Beam-Foil Mean Life Measurements of Levels in N I–N V

1974 ◽  
Vol 52 (19) ◽  
pp. 1895-1902 ◽  
Author(s):  
J. A. Kernahan ◽  
A. E. Livingston ◽  
E. H. Pinnington
Keyword(s):  
Wavelength Range ◽  
Theoretical Calculations ◽  
Closed Shell ◽  
Oscillator Strengths ◽  
Electron Theory ◽  
Beam Foil ◽  
Experimental Absorption ◽  
Foil Technique

Using the beam-foil technique, we have measured radiative mean lives for 41 levels in N I–N V within the wavelength range 374 to 2064 Å. In some cases we deduce experimental absorption oscillator strengths for comparison with recent theoretical calculations of Nicolaides, who used the 'Non-closed shell many electron theory' of Öksüz and Sinanoğlu. The agreement for lines of higher stages of ionization is very good.

Beam-foil spectroscopy of neon in the wavelength range 209–602 Å

1977 ◽  
Vol 55 (15) ◽  
pp. 1310-1315 ◽  
Author(s):  
J. A. Kernahan ◽  
K. E. Donnelly ◽  
E. H. Pinnington
Keyword(s):  
Wavelength Range ◽  
Theoretical Calculations ◽  
Experimental Values ◽  
Beam Foil ◽  
Foil Technique

We have measured radiative mean lives from 24 transitions in Ne II–Ne VI in the wavelength range 209–602 Å using the beam-foil technique. We present the first experimental mean lives for nine levels, and our results are compared where possible with theoretical calculations and with other experimental values.

Mean-life measurements for some fluorine transitions in the quartz region

1978 ◽  
Vol 56 (5) ◽  
pp. 517-521 ◽  
Author(s):  
E. H. Pinnington ◽  
D. J. G. Irwin ◽  
A. E. Livingston ◽  
J. A. Kernahan ◽  
R. N. Gosselin ◽  
...  
Keyword(s):  
Data Analysis ◽  
Wavelength Range ◽  
Decay Curve ◽  
The Mean ◽  
Beam Foil ◽  
Foil Technique

The beam-foil technique has been applied to the measurement of the mean lives of seven terms in F III and three terms in F IV, giving rise to transitions in the wavelength range 2150 to 3200 Å. The results are compared with other experimental and theoretical values. Forecasts are made for f-values of some F IV transitions below 500 Å in the 2s2p3–2s22p3p array. Examples of the application of the arbitrarily normalized decay curve (ANDC) method for including the effects of cascade repopulation in the data analysis are discussed.

Fluorine mean-life measurements below 1000 Å using the beam–foil technique

1976 ◽  
Vol 54 (10) ◽  
pp. 1014-1021 ◽  
Author(s):  
E. H. Pinnington ◽  
D. J. G. Irwin ◽  
A. E. Livingston ◽  
J. A. Kernahan
Keyword(s):  
Satellite Data ◽  
Wavelength Region ◽  
Wave Functions ◽  
Interstellar Clouds ◽  
Beam Foil ◽  
Foil Technique ◽  
Good Agreement

We have used the beam–foil technique to measure mean lives for 16 transitions in F I–F IV in the wavelength region 400 Å–1000 Å. Good agreement is found with the results of recent calculations, particularly those employing correlated wave functions. The f-value trends for 5 isoelectronic sequences are presented in detail (2p5 2P0–2p43s2 D and 2p5 2P0–2p43s 2P in F I; 2p4 3P–2p33s 3D0 in F II; 2p3 2D0–2s2p4 2D and 2p3 4S0–2s2p4 4P in F III). Our f value for the 955 Å multiplet in F I is also used in conjunction with some new satellite data to show that the fluorine abundance is apparently depleted in interstellar clouds by a factor of at least 3 below its solar value.

The Measurement of f-values for Lines of Astrophysical Interest by Beam-Foil Spectroscopy

1978 ◽  
Vol 3 (4) ◽  
pp. 263-264
Author(s):  
J. E. Ross ◽  
B. J. O’Mara
Keyword(s):  
Life Time ◽  
Absolute Number ◽  
Branching Ratios ◽  
Oscillator Strengths ◽  
Separate Experiment ◽  
Number Density ◽  
Reasonable Accuracy ◽  
Initial Excitation ◽  
The One ◽  
Beam Foil

