Study of the solar anisotropy of cosmic ray primaries of about 200 GeV energy with the L3+C muon detector
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 10-4. The measurements were performed in the years 1999 and 2000.
Additional Information© 2008 ESO. Article published by EDP Sciences. Received 22 February 2008; Accepted 3 June 2008; Published online 09 July 2008. The L3 collaboration would like to thank CERN for the support given to this experiment, and express in particular its gratitude to the crew operating at LEP point 2 for the successful installation of the additional hardware needed for L3+C.
Published - aa09634-08.pdf