Laboratory Measurements of FexxivLine Emission: \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\c

Measurement of Emission Cross Sections for n = 3 → 2 Lines in Li-like Fe 23+

“…This combination is needed because the RR cross sections are about 3 orders of magnitude smaller than the electron impact excitation cross sections of L-shell ions, making it necessary to observe with largearea detectors for long times without electronic gain drift. In this Letter we report our results for the three Fe xxiv n p 3 r 2 lines ( , , and ) that in pre3p r 2s 3p r 2s 3d r 2 p 3/2 1/2 1/2 1/2 5/2 3/2 vious measurements were normalized to theoretical values (Gu et al 1999b). …”

“…For the crystal spectrometer, factor G includes not only the effect of the angular distribution of the polarized radiation but also the response of the crystal reflectivity to polarized radiation (Beiersdorfer et al , 1996Gu et al 1999b). For the crystal reflectivity, we used a value averaged between perfect and mosaic crystals (Henke, Gullikson, & Davis 1993).…”

“…The cross sections from the present measurement are compared with the theoretical values of the cross sections from R-matrix calculations by Berrington & Tully (1997). These cross sections have been used by Gu et al (1999b) for normalizing their line intensity measurements. The emission cross sections from Berrington & Tully (1997) include cascade contributions from and 4. n p 3 In principle, cascades from all n levels can contribute to the measured emission cross section, whereby the total contribution from all cascades is estimated to be about 15% (Gu et al 1999b).…”

“…These cross sections have been used by Gu et al (1999b) for normalizing their line intensity measurements. The emission cross sections from Berrington & Tully (1997) include cascade contributions from and 4. n p 3 In principle, cascades from all n levels can contribute to the measured emission cross section, whereby the total contribution from all cascades is estimated to be about 15% (Gu et al 1999b). Adding cascade contributions from to the caln ≥ 5 culated values will increase the calculated emission cross sections.…”

“…To address this need, the laboratory astrophysics program utilizing the electron beam ion trap facility EBIT-II at the Lawrence Livermore National Laboratory has produced detailed sets of Fe L-shell line positions and relative line intensities (Brown et al 1999a). It also has measured a number of line emission cross sections (Gu et al 1999b(Gu et al , 2001, where the Fe L-shell line emission measurements were normalized to theoretical calculations.…”