scholarly journals Summary of the IRON and OPACITY Projects

1995 ◽  
Vol 10 ◽  
pp. 571-572
Author(s):  
Keith A. Berrington
Keyword(s):  
Cross Sections ◽  
Electron Excitation ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Resonance Structure ◽  
Quantum Numbers ◽  
Sufficient Detail ◽  
Excitation Cross Sections ◽  
Light Ions ◽  
On Line

Considerable effort has been made recently by international collaborations, exploiting advances in atomic physics and in supercomputing, to compute complete sets of accurate data for astrophysically important processes; in particular, the Opacity Project and the IRON Project.The Opacity Project computed atomic data for opacity calculations• for H, He, Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe.• energies of terms having effective quantum numbers v≤10 and total angular momentum L≤3 or 4, all spin and parity combinations;• gƒ-values for all dipole transitions between these bound terms;• total cross sections for photoionizaion from all calculated bound terms, tabulated on a grid of photon energies suitable to describe the resonance structure in sufficient detail to calculate reliable opacities;• line broadening parameters.28 key research papers arising from the Project, together with calculated energies and oscillator strengths for light ions, are reprinted in ‘The Opacity Project Volume 1’ (Opacity Project Team, 1994, IOP Publ. ISBN 0 7503 0288 7). All data are available from TOPbase, an on-line database at the CDS (Cunto et al. 1993, A&A 275, L5).The IRON Project aims to systematically compute electron excitation cross sections for the iron group of elements. Particular attention is given to requirements for the interpretation of data from specific space observations.In the first stage of the Project excitation cross sections have been computed for fine-structure transitions in the ground configuration of all ions of astrophysical interest. These data are essential for the interpretation of IR lines to be observed by ISO, as well as for coronal spectra.

scholarly journals Parametric potential for modelling of highly charged heavy ions

1996 ◽  
Vol 14 (4) ◽  
pp. 575-586 ◽  
Author(s):  
S. Mabong ◽  
G. Maynard ◽  
K. Katsonis
Keyword(s):  
Cross Sections ◽  
Heavy Ions ◽  
Inertial Confinement Fusion ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Inertial Confinement ◽  
Excitation Energies ◽  
Confinement Fusion ◽  
Self Consistent Field ◽  
On Line

Parametric electron-ion potential for fast estimation of atomic data required for “on-line” calculations in inertial confinement fusion (ICF) driven by heavy ions is presented. Comparisons of our results (outer- and inner-shell ionization energies, oscillator strengths, and logarithmic mean excitation energies) with experimental and self-consistent-field (SCF) calculation values are made. Using the wave functions generated by the previously mentioned potential, generalized oscillator strengths and integrated inelastic collision cross sections are computed within the frame of Born approximation.

scholarly journals Electron Impact Excitation Cross Sections for B III

1983 ◽  
Vol 36 (5) ◽  
pp. 659
Author(s):  
PS Ganas ◽  
M Aryafar ◽  
LP Gately
Keyword(s):  
Electron Impact ◽  
Excited States ◽  
Cross Sections ◽  
Born Approximation ◽  
Oscillator Strengths ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Central Potential ◽  
Excitation Cross Sections ◽  
Generalized Oscillator

A realistic analytical central potential with two adjustable parameters is used to generate wavefunctions for the ground and excited states of doubly ionized boron. Generalized oscillator strengths and integrated cross sections from threshold up to 5 keY are calculated in the Born approximation for 2s-ns, 2s-np and 2s-nd excitations. Convenient analytic formulae for the cross sections are presented.

scholarly journals Cross Sections for Electron Impact Excitation of O VI Lines

2011 ◽  
Vol 20 (4) ◽  
Author(s):  
Haykel Elabidi ◽  
Sylvie Sahal-Bréchot ◽  
Nébil Ben Nessib
Keyword(s):  
Fine Structure ◽  
Electron Impact ◽  
Cross Sections ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Atomic Data ◽  
Excitation Cross Sections

AbstractRadiative atomic data and electron impact excitation cross sections for the 2s-2p transitions in O VI for transitions among the fine structure levels belonging to the 1s

scholarly journals On the Interpretation of the Relative Intensities of the Solar XUV Lines of Lithium-Like Ions

1972 ◽  
Vol 14 ◽  
pp. 738-739
Author(s):  
D. R. Flower
Keyword(s):  
Cross Sections ◽  
Electron Excitation ◽  
Energy Separation ◽  
Temperature Structure ◽  
Isoelectronic Sequence ◽  
Ionization Equilibrium ◽  
Excitation Cross Sections ◽  
Powerful Means ◽  
Intensity Ratios ◽  
Equilibrium Calculations

The relative intensities of the 2s–2p and 2l–3l′ (l=0, l′= 1; l= 1, l′ = 0, 2) solar XUV lines of ions in the lithium isoelectronic sequence are sensitive to electron temperature because of the large energy separation of the 2p and 3/’ levels. Recent observations of these lines for three members of the sequence, O+5, Ne+7 and Mg+9 (Heroux and Cohen, 1971), consequently provide a potentially powerful means of studying the temperature structure of the upper chromosphere-corona transition region. These observations have been examined in the light of recent calculations of the electron excitation cross-sections for the relevant transitions (Flower, 1971). It is found that the observed intensity ratios are systematically greater than values calculated assuming that all the lines of a given ion are produced at essentially the same temperature, namely, the temperature for which the ionization equilibrium calculations of Jordan (1969) predict that emission in the lines is most highly favoured. Part of the discrepancy is removed if this assumption is dropped and the emission in each line is calculated separately before taking the ratio. These two calculations do not yield the same result because there is a high temperature tail in the ionization curve of the lithium-like ions which results in the transitions of higher excitation energy, the 2l–3l′ transitions, being enhanced relative to the 2s–2p transition. The unsatisfactory agreement between theory and observation could have important implications for current theories of the ionization equilibrium, but, before definite conclusions can be reached, further observations of the same type need to be made and remaining uncertainties in the cross-sections to be resolved.

Sign in / Sign up

Export Citation Format

Share Document