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Isomers in heavy nuclei: structure and projectile fragmentation studies

This article explores the isomeric states in heavy nuclei and their potential as tools for studying shape transition and high-spin states. The article discusses various experimental techniques and theoretical models used to study isomers and their properties.

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Isomers in heavy nuclei: structure and projectile fragmentation studies

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  1. Isomers in heavy nuclei: structure and projectile fragmentation studies Zsolt Podolyák University of Surrey

  2. Isomers as tools (1): prolate-oblate shape transition J.-P Delaroche, M. Girod, J. Libert, H. Goutte, S. Hilaire, S. Péru, N. Pillet, G.F. Bertsch, Phys.Rev. C 81, 014303 (2010) www-phynu.cea.fr HFB using D1S Gogny force

  3. Z 70 74 78 110 N Shape transition, triaxiality (SLy4 Skyrme interaction) 122 L.M. Robledo et al., J. Phys. G. 36, 115104 (2009).

  4. Production of heavy neutron-rich nuclei deep-inelastic fragmentation large arrays separators (storage rings)

  5. In flight fragmentation (and fission): separation and identification Fragment Separator (GSI, Darmstadt, Germany) Ge Relativistic energy fragmentation: => heavy ions Decay (internal and β, α) spectroscopy: - decay correlated with the fragment - very sensitive (ion beams > 1 ion/hour)

  6. Isomeric states (from fragmentation) Gottardo et al. PRL 109 (2012) 162502 ■ ■ 208Hg,209Tl N. Aldahan et al., PRC80, 061302(R) (2009). M.Reed et al., PRL 105 (2010) 172501, PRC 86 (2012) 054321 (ESR storage ring) Isomeric state * RISING: isomeric decays S. Steer et al., Phys. Rev. C 84 (2011) 044313

  7. Beta decay Benzoni et al., PLB 715 (2012) 293 A.I. Morales, J. Benlliure et al., submitted 194Os 194Re 188W 190W 192W 188Ta 190Ta 192Ta N. Alkhomashi et al., PRC80 (2009) 064308 N. Al-Dahan et al., PRC85 (2012) 034301 decay into implanted

  8. Tools Spin traps K-isomers Nilsson model BCS calculations for multi-quasiparticle states (K isomers) Shell model calculations

  9. Osmium (Z=76) isotopes: (prolate A<=196; oblate A>196)

  10.  prolate oblate  C.Wheldon et al., PRC 63, 011304 (2001) S.J. Steer. et al, PRC 84 (2011) 044313 Zs. P. et al, PRC79, 031305 (2009)

  11. Shape of 196Os? 196Os 198,200,202Pt,198Os All slightly oblate All have 7- and 12+ isomeric states. No (equivalent) isomeric states in 192,194,196Os

  12. 194Re (Z=75): prolate-oblate shape coexistence beta decay of 194Re Iπ T1/2 0+ 5(1) s oblate (ε2=-0.158) 11- 25(8) s prolate (ε2=0.125) 6+ 100(10) s prolate (ε2=0.125) 194Os N. Al-Dahan et al., Phys. Rev. C 85 (2012) 024313

  13. Prolate-oblate shape transition www-phynu.cea.fr J.-P Delaroche, M. Girod, J. Libert, H. Goutte, S. Hilaire, S. Péru, N. Pillet, G.F. Bertsch, PRC 81, 014303 (2010) P. Moller, J.R. Nix, W.D. Meyers, W.J. Swiatecki, At. Data Nucl. Data Tables 59, 185 (1995)

  14. Prolate-oblate shape transition ( ) www-phynu.cea.fr J.-P Delaroche, M. Girod, J. Libert, H. Goutte, S. Hilaire, S. Péru, N. Pillet, G.F. Bertsch, PRC 81, 014303 (2010) P. Moller, J.R. Nix, W.D. Meyers, W.J. Swiatecki, At. Data Nucl. Data Tables 59, 185 (1995)

  15. Isomers as tools (2): fragmentation studies M. Thoennessen, B.M. Sherril, Nature 473 (2011) 25

  16. Fragmentation (spallation) reactions at relativistic energies: multi-hole state abrasion ablation σ (mb) H. Alvarez-Pol et al., Phys. Rev. C 82, 041602(R) (2110) Cross section: measures the end product What would give information about abrasion? Angular (and linear) momentum

  17. Im P(I) Im I Isomeric ratio (sharp cut-off approx.) J.-J. Gaimard and K.-H. Schmidt, Nucl. Phys. A 531 (1991) 709 M. De Jong, A.V. Ignatyuk and K.-H. Schmidt,Nucl.Phys. A 613 (1997) 435

  18. Isomeric ratios from 208Pb and 238U fragmentation Bowry et al A.M. Denis Bacelar et al., Phys. Lett. B, in press M. Bowry et al., submitted

  19. Experimental isomeric ratios M. Bowry et al Spin (hbar) M. Bowry et al., submitted

  20. Highest spin from fragmentation: (55/2) A.E. Stuchbery et al., NPA 482 (1988) 692 A.M. Denis Bacelar et al., Phys. Lett. B, in press

  21. Abrasion-ablasion model (ABRABLA code) Excitation energy ~27 MeV/abrated nucleon= =2 x single particle (holes) energy Ablated nuclei/abraded nuclei ~2 Good cross sections Angular momentum from single particle states only Is this good enough? M. De Jong, A.V. Ignatyuk and K.-H. Schmidt,Nucl.Phys. A 613 (1997) 435

  22. Comparison with theory M. Bowry et al

  23. Fragments are slower than projectile: momentum shift (friction) fragmentation of 238U velocity change (cm/ns) M.V. Ricciardi et al., PRL 90 (2003) 212302 angular momentum produced (collective) I perpendicular to the beam

  24. Abrasion (incl. friction) (relativistic transport model) Abrasion+ablation (+sequential binary decay) Better agreement S. Pal and R. Palit, Phys. Lett. B 665 (2008) 164.

  25. Comparison with theory (sharp cut-off approx.) 100 M. Bowry (2013) A.M. Denis Bacelar (2013) Zs. Podolyák (2006) 10 excitations? friction ablation 1 0.1 0.01 Spin (hbar) 0 5 10 15 20

  26. Conclusions Isomers are special Provide a tool: add sensitivity to measurements Prolate-(triaxial)-oblate shape transition at A~180-200 High-spin states are produced with higher probability than expected (isomeric beams) Unpublished results from: M. Bowry (Surrey PhD, 2013), submitted A.M. Denis-Bacelar (Brighton PhD, 2011), PLB, in press

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