Near 13.5-day periodicity in Muon Detector data during late 2001 and early 2002

Abstract

In this study we perform a continuous Morlet Wavelet transform method in time series of secondary cosmic rays and 1 AU interplanetary medium parameters for the interval from October 2001 to October 2002. The approximately 13.5-day periodicity was obtained during the late 2001, and it was remarkable for muon data. Even though some works have pointed out that the main activations of the 13.5-day recurrence in near-Earth solar wind are related, e.g., with the heliosheet crossings or to the occurrence at 1 AU of two high speed streams approximately 180 o apart in solar longitude per solar rotation, we aim to show that the period of about half the solar rotation during the end months of 2001 present in muon time series was apparently due to the occurrence of non-recurrent interplanetary disturbances. The interconnections among successive Forbush decreases, recovery phases and gradual muon depressions (associated with corotating interaction regions) seem to play an important role in such 13.5-day periodicity.

Correlations Between Secondary Cosmic Ray Rates and Strong Electric Fields at Lomnický štít

“…The diurnal and semidiurnal modulation is clearly visible. At lower frequencies the pronounced peak is at ~13.7 day (close to that observed in muons, e.g, by Vieira et al, ) and possibly the ~27 day, one of interplanetary/solar origin. To eliminate those quasiperiodicities and to extract short time increases, we have used the high‐pass fast Fourier transform (FFT) filter with the cutoff frequency 2.5 × 10 −5 Hz (corresponding to elimination also the second harmonic of the diurnal wave).…”

Evidence of Energy and Charge Sign Dependence of the Recovery Time for the 2006 December Forbush Event Measured by the PAMELA Experiment

“…This extends and completes studies based on other measurements, typically performed on the ground, either by neutron monitors or muon telescopes (e.g. Vieira et al (2012); Usoskin et al (2008)). The performance of these ground-based detectors is limited since they can only determine an integral flux above an energy threshold that depends on the latitudinal geomagnetic cutoff at the location of the monitor.…”

Temperature effect correction for the cosmic ray muon data observed at the Brazilian Southern Space Observatory in São Martinho da Serra

“…We use hourly muon count rates in 17 directional channels for each detector after correcting for the atmospheric pressure effect, as explained in [7]. In order to minimize influences from solarinterplanetary related phenomena, we select the year of 2008 which is within the last minimum solar activity period.…”