What are Cosmic Rays?
Galactic cosmic rays are the high-energy particles that stream into our solar system from distant corners of our Galaxy and some from outside the solar system. The Earth atmosphere serves as an ideal detector for the high energy cosmic rays (CRs) which interact with the air molecule nuclei causing propagation of extensive air showers. The primary CR particles interact with the molecules in the atmosphere and produce showers of secondary particles (mainly pions) at about 15 km altitude. These pions are decaying into muons which are the dominant particles of radiation (about 80%) at the surface of the Earth. Over the past decades, numerous studies have reported the correlations between the Earth’s climate and CR flux measured at the surface of the Earth. While the true impact of CRs on the Earth’s climate change is currently far from conclusive, extended efforts of long-term monitoring of cosmic ray flux variations are imperative.
The Nuclear Physics Group at Georgia State University (GSU) has been measuring cosmic ray flux over the past decade the display and the data query of which is available via our local CR monitoring page. The group has also developed a multivariable regression method for using cosmic ray data measured at multiple locations (Nagoya, Japan and Yakutsk, Russia) to reconstruct the stratospheric temperature over the past several decades. In the meantime, a GEANT4-based Monte Carlo simulation, Earth Cosmic Ray Showers (ECRS), has been developed at GSU to systematically model CR showers in the atmosphere with the effects of the geomagnetic field variations. The ECRS simulation is used for and extensive study of solar, geomagnetic field, and barometric pressure effects on CR showers in the atmosphere. Associate applications of proposed Monte Carlo simulation program include, but not limited to, the dynamic climate patterns study, Homeland Security, and muon tomography. The calculation of the radiation dose received by the aircraft crews at different locations around the globe is another important application of the CR shower analysis.
The CR research aims to complement the atmospheric temperature data maintained by the NOAA National Weather Service. The availability of online CR data and analysis tools will make significant contributions to the existing CR network. The goals of the research is to advance the technology for determining the atmospheric temperature in real-time on global scale, which will reduce the uncertainty in global temperature measurements and enhance the understanding of climate change.
Cosmic Ray Muon Detectors at GSU