First observation of PeV-energy neutrinos with IceCube
ArXiv 1304.5356 (2013)
Authors:
IceCube Collaboration, MG Aartsen, R Abbasi, Y Abdou, M Ackermann, J Adams, JA Aguilar, M Ahlers, D Altmann, J Auffenberg, X Bai, M Baker, SW Barwick, V Baum, R Bay, JJ Beatty, S Bechet, J Becker Tjus, K-H Becker, M Bell, ML Benabderrahmane, S BenZvi, J Berdermann, P Berghaus, D Berley, E Bernardini, A Bernhard, D Bertrand, DZ Besson, G Binder, D Bindig, M Bissok, E Blaufuss, J Blumenthal, DJ Boersma, S Bohaichuk, C Bohm, D Bose, S Böser, O Botner, L Brayeur, H-P Bretz, AM Brown, R Bruijn, J Brunner, M Carson, J Casey, M Casier, D Chirkin, A Christov, B Christy, K Clark, F Clevermann, S Coenders, S Cohen, DF Cowen, AH Cruz Silva, M Danninger, J Daughhetee, JC Davis, C De Clercq, S De Ridder, P Desiati, M de With, T DeYoung, JC Díaz-Vélez, M Dunkman, R Eagan, B Eberhardt, J Eisch, RW Ellsworth, S Euler, PA Evenson, O Fadiran, AR Fazely, A Fedynitch, J Feintzeig, T Feusels, K Filimonov, C Finley, T Fischer-Wasels, S Flis, A Franckowiak, R Franke, K Frantzen, T Fuchs, TK Gaisser, J Gallagher, L Gerhardt, L Gladstone, T Glüsenkamp, A Goldschmidt, G Golup, JG Gonzalez, JA Goodman, D Góra, D Grant, A Groß, M Gurtner, C Ha, A Haj Ismail, P Hallen, A Hallgren, F Halzen, K Hanson, D Heereman, D Heinen, K Helbing, R Hellauer, S Hickford, GC Hill, KD Hoffman, R Hoffmann, A Homeier, K Hoshina, W Huelsnitz, PO Hulth, K Hultqvist, S Hussain, A Ishihara, E Jacobi, J Jacobsen, K Jagielski, GS Japaridze, K Jero, O Jlelati, B Kaminsky, A Kappes, T Karg, A Karle, JL Kelley, J Kiryluk, F Kislat, J Kläs, SR Klein, J-H Köhne, G Kohnen, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, M Kowalski, M Krasberg, K Krings, G Kroll, J Kunnen, N Kurahashi, T Kuwabara, M Labare, H Landsman, MJ Larson, M Lesiak-Bzdak, M Leuermann, J Leute, J Lünemann, J Madsen, R Maruyama, K Mase, HS Matis, F McNally, K Meagher, M Merck, P Mészáros, T Meures, S Miarecki, E Middell, N Milke, J Miller, L Mohrmann, T Montaruli, R Morse, R Nahnhauer, U Naumann, H Niederhausen, SC Nowicki, DR Nygren, A Obertacke, S Odrowski, A Olivas, M Olivo, A O'Murchadha, L Paul, JA Pepper, C Pérez de los Heros, C Pfendner, D Pieloth, E Pinat, N Pirk, J Posselt, PB Price, GT Przybylski, L Rädel, M Rameez, K Rawlins, P Redl, R Reimann, E Resconi, W Rhode, M Ribordy, M Richman, B Riedel, JP Rodrigues, C Rott, T Ruhe, B Ruzybayev, D Ryckbosch, SM Saba, T Salameh, H-G Sander, M Santander, S Sarkar, K Schatto, M Scheel, F Scheriau, T Schmidt, M Schmitz, S Schoenen, S Schöneberg, A Schönwald, A Schukraft, L Schulte, O Schulz, D Seckel, Y Sestayo, S Seunarine, C Sheremata, MWE Smith, M Soiron, D Soldin, GM Spiczak, C Spiering, M Stamatikos, T Stanev, A Stasik, T Stezelberger, RG Stokstad, A Stößl, EA Strahler, R Ström, GW Sullivan, H Taavola, I Taboada, A Tamburro, S Ter-Antonyan, G Tešić, S Tilav, PA Toale, S Toscano, M Usner, D van der Drift, N van Eijndhoven, A Van Overloop, J van Santen, M Vehring, M Voge, M Vraeghe, C Walck, T Waldenmaier, M Wallraff, R Wasserman, Ch Weaver, M Wellons, C Wendt, S Westerhoff, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, H Wissing, M Wolf, TR Wood, K Woschnagg, C Xu, DL Xu, XW Xu, JP Yanez, G Yodh, S Yoshida, P Zarzhitsky, J Ziemann, S Zierke, A Zilles, M Zoll
Abstract:
We report on the observation of two neutrino-induced events which have an
estimated deposited energy in the IceCube detector of 1.04 $\pm$ 0.16 and 1.14
$\pm$ 0.17 PeV, respectively, the highest neutrino energies observed so far.
These events are consistent with fully contained particle showers induced by
neutral-current $\nu_{e,\mu,\tau}$ ($\bar\nu_{e,\mu,\tau}$) or charged-current
$\nu_{e}$ ($\bar\nu_{e}$) interactions within the IceCube detector. The events
were discovered in a search for ultra-high energy neutrinos using data
corresponding to 615.9 days effective livetime. The expected number of
atmospheric background is $0.082 \pm 0.004 \text{(stat)}^{+0.041}_{-0.057}
\text{(syst)}$. The probability to observe two or more candidate events under
the atmospheric background-only hypothesis is $2.9\times10^{-3}$ ($2.8\sigma$)
taking into account the uncertainty on the expected number of background
events. These two events could be a first indication of an astrophysical
neutrino flux, the moderate significance, however, does not permit a definitive
conclusion at this time.
