Long Term Modulation of the Galactic Cosmic Radiation

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The investigators will use the understanding gained from satellite and other contemporary investigations of the cosmic radiation and its interaction with the heliospheric magnetic field, to investigate the temporal variability of the cosmic ray modulation over the past 10,000 years. Current evidence indicates that solar activity exhibits a "long" periodicity of about 2200 years, and the investigation is expected to yield important results regarding the origin of the heliospheric magnetic field, and its quantitative variability over time. This activity may have considerable impact upon cosmic ray theory, solar physics, and aspects of space weather. The research will use cosmogenic data, and mathematical solutions of the cosmic ray transport equation, to investigate the long term modulation processes to infer the state of the heliosphere and of the solar magnetic field. The investigation will (1) develop analytical techniques to provide better resolution of the 11 year variation in beryllium-10 isotope data, and to better remove geomagnetic effects from the carbon-14 record; (2) use the cosmogenic data, and all available solar proxies, to study the associations between the cosmic ray modulation, and solar activity throughout the interval 850-1950 A.D.; (3) use the understanding gained in (1) and (2) to study the modulation processes for the past 10,000 years; and (4) assess the feasibility of making high precision measurements of the beryllium-10 production since 1951, to allow detailed comparison with the neutron monitor record and to better understand the coupling between beryllium-10, carbon-14, and galactic cosmic ray observations. A major outcome will be strengthened collaboration among the cosmic ray, solar, and cosmogenic research communities. The cosmogenic data are one of the few quantitative measurements available to study solar processes in the past, and their effects at Earth, and the quantitative information that will be obtained on the heliospheric magnetic fields is expected to be of interest to disciplines concerned with climatic, geological, and biological changes during the Holocene. Quantifying the heliospheric effects in the past will assist the prediction of the solar effects upon our technological infrastructure in the future.