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Multinucleon Transfer Reactions to Study Nuclear Structural Evolution

Multinucleon Transfer Reactions to Study Nuclear Structural Evolution. Paddy Regan Dept. of Physics University of Surrey, Guildford, UK e-mail: p.regan@surrey.ac.uk. Surrey – ND MPhys Students. Victoria Barnard (2000) – PhD, ICST Jose Galache (2001) – PhD Southampton

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Multinucleon Transfer Reactions to Study Nuclear Structural Evolution

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  1. Multinucleon Transfer Reactions to Study Nuclear Structural Evolution Paddy Regan Dept. of Physics University of Surrey, Guildford, UK e-mail: p.regan@surrey.ac.uk

  2. Surrey – ND MPhys Students • Victoria Barnard (2000) – PhD, ICST • Jose Galache (2001) – PhD Southampton • Mary Beard (2002) – PhD Notre Dame + Dan Robertson (CERN 2002) – PhD Notre Dame • Kelly Vaughan (2002) – PhD York • Amy Bartlett (2003) – PhD Surrey • Edward Simpson (2005) - ? • Other nuclear students placed for nuclear physics/astrophysics placements at WNSL-Yale, MSU, UNC-TUNL, Kentucky, TRIUMF, Florida State, YSU, (+ CERN, GSI etc.) • If you are interested in taking one, see PHR, Jeff Tostevin and/or Phil Walker

  3. Outline • (Some) questions in heavy, neutron-rich nuclei addressed by Surrey experiments using multinucleon transfer: • 100Mo+136Xe : Vibration-rotation changes in A~100. • 198Pt+136Xe: 136Ba, N=80 Ip=10+seniority isomers, effective charges, explanation of the B(E2:10+8+) collapse. • 82Se+192Os: Se across N=50; high-spin population of Os. • Study DIC population in (N,Z,I) plane in all cases.

  4. See eg. Broda et al. Phys. Rev Lett. 74 (1995) p868 Juutinen et al. Phys. Lett. 386B (1996) p80 Wheldon et al. Phys. Lett. 425B (1998) p239 Cocks et al. J. Phys. G26 (2000) p23 Krolas et al. Acta. Phys. Pol. B27 (1996) p493 Asztalos et al. Phys. Rev. C60(1999) 044307 Aim? To perform high-spin physics in stable and neutron rich nuclei. Problem: Fusion makes proton-rich nuclei. Solutions? binary collisions/multi-nucleon transfer Modified from Introductory Nuclear Physics, Hodgson, Gadioli and Gadioli Erba, Oxford Press (2000) p509

  5. 136Xe + 100Mothin-target @ Berkeleywithchico + gammasphere

  6. z x q1 q2 f1 f2 y

  7. Ge TLF beam qtlf,ftlf qblf,fblf BLF M . Simon et al., Nucl. Inst. Meth. A452, 205 (2000) Rochester Group TOF ~5-10 ns. ns-ms isomers can de-excite in be stopped byCHICO position detector. Delayed gs can still be viewed by GAMMASPHERE.

  8. 100Mo + 136Xe @ 700 MeV GAMMASPHERE + CHICO PHR, A.D. Yamamoto et al., AIP Conf. Proc. 701 (2004) p329

  9. PHR, A.D.Yamamoto et al., Phys. Rev. C68 (2003) 044313 Can see clearly to spins of 20ħ using thin-target technique.

  10. N=57,58 crossing and alignments well reproduced by CSM… But other low-spin data suggests these nuclei are although AHVs PHR, A.D.Yamamoto et al., Phys. Rev. C68 (2003) 044313

  11. E-GOS plot appears to indicate that Vibrator-Rotator phase change is a feature of near stable (green) A~100 nuclei. BUT….what is the microscopic basis ? ‘Rotational alignment’ can be a crossing between quasi-vibrational GSB & deformed rotational sequence. (stiffening of potential by population of high-j, equatorial (h11/2) orbitals). PHR, Beausang, Zamfir, Casten, Zhang et al., Phys. Rev. Lett. 90 (2003) 152502

  12. 136Xe + 198Ptthin target @ Berkeleywith chico + gammasphere

  13. 198Pt +136Xe, 850 MeV J.J. Valiente-Dobon, PHR, C.Wheldon et al., Phys. Rev. C69 (2004) 024316

  14. 136Xe+198Pt reaction beam-like fragment isomers. 132Xe 128Te 130Te 136Xe 138Ba 131I 137La 133I J.J.Valiente-Dobon, PHR, C.Wheldon et al., PRC69 (2004) 024313

