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Systematic studies of doublet bands in doubly-odd nuclei using a simple model

Systematic studies of doublet bands in doubly-odd nuclei using a simple model. N. Yoshinaga and K. Higashiyama. Department of Physics, Saitama university Department of Physics, Chiba institute of technology. Outline of my talk

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Systematic studies of doublet bands in doubly-odd nuclei using a simple model

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  1. Systematic studies of doublet bands in doubly-odd nuclei using a simple model N. Yoshinaga and K. Higashiyama Department of Physics, Saitama university Department of Physics, Chiba institute of technology Outline of my talk • Experiment studies of doublet bands in A~130 and our theoretical results • A simple theoretical framework and its application to doubly-odd nuclei • Analysis of structure of doublet bands • Summary n-yoshinaga-2007INPC

  2. Experimental studies of doubly-odd nuclei in A~130 Yrast Band configuration Yrare Band Praseodymium T. Koike et al., Phys. Rev. C 63, 061304(R) (2001).

  3. Truncated Shell model calculations 134La 15+ 14+ Core spin 13+ 12+ Proton spin 11+ Neutron spin 10+

  4. Our results of the PTSM calculations (2005) The Pair-truncated shell model (PTSM) reproduces energy levels and electromagnetic properties of doublet bands of doubly-odd nuclei with mass A~130. Band structure of doublet bands is well explained by the movement of two spins of a neutron and a proton, weakly coupled with the even-even core. Thus the PTSM provides us with an ideal tool for a study of doublet bands. However… The calculation becomes quite difficult because the configuration space grows up as the number of valence nucleon increases. We propose a very simple model !

  5. Our Simple Model Quadrupole coupling model Basis state of doubly-odd nucleus : Collective core state (even-even nucleus) : Two-particle state (neutron and proton) Hamiltonian are fixed to describe even-even nucleus !

  6. Theoretical energies and experimental energies configuration

  7. Yrast and Yrare energies for 130La and 128La

  8. Staggering behavior of B(M1)/B(E2) ratios

  9. Analysis of QCM wave functions Effective angle of neutron spin and proton spin Square of core angular momentum Proton spin q R Neutron spin Core spin : Eigenstate obtained by the diagonalization

  10. Angles between neutron and proton, and squares of core spin Angles Core spin

  11. Structure of yrast states M1 transition 134La 14+ 15+ Core spin 12+ 13+ Proton spin 10+ 11+ Neutron spin

  12. Structure of yrast states 134La 14+ 15+ Strong M1 transition Core spin 12+ 13+ Proton spin 10+ 11+ Neutron spin

  13. Structure of yrast states 134La 14+ 15+ Core spin Weak M1 transition 12+ 13+ Proton spin 10+ 11+ Neutron spin

  14. Summary We propose a simple model (QCM) for doublet bands in doubly-odd nuclei, where the neutron and the proton are coupled with the core through quadrupole interactions. The model well reproduces energy spectra and electromagnetic properties of doublet bands. The mechanism of the strong staggering of B(M1)/B(E2) ratios is now well understood. It explains why the strong staggering occurs only in the vibrational or transitional region, and not in the deformed region.

  15. Backups

  16. More about our model Our model is different from the particle-rotor model in two respects. 1. Information of rotor state is extracted from experimental data of even-even nucleus. 2.All interactions are assumed to be of quadrupole types. Interaction strength

  17. Electromagnetic transitions E2 operator : E2 transition of even-even nucleus : same values adopted in PTSM calculations M1 operator : dipole moment of even-even nucleus : same values adopted in PTSM calculations

  18. Partial level scheme of 134La E2 transition M1 transition

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