Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum

We report a first measurement for ultra-high 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 $\lg(E/{\rm eV})=18.5-19.0$ 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 disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report Numbe

On the sensitivity of the HAWC observatory to gamma-ray bursts

We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very high-energy gamma-ray observatory currently under construction in Mexico at an altitude of 4100 m. It will observe atmospheric air showers via the water Cherenkov method. HAWC will consist of 300 large water tanks instrumented with 4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main DAQ system reads out coincident signals in the tanks and reconstructs the direction and energy of individual atmospheric showers. The scaler DAQ counts the hits in each photomultiplier tube (PMT) in the detector and searches for a statistical excess over the noise of all PMTs. We show that HAWC has a realistic opportunity to observe the high-energy power law components of GRBs that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The two DAQ systems have an energy threshold that is low enough to observe events similar to GRB 090510 and GRB 090902b with the characteristics observed by Fermi LAT. HAWC will provide information about the high-energy spectra of GRBs which in turn could help to understanding about e-pair attenuation in GRB jets, extragalactic background light absorption, as well as establishing the highest energy to which GRBs accelerate particles

Astrophysical Interpretation Of Pierre Auger Observatory Measurements Of The Uhecr Energy Spectrum And Mass Composition

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Evidence For A Mixed Mass Composition At The ‘ankle’ In The Cosmic-ray Spectrum

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The Pierre Auger Observatory Status And Latest Results

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Exploiting the radio signal from air showers: The AERA progress

