Power Spectral Analysis of Cosmic Ray Time Series Data over a Wide Rigidity Range.

Abstract

Power spectra and fractal dimensions have been determined for cosmic ray data obtained from the Mt. Norikura air shower experiment between 1972 and 1987, and from the Matsushiro underground station (220 m.w.e) for the years 1985-1991. The power law indices for Matsushiro and Mt. Norikura are found to be similar to each other, and it is confirmed that these values (-1.0) are low compared to those (-5/3) for neutron monitors and for muon telescopes at shallower underground stations. The power spectrum of the Matsushiro data breaks at about 2.5 uHz, corresponding to a period of about five days. These results may give information on magnetic field fluctuations in inter-stellar space in the vicinity of the heliosphere.