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Exotic Nuclei and Yukawa’s Forces

INPC Tokyo June 4-8, 2007. Exotic Nuclei and Yukawa’s Forces. Takaharu Otsuka University of Tokyo / RIKEN / MSU. D. Abe Tokyo T. Matsuo Hitachi Ltd. M. Honma U. Aizu Y. Utsuno JAEA G. Lalazissis Thessaloniki. T. Suzuki Nihon U.

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Exotic Nuclei and Yukawa’s Forces

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  1. INPC Tokyo June 4-8, 2007 Exotic NucleiandYukawa’s Forces Takaharu OtsukaUniversity of Tokyo / RIKEN / MSU D. Abe Tokyo T. Matsuo Hitachi Ltd. M. Honma U. Aizu Y. Utsuno JAEA G. Lalazissis Thessaloniki T. Suzuki Nihon U. R. Fujimoto Hitachi Ltd. H. Grawe GSI Y. Akaishi KEK P. Ring TUM Many experimentalists

  2. Outline • Introduction - Past and present issues - • Shell structure and magic numbers of exotic nuclei • Deformation driven by tensor force • Relevant topics (neutrino, Lattice QCD, Superheavy) • 5. Summary

  3. nuclei (mass number) stable exotic -- with halo A Proton number  Neutron number  Studies on exotic nuclei in 1990’s Left-lower part of the NuclearChart Stability line and drip lines are not so far from each other  Physics of loosely bound neutrons, e.g., halo while other issues like 32Mg proton halo neutron halo リチウム１１ 11Li neutron skin

  4. About same radius 11Li 208Pb Neutron halo Strong tunneling of loosely bound excess neutrons Breakup of 11Li Nakamura et al., Phys. Rev. Lett. 96, 252502 (2006) F7-1 Nakamura

  5. In the 21st century, a wide frontier emerges between the stability and drip lines. Stability line Drip line What happens here ? 1990’s neutron halo etc. nuclei (mass number) stable exotic Riken’s work A Neutron number  Proton number  中性子数　 （同位元素の種類）

  6. Basic picture was deformed 2p2h state energy intruder ground state stable exotic pf shell gap ~ constant N=20 sd shell Island of Inversion Island of Inversion : Ne, Na, Mg with N=20-22 Phys. Rev. C 41, 1147 (1990), Warburton, Brown and Becker

  7. The Key : Tensor Force p meson : primary source r meson (~ p+p) : minor (~1/4) cancellation Ref:Osterfeld, Rev. Mod. Phys. 64, 491 (92) p, r Multiple pion exchanges  strong effectivecentral forces in NN interaction (as represented bysmeson, etc.)  nuclear binding This talk : First-order tensor-force effect (at medium and long ranges) One pion exchange  Tensor force

  8. Intuitive picture of monopole effect of tensor force wave function of relative motion spin of nucleon large relative momentum small relative momentum repulsive attractive j> = l + ½, j< = l – ½ TO et al., Phys. Rev. Lett. 95, 232502 (2005)

  9. N=16 gap : Ozawa, et al., PRL 84 (2000)5493; Brown, Rev. Mex. Fis. 39 21 (1983) only exchange term d3/2 Tensor force d5/2 Example : Dripline of F isotopes is 6 units away from O isotopes Sakurai et al., PLB 448 (1999) 180, …

  10. Superheavy Island of Inversion 51Sb 50Sn 36Kr 78Ni 42Si Neutrino reaction Chart provided by Sakurai Nuclei or regions to be discussed R process

  11. 2. Shell structure and magic numbers of exotic nuclei

  12. 1h11/2 protons 1g7/2 protons 51Sb case Opposite monopole effect from tensor force with neutrons in h11/2. Z=51 isotopes Tensor by • + r meson exchange h11/2 g7/2 + common effect (Woods-Saxon) No mean field theory, (Skyrme, Gogny, RMF) explained this before. 1h11/2 neutrons Exp. data from J.P. Schiffer et al., Phys. Rev. Lett. 92, 162501 (2004)

  13. N=28 Gap neutron g9/2 neutron g9/2 Hartree-Fock calculation including tensor force Single-particle energies of exotic Ni isotopes Gogny-type (finite-range) + Tensor Force with tensor w/o tensor Z=28 Gap TO, Matsuo, Abe, Phys. Rev. Lett. 97, 162501 (2006)

  14. Contributions ofKinetic+Central, 2-body LS, andTensor components to the change of f7/2 – f5/2 gap in going from N=40 to N=50 (g9/2 occupancy) Kin+Cent andLS: almost the same among three calculations Tensor: largest effect TO, Matsuo, Abe, Phys. Rev. Lett. 97, 162501 (2006)

