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The Longitudinal Distribution of Solar Energetic Particles

von Rosenvinge, T. T. and Richardson, I. G. and Cane, H. V. and Christian, E. R. and Cohen, C. M. S. and Cummings, A. C. and Labrador, A. W. and Leske, R. A. and Mewaldt, R. A. and Stone, E. C. and Wiedenbeck, M. E. (2015) The Longitudinal Distribution of Solar Energetic Particles. In: 34th International Cosmic Ray Conference (ICRC2015). Proceedings of Science. No.236. SISSA , Trieste, Italy, Art. No. 104.

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Using observations from the High Energy Telescopes (HETs) on STEREO A and B and similar observations from SoHO, near-Earth, we have identified ~250 individual solar energetic particle events that include >14 MeV protons since the beginning of the STEREO mission [1]. Between the end of December 2009, when the STEREO A and B spacecraft were, respectively, ahead and behind Earth by ~ 65° in ecliptic longitude, and the end of December 2013, 43 different events were clearly detected at all three locations. The observed intensities of such an event are usually assumed to be Gaussian distributed as a function of the longitudes of the Parker Spiral footpoints at the Sun for each observer. This neglects the fact that the interplanetary magnetic field may have large deviations from Parker Spirals, e.g. due to coronal mass ejections from prior events. Nonetheless, we have fit Gaussians to the peak intensities observed simultaneously at three spacecraft for all 43 events. The Gaussian peak intensity is poorly correlated with the corresponding CME speed and the FWHM is uncorrelated with the CME speed. Surprisingly, however, there appear to be distinctly non-random variations of the FWHM values from event to event.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Richardson, I. G.0000-0002-3855-3634
Christian, E. R.0000-0003-2134-3937
Cohen, C. M. S.0000-0002-0978-8127
Cummings, A. C.0000-0002-3840-7696
Labrador, A. W.0000-0001-9178-5349
Leske, R. A.0000-0002-0156-2414
Mewaldt, R. A.0000-0003-2178-9111
Stone, E. C.0000-0002-2010-5462
Wiedenbeck, M. E.0000-0002-2825-3128
Additional Information:Copyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-ShareAlike.
Group:Space Radiation Laboratory
Series Name:Proceedings of Science
Issue or Number:236
Record Number:CaltechAUTHORS:20180828-122925629
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89240
Deposited By: George Porter
Deposited On:30 Aug 2018 21:21
Last Modified:16 Nov 2021 00:33

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