J/ApJ/813/16 Fe7+ ionization cross section (Hahn+, 2015)
Storage ring cross section measurements for electron impact ionization of Fe7+.
Hahn M., Becker A., Bernhardt D., Grieser M., Krantz C., Lestinsky M.,
Muller A., Novotny O., Repnow R., Schippers S., Spruck K., Wolf A.,
Savin D.W.
<Astrophys. J., 813, 16 (2015)>
=2015ApJ...813...16H 2015ApJ...813...16H (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics
Keywords: atomic data; atomic processes
Abstract:
We have measured electron impact ionization for Fe7+ from the
ionization threshold up to 1200eV. The measurements were performed
using the TSR heavy ion storage ring. The ions were stored long enough
prior to measurements to remove most metastables, resulting in a beam
of 94% ground-level ions. Comparing with the previously recommended
atomic data, we find that the Arnaud & Raymond (1992ApJ...398..394A 1992ApJ...398..394A)
cross section is up to about 40% larger than our measurement, with the
largest discrepancies below about 400eV. The cross section of Dere
(2007, J/A+A/466/771) agrees to within 10%, which is about the
magnitude of the experimental uncertainties. The remaining
discrepancies between our measurement and the Dere calculations are
likely due to shortcomings in the theoretical treatment of the
excitation-autoionization contribution.
Description:
Cross-section measurements were carried out using the TSR heavy ion
storage ring located at the Max-Planck-Institut fur Kernphysik in
Heidelberg, Germany.
Additionally, recombination measurements for Fe7+ were performed at
TSR by Schmidt et al. (2008A&A...492..265S 2008A&A...492..265S) using similar methods.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 27 523 Fe7+ ionization cross section
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See also:
J/ApJ/767/47 : Fe13+, Fe16+, Fe17+ cross-section measures (Hahn+, 2013)
J/ApJ/760/80 : Fe9+ and Fe10+ cross-section measurements (Hahn+, 2012)
J/ApJ/743/206 : Effective collision strengths of FeVIII (Tayal+, 2011)
J/A+A/466/771 : Ionization rate coefficients for elements H to Zn (Dere+, 2007)
J/A+AS/97/443 : Fluorescence for Be to Zn (Kaastra+ 1993)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 eV E [80/1200] Collision energy
6- 16 E11.3 cm2 CS Cross section (1)
18- 27 E10.3 cm2 e_CS Statistical uncertainty in CS (1)
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Note (1): There is a systematic uncertainty of 12% in the magnitude
of the cross section (see the text).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 10-Feb-2016