Electron-ion recombination of Fe xii forming Fe xi: laboratory measurements and theoretical calculations

O. Novotný, N. R. Badnell, D. Bernhardt, M. Grieser, M. Hahn, C. Krantz, M. Lestinsky, A. Müller, R. Repnow, S. Schippers, A. Wolf, D. W. Savin

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

We have measured electron-ion recombination for Fe XII forming Fe XI using a merged-beam configuration at the heavy-ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. The measured merged-beam recombination rate coefficient (MBRRC) for collision energies from 0 to 1500 eV is presented. This work uses a new method for determining the absolute MBRRC based on a comparison of the ion beam decay rate with and without the electron beam on. For energies below 75 eV, the spectrum is dominated by dielectronic recombination (DR) resonances associated with 3s → 3p and 3p → 3d core excitations. At higher energies, we observe contributions from 3 → N' and 2 → N' core excitation DR. We compare our experimental results to state-of-the-art multi-configuration Breit-Pauli (MCBP) calculations and find significant differences, both in resonance energies and strengths. We have extracted the DR contributions from the measured MBRRC data and transformed them into a plasma recombination rate coefficient (PRRC) for temperatures in the range of 103-107 K. We show that the previously recommended DR data for Fe XII significantly underestimate the PRRC at temperatures relevant for both photoionized plasmas (PPs) and collisionally ionized plasmas (CPs). This is contrasted with our MCBP PRRC results, which agree with the experiment to within 30% at PP temperatures and even better at CP temperatures. We find this agreement despite the disagreement shown by the detailed comparison between our MCBP and experimental MBRRC results. Last, we present a simple parameterized form of the experimentally derived PRRC for easy use in astrophysical modeling codes.
LanguageEnglish
Article number57
Number of pages11
JournalAstrophysical Journal
Volume753
Issue number1
Early online date13 Jun 2012
DOIs
Publication statusPublished - 1 Jul 2012

Fingerprint

electron-ion recombination
recombination
electron
ion
coefficients
plasma
plasma temperature
configurations
ion storage
laboratory
calculation
energy
nuclear physics
Germany
temperature
decay rates
excitation
heavy ions
astrophysics
rate

Keywords

  • atomic data
  • atomic processes
  • active galactic nuclei
  • nuclei
  • plasmas
  • x-rays
  • galaxies

Cite this

Novotný, O. ; Badnell, N. R. ; Bernhardt, D. ; Grieser, M. ; Hahn, M. ; Krantz, C. ; Lestinsky, M. ; Müller, A. ; Repnow, R. ; Schippers, S. ; Wolf, A. ; Savin, D. W. / Electron-ion recombination of Fe xii forming Fe xi : laboratory measurements and theoretical calculations. In: Astrophysical Journal. 2012 ; Vol. 753, No. 1.
@article{5a3f00b08c224d2a9a4d11e3769bd5fb,
title = "Electron-ion recombination of Fe xii forming Fe xi: laboratory measurements and theoretical calculations",
abstract = "We have measured electron-ion recombination for Fe XII forming Fe XI using a merged-beam configuration at the heavy-ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. The measured merged-beam recombination rate coefficient (MBRRC) for collision energies from 0 to 1500 eV is presented. This work uses a new method for determining the absolute MBRRC based on a comparison of the ion beam decay rate with and without the electron beam on. For energies below 75 eV, the spectrum is dominated by dielectronic recombination (DR) resonances associated with 3s → 3p and 3p → 3d core excitations. At higher energies, we observe contributions from 3 → N' and 2 → N' core excitation DR. We compare our experimental results to state-of-the-art multi-configuration Breit-Pauli (MCBP) calculations and find significant differences, both in resonance energies and strengths. We have extracted the DR contributions from the measured MBRRC data and transformed them into a plasma recombination rate coefficient (PRRC) for temperatures in the range of 103-107 K. We show that the previously recommended DR data for Fe XII significantly underestimate the PRRC at temperatures relevant for both photoionized plasmas (PPs) and collisionally ionized plasmas (CPs). This is contrasted with our MCBP PRRC results, which agree with the experiment to within 30{\%} at PP temperatures and even better at CP temperatures. We find this agreement despite the disagreement shown by the detailed comparison between our MCBP and experimental MBRRC results. Last, we present a simple parameterized form of the experimentally derived PRRC for easy use in astrophysical modeling codes.",
keywords = "atomic data, atomic processes, active galactic nuclei, nuclei, plasmas, x-rays, galaxies",
author = "O. Novotn{\'y} and Badnell, {N. R.} and D. Bernhardt and M. Grieser and M. Hahn and C. Krantz and M. Lestinsky and A. M{\"u}ller and R. Repnow and S. Schippers and A. Wolf and Savin, {D. W.}",
note = "{\circledC} 2012. The American Astronomical Society.",
year = "2012",
month = "7",
day = "1",
doi = "10.1088/0004-637X/753/1/57",
language = "English",
volume = "753",
journal = "Astrophysical Journal",
issn = "0004-637X",
number = "1",

