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Measurement of the cosmic ray composition at the knee with the SPASE-2/AMANDA-B10 detectors |
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| Institution: | a Institute of Physics, University of Mainz, Staudinger Weg 7, D-55099, Mainz, Germany b DESY-Zeuthen, D-15735, Zeuthen, Germany c Department of Physics, University of Wisconsin, Madison, WI 53706, USA d Bartol Research Institute, University of Delaware, Newark, DE 19716, USA e Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA f Department of Physics, University of California, Berkeley, CA 94720, USA g Fachbereich 8 Physik, BUGH Wuppertal, D-42097, Wuppertal, Germany h Université Libre de Bruxelles, Science Faculty CP230, Boulevard du Triomphe, B-1050, Brussels, Belgium i Division of High Energy Physics, Uppsala University, S-75121, Uppsala, Sweden j Department of Physics, Stockholm University, SCFAB, SE-10691, Stockholm, Sweden k Department of Technology, Kalmar University, S-39182, Kalmar, Sweden l Université de Mons-Hainaut, 19 Avenue Maistriau 7000, Mons, Belgium m Department of Physics, Pennsylvania State University, University Park, PA 16802, USA n School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK o Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA p Vrije Universiteit Brussel, Dienst ELEM, B-1050, Brussel, Belgium q Imperial College, London SW7 2AZ, UK r Department of Physics, University of Wisconsin, River Falls, WI 54022, USA s Departamento de Física, Universidad Simon Bolívar, Apdo. Postal 89000, Caracas, Venezuela |
| Abstract: | The mass composition of high-energy cosmic rays at energies above 1015 eV can provide crucial information for the understanding of their origin. Air showers were measured simultaneously with the SPASE-2 air shower array and the AMANDA-B10 Cherenkov telescope at the South Pole. This combination has the advantage to sample almost all high-energy shower muons and is thus a new approach to the determination of the cosmic ray composition. The change in the cosmic ray mass composition was measured versus existing data from direct measurements at low energies. Our data show an increase of the mean log atomic mass  lnA by about 0.8 between 500 TeV and 5 PeV. This trend of an increasing mass through the “knee” region is robust against a variety of systematic effects. |
| Keywords: | Cosmic Rays Neutrino astronomy Mass composition |
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