none424noneRevenu B.; Aab A.; Abreu P.; Aglietta M.; Ahn E.J.; Al Samarai I.; Albuquerque I.F.M.; Allekotte I.; Allison P.; Almela A.; Alvarez Castillo J.; Alvarez-Muniz J.; Ambrosio M.; Anastasi G.A.; Anchordoqui L.; Andrada B.; Andringa S.; Aramo C.; Arqueros F.; Arsene N.; Asorey H.; Assis P.; Aublin J.; Avila G.; Badescu A.M.; Balaceanu A.; Baus C.; Beatty J.J.; Becker K.H.; Bellido J.A.; Berat C.; Bertaina M.E.; Bertou X.; Biermann P.L.; Billoir P.; Biteau J.; Blaess S.G.; Blanco A.; Blazek J.; Bleve C.; Bohacova M.; Boncioli D.; Bonifazi C.; Borodai N.; Botti A.M.; Brack J.; Brancus I.; Bretz T.; Bridgeman A.; Briechle F.L.; Buchholz P.; Bueno A.; Buitink S.; Buscemi M.; Caballero-Mora K.S.; Caccianiga B.; Caccianiga L.; Cancio A.; Canfora F.; Caramete L.; Caruso R.; Castellina A.; Cataldi G.; Cazon L.; Cester R.; Chavez A.G.; Chiavassa A.; Chinellato J.A.; Chudoba J.; Clay R.W.; Colalillo R.; Coleman A.; Collica L.; Coluccia M.R.; Conceicao R.; Contreras F.; Cooper M.J.; Coutu S.; Covault C.E.; Cronin J.; Dallier R.; D'Amico S.; Daniel B.; Dasso S.; Daumiller K.; Dawson B.R.; De Almeida R.M.; De Jong S.J.; De Mauro G.; De Mello Neto J.R.T.; De Mitri I.; De Oliveira J.; De Souza V.; Debatin J.; Del Peral L.; Deligny O.; Di Giulio C.; Di Matteo A.; Diaz Castro M.L.; Diogo F.; Dobrigkeit C.; D'Olivo J.C.; Dorofeev A.; Dos Anjos R.C.; Dova M.T.; Dundovic A.; Ebr J.; Engel R.; Erdmann M.; Erfani M.; Escobar C.O.; Espadanal J.; Etchegoyen A.; Falcke H.; Fang K.; Farrar G.; Fauth A.C.; Fazzini N.; Fick B.; Figueira J.M.; Filevich A.; Filipcic A.; Fratu O.; Freire M.M.; Fujii T.; Fuster A.; Garcia B.; Garcia-Pinto D.; Gate F.; Gemmeke H.; Gherghel-Lascu A.; Ghia P.L.; Giaccari U.; Giammarchi M.; Giller M.; Glas D.; Glaser C.; Glass H.; Golup G.; Gomez Berisso M.; Gomez Vitale P.F.; Gonzalez N.; Gookin B.; Gordon J.; Gorgi A.; Gorham P.; Gouffon P.; Grillo A.F.; Grubb T.D.; Guarino F.; Guedes G.P.; Hampel M.R.; Hansen P.; Harari D.; Harrison T.A.; Harton J.L.; Hasankiadeh Q.; Haungs A.; Hebbeker T.; Heck D.; Heimann P.; Herve A.E.; Hill G.C.; Hojvat C.; Holt E.; Homola P.; Horandel J.R.; Horvath P.; Hrabovsky M.; Huege T.; Hulsman J.; Insolia A.; Isar P.G.; Jandt I.; Jansen S.; Johnsen J.A.; Josebachuili M.; Kaapa A.; Kambeitz O.; Kampert K.H.; Kasper P.; Katkov I.; Keilhauer B.; Kemp E.; Kieckhafer R.M.; Klages H.O.; Kleifges M.; Kleinfeller J.; Krause R.; Krohm N.; Kuempel D.; Kukec Mezek G.; Kunka N.; Kuotb Awad A.; LaHurd D.; Latronico L.; Lauscher M.; Lautridou P.; Lebrun P.; Legumina R.; Leigui De Oliveira M.A.; Letessier-Selvon A.; Lhenry-Yvon I.; Link K.; Lopes L.; Lopez R.; Lopez Casado A.; Luce Q.; Lucero A.; Malacari M.; Mallamaci M.; Mandat D.; Mantsch P.; Mariazzi A.G.; Maris I.C.; Marsella G.; Martello D.; Martinez H.; Martinez Bravo O.; Masias Meza J.J.; Mathes H.J.; Mathys S.; Matthews J.; Matthews J.A.J.; Matthiae G.; Mayotte E.; Mazur P.O.; Medina C.; Medina-Tanco G.; Melo D.; Menshikov A.; Messina S.; Micheletti M.I.; Middendorf L.; Minaya I.A.; Miramonti L.; Mitrica B.; Mockler D.; Molina-Bueno L.; Mollerach S.; Montanet F.; Morello C.; Mostafa M.; Muller G.; Muller M.A.; Muller S.; Naranjo I.; Navas S.; Nellen L.; Neuser J.; Nguyen P.H.; Niculescu-Oglinzanu M.; Niechciol M.; Niemietz L.; Niggemann T.; Nitz D.; Nosek D.; Novotny V.; Nozka H.; Nunez L.A.; Ochilo L.; Oikonomou F.; Olinto A.; Pakk Selmi-Dei D.; Palatka M.; Pallotta J.; Papenbreer P.; Parente G.; Parra A.; Paul T.; Pech M.; Pedreira F.; Pekala J.; Pelayo R.; Pena-Rodriguez J.; Pereira L.A.S.; Perrone L.; Peters C.; Petrera S.; Phuntsok J.; Piegaia R.; Pierog T.; Pieroni P.; Pimenta M.; Pirronello V.; Platino M.; Plum M.; Porowski C.; Prado R.R.; Privitera P.; Prouza M.; Quel E.J.; Querchfeld S.; Quinn S.; Ramos-Pollant R.; Rautenberg J.; Ravel O.; Ravignani D.; Reinert D.; Ridky J.; Risse M.; Ristori P.; Rizi V.; De Carvalho W.R.; Rodriguez Fernandez G.; Rodriguez Rojo J.; Rodriguez-Frias M.D.; Rogozin D.; Rosado J.; Roth M.; Roulet E.; Rovero A.C.; Saffi S.J.; Saftoiu A.; Salazar H.; Saleh A.; Salesa Greus F.; Salina G.; Sanabria Gomez J.D.; Sanchez F.; Sanchez-Lucas P.; Santos E.M.; Santos E.; Sarazin F.; Sarkar B.; Sarmento R.; Sarmiento-Cano C.; Sato R.; Scarso C.; Schauer M.; Scherini V.; Schieler H.; Schmidt D.; Scholten O.; Schovanek P.; Schroder F.G.; Schulz A.; Schulz J.; Schumacher J.; Sciutto S.J.; Segreto A.; Settimo M.; Shadkam A.; Shellard R.C.; Sigl G.; Silli G.; Sima O.; Smialkowski A.; Smida R.; Snow G.R.; Sommers P.; Sonntag S.; Sorokin J.; Squartini R.; Stanca D.; Stanic S.; Stasielak J.; Strafella F.; Suarez F.; Suarez Duran M.; Sudholz T.; Suomijarvi T.; Supanitsky A.D.; Sutherland M.S.; Swain