FRACTAL STRUCTURE OF COSMIC-RAY INTENSITY VARIATIONS

Time series of cosmic ray (CR) intensity recorded at a low cut-off rig idity neutron monitor, Calgary (CA), are checked for scaling propertie s. Three years of 5-min data from CA and ten days of 10-sec measuremen ts at Lomnicky stit (LS) are analyzed. Power spectrum analysis, and tw o methods of checking fractality, namely the yardstick length method a nd the method of scaling exponent, are applied to the 2(14) data point s. As compared to CRs at higher energies, the examined data have a mor e complicated scaling structure, affected by disturbances in the helio sphere. Regions, where fractal description is appropriate, are 30 - 30 0 hours and 40 min - 8 hours. While the 40-minute limit is probably th e signature of a vanishing effect of interplanetary magnetic held (IMF ) on CRs, the other limits are due to diurnal and 27 day variations. S caling of the higher moments of CR time series involves the signature of multifractality. However, the present statistical significance is n ot sufficient for a detailed investigation of this problem.