published version - core

PUBLISHED VERSION

Abreu P Barber Kerridwen Bette Bellido Caceres Jose Alfredo Clay Roger William Cooper Matthew John Dawson Bruce Robert Harrison Thomas Alan Herve Alexander Edward Holmes Vanessa Catherine Sorokin Jennifer Sally Wahrlich Philip Shane Whelan Benjamin James et al Search for ultrahigh energy neutrinos in highly inclined events at the Pierre Auger Observatory Physical Review D 2011 84(12)122005

copy 2011 American Physical Society

httplinkapsorgdoi101103PhysRevD84122005

httplinkapsorgdoi101103PhysRevD62093023

httphdlhandlenet244070840

PERMISSIONS

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ldquoThe author(s) and in the case of a Work Made For Hire as defined in the US Copyright Act 17 USC

sect101 the employer named [below] shall have the following rights (the ldquoAuthor Rightsrdquo)

[]

3 The right to use all or part of the Article including the APS-prepared version without revision or modification on the author(s)rsquo web home page or employerrsquos website and to make copies of all or part of the Article including the APS-prepared version without revision or modification for the author(s)rsquo andor the employerrsquos use for educational or research purposesrdquo

11th April 2013

Search for ultrahigh energy neutrinos in highly inclined events at the Pierre Auger Observatory

P Abreu1 M Aglietta2 M Ahlers3 E J Ahn4 I FM Albuquerque5 D Allard6 I Allekotte7 J Allen8 P Allison9

A Almela1011 J Alvarez Castillo12 J Alvarez-Muniz13 M Ambrosio14 A Aminaei15 L Anchordoqui16 S Andringa1

T Anticic17 C Aramo14 E Arganda1819 F Arqueros19 H Asorey7 P Assis1 J Aublin20 M Ave21 M Avenier22

G Avila23 T Backer24 AM Badescu25 M Balzer26 K B Barber27 A F Barbosa28 R Bardenet29 S L C Barroso30

B Baughman9dagger J Bauml31 J J Beatty9 B R Becker32 K H Becker33 A Belletoile34 J A Bellido27 S BenZvi3

C Berat22 X Bertou7 P L Biermann35 P Billoir20 F Blanco19 M Blanco36 C Bleve33 H Blumer2131 M Bohacova37

D Boncioli38 C Bonifazi3920 R Bonino2 N Borodai40 J Brack41 I Brancus42 P Brogueira1 W C Brown43

R Bruijn44Dagger P Buchholz24 A Bueno45 R E Burton46 K S Caballero-Mora47 B Caccianiga48 L Caramete35

R Caruso49 A Castellina2 O Catalano50 G Cataldi51 L Cazon1 R Cester52 J Chauvin22 S H Cheng47

A Chiavassa2 J A Chinellato53 J Chirinos Diaz54 J Chudoba37 RW Clay27 MR Coluccia51 R Conceicao1

F Contreras55 H Cook44 M J Cooper27 J Coppens1556 A Cordier29 S Coutu47 C E Covault46 A Creusot6

A Criss47 J Cronin57 A Curutiu35 S Dagoret-Campagne29 R Dallier34 S Dasso5859 K Daumiller31 B R Dawson27

RM de Almeida60 M De Domenico49 C De Donato12 S J de Jong1556 G De La Vega61 W JM de Mello Jr53

J R T de Mello Neto39 I De Mitri51 V de Souza62 KD de Vries63 L del Peral36 M del Rıo3855 O Deligny64

H Dembinski21 N Dhital54 C Di Giulio65 M L Dıaz Castro66 P N Diep67 F Diogo1 C Dobrigkeit53 W Docters63

J C DrsquoOlivo12 P N Dong6764 A Dorofeev41 J C dos Anjos28 M T Dova18 D DrsquoUrso14 I Dutan35 J Ebr37

R Engel31 M Erdmann68 C O Escobar453 J Espadanal1 A Etchegoyen1110 P Facal San Luis57 I Fajardo Tapia12

H Falcke1569 G Farrar8 A C Fauth53 N Fazzini4 A P Ferguson46 B Fick54 A Filevich11 A Filipcic7071

S Fliescher68 C E Fracchiolla41 E D Fraenkel63 O Fratu25 U Frohlich24 B Fuchs28 R Gaior20 R F Gamarra11

S Gambetta72 B Garcıa61 S T Garcia Roca13 D Garcia-Gamez29 D Garcia-Pinto19 A Gascon45 H Gemmeke26

P L Ghia20 U Giaccari51 M Giller73 H Glass4 M S Gold32 G Golup7 F Gomez Albarracin18 M Gomez Berisso7

P F Gomez Vitale23 P Goncalves1 D Gonzalez21 J G Gonzalez31 B Gookin41 A Gorgi2 P Gouffon5 E Grashorn9

S Grebe1556 N Griffith9 M Grigat68 A F Grillo74 Y Guardincerri59 F Guarino14 G P Guedes75 A Guzman12

P Hansen18 D Harari7 S Harmsma6356 T A Harrison27 J L Harton41 A Haungs31 T Hebbeker68 D Heck31

A E Herve27 C Hojvat4 N Hollon57 V C Holmes27 P Homola40 J R Horandel15 A Horneffer15 P Horvath76

M Hrabovsky7637 D Huber21 T Huege31 A Insolia49 F Ionita57 A Italiano49 C Jarne18 S Jiraskova15

M Josebachuili11 K Kadija17 K H Kampert33 P Karhan77 P Kasper4 B Kegl29 B Keilhauer31 A Keivani78

J L Kelley15 E Kemp53 RM Kieckhafer54 HO Klages31 M Kleifges26 J Kleinfeller5531 J Knapp44

D-H Koang22 K Kotera57 N Krohm33 O Kromer26 D Kruppke-Hansen33 F Kuehn4 D Kuempel2433

J K Kulbartz79 N Kunka26 G La Rosa50 C Lachaud6 R Lauer32 P Lautridou34 S Le Coz22 M S A B Leao80

D Lebrun22 P Lebrun4 MA Leigui de Oliveira80 A Letessier-Selvon20 I Lhenry-Yvon64 K Link21 R Lopez81

A Lopez Aguera13 K Louedec2229 J Lozano Bahilo45 L Lu44 A Lucero11 M Ludwig21 H Lyberis64 C Macolino20

S Maldera2 D Mandat37 P Mantsch4 AG Mariazzi18 J Marin552 V Marin34 I C Maris20 H R Marquez Falcon82

G Marsella83 D Martello51 L Martin34 H Martinez84 O Martınez Bravo81 H J Mathes31 J Matthews7885

J A J Matthews32 G Matthiae38 D Maurel31 D Maurizio52 P O Mazur4 G Medina-Tanco12 M Melissas21

D Melo11 E Menichetti52 A Menshikov26 P Mertsch86 C Meurer68 S Micanovic17 M I Micheletti87

L Miramonti48 L Molina-Bueno45 S Mollerach7 M Monasor57 D Monnier Ragaigne29 F Montanet22 B Morales12

C Morello2 E Moreno81 J C Moreno18 M Mostafa41 CA Moura80 MA Muller53 G Muller68 M Munchmeyer20

R Mussa52 G Navarra2 J L Navarro45 S Navas45 P Necesal37 L Nellen12 A Nelles1556 J Neuser33 D Newton44

P T Nhung67 M Niechciol24 L Niemietz33 N Nierstenhoefer33 D Nitz54 D Nosek77 L Nozka37 M Nyklicek37

J Oehlschlager31 A Olinto57 M Ortiz19 N Pacheco36 D Pakk Selmi-Dei53 M Palatka37 J Pallotta88 N Palmieri21

G Parente13 E Parizot6 A Parra13 S Pastor89 T Paul90 M Pech37 J Pekala40 R Pelayo8113 IM Pepe91

L Perrone83 R Pesce72 E Petermann92 S Petrera65 P Petrinca38 A Petrolini72 Y Petrov41 C Pfendner3 R Piegaia59

T Pierog31 P Pieroni59 M Pimenta1 V Pirronello49 M Platino11 V H Ponce7 M Pontz24 A Porcelli31 P Privitera57

M Prouza37 E J Quel88 S Querchfeld33 J Rautenberg33 O Ravel34 D Ravignani11 B Revenu34 J Ridky37

S Riggi13 M Risse24 P Ristori88 H Rivera48 V Rizi65 J Roberts8 W Rodrigues de Carvalho13 G Rodriguez13

J Rodriguez Martino55 J Rodriguez Rojo55 I Rodriguez-Cabo13 MD Rodrıguez-Frıas36 G Ros36 J Rosado19

T Rossler76 M Roth31 B Rouille-drsquoOrfeuil57 E Roulet7 A C Rovero58 C Ruhle26 A Saftoiu42 F Salamida64

H Salazar81 F Salesa Greus41 G Salina38 F Sanchez11 C E Santo1 E Santos1 EM Santos39 F Sarazin93

PHYSICAL REVIEW D 84 122005 (2011)

1550-7998=2011=84(12)=122005(16) 122005-1 2011 American Physical Society

B Sarkar33 S Sarkar86 R Sato55 N Scharf68 V Scherini48 H Schieler31 P Schiffer7968 A Schmidt26 O Scholten63

H Schoorlemmer1556 J Schovancova37 P Schovanek37 F Schroder31 S Schulte68 D Schuster93 S J Sciutto18

M Scuderi49 A Segreto50 M Settimo24 A Shadkam78 R C Shellard2866 I Sidelnik11 G Sigl79 H H Silva Lopez12

O Sima94 A Smialkowski73 R Smıda31 G R Snow92 P Sommers47 J Sorokin27 H Spinka954 R Squartini55

Y N Srivastava90 S Stanic71 J Stapleton9 J Stasielak40 M Stephan68 A Stutz22 F Suarez11 T Suomijarvi64

AD Supanitsky58 T Susa17 M S Sutherland78 J Swain90 Z Szadkowski73 M Szuba31 A Tapia11 M Tartare22

