Absolute rate coefficients for photorecombination and electron-impact ionization of magnesiumlike iron ions from measurements at a heavy-ion storage ring

Bernhardt, D.; Becker, Andreas; Grieser, M.; Hahn, Michael; Krantz, Claude; Lestinsky, M.; Novotný, Oldřich; Repnow, R.; Savin, D. W.; Spruck, K.; Wolf, A.; Müller, A.; Schippers, S.

doi:10.1103/physreva.90.012702

Cited by 15 publications

(12 citation statements)

References 62 publications

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“…Our cross section measurements were performed using the TSR heavy ion storage ring [11,12] located at the Max-Planck-Institut für Kernphysik in Heidelberg, Germany. The procedures used here are basically the same as those we have described for previous EII measurements and are described in detail in [13][14][15][16][17][18][19][20][21]. Recombination measurements for Fe 8+ were previously performed at TSR by [22], who used similar methods.…”

Section: Experimental Methods and Analysismentioning

confidence: 99%

STORAGE RING CROSS SECTION MEASUREMENTS FOR ELECTRON IMPACT IONIZATION OF Fe⁷⁺

Hahn¹,

Becker

Bernhardt

et al. 2015

ApJ

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We have measured electron impact ionization (EII) for Fe 8+ forming Fe 9+ from below the ionization threshold to 1200 eV. These measurements were carried out at the TSR heavy ion storage ring. The objective of using a storage ring is to store the ion beam initially so that metastable levels decay, thereby allowing for measurements on a well-defined ground-level ion beam. In this case, however, some metastable levels were too long lived to be removed. We discuss several methods for quantifying the metastable fraction, which we estimate to be ∼30%-40%. Although metastables remain problematic, the present storage ring work improves upon other experimental geometries by limiting the metastable contamination to only a few long-lived excited levels. We discuss some future prospects for obtaining improved measurements of Fe 8+ and other ions with long-lived metastable levels.

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Section: Experimental Methods and Analysismentioning

confidence: 99%

STORAGE RING CROSS SECTION MEASUREMENTS FOR ELECTRON IMPACT IONIZATION OF Fe⁷⁺

Hahn¹,

Becker

Bernhardt

et al. 2015

ApJ

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“…More distantly related experimental work comprises the spectroscopy of the L-shell emission -as is observed, e.g., in X-ray spectra of active galactic nuclei (Fabian et al 2009) -from electron-impact excitation of highly ionized iron ions at an EBIT (Gu et al 2001;Chen et al 2006;Beiersdorfer et al 2013), photoexcitation of highly charged iron ions in an EBIT (Epp et al 2007;Bernitt et al 2012;Rudolph et al 2013;Steinbrügge et al 2015), 3p detachment from Fe − (Dumitriu et al 2010), and electron-impact ionization and electron-ion recombination of multiply-charged iron ions in a heavy-ion storage ring (e.g., Savin et al 2002;Schippers et al 2010;Bernhardt et al 2014;Hahn et al 2015). The latter process can be viewed as the timeinverse of photoionization and is therefore very suitable to test corresponding theories (Schippers et al 2002;Müller et al 2009;Müller et al 2014).…”

Section: Previous Related Workmentioning

confidence: 99%

Near L-edge Single and Multiple Photoionization of Singly Charged Iron Ions

Beerwerth

Buhr

Perry‐Sassmannshausen

et al. 2017

ApJ

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Absolute cross sections for m-fold photoionization (m = 1, . . . , 6) of Fe + by a single photon were measured employing the photon-ion merged-beams setup PIPE at the PETRA III synchrotron light source, operated by DESY in Hamburg, Germany. Photon energies were in the range 680-920 eV which covers the photoionization resonances associated with 2p and 2s excitation to higher atomic shells as well as the thresholds for 2p and 2s ionization. The corresponding resonance positions were measured with an uncertainty of ±0.2 eV. The cross section for Fe + photoabsorption is derived as the sum of the individually measured cross-sections for m-fold ionization. Calculations of the Fe + absorption cross sections have been carried out using two different theoretical approaches, Hartree-Fock including relativistic extensions and fully relativistic Multi-Configuration Dirac Fock. Apart from overall energy shifts of up to about 3 eV, the theoretical cross sections are in good agreement with each other and with the experimental results. In addition, the complex deexcitation cascades after the creation of inner-shell holes in the Fe + ion have been tracked on the atomic fine-structure level. The corresponding theoretical results for the product charge-state distributions are in much better agreement with the experimental data than previously published configuration-average results. The present experimental and theoretical results are valuable for opacity calculations and are expected to pave the way to a more accurate determination of the iron abundance in the interstellar medium.

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“…Over decades already, close interaction between experiment and theory has provided relatively satisfying understanding of plasma-relevant processes of light atomic ions [6]. An ongoing project for intermediate heavy ions is the systematic experimental and theoretical study of electron-impact ionization and recombination of iron L-shell and M-shell ions that is primarily motivated by the importance of iron ions in astrophysical but also in fusion-plasma environments ( [12][13][14][15] and references therein).…”

Section: Introductionmentioning

confidence: 99%

Fusion-Related Ionization and Recombination Data for Tungsten Ions in Low to Moderately High Charge States

Müller

2015

Atoms

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Collisional processes and details of atomic structure of heavy many-electron atoms and ions are not yet understood in a fully satisfying manner. Experimental studies are required for guiding new theoretical approaches. In response to fusion-related needs for collisional and spectroscopic data on tungsten atoms in all charge states, a project has been initiated in which electron-impact and photon-induced ionization as well as photorecombination of W q+ ions are studied. Cross sections and rate coefficients were determined for charge states q ranging from q = 1 to q = 5 for photoionization, for q = 1 up to q = 19 for electron-impact ionization and for q = 18 to q = 21 for electron-ion recombination. An overview, together with a critical assessment of the methods and results is provided.

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Absolute rate coefficients for photorecombination and electron-impact ionization of magnesiumlike iron ions from measurements at a heavy-ion storage ring

Abstract: Rate coefficients for photorecombination (PR)

Cited by 15 publications

References 62 publications

STORAGE RING CROSS SECTION MEASUREMENTS FOR ELECTRON IMPACT IONIZATION OF Fe⁷⁺

STORAGE RING CROSS SECTION MEASUREMENTS FOR ELECTRON IMPACT IONIZATION OF Fe⁷⁺

Near L-edge Single and Multiple Photoionization of Singly Charged Iron Ions

Fusion-Related Ionization and Recombination Data for Tungsten Ions in Low to Moderately High Charge States

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Absolute rate coefficients for photorecombination and electron-impact ionization of magnesiumlike iron ions from measurements at a heavy-ion storage ring

Abstract: Rate coefficients for photorecombination (PR)

Cited by 15 publications

References 62 publications

STORAGE RING CROSS SECTION MEASUREMENTS FOR ELECTRON IMPACT IONIZATION OF Fe7+

STORAGE RING CROSS SECTION MEASUREMENTS FOR ELECTRON IMPACT IONIZATION OF Fe7+

Near L-edge Single and Multiple Photoionization of Singly Charged Iron Ions

Fusion-Related Ionization and Recombination Data for Tungsten Ions in Low to Moderately High Charge States

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STORAGE RING CROSS SECTION MEASUREMENTS FOR ELECTRON IMPACT IONIZATION OF Fe⁷⁺

STORAGE RING CROSS SECTION MEASUREMENTS FOR ELECTRON IMPACT IONIZATION OF Fe⁷⁺