Wobbling Motion in Triaxial Superdeformed Nuclei

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Wobbling Motion in Triaxial Superdeformed Nuclei
Masayuki Matsuzaki
Fukuoka University of Education
based on MM, Shimizu and Matsuyanagi, PR C65,
041303(R) and C69, 034325
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Shell gap ? stable configurations
Superdeformation
single particle energy
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2
deformation
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Shell gaps in Nilsson diagram at
neutron
proton
? Suggest triaxial superdeformation (TSD) around
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? deformation in rotating systems
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-----?20?
TSD
ND
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-----?-20?
TSD
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R.Bengtsson, http//www.matfys.lth.se/ragnar/TSD-
ensyst.html
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TSD (?gt0) TSD(?lt0) ND
R.Bengtsson, http//www.matfys.lth.se/ragnar/TSD-
ensyst.html
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Triaxial ? rotations about 3 axes are possible ?
wobbling
phonon
rot
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TSD1 0 phonon (yrast)
TSD2 1 phonon
TSD3 2 phonon
TSD4 another conf.
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?20? contradicts irrotational ?
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• Rotating odd-mass nucleus can be regarded as
  rotor plus 1qp
• 1qp also carries moment of inertia
• Thus, inertia of the whole system should be
  considered (in contrast to PRM)

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Irrotational QP align ? ?
wobbling allowed
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(If inertia are constant,
)
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Extremely collective as an RPA solution but
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Parameterizations of triaxial deformation
?(dens)20rather than ?(Nils)20 resolves
discrepancy in B(E2) ratio
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TSD1 0 phonon (yrast)
TSD2 1 phonon
TSD3 2 phonon
TSD4 another conf.
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2 phonon
1 phonon
indicates softening of potential
? Removal of 1qp makes wobbling unstable
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Summary

• ?Jx from QP alignment superimposed on irrot.-like
  inertia brings Jx gt Jy for ?gt0 --- This assures
  the existence of wobbling exc.
• Wobbling mode in 163Lu is naturally described
  semi-quantitatively in terms of RPA
• Anharmonicity of 2-phonon states suggests
  softening of potential surface