O Tascau33 C G Tavera Ruiz12 R Tcaciuc24 D Tegolo49 N T Thao67 D Thomas41 J Tiffenberg59

C Timmermans5615 W Tkaczyk73 C J Todero Peixoto62 G Toma42 B Tome1 A Tonachini52 P Travnicek37

D B Tridapalli5 G Tristram6 E Trovato49 M Tueros13 R Ulrich31 M Unger31 M Urban29 J F Valdes Galicia12

I Valino13 L Valore14 AM van den Berg63 E Varela81 B Vargas Cardenas12 J R Vazquez19 R A Vazquez13

D Veberic7170 V Verzi38 J Vicha37 M Videla61 L Villasenor82 H Wahlberg18 P Wahrlich27 O Wainberg1110

D Walz68 AA Watson44 M Weber26 K Weidenhaupt68 A Weindl31 F Werner21 S Westerhoff3 B J Whelan27

A Widom90 G Wieczorek73 L Wiencke93 B Wilczynska40 H Wilczynski40 M Will31 C Williams57 T Winchen68

M Wommer31 B Wundheiler11 T Yamamoto57sect T Yapici54 P Younk2496 G Yuan78 A Yushkov13 B Zamorano45

E Zas13 D Zavrtanik7170 M Zavrtanik7071 I Zaw8kA Zepeda84 Y Zhu26 M Zimbres Silva3353 andM Ziolkowski24

1LIP and Instituto Superior Tecnico Technical University of Lisbon Lisbon Portugal2Istituto di Fisica dello Spazio Interplanetario (INAF) Universita di Torino and Sezione INFN Torino Italy

3University of Wisconsin Madison Wisconsin USA4Fermilab Batavia Illinois USA

5Universidade de Sao Paulo Instituto de Fısica Sao Paulo SP Brazil6Laboratoire AstroParticule et Cosmologie (APC) Universite Paris 7 CNRS-IN2P3 Paris France

7Centro Atomico Bariloche and Instituto Balseiro (CNEA-UNCuyo-CONICET) San Carlos de Bariloche Argentina8New York University New York New York USA9Ohio State University Columbus Ohio USA

10Universidad Tecnologica NacionalndashFacultad Regional Buenos Aires Buenos Aires Argentina11Instituto de Tecnologıas en Deteccion y Astropartıculas (CNEA CONICET UNSAM) Buenos Aires Argentina

12Universidad Nacional Autonoma de Mexico Mexico DF Mexico13Universidad de Santiago de Compostela Santiago de Compostela Spain

14Universita di Napoli lsquolsquoFederico IIrsquorsquo and Sezione INFN Napoli Italy15IMAPP Radboud University Nijmegen Netherlands16University of Wisconsin Milwaukee Wisconsin USA17Rudjer Boskovic Institute 10000 Zagreb Croatia

18IFLP Universidad Nacional de La Plata and CONICET La Plata Argentina19Universidad Complutense de Madrid Madrid Spain

20Laboratoire de Physique Nucleaire et de Hautes Energies (LPNHE) Universites Paris 6 et Paris 7 CNRS-IN2P3 Paris France21Karlsruhe Institute of Technology - Campus South - Institut fur Experimentelle Kernphysik (IEKP) Karlsruhe Germany

22Laboratoire de Physique Subatomique et de Cosmologie (LPSC) Universite Joseph Fourier INPG CNRS-IN2P3Grenoble France

23Observatorio Pierre Auger and Comision Nacional de Energıa Atomica Malargue Argentina24Universitat Siegen Siegen Germany

25University Politehnica of Bucharest Bucharest Romania26Karlsruhe Institute of Technology - Campus North - Institut fur Prozessdatenverarbeitung und Elektronik Karlsruhe Germany

27University of Adelaide Adelaide SA Australia28Centro Brasileiro de Pesquisas Fisicas Rio de Janeiro RJ Brazil

29Laboratoire de lrsquoAccelerateur Lineaire (LAL) Universite Paris 11 CNRS-IN2P3 Orsay France30Universidade Estadual do Sudoeste da Bahia Vitoria da Conquista BA Brazil

31Karlsruhe Institute of Technology - Campus North - Institut fur Kernphysik Karlsruhe Germany32University of New Mexico Albuquerque New Mexico USA

33Bergische Universitat Wuppertal Wuppertal Germany34SUBATECH Ecole des Mines de Nantes CNRS-IN2P3 Universite de Nantes Nantes France

35Max-Planck-Institut fur Radioastronomie Bonn Germany36Universidad de Alcala Alcala de Henares (Madrid) Spain

37Institute of Physics of the Academy of Sciences of the Czech Republic Prague Czech Republic38Universita di Roma II lsquolsquoTor Vergatarsquorsquo and Sezione INFN Roma Italy

39Universidade Federal do Rio de Janeiro Instituto de Fısica Rio de Janeiro RJ Brazil40Institute of Nuclear Physics PAN Krakow Poland

41Colorado State University Fort Collins Colorado USA42lsquolsquoHoria Hulubeirsquorsquo National Institute for Physics and Nuclear Engineering Bucharest-Magurele Romania

P ABREU et al PHYSICAL REVIEW D 84 122005 (2011)

122005-2

43Colorado State University Pueblo Colorado USA44School of Physics and Astronomy University of Leeds Leeds United Kingdom

45Universidad de Granada amp CAFPE Granada Spain46Case Western Reserve University Cleveland Ohio USA

47Pennsylvania State University University Park Pennsylvania USA48Universita di Milano and Sezione INFN Milan Italy

49Universita di Catania and Sezione INFN Catania Italy50Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo (INAF) Palermo Italy51Dipartimento di Fisica dellrsquoUniversita del Salento and Sezione INFN Lecce Italy

52Universita di Torino and Sezione INFN Torino Italy53Universidade Estadual de Campinas IFGW Campinas SP Brazil54Michigan Technological University Houghton Michigan USA

55Observatorio Pierre Auger Malargue Argentina56Nikhef Science Park Amsterdam Netherlands

57University of Chicago Enrico Fermi Institute Chicago Illinois USA58Instituto de Astronomıa y Fısica del Espacio (CONICET-UBA) Buenos Aires Argentina

59Departamento de Fısica FCEyN Universidad de Buenos Aires y CONICET Ciudad de Buenos Aires Argentina60Universidade Federal Fluminense EEIMVR Volta Redonda RJ Brazil

61National Technological University Faculty Mendoza (CONICETCNEA) Mendoza Argentina62Universidade de Sao Paulo Instituto de Fısica Sao Carlos SP Brazil

63Kernfysisch Versneller Instituut University of Groningen Groningen Netherlands64Institut de Physique Nucleaire drsquoOrsay (IPNO) Universite Paris 11 CNRS-IN2P3 Orsay France

65Universita dellrsquoAquila and INFN LrsquoAquila Italy66Pontifıcia Universidade Catolicaa Rio de Janeiro RJ Brazil

67Institute for Nuclear Science and Technology (INST) Hanoi Vietnam68RWTH Aachen University III Physikalisches Institut A Aachen Germany

69ASTRON Dwingeloo Netherlands70J Stefan Institute Ljubljana Slovenia

71Laboratory for Astroparticle Physics University of Nova Gorica Nova Gorica Slovenia72Dipartimento di Fisica dellrsquoUniversita and INFN Genova Italy

73University of Lodz Lodz Poland74INFN Laboratori Nazionali del Gran Sasso Assergi (LrsquoAquila) Italy

75Universidade Estadual de Feira de Santana Feira de Santana BA Brazil76Palacky University RCPTM Olomouc Czech Republic

77Charles University Faculty of Mathematics and Physics Institute of Particle and Nuclear Physics Prague Czech Republic78Louisiana State University Baton Rouge Louisiana USA

79Universitat Hamburg Hamburg Germany80Universidade Federal do ABC Santo Andre SP Brazil

81Benemerita Universidad Autonoma de Puebla Puebla Mexico82Universidad Michoacana de San Nicolas de Hidalgo Morelia Michoacan Mexico

83Dipartimento di Ingegneria dellrsquoInnovazione dellrsquoUniversita del Salento and Sezione INFN Lecce Italy84Centro de Investigacion y de Estudios Avanzados del IPN (CINVESTAV) Mexico DF Mexico

85Southern University Baton Rouge Louisiana USA86Rudolf Peierls Centre for Theoretical Physics University of Oxford Oxford United Kingdom

87Instituto de Fısica de Rosario (IFIR) - CONICETUNR and Facultad de Ciencias Bioquımicas y Farmaceuticas UNRRosario Argentina

88Centro de Investigaciones en Laseres y Aplicaciones CITEFA and CONICET Villa Martelli Buenos Aires Argentina89Instituto de Fısica Corpuscular CSIC-Universitat de Valencia Valencia Spain

90Northeastern University Boston Massachusetts USA91Universidade Federal da Bahia Salvador BA Brazil

92University of Nebraska Lincoln Nebraska USA93Colorado School of Mines Golden Colorado USA

94University of Bucharest Physics Department Bucharest Romania95Argonne National Laboratory Argonne Illinois USA

kNow at NYU Abu Dhabi Abu Dhabi United Arab Emirates

sectNow at Konan University Kobe Japan

DaggerNow at Universit de Lausanne Lausanne Switzerland

daggerNow at University of Maryland College Park Maryland USA

Deceased

SEARCH FOR ULTRAHIGH ENERGY NEUTRINOS IN PHYSICAL REVIEW D 84 122005 (2011)

122005-3

96Los Alamos National Laboratory Los Alamos New Mexico USA(Received 16 August 2011 published 30 December 2011 corrected 5 January 2012)

The Surface Detector of the Pierre Auger Observatory is sensitive to neutrinos of all flavors above

