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N = Z

LOI for the AGATA-PRESPEC campaign, GSI Relativistic Coulomb excitation for probing special effects of neutron-proton correlations around 100 Sn B. C ederwall , R. Wadsworth, G. De France et al. N = Z. N=Z line coincides with doubly-magic core Single-particle states wrt 100 Sn core

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N = Z

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  1. LOI for the AGATA-PRESPEC campaign, GSI Relativistic Coulomb excitation for probing special effects of neutron-proton correlations around 100Sn B. Cederwall, R. Wadsworth, G. De France et al. N = Z N=Z line coincides with doubly-magic core Single-particle states wrt 100Sn core Neutron-proton correlations in identical orbitals Neutron-proton (isoscalar) pairing Emergence of collectivity ... Bo Cederwall AGATA Physics WS, Istanbul May 2010

  2. Main physics aims • Verify Isoscalarspin-aligned neutron-proton couplingscheme in92Pd (96Cd) • Investigate Collective strength in 106,108Te,112Xe • by measuring B(E2; 0+→ 2+) • Builds on our spectroscopic work at GANIL and JYFL • and theoretical calculations by J. Blomqvist, R. Liotta, C. Qi, D. Delion et al. Bo Cederwall AGATA Physics WS, Istanbul May 2010

  3. The nature of nuclear pair correlationsand their effect on nuclei near N=Z Whenapproaching N=Z, ”normal” pair correlationsmayremain or even be extended: Near N=Z wecanhaveT=1, I=0(”isovector”)nn, ppCooper pairs as well asnpCooper pairs(neutrons and protons occupyidenticalorbits) and/or: T=0, I=1... (”isoscalar”) nppairing Does T=0pairingexist and, if so, howshould it best be revealed? So far, the search for T=0 np pairing has focused on special features: - g.s. binding energies of odd-odd nuclei - high-spin properties of N=Z nuclei (delayed alignments?) - deuteron transfer reactions Bo Cederwall AGATA Physics WS, Istanbul May 2010

  4. The isoscalar (np) pair gap is predicted toincrease sharply as NZ Calculation by W. Satula, R. Wyss Phys. Rev. Lett. Vol. 86, 4488 (2001) Bo Cederwall AGATA Physics WS, Istanbul May 2010

  5. “New” effects of neutron-proton correlations around 100Sn • Shell model calculations by J. Blomqvist et al. predict strong T=0 neutron-proton (np) correlations leading to an isoscalar spin-aligned np coupling scheme for N=Z nuclei close to 100Sn. • An ”unexpected effect” of the NSM appearing in this exotic region of the nuclear chart • Evidence for onset of collectivity, possibly induced by np pairing*) in neutron deficient Te and Xe nuclei • The proposed experiments aim to confirm these theoretical predictions by measuring B(E2;0+ 2+) values. *) M. Sandzelius, B. Hadinia, B. Cederwall, et al., Phys. Rev. Lett. 99, 022501 (2007). QRPA + nppairingcalculations by D.S. Delion, R. Liottaet al. , PRC in press Bo Cederwall AGATA Physics WS, Istanbul May 2010

  6. What is the g.s. structure of N=Z nucleibelow100Sn? 92Pd 100Sn πg9/2-1 πg9/2-1 πg9/2-1 πg9/2-1 πg9/2-1 πg9/2-1 νg9/2-1 νg9/2-1 νg9/2-1 νg9/2-1 νg9/2-1 νg9/2-1 For 92Pd and 96Cd neutrons and protons mainlyoccupy the g 9/2subshell 96Cd 100Sn The conventionalpicture : Ψ=({νg9/2-2}0+)n x ({πg9/2-2}0+)n This wouldlead to a normal senioritytypespectrum of low-lyingexcitedstates Bo Cederwall AGATA Physics WS, Istanbul May 2010

