Infoscience

Journal article

Study of the solar anisotropy of cosmic ray primaries of about 200 GeV energy with the L3+C muon detector

Achard, P.; Adriani, O.; Aguilar-Benitez, M.; Van Den Akker, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.

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.

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