IceCube collaboration, M. G. Aartsen, R. Abbasi, Y. Abdou, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, D. Altmann, K. Andeen, J. Auffenberg, X. Bai, M. Baker, S. W. Barwick, V. Baum, R. Bay, K. Beattie, J. J. Beatty, S. Bechet, J. Becker Tjus, K. -H. Becker, M. Bell, M. L. Benabderrahmane, S. BenZvi, J. Berdermann, P. Berghaus, D. Berley, E. Bernardini, D. Bertrand, D. Z. Besson, D. Bindig, M. Bissok, E. Blaufuss, J. Blumenthal, D. J. Boersma, S. Bohaichuk, C. Bohm, D. Bose1, S. Böser, O. Botner, L. Brayeur, A. M. Brown, R. Bruijn, J. Brunner, S. Buitink, M. Carson, J. Casey, M. Casier, D. Chirkin, B. Christy, K. Clark, F. Clevermann, S. Cohen, D. F. Cowen, A. H. Cruz Silva, M. Danninger, J. Daughhetee, J. C. Davis, C. De Clercq, S. De Ridder, F. Descamps, P. Desiati, G. de Vries-Uiterweerd, T. DeYoung, J. C. Díaz-Vélez, J. Dreyer, J. P. Dumm, M. Dunkman, R. Eagan, B. Eberhardt, J. Eisch, R. W. Ellsworth, O. Engdegård, S. Euler, P. A. Evenson, O. Fadiran, A. R. Fazely, A. Fedynitch, J. Feintzeig, T. Feusels, K. Filimonov, C. Finley, T. Fischer-Wasels, S. Flis, A. Franckowiak, R. Franke, K. Frantzen, T. Fuchs, T. K. Gaisser, J. Gallagher, L. Gerhardt, L. Gladstone, T. Glüsenkamp, A. Goldschmidt, G. Golup, J. A. Goodman, D. Góra, D. Grant, A. Groß, S. Grullon, M. Gurtner, C. Ha, A. Haj Ismail, A. Hallgren, F. Halzen, K. Hanson, D. Heereman, P. Heimann, D. Heinen, K. Helbing, R. Hellauer, S. Hickford, G. C. Hill, K. D. Hoffman, R. Hoffmann, A. Homeier, K. Hoshina, W. Huelsnitz, P. O. Hulth, K. Hultqvist, S. Hussain, A. Ishihara, E. Jacobi, J. Jacobsen, G. S. Japaridze, O. Jlelati, A. Kappes, T. Karg, A. Karle, J. Kiryluk, F. Kislat, J. Kläs, S. R. Klein, J. -H. Köhne, G. Kohnen, H. Kolanoski, L. Köpke, C. Kopper, S. Kopper, D. J. Koskinen, M. Kowalski, M. Krasberg, G. Kroll, J. Kunnen, N. Kurahashi, T. Kuwabara, M. Labare, H. Landsman, M. J. Larson, R. Lauer, M. Lesiak-Bzdak, J. Lünemann, J. Madsen, R. Maruyama, K. Mase, H. S. 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, S. C. Nowicki, D. R. Nygren, A. Obertacke, S. Odrowski, A. Olivas, M. Olivo, A. O'Murchadha, S. Panknin, L. Paul, J. A. Pepper, C. Pérez de los Heros, D. Pieloth, N. Pirk, J. Posselt, P. B. Price, G. T. Przybylski, L. Rädel, K. Rawlins, P. Redl, E. Resconi, W. Rhode, M. Ribordy, M. Richman, B. Riedel, J. P. Rodrigues, C. Rott, T. Ruhe, B. Ruzybayev, D. Ryckbosch, S. M. Saba, T. Salameh, H. -G. Sander, M. Santander, S. Sarkar, K. Schatto, M. Scheel, F. Scheriau, T. Schmidt, M. Schmitz, S. Schoenen, S. Schöneberg, L. Schönherr, A. Schönwald, A. Schukraft, L. Schulte, O. Schulz, D. Seckel, S. H. Seo, Y. Sestayo, S. Seunarine, C. Sheremata, M. W. E. Smith, M. Soiron, D. Soldin, G. M. Spiczak, C. Spiering, M. Stamatikos, T. Stanev, A. Stasik, T. Stezelberger, R. G. Stokstad, A. Stöß, E. A. Strahler, R. Ström, G. W. Sullivan, H. Taavola, I. Taboada, A. Tamburro, S. Ter-Antonyan, S. Tilav, P. A. Toale, S. Toscano, M. Usner, D. van der Drift, N. van Eijndhoven, A. Van Overloop, J. van Santen, M. Vehring, M. Voge1, M. Vraeghe, C. Walck, T. Waldenmaier, M. Wallraff, M. Walter, R. Wasserman, Ch. Weaver, C. Wendt, S. Westerhoff, N. Whitehorn, K. Wiebe, C. H. Wiebusch, D. R. Williams, H. Wissing, M. Wolf, T. R. Wood, K. Woschnagg, C. Xu, D. L. Xu, X. W. Xu, J. P. Yanez, G. Yodh, S. Yoshida, P. Zarzhitsky, J. Ziemann, S. Zierke, A. Zilles, M. Zoll
Gamma-ray induced air showers are notable for their lack of muons, compared to hadronic showers. Hence, air shower arrays with large underground muon detectors can select a sample greatly enriched in photon showers by rejecting showers containing muons. IceCube is sensitive to muons with energies above ~500 GeV at the surface, which provides an efficient veto system for hadronic air showers with energies above 1 PeV. One year of data from the 40-string IceCube configuration was used to perform a search for point sources and a Galactic diffuse signal. No sources were found, resulting in a 90% C.L. upper limit on the ratio of gamma rays to cosmic rays of 1.2 x 10^(-3)for the flux coming from the Galactic Plane region (-80 deg < l < -30 deg; -10 deg < b < 5 deg) in the energy range 1.2 - 6.0 PeV. In the same energy range, point source fluxes with E^(-2) spectra have been excluded at a level of (E/TeV)^2 d\Phi/dE ~ 10^(-12)-10^(-11) cm^2/s/TeV depending on source declination. The complete IceCube detector will have a better sensitivity, due to the larger detector size, improved reconstruction and vetoing techniques. Preliminary data from the nearly-final IceCube detector configuration has been used to estimate the 5 year sensitivity of the full detector. It is found to be more than an order of magnitude better, allowing the search for PeV extensions of known TeV gamma-ray emitters.
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http://arxiv.org/abs/1210.7992
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