  7. Shell Modelcalculationspredict strong npinteractionsTransition to new spin-aligned T=0 npcouplingschemefor N=Z nucleibelow100Sn (J. Blomqvist et al.) νg9/2-1 νg9/2-1 πg9/2-1 πg9/2-1 πg9/2-1 νg9/2-1 πg9/2-1 νg9/2-1 νg9/2-1 νg9/2-1 πg9/2-1 πg9/2-1 Model space: g9/2 (and f5/2 , p3/2 ,p½ ) 96Cd 92Pd 100Sn 100Sn Aligned npcoupling: Ψ=[({νg9/2-1 xπg9/2-1}9+)2]0+ x [({νg9/2-1 xπg9/2-1}7+)2]0+ Ψ=[({νg9/2-1 xπg9/2-1}9+)2]0+ Bo Cederwall AGATA Physics WS, Istanbul May 2010

  8. Pd level systematics near N=Z Shell model calculations by J. Blomqvist, R. Liotta, C. Qi 92Pd, theory 92Pd, exp 94Pd, theory 94Pd, exp 96Pd, theory 96Pd, exp Bo Cederwall AGATA Physics WS, Istanbul May 2010

  9. Pdlevelsystematicsnear N=Z- effects of npinteractions Shell model calculations by J. Blomqvist, R. Liotta, C. Qi Bo Cederwall AGATA Physics WS, Istanbul May 2010

  10. New manifestation of T=0 np ”pairing”? 92Pd 96Cd l=8 l=8 l=8 l=8 100Sn 100Sn l=6 l=6 ”Nuclear belly dancers” Special deuteron-hole cluster like ground states imply significant deformation Bo Cederwall AGATA Physics WS, Istanbul May 2010

  11. B(E2; 0+ 2+) – sensitive probe of neutron-protoninteractions Shell model calculations by J. Blomqvist, R. Liotta, C. Qi Bo Cederwall AGATA Physics WS, Istanbul May 2010

  12. Enhanced collective strength at N=Z Bo Cederwall AGATA Physics WS, Istanbul May 2010

  13. Evidence for enhancedcollectivestrength in Te and Xenucleiapproaching N=Z Te experimental E(2+) and B(E2; 2+→ 0+) TZ=1 nucleus106Te : B. Hadinia, B. Cederwall et al., Phys. Rev. C 72, 041303 (2005) Bo Cederwall AGATA Physics WS, Istanbul May 2010

  14. Xe experimental E(2+) and B(E2; 2+→ 0+) TZ=1 nucleus110Xe; M. Sandzelius, B. Hadinia,, B. Cederwall et al., Phys. Rev. Lett. 99, 022501 (2007) Bo Cederwall AGATA Physics WS, Istanbul May 2010

  15. QuadrupolecollectivityThe traditionalview of the mechanismbehind deformation and collectivity: longrangenp QQ interactions Taken from R.F. Casten, 2003 Taken from R.F. Casten, 2003 These trends can change with np pairing as N→Z ! Enhancement of collectivity due to np (short-range) pairing correlations predicted in new calculations by D.S Delion, R. Liotta et al. Bo Cederwall AGATA Physics WS, Istanbul May 2010

  16. New QRPA + nppairingcalculationspredictenhancedcollectivitynear the N=Z=50 doubleshellclosureinduced by nppairingcorrelations (D.S. Delion, R. Liottaet al.) p-h excitations induced by np pairing Strong decrease in E(2+) with increasing Δpn Much smaller effect from long-range QQ np int. Bo Cederwall AGATA Physics WS, Istanbul May 2010

  17. Shell modelcalculations for light Te isotopes indicate that configurationmixingdue to the monopoletensorforce between primarily the proton 0g7/2 and neutron 1d5/2orbitalscaninduceenhancedcollectivity (C. Qi, R. Liottaet al.) Bo Cederwall AGATA Physics WS, Istanbul May 2010

  18. 202 134 “Doubly-magic octupole-deformed” nucleus predicted by theory 88 56 34 Octupole deformation and correlations near N=Z Strong octupole correlations are expected in nuclei where normal-parity single-particle states and intruder states differing by Δl = Δj = 3 are near the Fermi surface. Next to 112Ba (accessible with current technology?) 110Xe56 and 109I56 might have thelargest octupole stability. Coherent octupole correlations for neutrons and protons should occur near N=Z. Can we observe additional enhancement due to dynamic np correlations ?

