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Introduction The 137 Xe experiment The 139 Ba experiment Conclusions

Detailed spectroscopy of 137 Xe and 139 Ba – role of the ν i 13/2 intruder in the heavy tin region Walter Reviol (Washington University, St. Louis, USA). Introduction The 137 Xe experiment The 139 Ba experiment Conclusions. Nuclear Structure 2016, Knoxville, Tennessee, July 24 - 29.

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Introduction The 137 Xe experiment The 139 Ba experiment Conclusions

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  1. Detailed spectroscopy of 137Xe and 139Ba – role of the νi13/2 intruder in the heavy tin regionWalter Reviol (Washington University, St. Louis, USA) • Introduction • The 137Xe experiment • The 139Ba experiment • Conclusions Nuclear Structure 2016, Knoxville, Tennessee, July 24 - 29

  2. Slide taken from a CERN-ISOLDE talk Ba 139

  3. Example: SM calculations by the group in Naples/Italy Neutron states Level energies • Pure and effective single-particle energies (location of a particular orbital) • Coupling of these SP states with core-excited states Level lifetimes • Further constraints on the wave function (info obtained from the operator used to calculate EM transition rates) The knowledge for the 132Sn and 48Ca regions is less complete than that for other regions (208Pb,40Ca, etc.). New knowledge in one of these regions improves the predictive power for more neutron-rich nuclei there. Corragio et al., PRC87, 021301(R) (2013) 83

  4. Some one-neutron transfer studies near 132Sn 134Te + 13C (9Be), Elab = 565 MeV, I= 3·105 s-1 (Holifield)Channel of interest: 135Te83 + 12C (8Be)Hyball + CLARION detector combination particleTLF −γPLF coincidences gate 929 gate 1180 0p1/2 8 13C preference for j> states (TLF) 0p3/2 6 9Be preference for j< states (TLF) 0s1/2 2 Allmond et al., PRC 86, 031307R (2012) ; Radford et al., Nucl. Phys. A 752, 264c (2005) 5/15/14 WR 5/15/14 WR 4 4 4 4 4 7/27/16 WR

  5. Some one-neutron transfer studies near 132Sn 134Te + 13C (9Be), Elab = 565 MeV, I= 3·105 s-1 (Holifield)Channel of interest: 135Te83 + 12C (8Be)Hyball + CLARION detector combination particleTLF −γPLF coincidences gate 929 gate 1180 248Cm SF Bhattacharyya et al. PRC 56, R2363 (1997) Fornal et al. PRC 63, 024322 (2001) Yrast spectroscopy Allmond et al., PRC 86, 031307R (2012) ; Radford et al., Nucl. Phys. A 752, 264c (2005) 5/15/14 WR 5/15/14 WR 5 5 5 5 5 7/27/16 WR

  6. II. The 137Xe experiment 6

  7. 136Xe + 13C (9Be) experiment: conditions and analysis details → No. Pixels: 256 (4 PMT’s) Thin fast-plastic + CsI(Tl) Angle range: 9º ≤ θ≤ 72º Preferred position: downstream Phoswich Wall Reference: Sarantites et al., NIMA 790, 42 (2015) It is prudent to use the two-target approach.

  8. Particle Maps A: Fast B: Early C: Late

  9. 136Xe + 13C @ 560 MeV (a) Carbon gated, not γ gated gating transition newly observed transition (b) Additional γ gate: 1220 keV • Angular Distr. 1384-keV γ-ray* • Large negative A2/A0coef.: • unstretched dipole or E2 • Large positive A4/A0 : M1 • (* AD w.r.t. spin direction) (c) Additional γ gate: 1384 keV (533 keV inset)

  10. 136Xe + 9Be @ 560 MeV (a) 8Be → 2α gated gate newly observed (b) Additional γ gate: 385 keV (c) Additional γ gate: 1963 keV (2349 keV inset)

  11. 137Xe (13C target) Two states with spin-parity 13/2+ Transitions in red: newly observed 137Xe (9Be target) Reviol et al., PRC (accepted for pub.)

  12. Inet= Iout− Iin DWBA calculations with FRESCO 13C (0p1/2) cross section j> final states enhanced 9Be (0p3/2)cross section: j< final states enhanced

  13. Two sets of SM calculations*: (a) ν0i13/2 energy adapted to (πg7/2 x νi13/2)10+ in 134Te (b) …adapted to νi13/2 in 135Te and 137Xe Role of the 13/2+ states: another test of these conjectures (provided they have components with ν0i13/2 content) Calc. (b) is closer to the data. 13/2+ states: Why expt. and calc. deviate for Z > 56? Due in part to an increasing 3- x 7/2- component (the model space doesn’t fully account for). 2 red: present work 1 * A. Gargano, N. Itaco (Naples)

  14. Wave function components for the 13/2+ states in 137Xe (and 135Te) • Conclusions • The 13/2+1 state is essentially 0+ x 0i13/2; there is always (i.e., for 13/2+1 and 13/2+2) • a strong admixture from a member of the 2+ x 0i13/2 multiplet. • The w.f. predictions should be, however, taken with a grain of salt; the 3- x 1f7/2 • component is likely somewhat underpredicted. • The most important aspect are the 0i13/2 SPE’s; a realistic range of 2360 – 2600 keV • is proposed with the lower limit based on the present study.

