of the cosmic ray spectrum above 4 × 10<sup>18</sup> eV using inclined events detected with the Pierre Auger Observatory
No full textA measurement of the cosmic-ray spectrum for energies exceeding 4x10(18)
eV is presented, which is based on the analysis of showers with zenith
angles greater than 60 degrees detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured
spectrum confirms a flux suppression at the highest energies. Above
5.3x10(18) eV, the ``ankle{''}, the flux can be described by a power law
E-gamma with index gamma = 2.70 +/- 0.02 (stat) +/- 0.1 (sys) followed
by a smooth suppression region. For the energy (E-s) at which the
spectral flux has fallen to one-half of its extrapolated value in the
absence of suppression, we find E-s = (5.12 +/- 0.25 (stat)(-1.2)(+1.0)
(sys)) x10(19) eV
A search for point sources of EeV photons
No full textMeasurements of air showers made using the hybrid technique developed with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for point sources of EeV photons anywhere in the exposed sky. A multivariate analysis reduces the background of hadronic cosmic rays. The search is sensitive to a declination band from -85° to +20°, in an energy range from 1017.3 eV to 1018.5 eV. No photon point source has been detected. An upper limit on the photon flux has been derived for every direction. The mean value of the energy flux limit that results from this, assuming a photon spectral index of -2, is 0.06 eV cm-2 s -1, and no celestial direction exceeds 0.25 eV cm-2 s -1. These upper limits constrain scenarios in which EeV cosmic ray protons are emitted by non-transient sources in the Galax
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