01 EeV These interact through charged and neutral currents in the atmosphere giving rise to extensive air

showers When interacting deeply in the atmosphere at nearly horizontal incidence neutrinos can be

distinguished from regular hadronic cosmic rays by the broad time structure of their shower signals in the

water-Cherenkov detectors In this paper we present for the first time an analysis based on down-going

neutrinos We describe the search procedure the possible sources of background the method to compute

the exposure and the associated systematic uncertainties No candidate neutrinos have been found in data

collected from 1 January 2004 to 31 May 2010 Assuming an E2 differential energy spectrum the limit on

the single-flavor neutrino is E2dN=dE lt 174 107GeVcm2s1sr1 at 90 CL in the energy range

1 1017eVltElt 1 1020eV

DOI 101103PhysRevD84122005 PACS numbers 9555Vj 9585Ry 9870Sa

INTRODUCTION

Neutrinos play a key role in the understanding of theorigin of ultra-high-energy cosmic rays (UHECRs) Theirobservation should open a new window to the Universesince they can give information on regions that are other-wise hidden by large amounts of matter in the field of viewMoreover neutrinos are not deviated by magnetic fieldsand would point back to their sources

In the EeV range neutrinos are expected to be producedin the same sources where UHECRs are thought to beaccelerated as well as during the propagation ofUHECRs through the cosmic microwave background(CMB) radiation [1] The latter are called cosmogenicneutrinos and their presence is expected if the UHECRsabove the spectral cutoff reported in [2] contain a signifi-cant fraction of protons [3ndash8]

There are many current programs to search for high-energy neutrinos with dedicated experiments [9ndash11]Although the primary goal of the Pierre AugerObservatory Surface (SD) and Fluorescence Detectors(FD) is to detect UHECRs UHE neutrinos (UHEs)can also be identified and limits to the diffuse flux ofUHEs in the EeV range and above have been set usingearlier Auger data [12ndash14] Earth-skimming neutrinosare expected to be observed through the detection of

showers induced by the decay of emerging leptonswhich are created by interactions in the Earth [15]Using this mechanism for data collected from January 12004 until April 30 2008 an upper limit was setE2dN=dE lt 6thorn3

3 108GeVcm2s1sr1 at 90 CL

for each neutrino flavor [16] The SD of the Pierre AugerObservatory has also been shown to be sensitive tolsquolsquodown-goingrsquorsquo neutrinos of all flavors interacting in theatmosphere or in the mountains surrounding the SD andinducing a shower close to the ground [141718] In thispaper we present an analysis based on down-going neu-trinos and place a competitive limit on the all-flavordiffuse neutrino flux using data from January 1 2004until May 31 2010The main challenge in detecting UHE neutrinos with the

Pierre Auger Observatory is to identify a neutrino-inducedshower in the background of showers initiated byUHECRs possibly protons or heavy nuclei [19] and in amuch smaller proportion even photons [20]The identification of -induced showers is illustrated in

Fig 1 If the incidence is nearly horizontal lsquolsquooldrsquorsquo showersinduced in the upper atmosphere by protons nuclei orphotons have a thin and flat front at ground level contain-ing only high-energy muons and their radiative and decayproducts concentrated within a few tens of nanoseconds

FIG 1 (color online) Pictorial representation of the different types of showers induced by protons heavy nuclei and lsquolsquodown-goingrsquorsquo(DG) as well as lsquolsquoEarth-skimmingrsquorsquo (ES) neutrinos The search for down-going showers initiated deep in the atmosphere is the subjectof this work


122005-4

On the other hand lsquolsquoyoungrsquorsquo showers induced by neutrinosat a low altitude have a thick curved front with a signifi-cant electromagnetic component spread in time overhundreds of nanoseconds specially in their earlier partthat traverses less atmosphere In this work to obtain anunambiguous identification of neutrinos we select showerswith zenith angle gt 75 and we apply criteria to ensure adeep interaction Using less inclined showers is in principlepossible but will require a better control of the varioussources of background

The method was tuned using data taken at the SD in theperiod from January 1 2004 until October 31 2007 Ablind scan over the data collected in the remaining periodie from November 1 2007 until May 31 2010 reveals nocandidates and we place a stringent limit on the diffuse fluxof UHE neutrinos

For that purpose we calculate the probability for ashower produced deeply in the atmosphere to trigger theSD and to be identified as a neutrino candidate Thisprobability depends on the neutrino flavor and type ofinteractionmdashcharged current (CC) or neutral current(NC)mdashand is also a function of neutrino energy E inci-dent zenith angle and atmospheric interaction depthFrom these identification probabilities we calculate theexposure of the SD to deep inclined neutrino showersWe give an estimate of the systematic uncertainties onthe diffuse neutrino flux limit and discuss the impli-cations of our observations for models of UHE neutrinoproduction

THE PIERRE AUGER OBSERVATORY

The Pierre Auger Observatory is a hybrid detector lo-cated in Malargue Mendoza Argentina [21] It consists ofan array of particle detectors [22] and a set of fluorescencetelescopes [23] at four sites that provide a unique crosscalibration capability

The SD is spread over a surface of 3000 km2 at analtitude of 1400 m above sea level This corresponds toan average vertical atmospheric depth above ground ofXground frac14 880 g cm2 The slant depthD is the total gram-

mage traversed by a shower measured from ground in thedirection of the incoming primary particle In the flat-Earthapproximation D frac14 ethXground XintTHORN= cos where Xint is

the interaction depth and the zenith angle For veryinclined showers the curvature of the atmosphere is takeninto account

The four fluorescence sites are located at the perimeterof the surface array viewing the atmosphere above it [23]In this work only data collected with the SD of the PierreAuger Observatory are used to search for down-goingneutrinos

The Surface Detector

Since the beginning of its operation for physics analysisin January 2004 the SD array has grown steadily and it has

been recording an increasing amount of data It consists of1660 detector units (water-Cherenkov stations) regularlyspaced in a triangular grid of side 15 km Each detectorunit is a cylindrical polyethylene tank of 36 m diameterand 12 m height containing 12 000 liters of purified waterThe top surface has three photomultiplier tubes (PMTs) inoptical contact with the water in the tank The PMT signalsare sampled by flash analog digital converters (FADC) witha frequency of 40 MHz Each surface detector is regularlymonitored and calibrated in units of vertical equivalentmuons (VEM) corresponding to the signal produced by a traversing the tank vertically and through its center [24]The surface stations transmit information by radio links tothe Central Data Acquisition System (CDAS) located inMalargue The PMTs local processor GPS receiver andthe radio system are powered by batteries regulated bysolar panels Once installed the local stations work con-tinuously without external intervention

The trigger

A local trigger selects signals either with a high peakvalue or with a long duration The second condition favorsstations hit in the early stage of the shower development(moderately inclined or deeply induced showers) Theglobal trigger requires either 4 stations satisfying one ofthe conditions or 3 stations satisfying the second one in acompact configuration (see [25] for more details)With the complete array the global trigger rate is about

two events per minute one half being actual shower eventswith median energy of 3 1017 eV

SIMULATION OF NEUTRINO INTERACTIONSINDUCED SHOWERS AND THE RESPONSE OF

THE SURFACE DETECTOR

Monte Carlo simulations of neutrino-induced showersare used to establish identification criteria and to computethe acceptance of the SD to UHEs The whole simulationchain is divided in three stages(1) High-energy processes

(i) The -nucleon interaction is simulated withHERWIG [26]

(ii) In the case of CC interactions the leptonpropagation is simulated with a dedicated codeand its decay (when necessary) with TAUOLA

[27](2) The shower development in the atmosphere is pro-

cessed by AIRES [28](3) The Surface Detector simulation is performed with

the Offline software [29]In the next subsections we discuss each stage in detail

Neutrino interaction

HERWIG is a general-purpose event generator for high-

energy processes with particular emphasis on the detailed


122005-5

simulation of QCD parton showers Here it is used tocompute the fraction of the primary energy that goes intothe hadronic vertex and to provide the secondary particlesproduced for both charged (CC) and neutral current (NC)interactions (see Fig 2 for a summary of all the channelsconsidered in this work)

The energy carried by the hadronic jet is always con-verted into a shower which could be seen by the SD Inaddition the energy of the lepton produced in a CC inter-action may be totally or partially visible An electron ispromptly converted into an electromagnetic shower A atEeVenergies has a decay length of50 km and may decaybefore reaching the ground producing a secondary showerthat can be detected (so called lsquolsquodouble-bangrsquorsquo event) Onthe other hand it is very unlikely that a high-energy muonwill produce a detectable shower so its interaction andordecay are not simulated For all channels and neutrinoflavors a set of primary interactions is constructedfrom a grid of incoming neutrino energies zenith anglesand interaction depths In lsquolsquodouble-bangrsquorsquo events the decayproducts of the lepton are generated by TAUOLA Theenergies and momenta of the secondary particles are theninjected into the program AIRES to generate the atmos-pheric cascade

Down-going neutrinos interacting in the mountains

In addition to the interactions in the atmosphere we alsotake into account the possibility of neutrino interactionswithin the mountains around the Pierre Auger Observatory(mainly the Andes located to the northwest of the array)producing a hadronic jet and a lepton The hadronic orelectromagnetic showers produced by neutrinos of anyflavor are absorbed either in the rock itself or in the fewten kilometers of atmosphere between the mountains andthe Auger array and may be neglected So only showersinduced by the decay of the s may be seen In other termsthis process is exactly equivalent to the lsquolsquoEarth-skimmingrsquorsquomechanism but it is included in this study because suchshowers are going downwards

The topography surrounding the SD of the AugerObservatory is accounted for using a digital elevationmap [30] For the Auger site the line of sight interceptingthe mountains corresponds only to zenith angles very close

to the horizon ( gt 89) Even though the solid angle ismuch smaller than for showers with gt 75 this mecha-nism is still relevant because mountains are much moremassive It is simulated in the same way as the lsquolsquodouble-bangrsquorsquo process accounting in addition for energy loss ofthe lepton in the rock [31]