J.; Szadkowski Z.; Taborda O.A.; Tapia A.; Tepe A.; Theodoro V.M.; Timmermans C.; Todero Peixoto C.J.; Tomankova L.; Tome B.; Tonachini A.; Torralba Elipe G.; Torres Machado D.; Torri M.; Travnicek P.; Trini M.; Ulrich R.; Unger M.; Urban M.; Valbuena-Delgado A.; Valdes Galicia J.F.; Valino I.; Valore L.; Van Aar G.; Van Bodegom P.; Van Den Berg A.M.; Van Vliet A.; Varela E.; Vargas Cardenas B.; Varner G.; Vazquez J.R.; Vazquez R.A.; Veberic D.; Verzi V.; Vicha J.; Villasenor L.; Vorobiov S.; Wahlberg H.; Wainberg O.; Walz D.; Watson A.A.; Weber M.; Weindl A.; Wiencke L.; Wilczynski H.; Winchen T.; Wittkowski D.; Wundheiler B.; Wykes S.; Yang L.; Yelos D.; Yushkov A.; Zas E.; Zavrtanik D.; Zavrtanik M.; Zepeda A.; Zimmermann B.; Ziolkowski M.; Zong Z.; Zuccarello F.Revenu, B.; Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Al Samarai, I.; Albuquerque, I. F. M.; Allekotte, I.; Allison, P.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muniz, J.; Ambrosio, M.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Bohacova, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceicao, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; Dallier, R.; D'Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; De Almeida, R. M.; De Jong, S. J.; De Mauro, G.; De Mello Neto, J. R. T.; De Mitri, I.; De Oliveira, J.; De Souza, V.; Debatin, J.; Del Peral, L.; Deligny, O.; Di Giulio, C.; Di Matteo, A.; Diaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D'Olivo, J. C.; Dorofeev, A.; Dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fick, B.; Figueira, J. M.; Filevich, A.; Filipcic, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; Garcia, B.; Garcia-Pinto, D.; Gate, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glas, D.; Glaser, C.; Glass, H.; Golup, G.; Gomez Berisso, M.; Gomez Vitale, P. F.; Gonzalez, N.; Gookin, B.; Gordon, J.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Hasankiadeh, Q.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Horandel, J. R.; Horvath, P.; Hrabovsky, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Johnsen, J. A.; Josebachuili, M.; Kaapa, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A.; Lahurd, D.; Latronico, L.; Lauscher, M.; Lautridou, P.; Lebrun, P.; Legumina, R.; Leigui De Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; Lopez, R.; Lopez Casado, A.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Maris, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martinez Bravo, O.; Masias Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Messina, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Mockler, D.; Molina-Bueno, L.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafa, M.; Muller, G.; Muller, M. A.; Muller, S.; Naranjo, I.; Navas, S.; Nellen, L.; Neuser, J.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nozka, H.; Nunez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Pakk Selmi-Dei, D.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Pekala, J.; Pelayo, R.; Pena-Rodriguez, J.; Pereira, L. A. S.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollant, R.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Reinert, D.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; De Carvalho, W. R.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rodriguez-Frias, M. D.; Rogozin, D.; Rosado, J.; Roth, M.; Roulet, E.; Rovero, A. C.; Saffi, S. J.; Saftoiu, A.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sanabria Gomez, J. D.; Sanchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarkar, B.; Sarmento, R.; Sarmiento-Cano, C.; Sato, R.; Scarso, C.; Schauer, M.; Scherini, V.; Schieler, H.; Schmidt, D.; Scholten, O.; Schovanek, P.; Schroder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Smialkowski, A.; Smida, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Stanca, D.; Stanic, S.; Stasielak, J.; Strafella, F.; Suarez, F.; Suarez Duran, M.; Sudholz, T.; Suomijarvi, T.; Supanitsky, A. D.; Sutherland, M. S.; Swain, J.; Szadkowski, Z.; Taborda, O. A.; Tapia, A.; Tepe, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tome, B.; Tonachini, A.; Torralba Elipe, G.; Torres Machado, D.; Torri, M.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valbuena-Delgado, A.; Valdes Galicia, J. F.; Valino, I.; Valore, L.; Van Aar, G.; Van Bodegom, P.; Van Den Berg, A. M.; Van Vliet, A.; Varela, E.; Vargas Cardenas, B.; Varner, G.; Vazquez, J. R.; Vazquez, R. A.; Veberic, D.; Verzi, V.; Vicha, J.; Villasenor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczynski, H.; Winchen, T.; Wittkowski, D.; Wundheiler, B.; Wykes, S.; Yang, L.; Yelos, D.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zuccarello, F

