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Title: Nuclear hyperdeformation and the Jacobi shape transition

Abstract

The possibility that atomic nuclei possess stable, extremely elongated (hyperdeformed) shapes at very high angular momentum is investigated in the light of the most recent experimental results. The crucial role of the Jacobi shape transitions for the population of hyperdeformed states is discussed and emphasized. State-of-the-art mean-field calculations including the most recent parametrization of the liquid-drop energy together with thermal effects and minimization algorithms allowing the spanning of a large deformation space predict the existence of a region of hyperdeformed nuclei in the mass A{approx}120-130: Te, Cs, Xe, I, and Ba isotopes. In agreement with predictions presented in reviews by J. Dudek, K. Pomorski, N. Schunck, and N. Dubray [Eur. Phys. J. A 20, 15 (2003)] and J. Dudek, N. Schunck, and N. Dubray [Acta Phys Pol. B 36, 975 (2005)], our extended calculations predict that only very short hyperdeformed bands composed of a dozen discrete transitions at the most are to be expected-in contrast to the results known for the superdeformed bands. We stress the importance of the experimental research in terms of multiple-{gamma} correlation analysis that proved to be very efficient for the superdeformation studies and seems very helpful in the even more difficult search for the discretemore » transitions in hyperdeformed nuclei.« less

Authors:
 [1];  [2];  [3];  [4]
  1. Departamento de Fisica Teorica, Universidad Autonoma de Madrid, 28049 Cantoblanco, Madrid (Spain)
  2. (Denmark)
  3. Institut de Recherches Subatomiques IN2P3-CNRS/Universite Louis Pasteur, F-67037 Strasbourg Cedex 2 (France)
  4. Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark)
Publication Date:
OSTI Identifier:
20995266
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevC.75.054304; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ANGULAR MOMENTUM; BARIUM ISOTOPES; CESIUM ISOTOPES; IODINE ISOTOPES; MEAN-FIELD THEORY; NUCLEAR DEFORMATION; SHAPE; SUPERDEFORMED NUCLEI; TELLURIUM ISOTOPES; TEMPERATURE DEPENDENCE; XENON ISOTOPES

Citation Formats

Schunck, N., Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Dudek, J., and Herskind, B. Nuclear hyperdeformation and the Jacobi shape transition. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.054304.
Schunck, N., Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Dudek, J., & Herskind, B. Nuclear hyperdeformation and the Jacobi shape transition. United States. doi:10.1103/PHYSREVC.75.054304.
Schunck, N., Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Dudek, J., and Herskind, B. Tue . "Nuclear hyperdeformation and the Jacobi shape transition". United States. doi:10.1103/PHYSREVC.75.054304.
@article{osti_20995266,
title = {Nuclear hyperdeformation and the Jacobi shape transition},
author = {Schunck, N. and Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen and Dudek, J. and Herskind, B.},
abstractNote = {The possibility that atomic nuclei possess stable, extremely elongated (hyperdeformed) shapes at very high angular momentum is investigated in the light of the most recent experimental results. The crucial role of the Jacobi shape transitions for the population of hyperdeformed states is discussed and emphasized. State-of-the-art mean-field calculations including the most recent parametrization of the liquid-drop energy together with thermal effects and minimization algorithms allowing the spanning of a large deformation space predict the existence of a region of hyperdeformed nuclei in the mass A{approx}120-130: Te, Cs, Xe, I, and Ba isotopes. In agreement with predictions presented in reviews by J. Dudek, K. Pomorski, N. Schunck, and N. Dubray [Eur. Phys. J. A 20, 15 (2003)] and J. Dudek, N. Schunck, and N. Dubray [Acta Phys Pol. B 36, 975 (2005)], our extended calculations predict that only very short hyperdeformed bands composed of a dozen discrete transitions at the most are to be expected-in contrast to the results known for the superdeformed bands. We stress the importance of the experimental research in terms of multiple-{gamma} correlation analysis that proved to be very efficient for the superdeformation studies and seems very helpful in the even more difficult search for the discrete transitions in hyperdeformed nuclei.},
doi = {10.1103/PHYSREVC.75.054304},
journal = {Physical Review. C, Nuclear Physics},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • No abstract prepared.
  • We have studied the continuous gamma radiation from reactions of {sup 48}Ca beams on targets of {sup 50}Ti, {sup 64}Ni, {sup 96}Zr, and {sup 124}Sn at very high angular momentum. In all but the heaviest target, the nuclear moments of inertia rise rapidly with increasing angular momentum and the data suggest that the gamma ray energies may reach a maximum value. Whether this arises from a gradual transition towards a highly deformed Jacobi-like shape, or from other effects, is unclear.
  • The high-energy and discrete {gamma}-ray spectra, as well as the charged particle angular distribution have been measured in the reaction 105 MeV 18O+28Si using the EUROBALL IV, HECTOR and EUCLIDES arrays in order to investigate the predicted Jacobi shape transition in light nuclei. A comparison of the GDR line shape data with the predictions of the thermal shape fluctuation model, based on the most recent rotating liquid drop LSD calculations, shows evidence for such Jacobi shape transition in hot, rapidly rotating 46Ti. The found narrow low-energy component in the GDR line shape is interpreted as the consequence both of themore » elongated shape and of the Coriolis effect.« less
  • The systematic investigation of hyperdeformation (HD) at high spin in the Z=40-58 region of the nuclear chart was performed in the framework of the cranked relativistic mean-field theory. The properties of the moments of inertia of the HD bands, the role of the single-particle and necking degrees of freedom at HD, the spins at which the HD bands become yrast, the possibility to observe discrete HD bands, and so on are discussed in detail.
  • The low-lying dipole strength distributions in the odd-mass isotopes {sup 135,137}Ba were studied in nuclear resonance fluorescence experiments (NRF) performed at the Stuttgart Dynamitron facility using bremsstrahlung beams with end point energies of 4.1, 3.1, and 2.5 MeV. Numerous excited states, most of them unknown so far, were observed in the excitation energy range up to 4 MeV. Detailed spectroscopic information has been obtained on excitation energies, decay widths, decay branching ratios, and transition probabilities. The results for {sup 137}Ba are compared with calculations in the framework of the Quasiparticle-Phonon Model. The new data for {sup 135,137}Ba complete the systematicsmore » of low-lying dipole excitations as observed for the even Ba isotopes {sup 134,136,138}Ba in previous NRF experiments in Stuttgart. The complete systematics within the Ba isotopic chain, exhibiting a nuclear shape transition, is discussed with respect to E1 two-phonon excitations, M1 scissors mode excitations, and in regard to the new critical point symmetries.« less