Picture of person typing on laptop with programming code visible on the laptop screen

World class computing and information science research at Strathclyde...

The Strathprints institutional repository is a digital archive of University of Strathclyde's Open Access research outputs. Strathprints provides access to thousands of Open Access research papers by University of Strathclyde researchers, including by researchers from the Department of Computer & Information Sciences involved in mathematically structured programming, similarity and metric search, computer security, software systems, combinatronics and digital health.

The Department also includes the iSchool Research Group, which performs leading research into socio-technical phenomena and topics such as information retrieval and information seeking behaviour.

Explore

Dielectronic recombination (via N = 2→N = 2 core excitations) and radiative recombination of Fe xx: Laboratory measurements and theoretical calculations

Savin, D.W. and Behar, E. and Kahn, S.M. and Gwinner, G. and Saghiri, A.A. and Schmitt, M. and Grieser, M. and Repnow, R. and Schwalm, D. and Wolf, A. and Bartsch, T. and Müller, A. and Schippers, S. and Badnell, N.R. and Chen, M.H. and Gorczyca, T.W. (2002) Dielectronic recombination (via N = 2→N = 2 core excitations) and radiative recombination of Fe xx: Laboratory measurements and theoretical calculations. Astrophysical Journal, 138. pp. 337-370. ISSN 0004-637X

[img]
Preview
Text (strathprints005828)
strathprints005828.pdf - Accepted Author Manuscript

Download (960kB) | Preview

Abstract

We have measured the resonance strengths and energies for dielectronic recombination (DR) of Fe XX forming Fe XIX via N = 2 → N′ = 2 (N = 0) core excitations. We have also calculated the DR resonance strengths and energies using AUTOSTRUCTURE, HULLAC, MCDF, and R-matrix methods, four different state-of-the-art theoretical techniques. On average the theoretical resonance strengths agree to within . 10% with experiment. The AUTOSTRUCTURE, MCDF and R-matrix results are in better agreement with experiment than are the HULLAC results. However, in all cases the 1σ standard deviation for the ratios of the theoretical-to-experimental resonance strengths is & 30% which is significantly larger than the estimated relative experimental uncertainty of . 10%. This suggests that similar errors exist in the calculated level populations and line emission spectrum of the recombined ion. We confirm that theoretical methods based on inverse-photoionization calculations (e.g., undamped R-matrix methods) will severely overestimate the strength of the DR process unless they include the effects of radiation damping. We also find that the coupling between the DR and radiative recombination (RR) channels is small.