Prototype muon detectors for the AMIGA component of the Pierre Auger Observatory

International audienceAMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of the Pierre Auger Observatory to extend its range of detection and to directly measure the muon content of the particle showers. It consists of an infill of surface water-Cherenkov detectors accompanied by buried scintillator detectors used for muon counting. The main objectives of the AMIGA engineering array, referred to as the Unitary Cell, are to identify and resolve all engineering issues as well as to understand the muon-number counting uncertainties related to the design of the detector. The mechanical design, fabrication and deployment processes of the muon counters of the Unitary Cell are described in this document. These muon counters modules comprise sealed PVC casings containing plastic scintillation bars, wavelength-shifter optical fibers, 64 pixel photomultiplier tubes, and acquisition electronics. The modules are buried approximately 2.25 m below ground level in order to minimize contamination from electromagnetic shower particles. The mechanical setup, which allows access to the electronics for maintenance, is also described in addition to tests of the modules' response and integrity. The completed Unitary Cell has measured a number of air showers of which a first analysis of a sample event is included here

Search for top squark production in fully hadronic final states in proton-proton collisions at s =13 TeV

© 2021 CERN. for the CMS Collaboration.A search for production of the supersymmetric partners of the top quark, top squarks, is presented. The search is based on proton-proton collision events containing multiple jets, no leptons, and large transverse momentum imbalance. The data were collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV, and correspond to an integrated luminosity of 137 fb-1. The targeted signal production scenarios are direct and gluino-mediated top squark production, including scenarios in which the top squark and neutralino masses are nearly degenerate. The search utilizes novel algorithms based on deep neural networks that identify hadronically decaying top quarks and W bosons, which are expected in many of the targeted signal models. No statistically significant excess of events is observed relative to the expectation from the standard model, and limits on the top squark production cross section are obtained in the context of simplified supersymmetric models for various production and decay modes. Exclusion limits as high as 1310 GeV are established at the 95% confidence level on the mass of the top squark for direct top squark production models, and as high as 2260 GeV on the mass of the gluino for gluino-mediated top squark production models. These results represent a significant improvement over the results of previous searches for supersymmetry by CMS in the same final state