  19. G.F. Lane et al. Phys. Rev. C57, R1022 (1998) (Gammasphere) G. de Angelis et al. Phys. Lett B535, 153 (2002) (Euroball) J.F. Smith et al. Phys. Lett B523, 13 (2001) (Gammasphere) Enhanced octupole correlations in light Te-Xe nuclei Bo Cederwall AGATA Physics WS, Istanbul May 2010

  20. Proposed Experiments • Measure B(E2; 0+2+) for isotopicchain92,94,96Pd • (from N=Z to N=50 closedshell) • Measure E(2+) for 96Cd and B(E2; 0+2+) for 96,98Cd • (from N=Z to N=50 closedshell) • Search for decay of 16+ spin trap isomer for 96Cd • Confirmspin-alignedneutron-protoncouplingscheme and • characterizenpinteractions (T=0/T=1) • Measure E(2+) for 106Te and B(E2; 0+2+) for 106,108Te, 112Xe • Measure and characterizecollectivestrength Bo Cederwall AGATA Physics WS, Istanbul May 2010

  21. Experimental details Projectilefragmentation FRS – AGATA – LYCCA 92-96Pd: LISE++ calc for primarybeam106Cd Ebeam = 650 MeV/u Ibeam = 1 pnA S4 ion and γγ-ion rates Setting 1: optimizing for 92Pd Setting 2: optimizing for 94Pd Assume 15% AGATA ppefficiency, σ(Coulex) from DWEIKO Bo Cederwall AGATA Physics WS, Istanbul May 2010

  22. Experimental details, ct’d Projectilefragmentation FRS – AGATA – LYCCA 96-98Cd: LISE++ calc for primarybeam112Sn Ebeam = 650 MeV/u Ibeam = 1 pnA S4 ion and γγ-ion rates Setting optimized for 96Cd Assume 15% AGATA ppefficiency, σ(Coulex) from DWEIKO Bo Cederwall AGATA Physics WS, Istanbul May 2010

  23. Experimental details, ctd’ Projectilefragmentation FRS – AGATA – LYCCA 106,108Te, 112,114Xe : LISE++ calc for primarybeam144Sm Ebeam = 950 MeV/u Ibeam = 1 pnA S4 ion and γγ-ion rates Setting 1: optimizing for 106Te Setting 2: optimizing for 112Xe Assume 15% AGATA ppefficiency, σ(Coulex) from DWEIKO Bo Cederwall AGATA Physics WS, Istanbul May 2010

  24. Backup slides Bo Cederwall AGATA Physics WS, Istanbul May 2010

  25. 92Pd analysis (prel) γγ2nThree γraysfirmlyidentified, mutuallyconcident 2+- 0+ 4+- 2+ γ -gated on 6+- 4+ 6+- 4+ γ -gated on 2+- 0+ 4+- 2+ Bo Cederwall AGATA Physics WS, Istanbul May 2010

  26. 92.94,96Pd levels and the role of T=0 npinteractions at N=Z 92Pd T=0 92Pd theo full np 96Pd theo 92Pd T=1 96Pd exp 92Pd theo no np Bo Cederwall AGATA Physics WS, Istanbul May 2010

  27. 96,98Cd Shell model calculations by . Blomqvist, R. Liotta, C. Qi et al. Bo Cederwall AGATA Physics WS, Istanbul May 2010

  28. Pd level systematics near N=Z Shell model calculations by J. Blomqvist, R. Liotta, C. Qi Bo Cederwall AGATA Physics WS, Istanbul May 2010

  29. 96,98Cd level and the role of T=0 npinteractions at N=Z 96Cd theo full np 98Cd theo 98Cd 96Cd theo no np 96Cd T=0 96Cd T=1 Bo Cederwall AGATA Physics WS, Istanbul May 2010

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