  15. J.J.Valiente-Dobon, PHR, C.Wheldon et al., PRC69 (2004) 024313 C. Wheldon, J.J. Valiente Dobon, PHR et al., EPJ A20 (2004) p365 184W 195Os 192Pt 185Re 191Os 198Pt 193Au 192Os 136Xe+198Pt Target-like fragment isomers

  16. J.J. Valiente-Dobon, PHR, C.Wheldon et al., Phys. Rev. C69 (2004) 024316 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 84 83 82 81 80 79 78 77 nano and microsecond isomers on gated 198Pt+136Xe with GAMMASPHERE+CHICO DIC 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 76 75 74 73 59 58 57 56 55 54 53 52 51 50 N/Z compound

  17. Identification of new ‘seniority’ isomer in 136Ba, N=80 isotone. t1/2=91(2) ns, (nh11/2)-2I=10+ t1/2 = 91 (2) ns J.J. Valiente-Dobon, PHR, C.Wheldon et al., Phys. Rev. C69 (2004) 024316

  18. N=80 isotonic chain, 10+ isomers, (nh11/2)-2I=10+ Q. Why does Ex(10+) increase while E(2+) decreases ? 91(2) ns

  19. Structure of 8+ final state changes from 134Xe -> 136Ba ? See Valiente-Dobon, PHR, Wheldon et al., PRC69 (2004) 024313 Isomer decay also depends on structure of final state N=80, (nh11/2)-210+ isomers

  20. Energy of N=80 Ip=10+ isomers correlates with energy increase of 11/2- single neutron in N=81 isotones. Increase in 10+ energy, plus expansion of proton valence space means 8+ yrast state now (mostly) NOT (nh11/2)-2 for Z>54 Ex, Ip=11/2 - N=81 Ex, Ip=10 N=80

  21. Calculations by N. Yoshinaga and K. Higashiyama (Saitama/Tokyo)

  22. Pair Truncated Shell Model Calculations (by N. Yoshinaga, K. Higashiyama) predict yrast 8+ in 136Ba not (nh11/2)-2 but rather, (pd5/2)2(pg7/2)2

  23. Expect neutron ‘seniority scheme’ for (nh11/2)-2 ‘j2’ mutliplet configuration at N=80 (e.g. 130Sn). 132Te, 134Xe have proton excitations due to g7/2, d5/2 at 0+,2+,4+,6+ but not competing 8ħ and 10ħ states. Extra collectivity for higher-Z pushes down 0+ and 2+. Proton s.p. energies used in 136Ba SM calcs h11/2 2.760 Protons, max. seniority 2 spin = 6 ħ (from (pg7/2)2. Seniority 4 states though can have up to 7/2 + 5/2 + 5/2 +3/2 = 10 ħ d5/2 0.963 g7/2 0.000

  24. 82Se + 192Os backed target @ INFN-Legnaro

  25. Legnaro Experiment 82Se Projectile, at 460 MeV ~15% above Coulomb barrier Projectile-like species 192Os Target Target-like species • GASP • 40 Ge Detectors, e = 3% P/T = 60% (with 60Co) • 80 BGO Detectors, e = 70%

  26. T. Ishii et al., Eur. Phys. J. A13 (2002) 15 70Zn, 76Ge, 82Se beams on a 198Pt target with the ‘isomer scope’

  27. N=48 ‘core breaking’ 10+ 8+ cf 80Ge, 84Kr, 86Se, 88Zr… spins above Ip=8+ require extra particles..pp3/2

  28. 50 g9/2 Zr 40 p1/2 Sr 38 p3/2 34 Se f5/2 28 Ni f7/2

  29. Summary • 100Mo: High-spin vib. rot. transition observed • 136Ba: B(E2:10+8+) collapse explained in terms of nature of 8+ state. • (Many) new isomeric/s.p. states from A~180-195 from the data, map out shape evolution via change in K-hindrance. • Yrast states across N=48 isotones. 10+8+ in 82Se gives info. on f5/2 p3/2 proton separation. Important input for understanding generation of higher spin states.

  30. Thanks to (among others)Zsolt Podolyak*, Carl Wheldon*, Chris Pearson, Jose Javier Valiente-Dobon, Arata Yamamoto, Gareth Jones et al., : SurreyDoug Cline, Adam Hayes, Chin-Yen Wu et al., : RochesterAugusto Macchiavelli, Paul Fallon et al.,; BerkeleyDave Warner: CLRC DaresburySean Freeman, John Smith : ManchesterBob Chapman, Xioaying Liang et al., : PaisleyGiacomo DeAngelis*, YuHu Zhang, Andres Gadea et al.,: LegnaroSanto Lunardi et al.,: Padova

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