Instantaneous-shape sampling for calculation of the electromagnetic dipole strength in transitional nuclei

Zhang, S. Q.; Bentley, Ian; Brant, S.; Dönau, F.; Frauendorf, S.; Kämpfer, B.; Schwengner, R.; Wagner, A.

doi:10.1103/physrevc.80.021307

Cited by 17 publications

(19 citation statements)

References 23 publications

(28 reference statements)

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“…Taking into account collisional damping by applying a Lorentzian with an energy-dependent width = αE 2 MeV, with α = 0.014 MeV −1 , as suggested in Ref. [20], the calculated curve gets more smooth. Moreover, the calculated curve has two maxima at about 9 MeV and 11.5 MeV, respectively, which are relicts of the underlying particle-hole spectrum.…”

Section: Iss-qrpa Calculationsmentioning

confidence: 87%

“…[20], a series of QRPA calculations is performed that sample instantaneous quadrupole shapes of the collective motion in the nuclear ground state. The total absorption cross section is found by superimposing all these samples according to their probabilities, which are calculated using the interacting-boson approximation (IBA).…”

Section: Iss-qrpa Calculationsmentioning

confidence: 99%

“…In Sec. III, the experimental results are compared with results of calculations on the basis of the quasiparticle random-phase approximation, including instantaneous-shape sampling [20], taking into account shape fluctuations in soft nuclei.…”

Section: Introductionmentioning

confidence: 99%

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Dipole strength inLa139below the neutron-separation energy

et al. 2010

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The γ -ray strength function is an important input quantity for the determination of the photoreaction rate and the neutron capture rate for astrophysics as well as for nuclear technologies. To test model predictions, the photoabsorption cross section of 139 La up to the neutron-separation energy was measured using bremsstrahlung produced at the electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf with an electron beam of 11.5 MeV kinetic energy. The experimental data were analyzed by applying Monte Carlo simulations of γ -ray cascades to obtain the intensities of the ground-state transitions and their branching ratios. We found a significant enhancement of electric dipole strength in the energy range from 6 to 10 MeV that may be related with a pygmy dipole resonance. The present data are combined with photoneutron cross sections for 139 La and compared with results of calculations on the basis of a quasiparticle-random-phase approximation using an instantaneous-shape sampling.

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Section: Iss-qrpa Calculationsmentioning

confidence: 87%

Section: Iss-qrpa Calculationsmentioning

confidence: 99%

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Dipole strength inLa139below the neutron-separation energy

et al. 2010

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“…Another weakness of the IBM-1 Hamiltonian used, is that it is not capable of producing a triaxial minimum. Experimental evidence indicates that some of the studied nuclei change from oblate to triaxial and eventually to prolate shape as the number of neutrons increases [21]. Triaxial shapes result in experimental 2 + γ levels which are lower than those produced by the IBM mapping procedure.…”

Section: Energies and Transition Probabilities For Selected Nucleimentioning

confidence: 87%

Microscopic calculation of interacting boson model parameters by potential-energy surface mapping

Bentley

Frauendorf

2011

Phys. Rev. C

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A coherent state technique is used to generate an Interacting Boson Model (IBM) Hamiltonian energy surface which is adjusted to match a mean field energy surface. This technique allows for calculation of IBM Hamiltonian parameters, prediction of properties of low lying collective states, as well as generation of probability distributions of various shapes in the ground state of transitional nuclei. The last two of which are of astrophysical interest. The results for krypton, molybdenum, palladium, cadmium, gadolinium, dysprosium and erbium nuclei are compared with experiment.

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“…ISS was suggested in Ref. [1], where it was applied to the Mo, Zr, and Sr isotopes. Further it was applied to 139 La [2].…”

Section: Introductionmentioning

confidence: 99%

Instantaneous shape sampling: A model for theγ-absorption cross section of transitional nuclei

et al. 2011

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The influence of the quadrupole shape fluctuations on the dipole vibrations in transitional nuclei is investigated in the framework of the Instantaneous Shape Sampling Model, which combines the Interacting Boson Model for the slow collective quadrupole motion with the Random Phase Approximation for the rapid dipole vibrations. Coupling to the complex background configurations is taken into account by folding the results with a Lorentzian with an energy dependent width. The low-energy energy portion of the γ-absorption cross section, which is important for photo-nuclear processes, is studied for the isotopic series of Kr, Xe, Ba, and Sm. The experimental cross sections are well reproduced. The low-energy cross section is determined by the Landau fragmentation of the dipole strength and its redistribution caused by the shape fluctuations. Collisional damping only wipes out fluctuations of the absorption cross section, generating the smooth energy dependence observed in experiment. In the case of semi-magic nuclei, shallow pygmy resonances are found in agreement with experiment.

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Instantaneous-shape sampling for calculation of the electromagnetic dipole strength in transitional nuclei

Cited by 17 publications

References 23 publications

Dipole strength inLa139below the neutron-separation energy

Dipole strength inLa139below the neutron-separation energy

Microscopic calculation of interacting boson model parameters by potential-energy surface mapping

Instantaneous shape sampling: A model for theγ-absorption cross section of transitional nuclei

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