University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Friday, February 24th 2017
11:15 am:
Speaker: Daniel Baker, University of Colorado
Subject: Studying Relativistic Particle Acceleration and Loss in Our Cosmic Backyard: Van Allen Probes Radiation Belt Exploration
Please note change of time, room and day for the seminar, this week only.

Early observations of the Earth’s radiation environment suggested that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. Subsequent studies showed that electrons in the energy range 100 keV < E< 1 MeV often populated both the inner and outer zones with a pronounced “slot” region relatively devoid of energetic electrons existing between them. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. However, recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed wholly unexpected properties of the radiation belts, especially at highly relativistic (E > 2 MeV) and ultra-relativistic (E > 5 MeV) kinetic energies. In this talk we show using high spatial and temporal resolution data from the Relativistic Electron-Proton Telescope (REPT) experiment on board the Van Allen Probes that multiple belts can exist concurrently and that an exceedingly sharp inner boundary exists for ultra-relativistic electrons. Using additionally available Van Allen Probes data, we demonstrate that these remarkable features of energetic electrons are not due to a physical boundary within Earth’s intrinsic magnetic field. Rather it likely that human-generated electromagnetic transmitter wave fields produce such effects suggesting that human-made wave-particle scattering effects deep inside the Earth’s magnetosphere can contribute to an almost impenetrable barrier through which the most energetic Van Allen belt electrons cannot migrate

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