On the Temporal Scales of Solar Modulation of Galactic Cosmic Radiation

Charlotte Haley
Seminar

Every 44-year old knows that the Sun completes a full magnetic cycle in 22 years. During this period, galactic cosmic radiation reaching Earth is low when solar magnetic activity peaks and is high during troughs in solar activity. The key mechanism of solar modulation of the galactic cosmic radiation is the solar wind, a largely turbulent plasma extending from the solar corona throughout interplanetary space with charged particle speeds exceeding 900km/h. The ~5-minute seismic modes of the Sun, however, have been shown to produce coherent magnetic oscillations in the solar wind particle flux. We seek to quantify their effect on cosmic radiation reaching Earth using frequency-domain analysis of low energy (<~10GeV) neutron monitor time series.