  15. Two neutron separation energy Hartree-Fock-Bogoliubov calculation including tensor force Poster by Abe QW-048 D1S Sn no tensor GT3 tensor Kr EXP Heavy Sn and Kr are more bound ng7/2 nh11/2

  16. SkP 8 1g n n 1h SkP 1i d5/2-d3/2 d5/2-d3/2 6 p3/2-p1/2 p3/2-p1/2 4 Skyrme + Tensor’ : Many recent works An example by Dobaczewski et al. Zero-range version of tensor force (Skyrme 1956, Stancu et al. 1977) 2g T T SkP original 2 M. Zalewski, W. Satuła, J. Dobaczewski, (preliminary) Spin-orbit splittings [MeV] SkP Tensor + SO*0.8 1g p p 7 1h 6 5 4 3 2 f7/2-f5/2 f7/2-f5/2 1 90Zr 90Zr 132Sn 132Sn 40Ca 48Ca 40Ca 48Ca 56Ni 56Ni 208Pb 208Pb 16O 16O Crucial for 42Si mentioned later

  17. February, 2007 October, 2006 Dec. 22, 2006 F10-2 April, 2007

  18. Relativistic Mean Field Relativistic Hartree-Fock Exchange terms Proton 1h11/2 – 1g7/2 gap Lalazissis et al. NL3 is used Full tensor Half tensor No tensor Long et al., Toki et al., …

  19. 3. Deformation driven by Tensor-force

  20. Recent finding about the shell-model interaction Effective shell-model interaction (refined empirically) = central part + tensor ~ + … p + r meson exchange (for medium- and long-range parts) This feature is true also in G-matrix A new shell-model interaction has been constructed for the sd + pf shells.

  21. Short range central forces have complicated origins and should be adjusted. Chiral Perturbation of QCD S. Weinberg, PLB 251, 288 (1990) Tensor force is explicit

  22. Strong oblate Deformation ? Tensor force can drive nuclei to (or from) deformation Si isotopes Exp. f7/2 d3/2 neutron s1/2 d5/2 proton full Potential Energy Surface 4214Si28 Tensor force removed from cross-shell interaction Z=28 gap is reduced also by tensor force

  23. Debate over 42Si Nature 435 (2005), MSU 44S -> 42Si cross section small deformed PRL accepted (2007), GANIL 42Si oblate 44S prolate Cauier et al. Shell Model, Werner et al. Skyrme model, Lalazissis et al. RMF, Peru et al. Gogny model, Rodriguez-Guzman et al. Gogny model

  24. Modification to the Island of Inversion Terry et al, PLB 640 (2006) 86 Low-lying 3/2- level (0.765 MeV) in 27Ne  N=20 gap smaller N=20 gap changes ~6MeV ~3MeV Expansion of the territory Neyens et al. Mg Tripathi et al. Na Dombradi et al. Ne Ne O Mg Ca

  25. 3. Intriguing relevant topics

  26. Over Woosley Over PSDMK2 Relevance to Weak Processes Neutrino reaction cross section is enlarged by using interaction containing full tensor force Presented by Suzuki H4-2 Temperaturte of supernovae explosion

  27. Tensor effective forces are close to bare ones. accepted by PRL sstt central force calculated by a Lattice QCD calculation Presented by Ishii D1-4 Calculations for tensor and 3-body forces will be great

  28. Z=114 Modification of superheavy magic gap by tensor force Occupations of 1k17/2 and 2h11/2 reduces Z=114 gap to a half value 3p1/2 3p3/2 1k17/2 2f5/2 Energy (MeV) 2h11/2 2f7/2 N=184 1i13/2 1h9/2 Neutron Proton Story similar to Z=64 subshell closure Proton single-particle energies by Woods-Saxon potential (A=300)

  29. Summary There are typically 20~100 isotopes between the stability and drip lines. They may give us a rich fieldof “harvest” from the NN interaction. By changing N (Z) so much, unknown or unrecognized aspects of the NN interaction may emerge. This was the motivation of the project of the tensor force. The outcome so far are …

  30. Summary - 2 - Shell evolution due to tensor force - is a robust mechanism -- also for many classical cases -- • occurs from p-shell to superheavies • developments in pf shell ex. N=34 new magic • ANL, MSU, GANIL, REX-ISOLDE • affectsdeformation (ex. Doubly-magic 42Si strongly oblate) • Free tensor force (like p+r)  many-body structure • more input from ChP., eff. field th., lattice QCD • Other cases … • Weak processes, astrophysical implications, …. • 11Li and tensor forceMyo F3-3

  31. Thanks to Yukawa, mesons create variety and richness of exotic nuclei.

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