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Experimental oscill...
Experimental oscillator strengths for forbidden lines in complex spectra
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- Hartman, Henrik (author)
- Lund University,Lunds universitet,Astronomi - Genomgår omorganisation,Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation,Naturvetenskapliga fakulteten,Lund Observatory - Undergoing reorganization,Department of Astronomy and Theoretical Physics - Undergoing reorganization,Faculty of Science
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- Johansson, Sveneric (author)
- Lund University,Lunds universitet,Astronomi - Genomgår omorganisation,Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation,Naturvetenskapliga fakulteten,Lund Observatory - Undergoing reorganization,Department of Astronomy and Theoretical Physics - Undergoing reorganization,Faculty of Science
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- Lundberg, Hans (author)
- Lund University,Lunds universitet,Atomfysik,Fysiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Atomic Physics,Department of Physics,Departments at LTH,Faculty of Engineering, LTH
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Lundin, P (author)
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Mannervik, S (author)
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Schef, P (author)
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(creator_code:org_t)
- 2005
- 2005
- English.
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In: Physica Scripta. - 0281-1847. ; T119, s. 40-44
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Abstract
Subject headings
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- In dilute astrophysical plasmas, such as planetary nebulae and H II regions, strong lines appear that only have weak, if any, correspondence to the spectrum of laboratory light sources. Some of these are parity forbidden lines, i.e. emission from long-lived metastable states that cannot decay via normal electric dipole (E1) routes but only via the slower M1 and E2 transitions. The long lifetime of the upper levels and their sensitivity to collisions make the lines good diagnostics of the emitting plasma, but then the transition probability, or A-value, of these lines must be known. We report on a technique to experimentally determine A-values for forbidden lines using the method of combining the lifetime of the upper level with the branching fractions for the different decay channels. The lifetime is measured using the laser probing technique (LPT) on a stored ion beam. Since these lines are rarely produced in laboratory plasmas, we use astrophysical spectra to determine the branching fractions (BF). The lifetime and the BF then give the A-value, which is one quantity needed for modeling the spectrum of the plasma emitting the forbidden lines. The present measurements are performed within the FERRUM project, an international collaboration producing and evaluating transition probabilities for iron group element lines of astrophysical importance [Johansson, P. I. S. et al., Physica Scripta T100, 71 (2002).]
Subject headings
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Keyword
- Transition probability
- Decay channels
- Electric dipole
- Branching fractions
Publication and Content Type
- kon (subject category)
- ref (subject category)
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