Detector simulation

To avoid excessively long computing times AIRES usesthe standard thinning procedure [32] consisting in follow-ing only some branches in the tree of interactions in theatmosphere Weights are attributed to the survivingbranches obtaining a representative set of particles atany stage especially at ground level The first step in thedetector response simulation is to regenerate a fair sampleof the particles expected in each station from the thinnedoutput of AIRES This unthinning procedure is detailed in[33] Each particle reaching a surface detector station isinjected in the station and the amount of Cherenkov lightproduced in water calculated with GEANT4 [34] The FADC

traces of the PMT signals are simulated using the Offlineframework [29] The total signal due to the particles enter-ing the station as well as several quantities characterizingthe FADC trace which will be relevant for neutrino iden-tification (see below) are then calculated The local andglobal trigger conditions are applied in the same way as forreal data

INCLINED EVENT SELECTION ANDRECONSTRUCTION

Events occurring during periods of data acquisition in-stabilities [25] are excluded After a lsquolsquotrace cleaningrsquorsquoprocedure removing the accidental signals (mainly atmos-pheric muons) the start times of the signals in the stationsare requested to be compatible with a plane shower frontmoving at speed c If this condition is not fulfilled using allstations included in the global trigger an iterative proce-dure removes stations until a satisfactory configuration isfound with at least four stations Otherwise the event isrejected The angle between a vertical axis and the perpen-dicular direction to this plane is the reconstructed zenithangle rec of the shower Nearly horizontal showers are

FIG 2 Different types of atmospheric showers induced by neutrinos


122005-6

selected by requiring rec gt 75 In some cases a non-inclined event produced by detector fluctuations or twoindependent showers arriving close in time (less that60 ns) may be incorrectly reconstructed as inclined Toremove these events we also compute the apparent speedof propagation of the trigger between every pair of stations(Vij) and the average speed of the event (hVi) as in [16]

Genuine inclined showers have a lsquolsquofootprintrsquorsquo (configura-tion of the stations) elongated in the direction of arrival(left-hand panel of Fig 3) The apparent speed ofpropagation of the signal along the major axis of thefootprint is concentrated around the speed of light c

Under the plane front approximation the zenith angle isrsquo arcsinethc=hViTHORN In Fig 4 we show the distribution of hVifor events with rec gt 75 acquired between January 12004 and October 31 2007 The shaded region correspondsto misreconstructed or low quality events (see right-handpanel of Fig 3 for an example) To remove these events weoptimized a set of quality cuts using a MC sample of 5000regular inclined showers initiated by hadrons near the top

of the atmosphere hVi is required to be less than0313 mns1 with a relative spread smaller than 008Also the lsquolsquofootprintrsquorsquo is required to be elongated L=W gt3 where L andW are the length and the width (eigenvaluesof the inertia tensor as defined in [16]) These cuts rejectonly 10 of genuine inclined showersFor events where all stations are aligned along one of the

directions of the array rec cannot be computed and werely on the average speed of the event hVi These lsquolsquoinlinersquorsquoevents are of great importance since the Monte Carlosimulations show that low energy neutrinos (amp 1018 eV)typically present this type of configuration in the SDThere is an additional requirement for events constituted

by an inline event plus a nonaligned station (a nonalignedevent that would become inline by removing just onestation) This kind of spatial configuration is particularlyprone to bad reconstruction if the nonaligned station wastriggered by accidental muons not belonging to the showerfront To avoid this problem we also reconstruct the inlineevent obtained by the removal of the nonaligned stationand require it to have mean ground speed compatible with azenith angle larger than 75

IDENTIFICATION OF NEUTRINO CANDIDATES

For this analysis the whole data period (January 1 2004ndashMay 31 2010) was divided into two separate samplesSelected events recorded between January 1 2004 andOctober 31 2007 (equivalent to 14 yr of a complete SDarray working continuously) constitute the lsquolsquotrainingrsquorsquo sam-ple used to develop and optimize the neutrino identificationalgorithms Data collected between November 1 2007 andMay 31 2010 (equivalent to 2 yr of the full array)constitute the lsquolsquosearchrsquorsquo sample These latter events werenot processed before the final tuning of the algorithmsdefining the neutrino identification criteria

FIG 3 (color online) Left panel Event produced by a nearly horizontal shower (rec frac14 80) The footprint (ellipse) is elongatedalong the reconstructed direction of arrival (arrow) Right panel a noninclined event with rec frac14 79 The major axis of the footprintand the reconstructed direction of arrival do not point in the same direction Close inspection of the event suggests that stations 3 and 5are accidental and corrupt the reconstruction The numbers indicate the triggering order of the stations

FIG 4 Distribution of the mean ground speed of the signal forevents with rec gt 75 acquired between January 1 2004 andOctober 31 2007


122005-7

Discrimination of neutrinos from hadronic showers

Neutrinos unlike protons and heavier nuclei can gen-erate showers initiated deeply into the atmosphere Themain signature of these deep showers in the SD is asignificant electromagnetic (EM) component spread intime over hundreds of nanoseconds especially in the re-gion on the ground at which the shower arrives earlier (seeFig 5) On the other hand hadron-induced showers starthigh in the atmosphere their electromagnetic component isfully absorbed and only high-energy muons and theirradiative and decay products reach the surface concen-trated within a few tens of nanoseconds

We identify stations reached by wide EM-rich showerfronts via their Area-over-Peak ratio (AoP) defined as theratio of the integral of the FADC trace to its peak valuenormalized to 1 for the average signal produced by a singlemuon In background horizontal showers the muons andtheir electromagnetic products are concentrated within ashort time interval so their AoP is close to 1 In the firststations hit by a deep inclined shower it is typicallybetween 3 and 5 (see left-hand panel of Fig 6)

To quantify the distinctive features of hadronic anddeeply penetrating showers induced by neutrinos at largezenith angle improve the separation between the samplesand enhance the efficiency while keeping a simple physi-cal interpretation of the identification process we choose amultivariate technique known as the Fisher discriminantmethod [35] To tune it we used as a lsquolsquosignalrsquorsquo samplethe Monte Carlo simulationsmdashexclusively composed ofneutrino-induced showersmdashand as lsquolsquobackgroundrsquorsquo thetraining sample introduced abovemdashoverwhelmingly ifnot totally constituted of nucleonic showers We use realdata to train the Fisher discrimination method instead ofsimulations of hadronic showers for two main reasons thecomposition of the primary flux is not known and more-over the interaction models used to simulate hadronicshowers may bias some features of the tail of the distribu-tions of the observables used in this analysis Also thedetector simulation may not account for all possible detec-tor defects or fluctuations that may contribute to the back-ground to ultra-high-energy neutrinos while the real datacontain all of them including those which are not wellknown or even not yet diagnosed Note that since weapply a statistical method for the discrimination the useof real data as a background sample does not imply that weassume it contains no neutrinos but just that if any theyconstitute a small fraction of the total recorded eventsAfter training the Fisher method a good discrimination

is found when using the following ten variables [14] theAoP of the four earliest triggered stations in each eventtheir squares their product and a global early-late asym-metry parameter of the event We include the square of theAoP because when the distribution of the input variables isnot Gaussian the addition of a nonlinear combination ofthem improves the discrimination power [36] The productof the AoP of the earliest four stations in the event aims atminimizing the relative weight of an accidentally largeAoP produced for instance by a single muon whichdoes not belong to the shower front arriving at a stationbefore or after the shower itself This variable is also a verygood discriminator as shown in the right-hand panel ofFig 6 The early-late asymmetry parameter is a global

)1

(AoP10

Log

-02 0 02 04 06 08 1 12

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data

)4 AOPtimes3 AOPtimes2 AOPtimes1

(AOP10

Log

0 05 1 15 2 25 3

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data

FIG 6 Distributions of the AoP of the earliest station (left) and the product of the first four AoP (right) in background (real events inthe training sample) and simulated e CC events There is a clear separation between both samples indicating that the AoP of the earlystations is a good discrimination observable to be used in the Fisher method See text for more details

FIG 5 Upper panel sketch of an inclined shower induced by ahadron interacting high in the atmosphere The EM component isabsorbed and only the muons reach the detector Lower paneldeep inclined shower Its early region has a significant EMcomponent at the detector level


122005-8

observable of the event defined as the difference betweenthe mean AoP of the earliest and latest stations in the eventWe have checked in simulations that neutrino-inducedevents typically have an asymmetry parameter larger thanproton or nucleus-induced showers [14] Finally the addi-tion of other observables characterizing the time spread ofthe signals such as the rise-time (between 10 and 50 ofthe integrated signal) or the fall-time (between 50 and90 ) or including local observables of the stations thattrigger last in the event do not bring about significantimprovements in the discrimination

As the shower front is broader at larger distance from thecore for both young and old showers the discrimination isbetter when splitting the samples according to the multi-

plicity N (number of selected stations) A Fisher discrimi-nant was built separately for 4 N 6 7 N 11and N 12 The left-hand panel of Fig 7 shows theexcellent separation achieved for events in each of the 3subsamplesOnce the Fisher discriminant F is defined one has to

choose a threshold value that separates neutrino candidatesfrom regular hadronic showers Because the predictions ofthe neutrino detection rates are very low we want to keepthe expected rate of background events incorrectly classi-fied as neutrinos well below any detectable signal inpractice we wish it to be less than one event for eachmultiplicity subsample within the expected 20 yr lifetimeof the Auger Observatory

