Are octupole vibrations harmonic?

Metlay, M.P.; Johnson, John L.; Canterbury, Jesse D.; Cottle, P. D.; Nestor, C.W.; Raman, S.; Zelevinsky, Vladimir

doi:10.1103/physrevc.52.1801

Cited by 15 publications

(22 citation statements)

References 35 publications

(29 reference statements)

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“…Since the low energy octupole strength is known often to be fragmented among a number of 3 − states it might be more appropriate to consider all of this strength rather than just that in the 3 1 − state. Metlay et al [39] have plotted these measured total strengths as a function of the centroid energy.…”

Section: B Comparison With Measured Fusion Barriersmentioning

confidence: 99%

Systematic failure of the Woods-Saxon nuclear potential to describe both fusion and elastic scattering: Possible need for a new dynamical approach to fusion

et al. 2004

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A large number of precision fusion excitation functions, at energies above the average fusion barriers, have been fitted using the Woods-Saxon form for the nuclear potential in a barrier passing model of fusion. They give values for the empirical diffuseness parameter a ranging between 0.75 and 1.5 fm, compared with values of about 0.65 fm which generally reproduce elastic scattering data. There is a clear tendency for the deduced a to increase strongly with the reaction charge product Z 1 Z 2 , and some evidence for the effect of nuclear structure on the value of a, particularly with regard to the degree of neutron richness of the fusing nuclei, and possibly with regard to deformation. The measured fusion-barrier energies are always lower than those of the bare potentials used, which is expected as a result of adiabatic coupling to high energy collective states. This difference increases with increasing Z 1 Z 2 and calculations show that about 1 / 3 of it may be attributed to coupling to the isoscalar giant-quadrupole resonances in the target and projectile. Coupling to all giant resonances may account for a significant part. Fluctuations about the trend line may be due to systematic errors in the data and/or structure effects such as coupling to collective octupole states. Previously suggested reasons for the large values of a have been related to departures from the Woods-Saxon potential and to dissipative effects. This work suggests that the apparently large values of a may be an artifact of trying to describe the dynamical fusion process by use of a static potential. Another partial explaination might reside in fusion inhibition, due for example to deep-inelastic scattering, again a process requiring dynamical calculations.

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Section: B Comparison With Measured Fusion Barriersmentioning

confidence: 99%

Systematic failure of the Woods-Saxon nuclear potential to describe both fusion and elastic scattering: Possible need for a new dynamical approach to fusion

et al. 2004

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“…Since K = 0 bands can fall below the K = 0 octupole excitation band, it is essential for a complete theory of the octupole excitations in deformed nuclei. We note that collective models can be constructed that provide formulas relating the quadrupole excitation energies to the octupole energies, and octupole energies to the B(E3) transition strengths [35,36].…”

Section: Discussionmentioning

confidence: 99%

Global systematics of octupole excitations in even-even nuclei

2011

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We present a computational methodology for a theory of the lowest octupole excitations applicable to all even-even nuclei beyond the lightest. The theory is the well-known generator-coordinate extension (GCM) of the Hartree-Fock-Bogoliubov self-consistent mean field theory (HFB). We use the discrete-basis Hill-Wheeler method (HW) to compute the wave functions with an interaction from the Gogny family of Hamiltonians. Comparing to the compiled experimental data on octupole excitations, we find that the performance of the theory depends on the deformation characteristics of the nucleus. For nondeformed nuclei, the theory reproduces the energies to about ±20 % apart from an overall scale factor of ≈ 1.6. The performance is somewhat poorer for (quadrupole) deformed nuclei, and for both together the dispersion of the scaled energies about the experimental values is about ±25 %. This compares favorably with the performance of similar theories of the quadrupole excitations. Nuclei having static octupole deformations in HFB form a special category. These nuclei have the smallest measured octupole excitation energies as well as the smallest predicted energies. However, in these cases the energies are seriously underpredicted by the theory.We find that a simple two-configuration approximation, the Minimization After Projection method,

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“…[25] in the global review of octupole vibrations provides a clear correlation between the two modes. Recent measurements for the long chain of even-even xenon isotopes [24] show precisely such a correlation, with a rather large magnitude for the parameter x that exceeds the expectations for the anharmonic mode-mode coupling based on the standard RPA estimates.…”

Section: Microscopic Justification Of Enhancementmentioning

confidence: 98%

“…The model is a generalization of the approach suggested in Ref. [25] for a global analysis of quadrupole-octupole correlations. This idea was later used for the explanation of such correlations seen in the experimental data for xenon isotopes [24] and in the schematic arguments applied to the ehnancement of the Schiff moment in Ref.…”

Section: Microscopic Justification Of Enhancementmentioning

confidence: 99%

Nuclear Schiff moment and soft vibrational modes

2008

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The atomic electric dipole moment (EDM) currently searched by a number of experimental groups requires that both parity and time-reversal invariance be violated. According to current theoretical understanding, the EDM is induced by the nuclear Schiff moment. The enhancement of the Schiff moment by the combination of static quadrupole and octupole deformation was predicted earlier.Here we study a further idea of the possible enhancement in the absence of static deformation but in a nuclear system with soft collective vibrations of two types. Both analytical approximation and numerical solution of the simplified problem confirm the presence of the enhancement. We discuss related aspects of nuclear structure which should be studied beyond mean-field and random phase approximations.

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Are octupole vibrations harmonic?

Cited by 15 publications

References 35 publications

Systematic failure of the Woods-Saxon nuclear potential to describe both fusion and elastic scattering: Possible need for a new dynamical approach to fusion

Systematic failure of the Woods-Saxon nuclear potential to describe both fusion and elastic scattering: Possible need for a new dynamical approach to fusion

Global systematics of octupole excitations in even-even nuclei

Nuclear Schiff moment and soft vibrational modes

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