Shape decoupling in deformed halo nuclei

Transcription

1 ECT* Workshop: Towards consistent approaches for nuclear structure and reactions, Jun. 6 10, 2016, Trento Shape decoupling in deformed halo nuclei Shan-Gui Zhou ( 周善贵 ) Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing Supported by: NSFC & MOST; HPC Cluster of SKLTP/ITP-CAS ScGrid of CNIC-CAS

2 Contents Introduction Deformed RHB in a Woods-Saxon basis Prolate deformed core w/ nearly spherical halo: 42,44 Mg Deformed Skyrme HFB in r space (by Pei et al.) Nearly spherical core w/ prolate deformed halo: 38 Ne How to probe shape decoupling in deformed halo nuclei? Summary & perspectives

3 Characteristics of halo nuclei Weakly bound; large spatial extension Continuum can not be ignored Stable nuclei Dripline nuclei Self-consistent description: Weakly bound, continuum Large spatial distribution Couplings among Meng_Toki_SGZ_Zhang_Long_Geng2006 Prog. Part. Nucl. Phys Meng & SGZ 2015, J. Phys. G Bulgac1980; nucl-th/ Dobaczewski_Flocard_Treiner1984_NPA

4 Various shapes of atomic nuclei SGZ 2016, Phys. Scr. 91, Courtesy of Bing-Nan Lu ( 吕炳楠 )

5 Characteristics of halo nuclei w/ deformation Weakly bound; large spatial extension Continuum can not be ignored Stable nuclei Dripline nuclei Self-consistent description: Weakly bound, continuum Large spatial distribution Deformation effects Couplings among Meng_Toki_SGZ_Zhang_Long_Geng2006 Prog. Part. Nucl. Phys Meng & SGZ 2015, J. Phys. G Bulgac1980; nucl-th/ Dobaczewski_Flocard_Treiner1984_NPA

6 What we aim at A self-consistent description of Deformation Continuum contribution Large spatial distribution Interplays among them by developing a relativistic Hartree-Bogoliubov model

7 Covariant Density Functional Theory (CDFT) Serot_Walecka1986_ANP16-1 Reinhard1989_RPP Ring1996_PPNP Vretenar_Afanasjev_Lalazissis_Ring2005_PR Meng_Toki_SGZ_Zhang_Long_Geng2006_PPNP Liang_Meng_SGZ2015_PR570-1 Meng_SGZ2015_JPG

8 RMF theories in a Woods-Saxon basis Shapes Model Schrödinger W-S basis Dirac W-S basis Spherical Rela. Hartree SRH SWS SRH DWS SGZ_Meng_Ring2003_PRC

9 Why Woods-Saxon basis? Woods-Saxon basis is a reconciler between the HO basis & r space Reproduces results of r space Matrix diagonalization, numerically less complicated than HO SGZ_Meng_Ring 2003_PRC

10 RMF theories in a Woods-Saxon basis Shapes Model Schrödinger W-S basis Dirac W-S basis Spherical Rela. Hartree SRH SWS SRH DWS SGZ_Meng_Ring2003_PRC Axially deformed Rela. Hartree + BCS DRH DWS SGZ_Meng_Ring2006_AIP Conf. Proc Woods-Saxon basis is a reconciler between the HO basis & r space

11 RMF theories in a Woods-Saxon basis Shapes Model Schrödinger W-S basis Dirac W-S basis Spherical Rela. Hartree SRH SWS SRH DWS SGZ_Meng_Ring2003_PRC Axially deformed Axially deformed Rela. Hartree + BCS DRH DWS Rela. Hartree-Bogoliubov SGZ_Meng_Ring2006_AIP Conf. Proc DRHB DWS SGZ_Meng_Ring 2007_ISPUN Proc. SGZ_Meng_Ring_Zhao 2010_PRC R SGZ_Meng_Ring_Zhao 2011_JPConfProc Li_Meng_Ring_Zhao_SGZ 2012_PRC Li_Meng_Ring_Zhao_SGZ 2012_ChinPhysLett Woods-Saxon basis is a reconciler between the HO basis & r space

12 RMF theories in a Woods-Saxon basis Shapes Model Schrödinger W-S basis Dirac W-S basis Spherical Rela. Hartree SRH SWS SRH DWS SGZ_Meng_Ring2003_PRC Axially deformed Axially deformed Rela. Hartree + BCS DRH DWS Rela. Hartree-Bogoliubov SGZ_Meng_Ring2006_AIP Conf. Proc DRHB DWS SGZ_Meng_Ring 2007_ISPUN Proc. SGZ_Meng_Ring_Zhao 2010_PRC R SGZ_Meng_Ring_Zhao 2011_JPConfProc Li_Meng_Ring_Zhao_SGZ 2012_PRC Li_Meng_Ring_Zhao_SGZ 2012_ChinPhysLett Woods-Saxon basis is a reconciler between the HO basis & r space Density dependent DRHB theory in continuum Chen_Li_Liang_Meng2012_PRC Schunck_Egido2008_PRC R; PRC Long_Ring_Giai_Meng2010_PRC

13 Deformed RHB theory in continuum Kucharek_Ring1991_ZPA Woods-Saxon basis Axially deformed nuclei

14 Parameter set for ph & pp channels SGZ_Meng_Ring_Zhao 2010_PRC R SGZ_Meng_Ring_Zhao 2011_JPConfProc Li_Meng_Ring_Zhao_SGZ 2012_PRC Li_Meng_Ring_Zhao_SGZ 2012_ChinPhysLett

15 Ground states of Mg isotopes Li_Meng_Ring_Zhao_SGZ 2012_PRC The calc. reproduce well the experiment 42 Mg ( 44 Mg) is the last bound deformed nucl. from PK1 (NL3) A problem of many mean field models: N = 20 shell quenching can not be obtained 32 Mg is deformed according to the expt., but spherical from many MF calc.