}

Novotný, O, Badnell, NR, Bernhardt, D, Grieser, M, Hahn, M, Krantz, C, Lestinsky, M, Müller, A, Repnow, R, Schippers, S, Wolf, A & Savin, DW 2012, 'Electron-ion recombination of Fe xii forming Fe xi: laboratory measurements and theoretical calculations' Astrophysical Journal, vol. 753, no. 1, 57. https://doi.org/10.1088/0004-637X/753/1/57

Electron-ion recombination of Fe xii forming Fe xi : laboratory measurements and theoretical calculations. / Novotný, O.; Badnell, N. R.; Bernhardt, D.; Grieser, M.; Hahn, M.; Krantz, C.; Lestinsky, M.; Müller, A.; Repnow, R.; Schippers, S.; Wolf, A.; Savin, D. W.

In: Astrophysical Journal, Vol. 753, No. 1, 57, 01.07.2012.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Electron-ion recombination of Fe xii forming Fe xi

T2 - Astrophysical Journal

AU - Novotný, O.

AU - Badnell, N. R.

AU - Bernhardt, D.

AU - Grieser, M.

AU - Hahn, M.

AU - Krantz, C.

AU - Lestinsky, M.

AU - Müller, A.

AU - Repnow, R.

AU - Schippers, S.

AU - Wolf, A.

AU - Savin, D. W.

N1 - © 2012. The American Astronomical Society.

PY - 2012/7/1

Y1 - 2012/7/1

N2 - We have measured electron-ion recombination for Fe XII forming Fe XI using a merged-beam configuration at the heavy-ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. The measured merged-beam recombination rate coefficient (MBRRC) for collision energies from 0 to 1500 eV is presented. This work uses a new method for determining the absolute MBRRC based on a comparison of the ion beam decay rate with and without the electron beam on. For energies below 75 eV, the spectrum is dominated by dielectronic recombination (DR) resonances associated with 3s → 3p and 3p → 3d core excitations. At higher energies, we observe contributions from 3 → N' and 2 → N' core excitation DR. We compare our experimental results to state-of-the-art multi-configuration Breit-Pauli (MCBP) calculations and find significant differences, both in resonance energies and strengths. We have extracted the DR contributions from the measured MBRRC data and transformed them into a plasma recombination rate coefficient (PRRC) for temperatures in the range of 103-107 K. We show that the previously recommended DR data for Fe XII significantly underestimate the PRRC at temperatures relevant for both photoionized plasmas (PPs) and collisionally ionized plasmas (CPs). This is contrasted with our MCBP PRRC results, which agree with the experiment to within 30% at PP temperatures and even better at CP temperatures. We find this agreement despite the disagreement shown by the detailed comparison between our MCBP and experimental MBRRC results. Last, we present a simple parameterized form of the experimentally derived PRRC for easy use in astrophysical modeling codes.

AB - We have measured electron-ion recombination for Fe XII forming Fe XI using a merged-beam configuration at the heavy-ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. The measured merged-beam recombination rate coefficient (MBRRC) for collision energies from 0 to 1500 eV is presented. This work uses a new method for determining the absolute MBRRC based on a comparison of the ion beam decay rate with and without the electron beam on. For energies below 75 eV, the spectrum is dominated by dielectronic recombination (DR) resonances associated with 3s → 3p and 3p → 3d core excitations. At higher energies, we observe contributions from 3 → N' and 2 → N' core excitation DR. We compare our experimental results to state-of-the-art multi-configuration Breit-Pauli (MCBP) calculations and find significant differences, both in resonance energies and strengths. We have extracted the DR contributions from the measured MBRRC data and transformed them into a plasma recombination rate coefficient (PRRC) for temperatures in the range of 103-107 K. We show that the previously recommended DR data for Fe XII significantly underestimate the PRRC at temperatures relevant for both photoionized plasmas (PPs) and collisionally ionized plasmas (CPs). This is contrasted with our MCBP PRRC results, which agree with the experiment to within 30% at PP temperatures and even better at CP temperatures. We find this agreement despite the disagreement shown by the detailed comparison between our MCBP and experimental MBRRC results. Last, we present a simple parameterized form of the experimentally derived PRRC for easy use in astrophysical modeling codes.

KW - atomic data

KW - atomic processes

KW - active galactic nuclei

KW - nuclei

KW - plasmas

KW - x-rays

KW - galaxies

U2 - 10.1088/0004-637X/753/1/57

DO - 10.1088/0004-637X/753/1/57

M3 - Article

VL - 753

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 57

ER -