Fisher discriminant value-4 -2 0 2 4

Eve

nts

-110

1

10

210

310 simulationsνMCTraining data 1 yr

20 yrs

100 yrs

6)le N leFisher distribution - low mult (4

Fisher discriminant value-25 -2 -15 -1 -05 0 05

Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs

11)le N leFisher distribution - medium mult (7

Fisher discriminant value-6 -5 -4 -3 -2 -1 0

Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6

Fisher discriminant value-10 -5 0 5 10 15 20

Eve

nts

-110

1

10

210

310 simulationsνMCTraining data1 yr

20 yrs

100 yrs

N)leFisher distribution - large mult (12

Fisher discriminant value-8 -6 -4 -2 0

Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6

FIG 7 Left panel distribution of the Fisher discriminant (see text for details) for events with station multiplicity 4 N 6 (top)7 N 11 (middle) 12 N (bottom) Real data in the training period (January 1 2004ndashOctober 31 2007) describe the nucleonicbackground while Monte Carlo simulated down-going neutrinos correspond to the signal The vertical lines indicate the cut in theFisher value that needs to be placed to have less than 1 event in each period of time (1 yr 20 yr 100 yr) Right panel fit of anexponential function to the distribution of the Fisher discriminant F for the training data over the frac121 3 interval The predicted(Pred) see text and actual (Real) number of events are given for each of the test zones (frac123 4 frac124 5 frac125 6 and frac126 7)


122005-9

The training period was used to produce a reasonableprediction of the background We observe that the tail ofthe background distribution of F is consistent with anexponential shape In this way we produced a fit to thedistribution of F for the training data in the frac121 3region where is the RMS of the training sample Thisprocedure is illustrated in Fig 7 We then extrapolated it tofind the cuts corresponding to 1 event per 1 yr 20 yr or100 yr on the full array The validity of the extrapolation isnot guaranteed but some physical arguments support anexponential tail such as the fact that showers produced bynuclei or protons (or even photons) have a distribution ofXmax that shows an exponential shape dictated by thedistribution of the primary interaction The exponentialmodel may be checked below the cut by comparing theactual number of events observed in the frac123 4frac124 5 frac125 6 and frac126 7 regions to the numberof events predicted by extrapolating the fit done in thefrac121 3 region The values are in good agreement asshown in Fig 7 For our search sample (equivalent to2 yr of full detector data) we have an estimated backgroundof 01 events for each multiplicity class that add up to atotal of 03 events with a statistical uncertainty of 30 Aswe do not have at present a robust estimation of thebackground systematics we take a conservative approachand do not use this value to improve our flux upper limit

As can be seen in Fig 7 the identification cuts reject asmall fraction of the neutrino events Consequently itschoice has only a small impact on the neutrino identifica-tion efficiency The neutrino-induced showers rejected bythese cuts are those interacting far from the ground andsimilar to nucleonic-induced showers

IDENTIFICATION EFFICIENCIESAND EXPOSURE

During the data taking the array was growing and hadsporadic local inefficiencies Simulations of deep inclinedneutrino showers indicate that besides an elongated patternon the ground they have a large longitudinal uncertainty onthe core position For these reasons we cannot apply (asdone in the case of vertical showers [25]) a geometricalmethod relying on the estimated position of the showercore within a triangle or hexagon of active stations at eachtime Moreover a shower can trigger the surface detectoreven if the core falls outside the array Besides for deepinclined showers the trigger and identification efficienciesdepend not only on the shower energy and zenith angle butalso on the depth of the first interaction For these reasonsa specific procedure was designed to compute the time-dependent acceptance and the integrated exposure

The instantaneous status of the array is obtained fromthe trigger counting files which respond to the modifica-tions of the array configuration at every second To avoidhaving to cope with an enormous number of configura-tions we approximate the calculation of the aperture by

subdividing the search period in three-day intervals andwe select a reference array configuration to represent eachOnce this is done we calculate the neutrino identificationefficiencies and the aperture assuming that the arrayremains unchanged during each three-day intervalEach reference configuration was chosen so that thisapproximation if wrong underestimates the exposure bya small amount ( 1)MC-generated neutrino showers produced by AIRES

were randomly distributed over an extended circular areaaround the array such that a shower with a core fallingoutside this area has no chance to trigger the array For eachthree-day configuration the FADC traces of the activeCherenkov stations were simulated the local and globaltrigger conditions were applied and the events were pro-cessed through the same reconstruction and identificationalgorithms as the data (Sec V)Figure 8 shows an example of a shower that would be a

neutrino candidate in an ideal array placed at four randompositions on the circular surface defined above Two of therealizations are effectively recognized as neutrino events inthe real array for that particular layout The other two areeither not seen or not identified as neutrinos

FIG 8 An example of the result of placing the same deeplypenetrating neutrino-induced shower at 4 different positions inan actual array configuration (shaded area) corresponding toOctober 27 2007 The arrows indicate the azimuthal arrivaldirection of the shower the dots represent the infinite ideal arrayand the circumference the extended area (see text) Solid sym-bolsmdasheither circles or squaresmdashcorrespond to triggered stationsof the simulated shower that are also on the actual array Opensymbols are stations that are not in the real array Shower 1 iscompletely contained and identified as a neutrino Shower 2 fallsentirely outside the real array and it does not trigger the arrayAlthough shower 3 triggers the array it is not identified as aneutrino because the earliest three stations are not in the realarray Shower 4 loses some stations but keeps the earliest whichare enough to identify the event as a neutrino


122005-10

Figure 9 shows the efficiency (fraction of events whichpass all steps) as a function of interaction depth in theatmosphere for neutrinos of E frac14 1018 eVand frac14 80 inan lsquolsquoidealrsquorsquo array without holes nor edges There is essen-tially a plateau between a minimal depth (needed for the

-induced shower to reach a sufficient lateral expansion)and a maximal one (such that the electromagnetic compo-nent is almost extinguished at ground level) Below andabove this plateau the efficiency drops rapidly to zero Inother words for a given channel and given values of andE there is a slice of atmosphere above the array where theinteractions are detected and distinguished the mattercontained in this volume will be referred to as the lsquolsquomassaperturersquorsquo in the followingFor each three-day period we compute the effective area

defined as the integral of the efficiency over core position

AeffethE D tTHORN frac14Z

eth ~r E D tTHORNdA (1)

The effective mass aperture MeffethE tTHORN is obtained byintegrating over the injection depth D and the solid angle

MeffethEtTHORNfrac142ZZ

sincosAeffethEDtTHORNddD (2)

To compute this integral we perform a spline interpolationon the finite three-dimensional mesh where Aeff is deter-mined The total mass aperture is then obtained summingMeffethE tTHORN over different configurations corresponding to acertain period of time It is defined independently of the-nucleon cross sectionA combined exposure can be obtained by a summation

over the search period

E ethETHORN frac14Xi

frac12iiethETHORNZ Mi

effethE tTHORNm

dt (3)

The sum runs over the three neutrino flavors (with fractionsi) and the CC and NC interactions m is the mass of anucleon Here we assume a full $ mixing leading

to i frac14 1 for the three flavorsWe use the -nucleon cross section given in [37] (CSS

hereafter) to compute the reference exposure of our searchperiod It is shown in Fig 10 as a function of neutrinoenergy In Table I we also give the mass aperture inte-grated in time for all the considered channels allowing thereader to compute the exposure using different cross-sections or flux models

]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1

atmosphere Top of the

Ground

- 1EeV o CC channel 80eνTrigger and identification efficiency for

Trigger Efficiency

Selection before Fisher

Selection (after Fisher)ν

FIG 9 Example of trigger and identification efficiency as afunction of the slant depth of the interaction above the groundNotice that the Fisher discriminant neutrino selection actuallykeeps most of the neutrino showers that pass the quality andreconstruction cuts discussed in Sec IV

energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC

FIG 10 SD Exposure for our search period for down-goingneutrino-initiated showers The total exposure is shown as a fullline The exposure for individual neutrino flavors and interactionchannels is also shown

TABLE I Effective mass aperture integrated over time for the search period (November 12007 to May 31 2010) for down-going neutrinos of the Pierre Auger Surface Detector [in unitsof (g sr s)]

logE=eV e CC CC CC x NC Mount

1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11

SYSTEMATIC UNCERTAINTIES

The calculation of the mass aperture of the AugerObservatory for neutrino showers requires the input ofseveral ingredients which we have selected from amongstconventionally used options Some of these choices aredirectly related to the Monte Carlo simulation of the show-ers ie generator of the first neutrino interaction partondistribution function (PDF) air shower development andhadronic model Others have to do with the precision of ourknowledge of the topography of the mountains surroundingthe observatory and some come from the limitations on thetheoretical models estimating for instance the interactioncross section or the energy loss at high energies Byadding linearly all these contributions our estimate of

the total systematic uncertainty on the exposure amountsto +22ndash46In the following subsections we discuss in detail the

dependence of the exposure on each of the above men-tioned choices by modifying the different ingredients oneby one

Monte Carlo simulation of the shower

The reference Monte Carlo neutrino sample was pro-duced with HERWIG 6510 [26] as interaction generator incombination with the CTEQ06m [38] parton distributionfunctions AIRES 28 as shower simulator (thinning valueof 106) and QGSJETII03 [39] as hadronic modelIn order to assess the influence of this particular choice

of models on the detector aperture independent sets of CCe showers were generated at 1 EeV and 80 using differ-ent combinations of several interaction generators PDFsshower simulators thinning values and hadronic modelsWe chose this particular energy and angle bin because it isthe one that contributes the most to the limitIn Fig 11 we show as an example the detection effi-

ciency as a function of the slant depth when using ourreference options (HERWIG) and when changing only theinteraction generator (PYTHIA) Since the shapes of theneutrino-selection efficiency curves remain similar wecan estimate the effect of changing the interaction genera-tor by computing the integral of the curves and reportingthe relative difference (RD) between them The sameprocedure is applied to estimate the effect of changingother ingredients of the simulation A summary of thisRD is given in Table IIWe observe that the changes in interaction generator

PDF shower simulator and hadronic model brought about

]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground

- 1EeV o CC channel 80eνIdentification efficiency for

Selection HERWIGν

Selection PYTHIAν

FIG 11 Identification efficiency as function of the slant depthfor systematic uncertainties studies Comparison between inter-action generators (HERWIG and PYTHIA) The rest of theMonte Carlo input parameters remain the same

TABLE II Summary of the relative differences (RD) between the reference calculation of theexposure and the calculations done changing one of the ingredients of the Monte Carlosimulations at a time The RD were obtained for zenith angle frac14 80 and energyE frac14 1 EeV unless otherwise stated The statistical uncertainty of all the relative differences is4

