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Session Q16 - Astrophysics: Student Prize Talks.
MIXED session, Monday afternoon, May 01
202C, LBCC

[Q16.003] Observation of Energy-Dependent Electron-Capture Decay in Secondary Galactic Cosmic Rays

S.M. Niebur, W.R. Binns, P.L. Hink, M.H. Israel, J. Klarmann, M. Lijowski (Washington University), E.R. Christian, T.T von Rosenvinge (NASA/Goddard Space Flight Center), A.C. Cummings, J.S. George, R.A. Leske, R.A. Mewaldt, E.C. Stone (California Institute of Technology), M.E. Wiedenbeck, N.E. Yanasak (Jet Propulsion Laboratory)

Secondary galactic cosmic rays are produced at cosmic ray energies by fragmentation of primary cosmic rays during propagation through the interstellar medium; these nuclei carry a signature of the energy at which they were produced. Although electron-capture decay is inhibited at most of the energies typical of cosmic rays, decay is possible at the lower energies for isotopes such as 51Cr and 49V. We have analyzed Titanium, Vanadium, and Chromium isotopic data from the Cosmic Ray Isotope Spectrometer on ACE and found evidence of electron-capture decay at lower energies. We will present a comparison of secondary electron-capture decay isotope abundances and abundances of their decay products with results from improved propagation models in order to discuss the amount of electron-capture decay and subsequent acceleration that may have occurred during propagation.

Part Q of program listing