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Quiet time fluxes and radial gradients of low-energy protons in the inner and outer heliosphere

Kecskemety, K. and Zeldovich, M.A. and Logachev, Yu. I. and Heber, B. and Kiraly, P. and Mewaldt, R. A. and Posner, A. and Rodriguez-Pacheco, J. (2005) Quiet time fluxes and radial gradients of low-energy protons in the inner and outer heliosphere. In: Proceedings of the 29th International Cosmic Ray Conference. Vol.2. Tata Institute of Fundamental Research , Pune, India, pp. 57-60.

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Radial variations of low-energy (~1-8 MeV) quiet-time fluxes of protons are examined at distances of 20-85 AU during low solar activity periods using Voyager 1-2 data and compared with Ulysses fluxes at 1-5 AU as well as IMP-8 and SOHO at Earth and Helios between 0.3 and 1 AU. To obtain nearly background-free fluxes, the data are based on a careful pulse-height analysis. Except for high solar activity periods, contaminated with solar particles, all fluxes are very low, of the order of, and below 10^(-5) /(cm^2 s sr MeV). The Ulysses fluxes seem to be the lowest, whereas Helios and Voyager fluxes are nearly at the same level. The radial variation in 1-8 MeV suggests a negative gradient from 0.5 to about 2 AU that gradually turns positive beyond 2 AU. Whereas the true variation is difficult to infer between 5 and 17 AU due to solar contribution, from 30 to about 60 AU it exhibits a wide plateau, beyond which a slight increasing tendency is observed. At energies above ~6 MeV a clear contribution of anomalous hydrogen is observed.

Item Type:Book Section
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URLURL TypeDescription
Mewaldt, R. A.0000-0003-2178-9111
Additional Information:Pulse-height data from the Voyager CRS instrument was kindly provided by F.B. McDonald, Ulysses COSPIN LET data were obtained from R.G. Marsden. The International Space Science Institute (Bern, Switzerland) is thanked for financial and organizational support.
Group:Space Radiation Laboratory
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International Space Station InstituteUNSPECIFIED
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2005-21
Record Number:CaltechAUTHORS:20150408-081154385
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56460
Deposited By: Deborah Miles
Deposited On:16 Apr 2015 16:10
Last Modified:22 Nov 2019 09:58

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