  15. III. The 139Ba experiment Target Rod Beam

  16. 138Ba + 13C @ 560 MeV GRETINA instead of DGS (a) Raw γ-ray spectrum Mainly complete fusion (3n, 4n evaporation) and Coulex (b) Carbon gated (AC map, 1 pixel) * 139Ba transitions including the crucial ones (arrows) Gating on fragments works as expected; not prepared yet to give a partial half-life for the 231-keV 13/2+→ (11/2-) transition in 139Ba.

  17. IV. Conclusions Excited states in 137Xe83 and 139Ba83 have been studied using inverse-kinematic (13C,12C γ)/(9Be,8Be γ) reactions and the “Oak Ridge method” (correlation of TLF particles and PLF γ rays). In 137Xe, a 13/2+2 level is found. A new shell-model study of 13/2+1,2 levels in N = 83 nuclei indicates the need for an ESPE(νi13/2) value lower than the one in the literature. The different population patterns of the j = ℓ ± 1/2 single-particle states in the PLF nucleus for the different targets suggest a potential application in studies with low-intensity RIB’s. 17 17 17 17 17 17 17

  18. Co-workers Washington University, USA D.G. Sarantites, J.M. Elson, J.E. Kinnison ANL, USA R.V.F. Janssens, S. Bottoni, D. Ayangeakaa, M.P. Carpenter, H.M. David, F. Kondev, T. Lauritsen, S. Zhu ORNL, USA J.M. Allmond, A. Gallindo-Uribarri LBNL, USA C.M. Campbell, H.L. Crawford ICN UNAM, Mexico E. Padilla-Rodal U.S. Naval Academy D.J. Hartley NSCL, USA P.C. Bender INFN Naples, Italy A. Gargano, N. Itaco Thanks for your attention!

  19. N = 83 and 82 A combined plot: ESPE’s for calculations b 3- energies for the N=82 cores A quantity reflecting λ=2 vibrations Two opposite trends: (i) The 3- − ESPE gap decreases as Z increases. (ii) E(2+), E(4+) are lowest for Z ≤ 56 and so the constructed quantity. For Z ≥ 56 the calculated levels (previous slide) don’t keep up with the i13/2, 3- x f7/2 mixing.

  20. 0.848 0.005 0.096 0.836 0.020 0.090 0.802 0.037 0.096 0.815 0.044 0.085 0.836 0.055 0.064 0.843 0.035 0.098 0.763 0.117 0.085 0.634 0.241 0.070 0.540 0.345 0.051 0.492 0.411 0.035 Black numbers: w.f. components Heyde et al. PLB 57 (1975) Studied N = 83 nuclei Used a phenomenological model: coupling 13/2+ and 7/2- states to quadrupole and octupole vibrations Predicted the lowest 13/2+ states to be rather pure (but with admixturs of 3− x f7/2 and 2+ x i13/2) Phoswich W. Expt. Microball Expt.

  21. Kay et al. ?

  22. W=A0 (1 + A2P2 + A4P4) P2=1/2 (3α2 – 1) P4=1/8 (35α4 − 30α2 +3) α = cos χ χ : angle emitted γ ray and spin direction E1 (533 keV) E2 (400 keV) M1, ΔI=0 (1384 keV)

  23. for 13C and ℓ = 7: L ≤ 7 for 9Be and ℓ = 5: L ≤ 6 13C h9/2 suppressed 9Be

  24. Shell-model calculations (A. Gargano, N. Itaco INFN Naples) Two-body matrix elements (TMBE’s): use the CD-Bonn NN potential and consider two-valence nucleon systems Model space: 0g7/2, 1d, 2s, 0h11/2 (π) and 1f, 2p, 0h9/2, 0i13/2 (ν) Threatment of the νi13/2 energies - no information from semi-magic nuclei. Consider: πg7/2 x νi13/2 (134Te) and similar πν configurations (135Te) and νi13/2(odd-mass nuclei) Threatment of excitations in the N = 82 core nuclei: only πexcitations and TBME’s; the model space does not allow for particle-hole excitations 25 25 25 25 25 25 25

  25. Energies in keV ESPE(νi13/2)=2434+260=2694 Scaled TBME (208Pb region) VπνΔVπν (πg7/2 x νi13/2)10 -722 -260 E=2434+279=2713 (πg7/2 x νf7/2)7 -462 0 X=279 keV Shergur et al. PRC 71, 064321 (2005) (πg7/2 x νf7/2)0 Other estimates: ESPE(νi13/2)=2694, 2669 Corragio et al. (2013) Korgul, et al. (2015)

  26. 137Xe calculation = “calc 2” (b)

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