Eur. Phys. J. C (2015) 75: 116
https://doi.org/10.1140/epjc/s10052-015-3330-z

Regular Article - Experimental Physics

Development of a general analysis and unfolding scheme and its application to measure the energy spectrum of atmospheric neutrinos with IceCube

IceCube Collaboration

¹ III. Physikalisches Institut, RWTH Aachen University, 52056, Aachen, Germany
² School of Chemistry and Physics, University of Adelaide, Adelaide, SA, 5005, Australia
³ Department of Physics and Astronomy, University of Alaska Anchorage, 3211 Providence Dr., Anchorage, AK, 99508, USA
⁴ CTSPS, Clark-Atlanta University, Atlanta, GA, 30314, USA
⁵ School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
⁶ Department of Physics, Southern University, Baton Rouge, LA, 70813, USA
⁷ Department of Physics, University of California, Berkeley, CA, 94720, USA
⁸ Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
⁹ Institut für Physik, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
¹⁰ Fakultät für Physik & Astronomie, Ruhr-Universität Bochum, 44780, Bochum, Germany
¹¹ Physikalisches Institut, Universität Bonn, Nussallee 12, 53115, Bonn, Germany
¹² Université Libre de Bruxelles, Science Faculty CP230, 1050, Brussels, Belgium
¹³ Vrije Universiteit Brussel, Dienst ELEM, 1050, Brussels, Belgium
¹⁴ Department of Physics, Chiba University, Chiba, 263-8522, Japan
¹⁵ Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
¹⁶ Department of Physics, University of Maryland, College Park, MD, 20742, USA
¹⁷ Department of Physics and Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH, 43210, USA
¹⁸ Department of Astronomy, Ohio State University, Columbus, OH, 43210, USA
¹⁹ Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark
²⁰ Department of Physics, TU Dortmund University, 44221, Dortmund, Germany
²¹ Department of Computer Science, TU Dortmund University, 44221, Dortmund, Germany
²² Department of Physics, University of Alberta, Edmonton, AB, T6G 2E1, Canada
²³ Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058, Erlangen, Germany
²⁴ Département de physique nucléaire et corpusculaire, Université de Genève, 1211, Geneva, Switzerland
²⁵ Department of Physics and Astronomy, University of Gent, 9000, Ghent, Belgium
²⁶ Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
²⁷ Department of Physics and Astronomy, University of Kansas, Lawrence, KS, 66045, USA
²⁸ Department of Astronomy, University of Wisconsin, Madison, WI, 53706, USA
²⁹ Department of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin, Madison, WI, 53706, USA
³⁰ Institute of Physics, University of Mainz, Staudinger Weg 7, 55099, Mainz, Germany
³¹ Université de Mons, 7000, Mons, Belgium
³² Technische Universität München, 85748, Garching, Germany
³³ Department of Physics and Astronomy, Bartol Research Institute, University of Delaware, Newark, DE, 19716, USA
³⁴ Department of Physics, University of Oxford, 1 Keble Road, Oxford, OX1 3NP, UK
³⁵ Physics Department, South Dakota School of Mines and Technology, Rapid City, SD, 57701, USA
³⁶ Department of Physics, University of Wisconsin, River Falls, WI, 54022, USA
³⁷ Department of Physics, Oskar Klein Centre, Stockholm University, 10691, Stockholm, Sweden
³⁸ Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY, 11794-3800, USA
³⁹ Department of Physics, Sungkyunkwan University, Suwon, 440-746, Korea
⁴⁰ Department of Physics, University of Toronto, Toronto, ON, M5S 1A7, Canada
⁴¹ Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL, 35487, USA
⁴² Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA, 16802, USA
⁴³ Department of Physics, Pennsylvania State University, University Park, PA, 16802, USA
⁴⁴ Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden
⁴⁵ Department of Physics, University of Wuppertal, 42119, Wuppertal, Germany
⁴⁶ DESY, 15735, Zeuthen, Germany

^* e-mail: tim.ruhe@udo.edu

Received: 15 September 2014
Accepted: 19 February 2015
Published online: 11 March 2015

Abstract

We present the development and application of a generic analysis scheme for the measurement of neutrino spectra with the IceCube detector. This scheme is based on regularized unfolding, preceded by an event selection which uses a Minimum Redundancy Maximum Relevance algorithm to select the relevant variables and a random forest for the classification of events. The analysis has been developed using IceCube data from the 59-string configuration of the detector. 27,771 neutrino candidates were detected in 346 days of livetime. A rejection of 99.9999 % of the atmospheric muon background is achieved. The energy spectrum of the atmospheric neutrino flux is obtained using the TRUEE unfolding program. The unfolded spectrum of atmospheric muon neutrinos covers an energy range from 100 GeV to 1 PeV. Compared to the previous measurement using the detector in the 40-string configuration, the analysis presented here, extends the upper end of the atmospheric neutrino spectrum by more than a factor of two, reaching an energy region that has not been previously accessed by spectral measurements.