Nuclear<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>E</mml:mi><mml:mn>1</mml:mn><mml:mn /></mml:math>Overtones

Carver, J.H.; Peaslee, D. C.; Taylor, R.B.

doi:10.1103/physrev.127.2198

Cited by 28 publications

(3 citation statements)

References 30 publications

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“…In calculations of E2 transition energies in O 16 based on particle-hole interactions, Gillet and Vinh-Mau 18 have suggested that the two highest The remaining resonances may be associated with E2 transitions to l/ 7/2 levels, with the recently discussed nuclear El overtones, 20 or the 3#ou resonances postulated by Danos. 21 Further insight into the nature of these resonances will probably have to await higher resolution experiments and angular distribution studies of the particular resonances.…”

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confidence: 94%

Photoneutron Cross-Section Resonances inO16

et al. 1963

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The cross section for the reaction 0 16 (y,w)0 15 has been measured from threshold energy to 60 MeV using bremsstrahlung from the Iowa State University 70-MeV synchrotron. The O 15 radioactivity yield curve was measured and the relative cross section extracted using least-structure analysis. 1 " 3 The resulting relative cross section, the result of least-structure analysis of the average of three yield curves, is shown in Fig. 1. The structure appearing above the giant resonance has appeared in essentially all of a very large number of analyses of individual and averaged yield curves. The errors in least-structure results are highly correlated and vary smoothly over the energy range; consequently error flags have been shown only at a few points. The horizontal error flags above the resonances do not represent imprecision in the resonance energy, but instead they represent the extent to which least-structure analysis would spread an infinitely narrow resonance in the cross section at that energy. This spreading is determined by the full width at half-maximum of a "resolution function" resulting from least-structure smoothing, and it is directly correlated with the average error of the yield function analyzed. Consequently, resolution of resonances above the giant resonance can be improved by improving data precision.Three activation curves were measured in each of two separate experiments in which different samples, beam geometries, and energy control systems were used. In the first experiment data were taken and analyzed in 0. 5-MeV increments, while in the second experiment data were taken and analyzed in 0.483-MeV increments.Radioactivity was measured by detecting the annihilation radiation from the 123-second positron activity of O 15 in a 3x3-in. Nal(Tl) scintillation crystal coupled to an EMI 953IB photomultiplier tube. Samples were bombarded for 3 min, one minute was allowed to elapse during which samples were removed from the synchrotron and placed in a standard counting geometry, and the radioactivity was counted for 3 min. Above 20 MeV, counting rates were typically 500 000 counts per minute. Stability of the counting system was held to ±0. 25% during the experiments by frequent checks with a Na 22 standard source.Samples were cylinders of boric acid 2.8 cm long compressed to a density of 1.4 g/cm 3 . The T "T O^y.nJO 19 CROSS SECTION FROM AVERAGED YIELD DATA .-^-^Ni 30 35 40 ENERGY MEV 50 55 60 FIG. 1. Relative cross section for the reaction 0 16 (y,w)0 15 calculated from the average of three radioactivity yield curves by the least-structure method. 250

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confidence: 94%

Photoneutron Cross-Section Resonances inO16

et al. 1963

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“…Nevertheless several experiments have been reported which indicate that a good deal of cross section remains to be examined in the energy region above 30 Mev (22,23). In light of several theoretical papers which predict resonances at energies above 30 Mev (14,24), a more thorough investigation of this region is indicated.…”

Section: Studies Of Photoreaction Cross Sections In the Regionmentioning

confidence: 99%

Photodisintegration of Calcium-40

Anderson

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Photographs of the display of the analyzer memory Circuit for staircase generator and reset unit Circuit for dosage discriminator Circuit for control unit 4o Decay scheme for major Ca photoproducts 4o Effective decay constant for Ca photoproducts Distribution of chi-squared from background subtraction Yield curves for 0.6z2.4 mode and average of all data Distributions of chi-squared for yield and cross section Reduced yield for average of all data Beam swing comparison and intensity profile Cross section solutions for distorted yields-I Cross section solutions for average yield curves Cross section solutions for individual yield curves

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“…In light of several theoretical papers which predict resonances at energies above 30 Mev (14,24), a more thorough investigation of this region is indicated.…”

Section: Introduction a Historical Backgroundmentioning

confidence: 99%

Photodisintegration of Calcium-40

Anderson

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NuclearE1Overtones

Cited by 28 publications

References 30 publications

Photoneutron Cross-Section Resonances inO16

Photoneutron Cross-Section Resonances inO16

Photodisintegration of Calcium-40

Photodisintegration of Calcium-40

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