1 / 23

Shape of L hypernuclei in ( b,g ) deformation plane

Myaing Thi Win, K.Hagino and T.Koike Tohoku University. Shape of L hypernuclei in ( b,g ) deformation plane. University of Aizu-JUSTIPEN-EFES Symposium, “Cutting-Edge Physics of Unstable Nuclei 13 th November 2010. s. d. u. . Outline of this talk. Background Motivation

tuvya
Download Presentation

Shape of L hypernuclei in ( b,g ) deformation plane

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Myaing Thi Win, K.Hagino and T.Koike Tohoku University Shape of L hypernuclei in(b,g) deformation plane University of Aizu-JUSTIPEN-EFES Symposium, “Cutting-Edge Physics of Unstable Nuclei 13th November 2010 s d u  Outline of this talk • Background • Motivation • Formalism and Method • Results • Summary & Conclusion

  2. Impurity effect of L particle • No Pauli principle between nucleons • and lambda particle “Glue-Like Role of ” • an impurity to explore the various changes of the nuclear structure L • Shrinkage Effect in 7LLi • Theoreticallyby 3-body cluster model • Hiyama et al. PRC 59 (1999) 2351 • Experimentally by B(E2) value • K.Tanida,H.Tamura, D.Abe et al ucl.PhysA,684,560(2001) s Λ d u Smaller size or smaller deformation

  3. Self-consistent Mean Field studies on L hypernuclei the presence of strange L-particle • L makes the nucleus more stable • Lextends the drip lines • Lmakes the nucleus shrink • Core polarization effect ,such as Change of total energy and radius of the core • Non-relativistic HF method c.f , D.E.Lanskoy PRC58,3351(98) c.f, M.Rayet, Annals of Phys102,226(76) • Relativistic Mean Field c.f, J.Mares and J.Zofka, Z.Phys.A333,209(89) c.f Y. Sugahara and H.Toki , Prog.Theo.Phys.92,803(94) • Extension of Neutron drip line • Relativistic HFB c.f, D.Vretenar et al, PRC57,R1060(98) • Non-relativistic MF c.f, X.R.Zhou et al, PRC78, 054306(08)

  4. Theoretical and experimental interest Change of properties of nuclei induced by L (size, shape and cluster structure, changes of collective motion, etc...) • My interest • within Mean-field approach s d u Deformation?

  5. Nuclear deformation • Triaxial deformation Schematic level schemes of deformed nuclei L.M.Robledo,R.Rodriguez-Guzman and P.Sarriguren J.Phys.G.Nucl.Part.Phys.36(2009) • Shape of nuclei  important role in determining nuclear properties, such as quadrupole moment and radius. • Evidence for nuclear deformation • Rotational Bands

  6. Previous Studies of Deformation of L hypernuclei • Deformed Skyrme-Hartree Fock approach • No change in deformation due to addition of lambda • X.R.Zhou et.al, PRC76,034312 • Relativistic Mean Field Theory •  Disappearance of nuclear ｄeformation induced by a L • M.T.Win and K.Hagino, PRC78, 054311(08) 6 • SHF and RMF • H.J.Schulze, M.Thi Win, K.Hagino,H.Sagawa Prog.Theo.Phys123,3(10) • Physical origin of deformation changes in terms of lambda and nucleon mean field potentials • compare the results of SHF and RMF • RMF  stronger interaction of lambda with Nuclear core • Disappearance of deformation only in the case of

  7. Motivation • Extend the previous studies by taking into account triaxial degree of freedom • Skyrme Hartree Fock +BCS approach • To study the deformation of L hypernuclei in the full (b,g) plane • arXiv:1010.5561v1 g s b d u Triaxial deformation? • The previous studies of the deformation of Lambda hypernuclei  Axial symmetry Disapperance or change of deformation minimum

  8. Skyrme HF Formalism for Hypernuclei • M.Rayet, Nucl.Phys.A367,381(81) Total Hypernuclear energy • Skyrme parameters for L-N interaction HF equations for hypernuclear system

  9. HF equations for hypernuclear system arising from LN interaction • Skyrme parameters for L-N interaction

  10. Parameter sets of Skyrme type LN Interaction Skyrme typeLN interaction Y.Yamamoto et.al, Prog.Theo.Phys.80,5(88) • five parameters : t0L, x0L, t1L,t2L, t3L, a1L= t1+t2/4 • Fitted to reproduce • Small spin-orbit part is not considered. Similar with nuclear Skyrme force • Using these parameter sets BL and L level spacings （Dsp, Dsd ) as a function of A-2/3 are calculated • the results are within experimental error bar

  11. Calculation method • P.Bonche et.al. Comp.Phys.comu.171(05) r0 = 0.16 fm-3 V0 = -1000MeV fm3 • Application to sd-shell hypernuclei • Skyrme Interaction SGII • Extend ‘EV8 Code’ for hypernuclei • HF+BCS equations  solved by discretizing the single-particle wave function on 3-D Cartesian mesh • Imaginary Time step method • Pairing • BCS approximation with Density dependent pairing interaction

  12. Deformation energy surface of sd shell hypernuclei in (b,g) plane

  13. Results: 28Si , 28Si+L Oblate magic number +L

  14. Results: 24Mg, 24Mg+L prolate +L

  15. Results: 26Mg, 26Mg+L obate prolate Eprolate – Eoblate = 0.39MeV +L

  16. Results: 26Si , 26Si+L oblate prolate Eprolate – Eoblate = 0.12MeV +L

  17. Gain in Binding energy of L in spherical configuration • L prefers spherical configuration even if the core is deformed.

  18. Discussion on softerenergy surface for 26+LMg and 24+LMg Due to the effect of smaller value of b at oblate side Due to larger overlap between L and nucleon densities at the prolate side

  19. Overlap between nucleon and lambda densities • L particle density • Nucleon density Overlapl argest for prolate configuration

  20. g vibrational energy 24+L Mg, 26+LMg

  21. 24Mg • K=0 g.s rotational band and K=2 rotational band built upon the g-vibrational state 32+ 22+ 4+ w24Mg = 4.23MeV (expt) 2+ 0+ 24Mg +L 22+ 4+ 2+ Calculated value 0+ 24+LMg

  22. Similarly, g vibration energy for 26+L Mg

  23. Summary • Triaxial calculations by Skyrme Hartree-Fock method • PES in (b,g) deformation plane • sd shell hypernuclei • 28 Si+L (p=14, n=14), 24Mg +L (p=12, n=12) • 26Mg +L (p=12, n=14), 26Si +L (p=14, n=12) - similar between core and hypernuclei - Slightly softer along the triaxial degree of freedom • Qualitatively similar results with SGII and SIII parameter sets • Estimation of g vibration energy • g vibration energy is lowered by about 0.15 MeV with the addition of L hyperon

More Related