J/ApJ/767/47ivo://CDS.VizieR/J/ApJ/767/47doi:10.26093/cds/vizier.17670047CDSHahn 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.2017-07-05T06:59:14Z2014-12-12T14:22:33ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.fratomic-physicsWe report measurements of electron impact ionization for Fe^13+^, Fe^16+^, and Fe^17+^ over collision energies from below threshold to above 3000eV. The ions were recirculated using an ion storage ring. Data were collected after a sufficiently long time that essentially all the ions had relaxed radiatively to their ground state. For single ionization of Fe^13+^, we find that previous single pass experiments are more than 40% larger than our results. Compared to our work, the theoretical cross section recommended by Arnaud & Raymond (1992ApJ...398..394A) is more than 30% larger, while that of Dere (2007, J/A+A/466/771) is about 20% greater. Much of the discrepancy with Dere is due to the theory overestimating the contribution of excitation-autoionization via n=2 excitations. Double ionization of Fe^13+^ is dominated by direct ionization of an inner shell electron accompanied by autoionization of a second electron. Our results for single ionization of Fe^16+^ and Fe^17+^ agree with theoretical calculations to within the experimental uncertainties.2013ApJ...767...47Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/767/47CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJ/767/123 : FeXIV, FeXV and FeXVI transitions (Ferland+, 2013)J/ApJ/760/80 : Fe^9+^ and Fe^10+^ cross-section measurements (Hahn+, 2012)J/A+A/518/A64 : Na-like iso-electronic sequence. II. (Liang+, 2010)J/A+A/466/771 : Ionization rate coefficients for elements H to Zn (Dere+, 2007)J/A+A/459/307 : Fe XVIII Benchmarking atomic data (Del Zanna+, 2006)J/A+AS/97/443 : Fluorescence for Be to Zn (Kaastra+ 1993)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/767/47https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/767/47http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/767/47https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/767/47https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/767/47http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/767/47GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/ApJ/767/47/table6Fe^13+^ double ionization cross sectione_sigmaStatistical uncertainty in sigma (1)cm**2stat.errordoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintE[315/3212] Collision energyeVphys.energyfloatsigmaCross sectioncm**2meta.id.cross;phys.atmol.crossSectiondoubleJ/ApJ/767/47/table2Fe^13+^ single ionization cross sectionrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintE[315/3212] Collision energyeVphys.energyfloatsigmaCross sectioncm**2meta.id.cross;phys.atmol.crossSectiondoublee_sigmaStatistical uncertainty in sigma (1)cm**2stat.errordoubleJ/ApJ/767/47/table3Fe^16+^ single ionization cross sectionrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintE[315/3212] Collision energyeVphys.energyfloatsigmaCross sectioncm**2meta.id.cross;phys.atmol.crossSectiondoublee_sigmaStatistical uncertainty in sigma (1)cm**2stat.errordoubleJ/ApJ/767/47/table4Fe^17+^ single ionization cross sectionrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintE[315/3212] Collision energyeVphys.energyfloatsigmaCross sectioncm**2meta.id.cross;phys.atmol.crossSectiondoublee_sigmaStatistical uncertainty in sigma (1)cm**2stat.errordouble