Parameter Reference Modification RD

(A) (B)

RB

RA

ethRBthorn

RATHORN=2

Interaction generator HERWIG PYTHIA [40] -7

HERWIG++ [41] -7

PDF (gen level) CTEQ06m MSTW [42] -7

Shower Simulator AIRES CORSIKA 69 [43] -17

Hadronic Model QGSJETII QGSJETI [44] +2

SIBYLL [45] -2

SIBYLL (E=03 EeV) -1

SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12

a decrease of the estimated aperture with the choice of theshower simulation being the dominating effect On theother hand an improvement of the relative thinning levelcauses the opposite effect Although we cannot recomputethe aperture for all possible alternatives of the relevantingredients the relative differences reported in Table IIserve as an estimate of the systematic dependence of ourresult on the simulation options For each category ofpotential systematic effects in Table II we take the maxi-mum observed RD as an estimate of the correspondingsystematic uncertainty A total systematic uncertainty of+9ndash33 on the exposure is obtained by linear addition ofthe maximum positive and negative deviations

-nucleon cross sections and energy loss

We adopted the uncertainty in the -nucleon cross sec-tion as calculated in [37] It translates into a 7 uncer-tainty in the total exposure In any case as mentionedabove Table I shows the Auger mass aperture for down-going neutrinos which does not depend on the crosssection hence the expected neutrino event rate (and neu-trino flux limit) can be computed as necessary for othermodels and values of the cross section (see eg [4647])

Topography

As explained in Sec III B the actual topography sur-rounding the observatory has been taken into account bydetailed Monte Carlo simulations which include digitalelevation maps In principle uncertainties due to differenttau energy loss models should not be important for down-going neutrinos but due to the fact that the Pierre AugerObservatory is close to the Andes a non-negligible con-tribution to the event rate from down-going neutrinosinteracting in the mountains and producing a lepton isexpected (see Table III) The systematic error on the totalreference exposure due to this channel amounts to 6dominated by the uncertainties on the cross section andenergy loss models

RESULTS AND DISCUSSION

In this section we present the calculation of the upperlimit to the diffuse flux of UHEs and compare our results

to some selected model predictions and discuss theimplications

Upper limit on the diffuse neutrino flux

Once the multivariate algorithms and selection cutsdefining a neutrino candidate were studied and tunedwith the Monte Carlo simulations and the training datasample we applied them to the search data sample We firsttested the compatibility between the shapes of the tails ofthe Fisher distributions during training and search periodsby using an unbinned Kolmogorov hypothesis test and

TABLE III Expected fractions of neutrinos in the selectedsample according to their flavor and interaction channel (CC andNC) These fractions are derived assuming that electron muonand neutrinos are in the same proportion in the diffuse flux

Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310

6)le N leSearch sample - low mult (4

candidatesνno

Fisher discriminant value-6 -4 -2 0 2 4

Eve

nts

-110

1

10

210

310

11)le N leSearch sample - medium mult (7

candidatesνno

Fisher discriminant value-8 -6 -4 -2 0 2 4

Eve

nts

-110

1

10

210

310

N)leSearch sample - large mult (12

candidatesνno

FIG 12 Fisher distribution of the search sample (November 12007ndashMay 10 2010) for events with multiplicity 4 N 6(top) 7 N 11 (middle) 12 N (bottom) No neutrinocandidates are found


122005-13

found them to be in agreement with p-values of 037 016and 017 for the small medium and large multiplicityclasses respectively

We found no candidate events in the search period (seeFig 12) The highest test zone with events in the Fisherdistribution of the search sample is the 6ndash7 sigma region Ithas only one event and we expected 22 from the exponen-tial fit to the test sample

The expected number of events from a diffuse flux ofneutrinos in a given energy range is given by

Nexpected frac14Z Emax

Emin

ethETHORNEethETHORNdE (4)

where EethETHORN is our reference exposure [Eq (2) and Fig 10]The upper limit is derived for a differential neutrino fluxethETHORN frac14 k E2

Also we assume that due to neutrinooscillations the diffuse flux is composed of electronmuon and neutrinos in the same proportion We expectless than one background event after the neutrino-selectionprocedure is applied to the data sample corresponding to thereference exposure (see Sec 5) Given the uncertainties ofthis estimate the number of background events will beassumed to be zero which results in a more conservativeupper limit A semi-Bayesian extension [48] of theFeldmanndashCousins approach [49] is used to include theuncertainty in the exposure giving an upper limit at 90CL on the integrated flux of diffuse neutrinos of

k lt 174 107GeVcm2s1sr1 (5)

The effect of including the systematics fromMC-nucleoncross sections and energy loss is to increase the limit by15 The limit is quoted for a single neutrino flavor Therelative importance of each neutrino flavor in the determi-nation of the upper limit can be derived from Table IIIwhich gives the expected fractions of neutrinos in theselected sample according to their flavor and interaction

channel The largest contribution comes from e CC Thesecond largest is CC due to double-bang interactions andthe large average fraction of energy going into the shower inthe decay of the lepton Our result together with otherexperimental limits [50] is shown in Fig 13Another usual way of presenting the upper bound is in

the less-model-dependent differential form It assumes thatthe diffuse neutrino flux behaves as 1=E2 within energybins of unity width on a natural logarithmic scale and isgiven by 244=EethETHORNE accounting for statistical uncer-tainties only and assuming no background [51] The dif-ferential limit obtained including systematic uncertaintiesis shown in Fig 14 together with our previous result onup-going [13] and two theoretical predictions for cos-mogenic neutrinos [67] We observe that we achievemaximum sensitivity in the 03ndash10 EeV energy range

Model predictions

There is a wide variety of models predicting fluxes ofneutrinos with energies in the EeV range [1] They areusually separated into three groups cosmogenic neutrinoseg [67] neutrinos produced in accelerating sources eg[5253] and neutrinos of exotic origin eg [52] In allthese models there are parameters with unknown valueswhich can change the spectral shape and strength of theflux In Table IV we give the event rates after folding thesefluxes with our reference exposureCurrent theoretical flux predictions for cosmogenic neu-

trinos [67] seem to be out of reach of our present sensi-tivity Concerning neutrinos produced in acceleratingsources there are popular models [5354] which predictevent rates which could be detected in the next few yearsRegarding exotic models [52] TD-Necklaces will be

energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610

-510Single flavour neutrino integral limits (90 CL)

AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing

FIG 13 (color online) Integrated upper limits (90 CL) fromthe Pierre Auger Observatory for a diffuse flux of down-going in the period November 1 2007ndashMay 31 2010 For comparisonup-going (January 1 2004ndashFebruary 28 2009)[13] and limitsfrom other experiments [50] are also plotted

energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610

-510Single flavour neutrino differential limits (90 CL)

Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing

FIG 14 (color online) Differential limits (90 CL) from thePierre Auger Observatory for a diffuse flux of down-going inthe period November 1 2007ndashMay 31 2010 and up-going

(January 1 2004ndashFebruary 28 2009)[13] For reference tworecent calculations of this flux are shown lsquolsquoGZK-Fermirsquorsquo [6]takes into account the Fermi-LAT constraint on the GZK cascadephotons the other lsquolsquoGZK-evolFRIIrsquorsquo [7] adopts a strong sourceevolution model for FR-II galaxies assumed to be the sources ofUHECRs


122005-14

within our sensitivity range in one or two years whileZ-Burst models are already strongly disfavored Note thatall such lsquolsquotop downrsquorsquo models are also tightly constrained bythe limits of the Pierre Auger Observatory on the photonfraction in UHECR [20]

ACKNOWLEDGMENTS

The successful installation commissioning and opera-tion of the Pierre Auger Observatory would not have beenpossible without the strong commitment and effort from thetechnical and administrative staff in Malargue We are verygrateful to the following agencies and organizations forfinancial support Comision Nacional de EnergıaAtomica Fundacion Antorchas Gobierno De LaProvincia de Mendoza Municipalidad de MalargueNDM Holdings and Valle Las Lenas in gratitude for theircontinuing cooperation over land access Argentina theAustralian Research Council Conselho Nacional deDesenvolvimento Cientıfico e Tecnologico (CNPq)Financiadora de Estudos e Projetos (FINEP) Fundacao deAmparo a Pesquisa do Estado de Rio de Janeiro (FAPERJ)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo(FAPESP) Ministerio de Ciencia e Tecnologia (MCT)Brazil AVCR AV0Z10100502 and AV0Z10100522

GAAV KJB100100904 MSMT-CR LA08016 LC5271M06002 and MSM0021620859 Czech RepublicCentre de Calcul IN2P3CNRS Centre National de laRecherche Scientifique (CNRS) Conseil Regional Ile-de-France Departement Physique Nucleaire et Corpusculaire(PNC-IN2P3CNRS) Departement Sciences de lrsquoUnivers(SDU-INSUCNRS) France Bundesministerium furBildung und Forschung (BMBF) Deutsche Forschungs-gemeinschaft (DFG) Finanzministerium Baden-Wurttemberg Helmholtz-Gemeinschaft DeutscherForschungszentren (HGF) Ministerium fur Wissenschaftund Forschung Nordrhein-Westfalen Ministerium furWissenschaft Forschung und Kunst Baden-WurttembergGermany Istituto Nazionale di Fisica Nucleare (INFN)Ministero dellrsquoIstruzione dellrsquoUniversita e della Ricerca(MIUR) Italy Consejo Nacional de Ciencia y Tecnologıa(CONACYT) Mexico Ministerie van Onderwijs Cultuuren Wetenschap Nederlandse Organisatie voorWetenschappelijk Onderzoek (NWO) Stichting voorFundamenteel Onderzoek der Materie (FOM)Netherlands Ministry of Science and Higher EducationGrant Nos 1 P03 D 014 30 N202 090 310623 and PAP2182006 Poland Fundacao para a Ciencia e a TecnologiaPortugal Ministry for Higher Education Science andTechnology Slovenian Research Agency SloveniaComunidad de Madrid Consejerıa de Educacion de laComunidad de Castilla La Mancha FEDER fundsMinisterio de Ciencia e Innovacion and ConsoliderndashIngenio 2010 (CPAN) Xunta de Galicia Spain Scienceand Technology Facilities Council United Kingdom U SDepartment of Energy Contract Nos DE-AC02-07CH11359 DE-FR02-04ER41300 National ScienceFoundation Grant No 0450696 The GraingerFoundation USA ALFA-EC HELEN European Union6th Framework Program Grant No MEIF-CT-2005-025057 European Union 7th Framework Program GrantNo PIEF-GA-2008-220240 and UNESCO

