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Io encounters past and present: A heavy ion comparison

Cohen, C. M. S. and Garrard, T. L. and Stone, E. C. and Cooper, J. F. and Murphy, N. and Gehrels, N. (2000) Io encounters past and present: A heavy ion comparison. Journal of Geophysical Research A, 105 (A4). pp. 7775-7782. ISSN 0148-0227. doi:10.1029/1999JA000021.

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The heavy ion counter (HIC) on the Galileo spacecraft consists of two low-energy telescopes that were proof-test models of the telescopes used for the cosmic ray subsystem (CRS) on Voyager. The telescopes on HIC were improved to better withstand the intense radiation environment of the Jovian system and to measure higher-energy particles with greater sensitivity. The similarity of these two instruments makes it natural to compare the data in an effort to glean insight on the behavior of heavy ion fluxes at higher energies and how the inner Jovian magnetosphere has changed in the last 18 years. Inside L = 6, the oxygen spectrum suggests a spectral break at ∼ 7500 MeV/Gauss, corresponding to ions with gyroradii of ∼ 1.5 R_(Io) at L = 6. A comparison of the phase space densities show remarkable agreement between the two time periods outside of the Io orbit, with differential spectra consistent with γ ∼ −8 above ∼ 6 MeV/nucleon. Near Io Galileo observed a large density gradient not apparent in the Voyager data that may be due to local time asymmetries or a decrease in the radial diffusion rate.

Item Type:Article
Related URLs:
URLURL TypeDescription
Cohen, C. M. S.0000-0002-0978-8127
Stone, E. C.0000-0002-2010-5462
Additional Information:© 2000 American Geophysical Union. Received January 21, 1999; revised December 1, 1999; accepted December 1, 1999. Janet G. Luhmann thanks both referees for their assistance in evaluating this paper.
Group:Space Radiation Laboratory
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2000-40
Issue or Number:A4
Record Number:CaltechAUTHORS:20140827-090127162
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Official Citation:Cohen, C. M. S., T. L. Garrard, E. C. Stone, J. F. Cooper, N. Murphy, and N. Gehrels (2000), Io encounters past and present: A heavy ion comparison, J. Geophys. Res., 105(A4), 7775–7782, doi:10.1029/1999JA000021.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48965
Deposited On:27 Aug 2014 17:27
Last Modified:10 Nov 2021 18:38

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