Institute for Physical Science & Technology

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Eun-Suk Seo

Associate Professor, Ph.D.
Cosmic Ray Physics

Cosmic rays are known to exist with energies extending to about 10^20 eV, but there is no generally accepted theory for their source. Dr. Seo and her Cosmic Physics Group are working mainly on space-based experiments to resolve the shapes of the cosmic-ray H, He, and heavier nuclei energy spectra at energies approaching 10^15 eV. The composition changes in these data have implications for particle acceleration in supernova remnants or other exotic objects, transport of particles through the interstellar medium, and the nature of cosmic-ray sources. Direct measurements at such ultra-high energies have eluded scientists for decades, because of the low particle fluxes, but Dr. Seo's group has been involved in pioneering new experiments with adequate exposure to collect the needed data. These are the Advanced Thin Ionization Calorimeter (ATIC) to be exposed on several 10 day long-duration balloon flights, the Cosmic Ray Energetics and Mass (CREAM) mission to be flown on several 100 day ultra-long- duration balloon flights, and the Advanced Cosmic-ray Composition Experiment for the Space Station (ACCESS). Dr Seo's group is also collaborating with Goddard Space Flight Center, and Japanese scientists in a Balloon Experiment with a Superconducting magnet Spectrometer (BESS) to investigate antiprotons, antihelium, and low energy proton and helium isotopes over a solar cycle.

       http://cosmicray.umd.edu/homepage/

Selected publications:

1. Cosmic Ray Antiproton Flux in the Energy Range from 200-600 MeV, A. Moiseev, K. Yoshimura, and I. Ueda, et al., Astrophys. J., 474, 479, 1997.
2. Measurement of Cosmic Ray H and He Isotopes in a Balloon Borne Experiment with a Superconducting Solenoid Spectro-meter (BESS), E.S. Seo, H. Matsunaga, and K. Anraku, et al., Advances in Space Research, 19, No. 5, 751-754, 1997.
3. Advanced Thin Ionization Calorimeter to Measure Ultrahigh Energy Cosmic Rays, E.S. Seo, J.H. Adams Jr., and G.L. Bashindzhagyan, et al., Advances in Space Research, 19, No. 5, 711-718, 1997.