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Composition of Anomalous Cosmic Rays and Implications for the Heliosphere

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. http://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.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://adsabs.harvard.edu/abs/1996SSRv...78..117CADSArticle
http://dx.doi.org/10.1007/BF00170798DOIArticle
http://link.springer.com/article/10.1007%2FBF00170798PublisherArticle
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
Funders:
Funding AgencyGrant Number
NASANAS7-918
Subject Keywords:abundances, anomalous cosmic rays, Voyager, interstellar medium, heliosphere, solar wind termination shock
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1996-18
Record Number:CaltechAUTHORS:20140703-214818330
Persistent URL:http://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:24 Jul 2014 23:36

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