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ATOMDB Version 1.3.0 Caveats

• Ni XXVII (He-like Nickel): The forbidden line of the He-like triplet (1s2s 3S1 -> ground) for Nickel (and only Nickel) is missing from ATOMDB. This will be addresses in the next release, as we plan to significantly improve the Ni XXVII calculation. In the interim, we have confirmed that adding the line does not significantly change the total emission from the He-like triplet complex. We compared ATOMDB v1.3.0 (with and without the forbidden line) and Raymond-Smith (1993) and SPEX) against experimental Tokamak data and found that:
  • Many innershell and dielectronic satellites are missing in all codes
  • Adding the forbidden line improves the match to the lab data at the forbidden line position but also causes the intercombination line match to worsen. In all cases, the resonance line is well-modelled
  • Every code significantly underestimates the forbidden line.
  • This result led to our current work to improve the Ni XXVII results. Until this is ready, we feel the current ATOMDB model is as accurate as it is possible to be right now, and releasing a new version with the atomic data we have now would not significantly improve the situation.
• L-shell Ions: We still have very little data on the delta n >= 1 transitions from L-shell ions of Ne, Mg, Al, Si, S, Ar, or Ca, with the exception of Lithium-like ions. X-rays from these lines are largely below 0.25 keV, and as a result, our spectral calculations in this range are very deficient. We are working on this problem.
• n > 5 lines: Only for some of the strongest lines do we include lines from levels above n=5.
• Iron lines: Despite the addition of the Fe XVIII - Fe XXIV dielectronic recombination lines, we still do not include the so-called "cold" Iron line at 6.4 keV, which arises out of Fe I - Fe XVII ions. We are also missing some inner shell excitation transitions, for example from Fe XVI and O VI. We hope to include these data in the next release.
• Accuracy: These models are derived from theoretical atomic data for which few experimental measurements have been made. Most emissivities are thought to be good to better than 30 percent; however, larger discrepancies are being found in some caes, likely the result of incomplete atomic physics. Such cases are under investigation as part of the Emission Line Project.
• Fe XVII: We note that the line ratio of Fe XVII 15.014 to Fe XVII 15.261 is about 15 to 20 percent larger than the measured ratio (see Brown et al. 1998, ApJ, 502, 1015). While the discrepancy is within our expected uncertainties, it is quite likely that this discrepancy will be noticeable even at moderate (CCD) resolution.