Solar magnetic cycle dependence in corotating modulation of galactic cosmic rays

Gupta, Vivek; Badruddin,

doi:10.1007/s10509-009-0031-9

Cited by 10 publications

(4 citation statements)

References 43 publications

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“…Given that the synodic rotation period (the time taken for a fixed point on the solar equator to rotate to the same apparent position as viewed from Earth) is around 26 days one would expect GCR modulations on similar time-scales. Indeed, transient variations on such time-scales have been observed in the GCR flux during several solar cycles [26,27] and to a lesser extent, modulations with 13 to 14 day periods in a variety of solar parameters have also been studied [28]. Over the years such variations have been attributed to two possible causes: those related to heliospheric current sheet crossings and those related to co-rotating interaction regions.…”

Section: B Gcr Modulationmentioning

confidence: 99%

Measuring the Galactic Cosmic Ray flux with the LISA Pathfinder radiation monitor

Armano

Audley

Baird

et al. 2018

Astroparticle Physics

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Test mass charging caused by cosmic rays will be a significant source of acceleration noise for spacebased gravitational wave detectors like LISA. Operating between December 2015 and July 2017, the technology demonstration mission LISA Pathfinder included a bespoke monitor to help characterise the relationship between test mass charging and the local radiation environment. The radiation monitor made in situ measurements of the cosmic ray flux while also providing information about its energy spectrum. We describe the monitor and present measurements which show a gradual 40% increase in count rate coinciding with the declining phase of the solar cycle. Modulations of up to 10% were also observed with periods of 13 and 26 days that are associated with co-rotating interaction regions and heliospheric current sheet crossings. These variations in the flux above the monitor detection threshold (≈ 70 MeV) are shown to be coherent with measurements made by the IREM monitor on-board the Earth orbiting INTEGRAL spacecraft. Finally we use the measured deposited energy spectra, in combination with a GEANT4 model, to estimate the galactic cosmic ray differential energy spectrum over the course of the mission.

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Section: B Gcr Modulationmentioning

confidence: 99%

Measuring the Galactic Cosmic Ray flux with the LISA Pathfinder radiation monitor

Armano

Audley

Baird

et al. 2018

Astroparticle Physics

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“…There is some indication that the response of the cosmic rays to solar-wind speed changes during solar minima of different polarity (A<0 and A>0) are different (Badruddin, Yadav, and Yadav, 1985;Gupta and Badruddin, 2009;Modzelowska and Alania, 2011). For low B values (< 6 nT), in A>0 epochs, CRI is reported to decrease more slowly as B increases than in the case for A<0 epochs (e.g.…”

Section: Figure 3amentioning

confidence: 99%

Similarities and Distinctions in Cosmic-Ray Modulation During Different Phases of Solar and Magnetic Activity Cycles

Aslam

Badruddin

2013

Sol Phys

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We study the solar-activity and solar-polarity dependence of galactic cosmic-ray intensity (CRI) on the solar and heliospheric parameters playing a significant role in solar modulation. We utilize the data for cosmic-ray intensity as measured by neutron monitors, solar activity as measured by sunspot number (SSN), interplanetary plasma/field parameters, solar-wind velocity [V] and magnetic field [B], as well as the tilt of the heliospheric current sheet [Λ] and analyse these data for Solar Cycles 20 -24 (1965Cycles 20 -24 ( _ 2011. We divide individual Solar Cycles into four phases, i.e. low, high, increasing, and decreasing solar activity. We perform regression analysis to calculate and compare the CRI-response to changes in different solar/interplanetary parameters during (i) different phases of solar activity and (ii) similar activity phases but different polarity states. We find that the CRI-response is different during negative (A<0) as compared to positive (A>0) polarity states not only with SSN and Λ but also with B and V. The relative CRI-response to changes in various parameters, in negative (A<0) as compared to positive (A>0) state, is solar-activity dependent; it is ≈ 2 to 3 times higher in low solar activity, ≈ 1.5 to 2 times higher in moderate (increasing/decreasing) activity, and it is nearly equal in high solar-activity conditions. Although our results can be ascribed to preferential entry of charged particles via the equatorial/polar regions of the heliosphere as predicted by drift models, these results also suggest that we should look for, any polarity-dependent response of solar wind and transport parameters in modulating CRI in the heliosphere.

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“…Transport models (Gil et al, 2005) and measurements analyzed in paper (Richardson, 2004) suggest the dependence on solar magnetic field polarity. Vivek Gupta and Badruddin, (2009) found that the average behavior of GCR-oscillations during Carrington rotation is different in A > 0 from that in A < 0 epoch. Correlation of solar wind speed with GCR intensity during the course of Carrington rotation is stronger for A > 0 than for A < 0.…”

Section: Periodic and Quasi-periodic Variationsmentioning

confidence: 99%

Variability of Low Energy Cosmic Rays Near Earth

Kudela¹

2012

Exploring the Solar Wind

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Solar magnetic cycle dependence in corotating modulation of galactic cosmic rays

Cited by 10 publications

References 43 publications

Measuring the Galactic Cosmic Ray flux with the LISA Pathfinder radiation monitor

Measuring the Galactic Cosmic Ray flux with the LISA Pathfinder radiation monitor

Similarities and Distinctions in Cosmic-Ray Modulation During Different Phases of Solar and Magnetic Activity Cycles

Variability of Low Energy Cosmic Rays Near Earth

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