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Sudden intensity increases and radial gradient changes of cosmic ray MeV electrons and protons observed at Voyager 1 beyond 111 AU in the heliosheath

Webber, W. R. and McDonald, F. B. and Cummings, A. C. and Stone, E. C. and Heikkila, B. and Lal, N. (2012) Sudden intensity increases and radial gradient changes of cosmic ray MeV electrons and protons observed at Voyager 1 beyond 111 AU in the heliosheath. Geophysical Research Letters, 39 (6). Art. No. L06107. ISSN 0094-8276. https://resolver.caltech.edu/CaltechAUTHORS:20120502-145049365

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Abstract

Voyager 1 has entered regions of different propagation conditions for energetic cosmic rays in the outer heliosheath at a distance of about 111 AU from the Sun. The low energy 6–14 MeV galactic electron intensity increased by ~20% over a time period ≤10 days and the electron radial intensity gradient abruptly decreased from ∼19%/AU to ∼8%/AU at 2009.7 at a radial distance of 111.2 AU. At about 2011.2 at a distance of 116.6 AU a second abrupt intensity increase of ∼25% was observed for electrons. After the second sudden electron increase the radial intensity gradient increased to 18%/AU. This large positive gradient and the ∼13 day periodic variations of >200 MeV particles observed near the end of 2011 indicate that V1 is still within the overall heliospheric modulating region. The implications of these results regarding the proximity of the heliopause are discussed.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2012GL051171DOIArticle
ORCID:
AuthorORCID
Cummings, A. C.0000-0002-3840-7696
Stone, E. C.0000-0002-2010-5462
Additional Information:© 2012 American Geophysical Union. Received 3 February 2012; revised 1 March 2012; accepted 2 March 2012; published 29 March 2012. The authors all appreciate the support of the Voyager program by JPL. The data used here comes from both the Voyager CRS experiments web-site (http://voyager.gsfc.nasa.gov) and from internally generated CRS documents. The Editor thanks two anonymous reviewers for their assistance in evaluating this paper.
Group:Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
JPLUNSPECIFIED
Subject Keywords:cosmic rays; heliosheath; protons
Issue or Number:6
Record Number:CaltechAUTHORS:20120502-145049365
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20120502-145049365
Official Citation:Webber, W. R., F. B. McDonald, A. C. Cummings, E. C. Stone, B. Heikkila, and N. Lal (2012), Sudden intensity increases and radial gradient changes of cosmic ray MeV electrons and protons observed at Voyager 1 beyond 111 AU in the heliosheath, Geophys. Res. Lett., 39, L06107, doi:10.1029/2012GL051171.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:31278
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:03 May 2012 18:31
Last Modified:20 Feb 2020 14:33

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