The necessity of having accurate oscillator strengths in astrophysical applications is well known. The apparent discrepancy which existed between the solar and meteoritic abundance of iron is just one example of the problems which can arise from poor f-values. An excellent critique of methods for determining both absolute and relative f-values has been given by Blackwell & Collins (1972). Their comments on life-time techniques provide a clear indication of both the advantages and difficulties associated with these techniques: “In principle, a life-time method, as exemplified by the technique of beam foil spectroscopy, described for example by Wiese (1970), has the fundamental advantage that in some restricted circumstances its application does not depend upon a temperature measurement or any assumption of themodynamic equilibrium in the source: in addition it gives an absolute result without the need of an absolute number density of atoms. The hope is sometimes expressed that the method of beam foil spectroscopy will yield oscillator strengths of the required accuracy. In practice, the technique suffers from the difficulty that although the life-time of an excited state can be measured with reasonable accuracy, it is also necessary to measure in a separate experiment the branching ratios for radiative de-excitation. As these ratios are usually measured by an arc method, the accuracy of the final oscillator strengths is limited by the deficiencies of this source. Also, some atoms in the beam may be excited to higher levels than the one being examined, and because of the nature of the initial excitation is unknown, radiative de-excitation (cascading) takes place to this lower level in a way that is wholly unpredictable. This difficulty is especially important for levels of low excitation.” In this talk techniques will be described for overcoming the cascading problem in beam foil spectroscopy and for measuring the associated branching ratios.

scholarly journals The Solar X-Ray Line Spectrum 5.5 – 12Å

1984 ◽  
Vol 86 ◽  
pp. 136-136
Author(s):  
D.L. McKenzie
Keyword(s):  
Wavelength Range ◽  
Theoretical Calculations ◽  
High Sensitivity ◽  
Line Spectrum ◽  
Low Density ◽  
X Ray ◽  
R Ratio ◽  
G Ratio ◽  
Limiting Value ◽  
Line Strengths

The SOLEX X-ray spectrometers on the USAF P78–1 satellite have measured solar X-ray spectra in the 5.5–12Å range under a variety of flaring and nonflaring conditions. High sensitivity, obtained by summing data from several successive spectral scans, enabled the detection of 80 lines, 17 of which remain unidentified. The stronger lines were observed with individual scans during the course of flare development. This capability, along with the use of nonflare spectra, facilitated the identification of several lines. The lines of Fe XXII - XXIV, present in hot flare plasmas, are prominent in this wavelength range. For many of these lines, theoretical and observed line strengths will be compared. Diagnostically useful line ratios were evaluated for the helium-like species Mg XI, Al XII, and Si XIII. The density-sensitive R ratio was consistent with theoretical calculations of the low-density limiting value for Mg XI and Si XIII, the only species for which it was evaluated. In all cases the G ratio was below calculated values.

Systematic problems with the beam-foil technique

1970 ◽  
Vol 90 ◽  
pp. 223-227 ◽  
Author(s):  
H. Oona ◽  
W.S. Bickel
Keyword(s):  
Beam Foil ◽  
Foil Technique

A study of pre-equilibrium emission in α-induced reactions on 121,123Sb

1991 ◽  
Vol 69 (11) ◽  
pp. 1376-1382 ◽  
Author(s):  
B. P. Singh ◽  
H. D. Bhardwaj ◽  
R. Prasad
Keyword(s):  
Compound Nucleus ◽  
Mass Number ◽  
Neutron Emission ◽  
Theoretical Calculations ◽  
Exciton Model ◽  
Excitation Functions ◽  
Stacked Foil Technique ◽  
Equilibrium Emission ◽  
Charged Particle Emission ◽  
Foil Technique

Excitation functions for the 121Sb (α, n)+ 123Sb(α, 3n),,21Sb(α, 2n)+ 123Sb(α, 4n), 121Sb(α, 4n), 121Sb(α, 3np), and 123Sb(α, n) reactions are measured in the energy range 30–60 MeV using the stacked foil technique. In the cases of the 121Sb(α, n)+ 123Sb(α, 3n) and 121Sb(α, 2n)+ 123Sb(α, 4n) reaction pairs, the excitation functions for individual reactions were deduced using theoretical calculations. Excitation functions are also calculated theoretically using the compound-nucleus model with and without the inclusion of a pre-equilibrium emission. As expected, inclusion of a pre-equilibrium contribution based on the exciton model along with compound-nucleus calculations using the Hauser–Feshbach formalism reproduces well the measured excitation functions. Analysis of the data indicates a preference for a first chance neutron emission over charged-particle emission, and interesting trends in the energy and mass-number dependence of the pre-equilibrium fraction are observed.

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