IMP-8 observations of the spectra, composition, and variability of solar heavy ions at high energies relevant to manned space missions

Tylka, A. J.; Dietrich, William F.

doi:10.1016/s1350-4487(99)00062-1

Cited by 21 publications

(7 citation statements)

References 46 publications

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“…The statistical significance of this increase is modest here. However, very similar, complicated energy-dependent Fe/O ratios have been previously reported in large SEP events from a wide range of heliolongitudes (Tylka & Dietrich 1999). Remnant flare suprathermals may also account for the reported association between Fe enhancements above ∼40 MeV nucleon Ϫ1 and ground-level neutron-monitor events (Dietrich & Lopate 1999), which almost always occur during periods of high flare activity.…”

Section: ϫ4supporting

confidence: 74%

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Evidence for Remnant Flare Suprathermals in the Source Population of Solar Energetic Particles in the 2000 Bastille Day Event

Tylka

Cohen

Dietrich

et al. 2001

The Astrophysical Journal

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The energy spectra of Fe in the very large solar energetic particle (SEP) event of 2000 July 14 are strikingly different from those of lighter species. We show that this difference can be explained by shock acceleration from a two-component source population, comprising solar wind suprathermals and a small (∼5%) admixture of remnant flare particles, as previously proposed to explain enhanced 3 He/ 4 He in some gradual SEP events. Flare remnants can also account for several previously unexplained features of high-energy solar heavy ions as well as important aspects of SEP event-to-event variability. These results offer a new perspective on the enduring controversy over the relative roles of flares and coronal mass ejections (CMEs) in producing SEPs. Flare activity clearly makes a unique and critical contribution to the source population. But the predominate accelerator in large gradual SEP events is the CME-driven shock, and many spectral, compositional, and charge state characteristics of highenergy heavy ions can be understood without invoking other acceleration mechanisms.

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Section: ϫ4supporting

confidence: 74%

“…For example, above ∼20 MeV nucleon Ϫ1 , the Fe spectra are nearly power laws, whereas the other species are clearly exponentials. This spectral difference between Fe and lighter species at high energies has been previously noted (but not explained) in large SEP events in earlier solar cycles (Tylka & Dietrich 1999).…”

Section: ϫ4supporting

confidence: 67%

Evidence for Remnant Flare Suprathermals in the Source Population of Solar Energetic Particles in the 2000 Bastille Day Event

Tylka

Cohen

Dietrich

et al. 2001

The Astrophysical Journal

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“…Shielding against the protons and heavy ions can protect the astronauts and space‐based equipment; however, tradeoffs between cost/weight limitations and risk of reduced functionality or demise require effective planning by mission operators and design engineers [e.g., Fleetwood and Winokur , 2000]. Such planning requires accurate knowledge of the radiation environment resulting from both protons and heavy ions [ Tylka et al , 1996; Tylka and Dietrich , 1999; Dyer et al , 2002].…”

Section: Energetic Particlesmentioning

confidence: 99%

“…Shielding against the protons and heavy ions can protect the astronauts and space-based equipment; however, tradeoffs between cost/weight limitations and risk of reduced functionality or demise require effective planning by mission operators and design engineers [e.g., Fleetwood and Winokur, 2000]. Such planning requires accurate knowledge of the radiation environment resulting from both protons and heavy ions [Tylka et al, 1996;Tylka and Dietrich, 1999;Dyer et al, 2002]. [15] Efforts to understand the effects of SEP-related radiation typically utilize SEP proton data from 6 large events, day 54 (23 February) 1956, day 317 (12 November) 1960, day 215 (2 August) 1972, day 224 (12 August) 1989, day 272 (29 September) 1989, and day 292 (19 October) 1989[Nealy et al, 1992.…”

Section: Energetic Particlesmentioning

confidence: 99%

Space weather drivers in the ACE era

et al. 2006

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[1] We examine ACE observations of interplanetary disturbances and energetic particle activity for the period of solar maximum during solar cycle 23 and compare these measurements to the historical record as represented by the National Space Science Data Center Omnitape of near-Earth observations. Magnetospheric response parameters, Dst and Kp, are similarly compared for the two epochs. We find that ACE observed an unexpectedly large number of the strongest transient events with the strength of magnetospheric drivers exceeding the historical record for the space flight era. This is not entirely true of the magnetospheric response, which demonstrates that the magnetospheric response is an integrated effect that is more subtle than examination of single hourly averages would indicate. For these and other reasons, we argue that satellites at L1 orbit, such as ACE, provide an excellent database for the study of magnetospheric storm drivers and their associated energetic particle populations from which space weather models may be refined. We also compare and contrast energetic particle measurements. While protons are a large space weather concern, heavy ions are also a radiation hazard for hardware in particular. We argue that heavy ion radiation predictions based on the measurements of protons are not reliable and that only by measuring the actual composition of the solar energetic particle population can we hope to understand and address the threat posed by these particles to machines and to obtain a more complete view of the radiation environment.

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“…SPE can be hazardous to astronauts, particularly outside the geomagnetosphere and when shielding is minimal (e.g., on EVA, the lunar surface, etc.). Some events contain substantial fluxes of high‐energy protons; these are of particular concern, as are those rare events in which substantial fluxes of HZE ions are accelerated [ Tylka and Dietrich , 1999]. Spectral “hardness” is often characterized by fitting the differential flux, dJ/dE, with a power law, i.e., dJ/dE ∝ E − γ .…”

Section: Introductionmentioning

confidence: 99%

Mars Odyssey measurements of galactic cosmic rays and solar particles in Mars orbit, 2002-2008

et al. 2010

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The instrument payload aboard the 2001 Mars Odyssey orbiter includes several instruments that are sensitive to energetic charged particles from the galactic cosmic rays (GCR) and solar particle events (SPE). The Martian Radiation Environment Experiment (MARIE) was a dedicated energetic charged particle spectrometer, but it ceased functioning during the large solar storm of October/November 2003. Data from two other Odyssey instruments are used here: the Gamma Ray Spectrometer and the scintillator component of the High Energy Neutron Detector. Though not primarily designed to measure energetic charged particles, both systems are sensitive to them, and several years of data are available from both. Using the MARIE data for calibration of the other systems, count rates can be normalized (with significant uncertainties) to absolute fluxes of both GCR and solar energetic particles (SEP). The data, which cover the time span from early 2002 through the end of 2007, clearly show the solar cycle–dependent modulation of the GCR starting in 2004. Many SPEs were recorded as well and are cataloged here. Threshold energies were relatively high, ranging from 16 MeV in the most sensitive channel to 42 MeV. These thresholds are not optimal for detailed studies of SEPs, but this is the range of interest for calculations of dose and dose equivalent, pertinent to human flight, and covering that range was the original motivation for MARIE. The data are available on request and are potentially of use for the Earth‐Moon‐Mars Radiation Environment Module collaboration and other heliospheric modeling projects.

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IMP-8 observations of the spectra, composition, and variability of solar heavy ions at high energies relevant to manned space missions

Cited by 21 publications

References 46 publications

Evidence for Remnant Flare Suprathermals in the Source Population of Solar Energetic Particles in the 2000 Bastille Day Event

Evidence for Remnant Flare Suprathermals in the Source Population of Solar Energetic Particles in the 2000 Bastille Day Event

Space weather drivers in the ACE era

Mars Odyssey measurements of galactic cosmic rays and solar particles in Mars orbit, 2002-2008

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