• Measure the enhancements of trans-iron elements in impulsive SEPs (Mason et al., 2004, Reames et al., 2000). Correlate these properties with other properties of the events close to the Sun where their peak intensities are higher.

Puzzling extreme enrichments of rare trans-iron elements (Z = 30 to 83) have been reported in impulsive events (Reames 2000; Reames and Ng 2004). In some events trans-iron nuclei are enriched by ~10,000 with respect to oxygen. These results extend the range of particle mass (and rigidity) over which injection and acceleration models must apply. Although progress has been made in modeling 3He spectra using wave-particle interactions [e.g., Roth and Temerin 1997; Miller, 1998; Liu, et al., 2004], no single model yet addresses the combination of 3He-enrichment, heavy-ion enrichments, and the charge-state and electron associations in these events. Trans-iron enrichments have been reported at energies up to ~30 MeV/nuc (Leske et al. 2007). 

 


YZ: Confirm that we can still do this with SIS, after LET descoping.


  • EPD: All sensors: spectra, composition, fluxes, directional information, together with IS instruments. Solar source identification by RS instruments (full disk imaging). Also coordinated multi-s/c SEP observation campaigns with SPP & other missions.

 

Normal IS mode should be enough. We don't necessarily need a RS window (for this specific objective), however it would be great if we can identify the solar source as for all Obj. 3.


2 Comments

  1. David Williams

    I checked against Werner Curdt et al.'s Coronal EUV atlas for any lines of Z > 26.

    There are a couple of lines of Nickel (Z = 28) in SPICE's range:

    1. a flare line of Ni XXI (T ~ 10 MK) at 77.95 nm;
    2. Ni XV (T ~ 2.3 MK) at 103.30 nm. 

    Nominally #2 is visible in active regions, but it seems very weak compared to the O VI  103.19 nm line next door (so weak, in fact, that I couldn't see it in the SUMER spectrum that the atlas is meant to come from).

    The best chance to observe it would be in a flare (2 orders of magnitude brighter, when it's comparable in intensity to the Ni XXI line, but would likely appear afterwards as the plasma cools). 

    Note, however, that the original spec is to observe Z ≥ 30, so I'm not sure if this would help. But since I had to look at the spectrum anyway, I thought I may as well report this, in case Z > 26 is still useful.

     

     

    1. Yannis Zouganelis

      In any case we can't measure it anymore with EPD (because of LET descoping), so I would rather remove this sub-objective.