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The Time Delay between Nucleosynthesis and Acceleration Based on ACE Measurements of Primary Electron-Capture Nuclides

Mewaldt, R. A. and Wiedenbeck, M. E. and Binns, W. R. and Christian, E. R. and Cummings, A. C. and George, J. S. and Hink, P. L. and Klarmann, J. and Leske, R. A. and Lijowski, M. and Stone, E. C. and von Rosenvinge, T. T. and Yanasak, N. E. (1999) The Time Delay between Nucleosynthesis and Acceleration Based on ACE Measurements of Primary Electron-Capture Nuclides. In: Proceedings of the 26th International Cosmic Ray Conference. Vol.3. International Union of Pure and Applied Physics , pp. 45-48.

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Supernovae should produce the radioactive nuclide ^(59)Ni, and in the ejecta of the explosions these particles will decay by electron capture with a halflife of 7.6 x 10^5 yr to produce ^(59)Co. However, if the ^(59)Ni nuclei are accelerated to cosmic-ray energies on a time scale short compared to this halflife, they are stripped of their electrons and decay is prevented. Thus the abundances of ^(59)Ni and ^(59)Co can be used to determine whether the time between nucleosynthesis and cosmic-ray acceleration is short or long compared to the 59Ni halflife (Soutoul, Casse, & Juliusson 1978). We have used the Cosmic Ray Isotope Spectrometer (CRIS) on the Advanced Composition Explorer (ACE) to measure the abundances of 59Ni and 59Co in galactic cosmic rays, and find that the data are consistent with complete decay of 59Ni indicating a time delay 2 10^5 yr. We present the observations and discuss their significance for models of cosmic ray origin and acceleration.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Mewaldt, R. A.0000-0003-2178-9111
Wiedenbeck, M. E.0000-0002-2825-3128
Binns, W. R.0000-0001-6110-3407
Christian, E. R.0000-0003-2134-3937
Cummings, A. C.0000-0002-3840-7696
Leske, R. A.0000-0002-0156-2414
Stone, E. C.0000-0002-2010-5462
Additional Information:© University of Utah. Provided by the NASA Astrophysics Data System. This research was supported by NASA at the California Institute of Technology (under grant NAG5-6912), the Jet Propulsion Laboratory, the Goddard Space Flight Center, and Washington University.
Group:Space Radiation Laboratory
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Space Radiation Laboratory1999-29
Record Number:CaltechAUTHORS:20150213-093733570
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54820
Deposited By: Deborah Miles
Deposited On:22 Feb 2015 22:42
Last Modified:09 Mar 2020 13:19

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