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arXiv · 1501.00808

Electron impact excitation of Be-like ions: a comparison of DARC and ICFT results

K. M. Aggarwal·F. P. Keenan
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Abstract

Emission lines of Be-like ions are frequently observed in astrophysical plasmas, and many are useful for density and temperature diagnostics. However, accurate atomic data for energy levels, radiative rates (A-values) and effective electron excitation collision strengths ($Υ$) are required for reliable plasma modelling. In general it is reasonably straightforward to calculate energy levels and A- values to a high level of accuracy. By contrast, considerable effort is required to calculate $Υ$, and hence it is not always possible to assess the accuracy of available data. Recently, two independent calculations (adopting the $R$-matrix method) but with different approaches (DARC and ICFT) have appeared for a range of Be-like ions. Therefore, in this work we compare the two sets of $Υ$, highlight the large discrepancies for a significant number of transitions and suggest possible reasons for these.

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K. M. Aggarwal, F. P. Keenan. 2015-01-05. Electron impact excitation of Be-like ions: a comparison of DARC and ICFT results. https://doi.org/10.1093/mnras%2Fstu2727

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