Quadrupole-octupole deformations and high-K isomeric states in heavy nuclei

The manifestation of complex quadrupole-octupole shapes in atomic nuclei leads to variety of specific phenomena and effects in their collective and single particle (s.p.) motions, such as the appearance of alternating-parity bands in even-even nuclei as well as quasi parity-doublet sequences and mixed-parity s.p. states in odd-mass nuclei. After a brief overview of these phenomena and their description within a recently developed model formalism [1]-[3], the influence of the quadrupole-octupole deformations on the formation and the magnetic properties of high-K isomeric states in even-even nuclei will be discussed. Results of a recent study [4] of two-quasiparticle (2qp) isomeric states within a reflection-asymmetric deformed shell model with pairing correlations will be presented. Within this framework the behaviour of 2qp energies and magnetic dipole moments is examined over a wide range in the plane of quadrupole and octupole deformations [4]. The effect of the octupole deformation on the s.p. orbitals which form the isomeric state as well as on the respective 2qp energy will be demonstrated. It will be shown that in most of the considered nuclei the magnetic moments of the two-quasiparticle isomeric states exhibit a pronounced sensitivity to the octupole deformation. This result may suggest the need of detailed experimental measurements of magnetic moments in heavy deformed nuclei.
[1] N. Minkov, P. Yotov, S. Drenska and W. Scheid, J. Phys. G 32, 497 (2006).
[2] N. Minkov et al, Phys. Rev. C, 73, 044315 (2006); Phys. Rev. C, 76, 034324 (2007); Phys. Rev. C 85, 034306 (2012).
[3] N. Minkov, S. Drenska, M. Strecker and W. Scheid, J. Phys. G 36, 025108 (2009); J. Phys. G 37, 025103 (2010).
[4] P. M. Walker and N. Minkov, Phys. Lett. B 694, 119122 (2010).