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          Institute: MPI für extraterrestrische Physik     Collection: Space Plasma Physics     Display Documents

ID: 12954.0, MPI für extraterrestrische Physik / Space Plasma Physics
Relative recovery of galactic and anomalous cosmic rays at 1 AU: Further evidence for modulation in the heliosheath
Authors:McDonald, F. B.; Klecker, B.; McGuire, R. E.; Reames, D. V.
Date of Publication (YYYY-MM-DD):2002-08
Title of Journal:Journal of Geophysical Research A
Journal Abbrev.:J. Geophys. Res. A
Issue / Number:A8
End Page:1156
Sequence Number of Article:1156
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:[1] For solar cycle 22 the large-scale interplanetary disturbances produced by the intense solar activity of March/June 1991 had a long-term effect on the recovery of galactic cosmic rays throughout the heliosphere that persisted for almost 5 years. At 1 AU, the recovery of 13 MeV/nucleon anomalous cosmic ray oxygen (ACR O+) is much more rapid than that of 265 MeV/nucleon galactic cosmic ray helium (GCR He), consistent with previous observations in the distant heliosphere [McDonald et al., 2000] and strengthening the concept that the region of the heliosheath plays an important role in the modulation of galactic cosmic rays. A comparison of the time histories of GCR He and ACR O+ at 1 and 44 AU observations suggest the recovery moves from the distant heliosphere inward toward 1 AU for this particular phase of the heliomagnetic cycle. There is a very low relative modulation potential, Phi, between 1 and 70 AU of 116 +/- 6 MV for GCR He at solar minimum using the force field approximation. When combined with the small radial intensity gradients in the distant heliosphere, a much lower modulation potential is implied between 1 AU and the termination shock at solar minimum than had been assumed previously. There is no effect on the 13 MeV/nucleon ACR O+ intensity as the inclination of the heliospheric neutral current sheet decreases from 32degrees to its minimum value of 8degrees.
Free Keywords:anomalous cosmic rays; heliosheath; coronal mass ejections; interplanetary shocks; solar wind; galactic cosmic rays
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für extraterrestrische Physik
External Affiliations:Univ Maryland, Inst Phys Sci & Technol, Comp & Space Sci Bldg; 3245, College Pk, MD 20742 USA; Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA; Max Planck Inst Extraterr Phys, D-85741 Garching, Germany; NASA, Goddard Space Flight Ctr, Space Phys Data Facil, Greenbelt, MD 20771 USA
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