Uncertainties on atomic data. A case study: N IV

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    We consider three recent large-scale calculations for the radiative and electron-impact excitation data of N IV, carried out with different methods and codes. The scattering calculations employed the relativistic Dirac R-matrix (DARC) method, the intermediate coupling frame transformation (ICFT) R-matrix method, and the B-spline R-matrix (BSR) method. These are all large-scale scattering calculations with well-tested and sophisticated codes, which use the same set of target states. One concern raised in previous literature is related to the increasingly large discrepancies in the effective collision strengths between the three sets of calculations for increasingly weak and/or high-lying transitions. We have built three model ions and calculated the intensities of all the main spectral lines in this ion. We have found that, despite such large differences, excellent agreement (to within ±20 per cent) exists between all the spectroscopically relevant line intensities. This provides confidence in the reliability of the calculations for plasma diagnostics. We have used the differences in the radiative and excitation rates amongst the three sets of calculations to obtain a measure of the uncertainty in each rate. Using a Monte Carlo approach, we have shown how these uncertainties affect the main theoretical ratios that are used to measure electron densities and temperatures.

    Documents

    DOI

    Original languageEnglish
    Number of pages6
    Pages (from-to)4754-4759
    JournalMonthly Notices of the Royal Astronomical Society
    Journal publication date11 Feb 2019
    Issue number4
    Volume484
    Early online date11 Feb 2019
    DOIs
    Publication statusPublished - 11 Feb 2019

      Research areas

    • ATOMIC DATA, Techniques: spectroscopic

    ID: 166232651