Photon Scattering by Nuclei

Grosse, E.; Junghans, A.

doi:10.1007/978-3-642-30696-9_2

Cited by 2 publications

(3 citation statements)

References 255 publications

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“…mainly narrow peaks, which were interpreted as strength apparently of other character than isovector electric dipole [8,9,[21][22][23]. Even if it has minor importance for total photon absorption and the sum rules, it may influence the decay of the compound nucleus and consequently also the cross sections of capture reactions.…”

Section: Empirical Parametrization Of Minor Strengthmentioning

confidence: 99%

“…The nuclear level density will be described on the same grounds leading to collective enhancement [7]. a e-mail: a.junghans@hzdr.de b e-mail: e.grosse@tu-dresden.de A purely phenomenological parametrization of minor strengths on the low energy tail of the GDR is presented based on most of the available experimental data [8,9]. With these quantities averaged neutron capture cross sections can be calculated and are compared with experimental Maxwellian averaged cross sections [10,11].…”

Section: Introductionmentioning

confidence: 99%

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Breaking of axial symmetry in excited nuclei as identified in experimental data

2017

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Abstract.A phenomenological prediction for radiative neutron capture is presented and compared to recent compilations of Maxwellian averaged cross sections and average radiative widths. Photon strength functions and nuclear level densities near the neutron separation energy are extracted from data without the assumption of axial symmetry -at variance to common usage. A satisfactory description is reached with a small number of global parameters when theoretical predictions on triaxiality (from constrained HFB calculations with the Gogny D1S interaction) are inserted into conventional calculations of radiative neutron capture. The photon strength is parametrized using the sum of three Lorentzians (TLO) in accordance to the dipole sum rule. The positions and widths are accounted for by the droplet model with surface dissipation without locally adjusted parameters. Level densities are influenced strongly by the significant collective enhancement based on the breaking of axial symmetry. With the less stringent requirement of invariance against rotation by 180 • a global set of parameters which allows to describe the photon strength function and the level densities in the nuclear mass range from mass number 50 < A < 250 is found.

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Section: Empirical Parametrization Of Minor Strengthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Breaking of axial symmetry in excited nuclei as identified in experimental data

2017

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“…These curves result from TLO with an integrated cross section equivalent to the classical sum rule, divided equally between terms for k=1-3 [16,18,20,62]. Thus the TLOprediction for the absorption cross section into the isovector E1-mode s g ( )…”

Section: Isovector Giant Dipole Resonancesmentioning

confidence: 99%

Effect of broken axial symmetry on the electric dipole strength and the collective enhancement of level densities in heavy nuclei

2017

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The basic parameters for calculations of radiative neutron capture , photon strength functions and nuclear level densities near the neutron separation energy are determined based on experimental data without an ad-hoc assumption about axial symmetry -at variance to previous analysis. Surprisingly few global fit parameters are needed in addition to information on nuclear deformation, taken from Hartree Fock Bogolyubov (HFB) calculations with the Gogny force, and the generator coordinator method (GCM) assures properly defined angular momentum. For a large number of nuclei the GDR shapes and the photon strength are described by the sum of three Lorentzians (TLO), extrapolated to low energies and normalized in accordance to the dipole sum rule. Level densities are influenced strongly by the significant collective enhancement based on the breaking of shape symmetry. The replacement of axial symmetry by the less stringent requirement of invariance against rotation by 180 degree leads to a novel prediction for radiative neutron capture. It compares well to recent compilations of average radiative widths and Maxwellian average cross sections for neutron capture by even target nuclei. An extension to higher spin promises a reliable prediction for various compound nuclear reactions also outside the valley of stability. Such predictions are of high importance for future nuclear energy systems and waste transmutation as well as for the understanding of the cosmic synthesis of heavy elements. Fig. 1: Correlation between cos(3γ) and Q i in ≈ 130even nuclei with 60

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Photon Scattering by Nuclei

Cited by 2 publications

References 255 publications

Breaking of axial symmetry in excited nuclei as identified in experimental data

Breaking of axial symmetry in excited nuclei as identified in experimental data

Effect of broken axial symmetry on the electric dipole strength and the collective enhancement of level densities in heavy nuclei

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