Cummings, A. C. and Stone, E. C. (1996) Composition of Anomalous Cosmic Rays and Implications for the Heliosphere. Space Science Reviews, 78 (1-2). pp. 117-128. ISSN 0038-6308. doi:10.1007/BF00170798. https://resolver.caltech.edu/CaltechAUTHORS:20140703-214818330
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Abstract
We use energy spectra of anomalous cosmic rays (ACRs) measured with the Cosmic Ray instrument on the Voyager 1 and 2 spacecraft during the period 1994/157-313 to determine several parameters of interest to heliospheric studies. We estimate that the strength of the solar wind termination shock is 2.42 (-0.08, +0.04). We determine the composition of ACRs by estimating their differential energy spectra at the shock and find the following abundance ratios: H/He = 5.6 (-0.5, +0.6), C/He = 0.00048 ± 0.00011, N/He = 0.011 ± 0.001, O/He = 0.075 ± 0.006, and Ne/He = 0.0050 ± 0.0004. We correlate our observations with those of pickup ions to deduce that the long-term ionization rate of neutral nitrogen at 1 AU is ~8.3 × 10^(-7) s^(-1) and that the charge-exchange cross section for neutral N and solar wind protons is ~1.0 × 10^(-15) cm^2 at 1.1 keV. We estimate that the neutral C/He ratio in the outer heliosphere is 1.8(-0.7, +0.9) × 10^(-5). We also find that heavy ions are preferentially injected into the acceleration process at the termination shock.
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Additional Information: | © 1996 Springer. Provided by the NASAAstrophysics Data System. We are grateful to J. T. Hoeksema for providing the tilt observations prior to publication. We thank J. Richardson and J. Belcher for providing the Voyager 2 solar wind speed data. This work was supported by NASA under contract NAS7-918. | ||||||||||||
Group: | Space Radiation Laboratory | ||||||||||||
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Subject Keywords: | abundances, anomalous cosmic rays, Voyager, interstellar medium, heliosphere, solar wind termination shock | ||||||||||||
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Issue or Number: | 1-2 | ||||||||||||
DOI: | 10.1007/BF00170798 | ||||||||||||
Record Number: | CaltechAUTHORS:20140703-214818330 | ||||||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20140703-214818330 | ||||||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||
ID Code: | 46834 | ||||||||||||
Collection: | CaltechAUTHORS | ||||||||||||
Deposited By: | Deborah Miles | ||||||||||||
Deposited On: | 24 Jul 2014 23:36 | ||||||||||||
Last Modified: | 10 Nov 2021 17:29 |
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