Modulation of cosmic rays at different cutoff rigidity

Abstract

The present work deals with the study of first three harmonics of cosmic ray intensity on geo-magnetically quiet days over the period [1981][1982][1983][1984][1985][1986][1987][1988][1989][1990][1991][1992][1993] for Deep River and Inuvik neutron monitoring stations having mid and low cutoff rigidity. The amplitude of first harmonic remains high for Deep River having mid cutoff rigidity as compared to Inuvik neutron monitor having low cutoff rigidity on quiet days. The diurnal amplitude significantly decreases and phase shifts towards an earlier time during solar activity minimum years at both Deep River and Inuvik. The amplitude of second harmonic significantly enhanced during solar activity minimum as well as maximum at Deep River and remains low during solar activity maximum at Inuvik, whereas the phase shifts towards an earlier time during solar maximum for both the stations. The amplitude of the third harmonic significantly enhanced during solar activity minimum at Deep River and on solar activity minimum at Inuvik, whereas the phase does not show any significant characteristics and fluctuates quite frequently. The amplitude of semi/tri-diurnal anisotropy has a good positive correlation, while the others (i.e. amplitude and phase) have very weak correlation with solar wind velocity on quiet days at Deep River station during 1981-1993. The solar wind velocity significantly remains in the range 350 to 425 km/s i.e. being nearly average on quiet days. The amplitude and direction of the anisotropy on quiet days are weakly dependent on high-speed solar wind streams for two neutron monitoring station of mid and low cutoff rigidity threshold. The amplitude as well as direction of second harmonic has a good anti-correlation with IMF Bz and the product V x Bz on quiet days at Deep River station. However, the direction of second and third harmonic has a good anti-correlation with IMF Bz and the product V x Bz on quiet days at Inuvik station.

Response of dielectric behavior and magnetoelectric effect in ferroelectric rich (x) Ni0.9Zn0.1Fe2O4+(1−x)PZT ME composites

“…Hence (dE/dH) H decreases as the dc magnetic field is increased. The decrease in (dE/dH) H may be attributed to the low resistivity of ferrite phase as compared to the ferroelectric phase resulting in the leakage of charges developed in the piezoelectric grains through the low resistance path of the surrounding ferrite grains [9,15]. The maximum value of ME voltage coefficient is observed for the composite with x = 0.15.…”

“…As a result dielectric polarization increases causing an increase in dielectric constant and tan δ. Due to decrease of random vibrational motion of ions and electrons after the Curie temperature, the dielectric constant decreases after passing through the it [15].…”

Investigation of diurnal variations of cosmic ray fluxes measured with using ASEC and NMDB monitors

“…At the solar minimum in 1965, the annual mean diurnal variations were very small. Agarwal and Mishra (2008) showed that diurnal amplitude significantly decreases and phase shifts to the earlier hours during solar activity minimum years for high and middle latitude NMs.…”

Variability of quiet-time diurnal amplitude and phase of cosmic ray count rates in the mid- and high latitudes

“…The diurnal variation of CR can be characterized by the maximal value (amplitude) and phase (time of the maximal amplitude) in addition to the mean dispersion of the diurnal flux from the harmonic signatures. Simple harmonic analysis has been applied by many authors (Agarwal and Mishra, 2008;Kudela et al, 2008;Kane, 2009;Sabbah and Kudela, 2011;Okpala and Okeke, 2011;Singh and Badruddin, 2015) to understand the nature of diurnal variation of cosmic rays flux. Their statistical association with different possible drivers have also been investigated.…”