[1] F Halzen and D Hooper Rep Prog Phys 65 1025(2002)P Bhattacharjee and G Sigl Phys Rep 327 109(2000)J K Becker Phys Rep 458 173 (2008)

[2] J Abraham et al [Pierre Auger Collaboration] Phys RevLett 101 061101 (2008)R U Abbasi et al [HiRes]Phys Rev Lett 100 101101 (2008)

[3] V Beresinsky and G Zatsepin Phys Lett B28 423(1969)

[4] S Yoshida and M Teshima Prog Theor Phys 89 833(1993)

[5] R Engel D Seckel and T Stanev Phys Rev D 64093010 (2001)

[6] M Ahlers et al Astropart Phys 34 106 (2010)

[7] K Kotera D Allard and A V Olinto J CosmolAstropart Phys 10 (2010) 013

[8] V Berezinsky et al Phys Lett B 695 13(2011)

[9] A Achterberg et al [IceCube Collaboration] AstropartPhys 26 155 (2006)

[10] J A Aguilar et al [ANTARES Collaboration] Phys LettB 696 16 (2011)

[11] PW Gorham et al [ANITA Collaboration] Phys RevLett 103 051103 (2009)Astropart Phys 32 10(2009)

[12] J Abraham et al [Pierre Auger Collaboration] Phys RevLett 100 211101 (2008)

TABLE IV Expected number of events using the current expo-sure of down-going measured by the Pierre Auger Observatoryfor several models [6752ndash54] The third column gives theprobabilities of observing 0 events given that we expect N

Reference N expected Probabilities of observing 0

GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15

[13] J Tiffenberg [Pierre Auger Collaboration] in Proceedingsof the 31st International Cosmic Ray Conference Lodz(2009)

[14] D Gora [Pierre Auger Collaboration] in Proceedings ofthe 31st International Cosmic Ray Conference Lodz(2009)

[15] X Bertou et al Astropart Phys 17 183 (2002)[16] J Abraham et al [Pierre Auger Collaboration] Phys

Rev D 79 102001 (2009)[17] J Alvarez-Muniz [Pierre Auger Collaboration] in

Proceedings of the 30th International Cosmic RayConference Merida Vol 4 (2007) p 607I ValinoPhD thesis University de Santiago de CompostelaISBN 9788497509664 (2008)

[18] K S Capelle et al Astropart Phys 8 321 (1998)PBilloir [Pierre Auger Collaboration] J Phys Conf Ser203 012125 (2010)


[20] J Abraham et al [Pierre Auger Collaboration] AstropartPhys 27 155 (2007)J Abraham et al [Pierre AugerCollaboration] Astropart Phys 29 243 (2008)JAbraham et al [Pierre Auger Collaboration] AstropartPhys 31 399 (2009)

[21] J Abraham et al [Pierre Auger Collaboration] NuclInstrum Methods Phys Res Sect A 523 50 (2004)

[22] I Allekotte et al [Pierre Auger Collaboration] NuclInstrum Methods Phys Res Sect A 586 409 (2008)

[23] J Abraham et al [Pierre Auger Collaboration] NuclInstrum Methods Phys Res Sect A620 227 (2010)

[24] X Bertou et al [Pierre Auger Collaboration] NuclInstrum Methods Phys Res Sect A 568 839 (2006)


[26] G Corcella et al HERWIG 65 J High Energy Phys 01(2001) 010

[27] R Decker et al Comput Phys Commun 76 361 (1993)[28] S Sciutto AIRES httpwwwfisica unlpeduarauger

aires[29] S Argiro et al [The Offline group - Pierre Auger

Collaboration] Nucl Instrum Methods Phys Res SectA 580 1485 (2007)

[30] T G Farr et al Rev Geophys 45 33 (2007)[31] O Blanch Bigas et al Phys Rev D 77 103004

(2008)

[32] A M Hillas in Proceedings of the 17th InternationalCosmic Ray Conference Paris 8 (1981) p 193

[33] P Billoir Astropart Phys 30 270 (2008)[34] S Agostinelli et al Nucl Instrum Methods Phys Res

Sect A 506 250 (2003)J Allison et al IEEE TransNucl Sci 53 270 (2006) See also httpgeant4webcernchgeant4

[35] R Fisher Ann Eugenics 7 179 (1936)[36] B Roe PHYSTAT-2003-WEJT003 215 (2003)[37] A Cooper-Sarkar and S Sarkar J High Energy Phys 01

(2008) 075[38] J Pumplin et al J High Energy Phys 07 (2002) 012 [39] S Ostapchenko Nucl Phys B Proc Suppl 151 143

(2006)S Ostapchenko Nucl Phys B Proc Suppl 151147 (2006)

[40] T Sjostrand S Mrenna and P Skands Comput PhysCommun 178 852 (2008)

[41] M Bahr et al Eur Phys J C 58 639 (2008)[42] A D Martin Eur Phys J C 63 189 (2009)[43] D Heck et al Report No FZKA 6019 (1998)[44] N Kalmykov and S Ostapchenko Phys At Nucl 56 346

(1993)[45] R Engel et al in Proceedings of the 26th International

Cosmic Ray Conference Salt Lake City 1 (1999) p 415[46] A Connolly R S Thorne and D Waters Phys Rev D 83

113009 (2011)[47] A Cooper-Sarkar P Mertsch and S Sarkar

arXiv11063723[48] J Conrad et al Phys Rev D 67 12002 (2003)[49] G J Feldman and RD Cousins Phys Rev D 57 3873

(1998)[50] M Ackermann et al [AMANDA] Astrophys J 675 2

1014 (2008)R Abbasi et al [IceCube] Phys Rev D 83092003 (2011)I Kravchenko et al [RICE] Phys Rev D73 082002 (2006)PW Gorham et al [ANITA-IICollaboration] Phys Rev D 82 022004 (2010)Erratum arXiv10115004v1 [astro-ph]R Abbasi et al[HiRes] Astrophys J 684 790 (2008)K Martens[HiRes] arXiv07074417

[51] L A Anchordoqui et al Phys Rev D 66 103002 (2002)[52] O E Kalashev et al Phys Rev D 66 063004 (2002)[53] K Mannheim R J Protheroe and J P Rachen Phys Rev

D 63 23003 (2000)[54] J K Becker P L Biermann and W Rhode Astropart

Phys 23 355 (2005)


122005-16

Search for ultrahigh energy neutrinos in highly inclined events at the Pierre Auger Observatory

P Abreu1 M Aglietta2 M Ahlers3 E J Ahn4 I FM Albuquerque5 D Allard6 I Allekotte7 J Allen8 P Allison9

A Almela1011 J Alvarez Castillo12 J Alvarez-Muniz13 M Ambrosio14 A Aminaei15 L Anchordoqui16 S Andringa1

T Anticic17 C Aramo14 E Arganda1819 F Arqueros19 H Asorey7 P Assis1 J Aublin20 M Ave21 M Avenier22

G Avila23 T Backer24 AM Badescu25 M Balzer26 K B Barber27 A F Barbosa28 R Bardenet29 S L C Barroso30

B Baughman9dagger J Bauml31 J J Beatty9 B R Becker32 K H Becker33 A Belletoile34 J A Bellido27 S BenZvi3

C Berat22 X Bertou7 P L Biermann35 P Billoir20 F Blanco19 M Blanco36 C Bleve33 H Blumer2131 M Bohacova37

D Boncioli38 C Bonifazi3920 R Bonino2 N Borodai40 J Brack41 I Brancus42 P Brogueira1 W C Brown43

R Bruijn44Dagger P Buchholz24 A Bueno45 R E Burton46 K S Caballero-Mora47 B Caccianiga48 L Caramete35

R Caruso49 A Castellina2 O Catalano50 G Cataldi51 L Cazon1 R Cester52 J Chauvin22 S H Cheng47

A Chiavassa2 J A Chinellato53 J Chirinos Diaz54 J Chudoba37 RW Clay27 MR Coluccia51 R Conceicao1

F Contreras55 H Cook44 M J Cooper27 J Coppens1556 A Cordier29 S Coutu47 C E Covault46 A Creusot6

A Criss47 J Cronin57 A Curutiu35 S Dagoret-Campagne29 R Dallier34 S Dasso5859 K Daumiller31 B R Dawson27

RM de Almeida60 M De Domenico49 C De Donato12 S J de Jong1556 G De La Vega61 W JM de Mello Jr53

J R T de Mello Neto39 I De Mitri51 V de Souza62 KD de Vries63 L del Peral36 M del Rıo3855 O Deligny64

H Dembinski21 N Dhital54 C Di Giulio65 M L Dıaz Castro66 P N Diep67 F Diogo1 C Dobrigkeit53 W Docters63

J C DrsquoOlivo12 P N Dong6764 A Dorofeev41 J C dos Anjos28 M T Dova18 D DrsquoUrso14 I Dutan35 J Ebr37

R Engel31 M Erdmann68 C O Escobar453 J Espadanal1 A Etchegoyen1110 P Facal San Luis57 I Fajardo Tapia12

H Falcke1569 G Farrar8 A C Fauth53 N Fazzini4 A P Ferguson46 B Fick54 A Filevich11 A Filipcic7071