16 Conditions for occurrence of a halo & its shape Existence & deformation of neutron halo depend on quantum numbers of the main components of the s.p. orbits around Fermi surface s levels with L = 0 spherical halos p levels with L = 0 prolate halos p levels with L = 1 oblate halos d, f,... levels: no halos SGZ_Meng_Ring_Zhao 2010 PRC R Li_Meng_Ring_Zhao_SGZ 2012 PRC

17 Conditions for occurrence of a halo & its shape Existence & deformation of neutron halo depend on quantum numbers of the main components of the s.p. orbits around Fermi surface s levels with L = 0 spherical halos p levels with L = 0 prolate halos p levels with L = 1 oblate halos d, f,... levels: no halos SGZ_Meng_Ring_Zhao 2010 PRC R Li_Meng_Ring_Zhao_SGZ 2012 PRC Pei_Zhang_Xu2013PRC R

18 44 Mg: Density distributions SGZ_Meng_Ring_Zhao 2010 PRC R Li_Meng_Ring_Zhao_SGZ 2012 PRC Prolate deformation Large spatial extension in neutron density distribution

19 44 Mg: Single neutron states in canonical basis Weakly bound & continuum orbitals Deeply bound orbitals

20 44 Mg: Single neutron states in canonical basis Weakly bound & continuum orbitals halo Deeply bound orbitals core

21 44 Mg: Density of core & halo---shape decoupling

22 44 Mg: Density of core & halo---shape decoupling Core: prolate

23 44 Mg: Density of core & halo---shape decoupling Core: prolate halo: oblate

24 44 Mg: Density of core & halo---shape decoupling Core: prolate halo: oblate

25 44 Mg: Decomposition of neutron density distribution The 3rd & 4th states contribute to tail part of neutron density distribution Main component: 2p 3/2

26 Shape of low-l single particle orbital

27 Mechanism of shape decoupling

28 Mechanism of shape decoupling

29 Mechanism of shape decoupling

30 Skyrme HFB in r space & egg-like halo Methods 2D B-spline Galerkin operators Lattice direct diagonalization Broyden optimized iteration MPI+OpenMP Hybrid parallel Pei et al. PRC 78, (2008) Pei et al. PRL 102, (2009) Pei et al. PRA 82, R(2010) Pei et al. PRC 84, (2011) Pei et al. PRC 87, R(2013) Pei et al. PRC 90, R(2014) Courtesy of Junchen Pei ( 裴俊琛 )

31 Skyrme HFB in r space & egg-like halo Methods 2D B-spline Galerkin operators Lattice direct diagonalization Broyden optimized iteration MPI+OpenMP Hybrid parallel Pei et al. PRC 78, (2008) Pei et al. PRL 102, (2009) Pei et al. PRA 82, R(2010) Pei et al. PRC 84, (2011) Pei et al. PRC 87, R(2013) Pei et al. PRC 90, R(2014) Pei_Zhang_Xu2013PRC R Courtesy of Junchen Pei ( 裴俊琛 )

32 How to probe the shape decoupling? Larger cross section Narrower momentum distribution Double-hump?

33 How to probe the shape decoupling? Larger cross section Narrower momentum distribution Double-hump? Navin 1997_PRL Sakharuk_Zelevinsky1998_PRC

34 How to probe the shape decoupling? Larger cross section Narrower momentum distribution Double-hump? New dipole modes?

35 How to probe the shape decoupling? Larger cross section Narrower momentum distribution Double-hump? New dipole modes? Rotation?

36 How to probe the shape decoupling? Larger cross section Narrower momentum distribution Double-hump? New dipole modes? Rotation? Fusion?

37 Summary & perspectives Deformed relativistic HB theory in a Woods-Saxon basis Occurrence of a halo in deformed nuclei depending on intrinsic structure of valence orbitals Prolate deformed core w/ nearly spherical halo: 42,44 Mg Deformed Skyrme HFB in r space (by Pei et al.) Nearly spherical core w/ prolate deformed halo: 38 Ne How to probe shape decoupling?

38 Summary & perspectives Deformed relativistic HB theory in a Woods-Saxon basis Occurrence of a halo in deformed nuclei depending on intrinsic structure of valence orbitals Prolate deformed core w/ nearly spherical halo: 42,44 Mg Deformed Skyrme HFB in r space (by Pei et al.) Nearly spherical core w/ prolate deformed halo: 38 Ne How to probe shape decoupling? Collaborators (Deformed RHB model) : Lulu Li (ITP, PKU, IAPCM), Jie Meng (PKU), P. Ring (TU Munich & PKU), En-Guang Zhao (ITP) Deformed Skyrme HFB model: J. C. Pei (PKU), Y. N. Zhang (PKU), F. R. Xu (PKU)

39 Zhou, Shan-Gui ITP/CAS Beijing Thanks 谢谢 URL: