Aurelio Bay, Yifei Guo, Ji Hyun Kim, Yu Lei, Zhen Liu, Werner Lustermann, Eduardo Sanchez, Liang Sun, Horst Vogel, Qian Wang, Zheng Wang, Rui Wang, Xiao Wang, Matthias Weber, Zhirui Xu, Jian Zhao
Context. Primary cosmic rays experience multiple deflections in the non-uniform galactic and heliospheric magnetic fields which may generate anisotropies. Aims. A study of anisotropies in the energy range between 100 and 500 GeV is performed. This energy range is not yet well explored.Methods. The L3 detector at the CERN electron-positron collider, LEP, is used for a study of the angular distribution of atmospheric muons with energies above 20 GeV. This distribution is used to investigate the isotropy of the time-dependent intensity of the primary cosmic-ray flux with a Fourier analysis.Results. A small deviation from isotropy at energies around 200 GeV is observed for the second harmonics at the solar frequency. No sidereal anisotropy is found at a level above . The measurements were performed in the years 1999 and 2000. . © 2008 ESO.
2008