S Fliescher68 C E Fracchiolla41 E D Fraenkel63 O Fratu25 U Frohlich24 B Fuchs28 R Gaior20 R F Gamarra11

S Gambetta72 B Garcıa61 S T Garcia Roca13 D Garcia-Gamez29 D Garcia-Pinto19 A Gascon45 H Gemmeke26

P L Ghia20 U Giaccari51 M Giller73 H Glass4 M S Gold32 G Golup7 F Gomez Albarracin18 M Gomez Berisso7

P F Gomez Vitale23 P Goncalves1 D Gonzalez21 J G Gonzalez31 B Gookin41 A Gorgi2 P Gouffon5 E Grashorn9

S Grebe1556 N Griffith9 M Grigat68 A F Grillo74 Y Guardincerri59 F Guarino14 G P Guedes75 A Guzman12

P Hansen18 D Harari7 S Harmsma6356 T A Harrison27 J L Harton41 A Haungs31 T Hebbeker68 D Heck31

A E Herve27 C Hojvat4 N Hollon57 V C Holmes27 P Homola40 J R Horandel15 A Horneffer15 P Horvath76

M Hrabovsky7637 D Huber21 T Huege31 A Insolia49 F Ionita57 A Italiano49 C Jarne18 S Jiraskova15

M Josebachuili11 K Kadija17 K H Kampert33 P Karhan77 P Kasper4 B Kegl29 B Keilhauer31 A Keivani78

J L Kelley15 E Kemp53 RM Kieckhafer54 HO Klages31 M Kleifges26 J Kleinfeller5531 J Knapp44

D-H Koang22 K Kotera57 N Krohm33 O Kromer26 D Kruppke-Hansen33 F Kuehn4 D Kuempel2433

J K Kulbartz79 N Kunka26 G La Rosa50 C Lachaud6 R Lauer32 P Lautridou34 S Le Coz22 M S A B Leao80

D Lebrun22 P Lebrun4 MA Leigui de Oliveira80 A Letessier-Selvon20 I Lhenry-Yvon64 K Link21 R Lopez81

A Lopez Aguera13 K Louedec2229 J Lozano Bahilo45 L Lu44 A Lucero11 M Ludwig21 H Lyberis64 C Macolino20

S Maldera2 D Mandat37 P Mantsch4 AG Mariazzi18 J Marin552 V Marin34 I C Maris20 H R Marquez Falcon82

G Marsella83 D Martello51 L Martin34 H Martinez84 O Martınez Bravo81 H J Mathes31 J Matthews7885

J A J Matthews32 G Matthiae38 D Maurel31 D Maurizio52 P O Mazur4 G Medina-Tanco12 M Melissas21

D Melo11 E Menichetti52 A Menshikov26 P Mertsch86 C Meurer68 S Micanovic17 M I Micheletti87

L Miramonti48 L Molina-Bueno45 S Mollerach7 M Monasor57 D Monnier Ragaigne29 F Montanet22 B Morales12

C Morello2 E Moreno81 J C Moreno18 M Mostafa41 CA Moura80 MA Muller53 G Muller68 M Munchmeyer20

R Mussa52 G Navarra2 J L Navarro45 S Navas45 P Necesal37 L Nellen12 A Nelles1556 J Neuser33 D Newton44

P T Nhung67 M Niechciol24 L Niemietz33 N Nierstenhoefer33 D Nitz54 D Nosek77 L Nozka37 M Nyklicek37

J Oehlschlager31 A Olinto57 M Ortiz19 N Pacheco36 D Pakk Selmi-Dei53 M Palatka37 J Pallotta88 N Palmieri21

G Parente13 E Parizot6 A Parra13 S Pastor89 T Paul90 M Pech37 J Pekala40 R Pelayo8113 IM Pepe91

L Perrone83 R Pesce72 E Petermann92 S Petrera65 P Petrinca38 A Petrolini72 Y Petrov41 C Pfendner3 R Piegaia59

T Pierog31 P Pieroni59 M Pimenta1 V Pirronello49 M Platino11 V H Ponce7 M Pontz24 A Porcelli31 P Privitera57

M Prouza37 E J Quel88 S Querchfeld33 J Rautenberg33 O Ravel34 D Ravignani11 B Revenu34 J Ridky37

S Riggi13 M Risse24 P Ristori88 H Rivera48 V Rizi65 J Roberts8 W Rodrigues de Carvalho13 G Rodriguez13

J Rodriguez Martino55 J Rodriguez Rojo55 I Rodriguez-Cabo13 MD Rodrıguez-Frıas36 G Ros36 J Rosado19

T Rossler76 M Roth31 B Rouille-drsquoOrfeuil57 E Roulet7 A C Rovero58 C Ruhle26 A Saftoiu42 F Salamida64

H Salazar81 F Salesa Greus41 G Salina38 F Sanchez11 C E Santo1 E Santos1 EM Santos39 F Sarazin93

PHYSICAL REVIEW D 84 122005 (2011)

1550-7998=2011=84(12)=122005(16) 122005-1 2011 American Physical Society





































122005-2































Deceased


122005-3













INTRODUCTION











122005-4













The trigger















122005-5







Detector simulation







122005-6












122005-7






)1

(AoP10

Log

-02 0 02 04 06 08 1 12

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data


(AOP10

Log

0 05 1 15 2 25 3

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data




122005-8






Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6



122005-9











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16





































122005-2































Deceased


122005-3













INTRODUCTION











122005-4













The trigger















122005-5







Detector simulation







122005-6












122005-7






)1

(AoP10

Log

-02 0 02 04 06 08 1 12

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data


(AOP10

Log

0 05 1 15 2 25 3

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data




122005-8






Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6



122005-9











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16































Deceased


122005-3













INTRODUCTION











122005-4













The trigger















122005-5







Detector simulation







122005-6












122005-7






)1

(AoP10

Log

-02 0 02 04 06 08 1 12

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data


(AOP10

Log

0 05 1 15 2 25 3

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data




122005-8






Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6



122005-9











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16













INTRODUCTION











122005-4













The trigger















122005-5







Detector simulation







122005-6












122005-7






)1

(AoP10

Log

-02 0 02 04 06 08 1 12

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data


(AOP10

Log

0 05 1 15 2 25 3

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data




122005-8






Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6



122005-9











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16













The trigger















122005-5







Detector simulation







122005-6












122005-7






)1

(AoP10

Log

-02 0 02 04 06 08 1 12

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data


(AOP10

Log

0 05 1 15 2 25 3

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data




122005-8






Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6



122005-9











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16







Detector simulation







122005-6












122005-7






)1

(AoP10

Log

-02 0 02 04 06 08 1 12

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data


(AOP10

Log

0 05 1 15 2 25 3

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data




122005-8






Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6



122005-9











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16












122005-7






)1

(AoP10

Log

-02 0 02 04 06 08 1 12

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data


(AOP10

Log

0 05 1 15 2 25 3

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data




122005-8






Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6



122005-9











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16






)1

(AoP10

Log

-02 0 02 04 06 08 1 12

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data


(AOP10

Log

0 05 1 15 2 25 3

Eve

nts

-410

-310

-210

-110

1

simulationsνMC

Training data




122005-8






Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6



122005-9











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16






Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

32 305σ3

7 82σ4

1 22σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

34 336σ3

9 90σ4

2 24σ5

0 06σ6


Eve

nts

-110

1

10

210


20 yrs

100 yrs



Eve

nts

-110

1

10

210

310


RealPred

16 120σ3

6 36σ4

1 11σ5

0 03σ6



122005-9











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16











122005-10













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16













effethE tTHORNm

dt (3)




]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Trigger Efficiency




energy [eV]ν

1710 1810 1910 2010

s s

r]2

Exp

osu

re [

cm

1110

1210

1310

1410

1510

1610

1710

TotalCC e

microCCτCC

NC x MountainsτCC




1675 435 1021 527 1020 182 1021 211 1020 -

17 127 1022 316 1021 109 1022 126 1021 -

175 794 1022 234 1022 602 1022 937 1021 198 102218 217 1023 801 1022 177 1023 320 1022 121 1023185 395 1023 171 1023 284 1023 684 1022 251 102319 544 1023 256 1023 358 1023 103 1023 313 1023195 632 1023 299 1023 436 1023 120 1023 306 102320 729 1023 345 1023 519 1023 138 1023 282 1023


122005-11










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16










]-2Slant Depth [g cm0 500 1000 1500 2000 2500

Eff

icie

ncy

0

01

02

03

04

05

06

07

08

09

1


Ground


Selection HERWIGν

Selection PYTHIAν




(A) (B)

RB

RA

ethRBthorn

RATHORN=2


HERWIG++ [41] -7




SIBYLL [45] -2


SIBYLL (E=3 EeV) -2

SIBYLL (=85) 0

SIBYLL (=89) +4

Thinning 106 107 +7


122005-12




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16




Topography








Channel CC NC Total

e 33 5 38

13 5 18

air 24 5 29

mountains 15 15

Total 85 15 100


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno


Eve

nts

-110

1

10

210

310


candidatesνno



122005-13





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16





Emin








Model predictions



energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


AMANDA 08

IceCube40

RICE06

τHiRes e +

ANITA II 2010

Auger 2 yrτUpgoing

(ICRC 2009)

Auger 2 yrDowngoing


energy [eV]ν

1710 1810 1910 2010 2110 2210

]-1

sr

-1 s

-2 [

GeV

cm

Φ2

E

-810

-710

-610


Auger 2 yrDowngoing

GZK-Fermi

GZK-evolFRII

Auger 2 yrτUpgoing




122005-14


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16


ACKNOWLEDGMENTS

















GZK-Fermi 01 09

GZK-evolFRII 03 07

MPR-max 20 01

BBR 08 04

TD-Necklaces 08 04

Z-Burst 78 4 104


122005-15



















(2008)

















Phys 23 355 (2005)


122005-16



















(2008)

















Phys 23 355 (2005)


122005-16

published version - core

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