1 / 48

Structure of N~40 Ni isotopes studied by knock-out reactions

Structure of N~40 Ni isotopes studied by knock-out reactions. Francesco Recchia Università degli studi di Padova. Overview. Scientific motivation Study of Ni isotopes: Neutron knock-out with GRETINA and S800 at NSCL

freya-gaines
Télécharger la présentation

Structure of N~40 Ni isotopes studied by knock-out reactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Structure of N~40 Ni isotopes studied by knock-out reactions Francesco RecchiaUniversità degli studi di Padova

  2. Overview • Scientific motivation • Study of Ni isotopes: Neutron knock-out with GRETINA and S800 at NSCL • New data on 68Ni and implications for the structure of its low-spin states

  3. The “spin-orbit” magicnumbers N=4 2d d5/2 40 1g 50 g9/2 N=3 40 p1/2 2p f5/2 p3/2 1f 28 20 f7/2 20 N=2 d3/2 2s s1/2 1d d5/2 8 8 N=1 p1/2 1p p3/2 L2 + L.S H.O +

  4. Shell evolution • Disappearance / appearance of magic numbers • P-N attraction between spin-flip partner orbits m m’ • Monopole part of the tensor term D • Monopole part of the three-body force m’ m H. Grawe, EPJ A 25 (2005) 357 T. Otsuka Phys. Scr. T152 (2013) 014007 T. Otsuka et al. EPJ A 20 (2003) 69-73, PRL 95, 232502 (2005), J.D.Holt et al 2012 J. Phys. G: Nucl. Part. Phys. 39 085111

  5. A multipole expansion The effective interaction monopole Multipole • represents a spherical mean field extracted from the interacting shell model • - determines the single particle energies or ESPE. Deformation • correlations • energy gains Interplay spectacular phenomena ioi

  6. Island of inversion The islands of inversion (N=8,20,28) At N=8 and N=20 the h.o. shell gap vanishes for very neutron rich nuclei. N=8 Deformed intruder configurations fall below the spherical ones 11Li N=20 Si N=28 42Si A. Poves, 2011 T. Otsuka EPJ S. Top. 156, 169 (2008)

  7. 32Mg20 p3/2 f7/2 20 sd Islands of inversion Islands of Inversion are observed at the harmonic oscillator magic numbers. N=2 N=1 64Cr40 12Be8 N=4 N=3 d5/2 g9/2 d5/2 s1/2 40 8 pf N=2 N=3 p

  8. 68Ni region

  9. Observables at N=40 E(2+) R.Broda et al., PRL 74, 868 (95) B(E2) O. Sorlin et al. PRL 88, 092501 (2002) W. Rotheret al.Phys.Rev.Lett. 106, 022502 (2011) A. Kankainen, et al., J.Phys.G 39, 093101 (2012)

  10. 32 Neutron excess and shell migration ng9/2 • 68Ni is at the limit of region of deformation 40 nf5/2 Monopole shifts np1/2 np3/2 neutrons pf7/2 protons 0g9/2 0g9/2 0f5/2 Z = 20 40 Z = 28 0f5/2 1p1/2 32 1p1/2 1p3/2 1p3/2 28 28 0f7/2 0f7/2 0f7/2 0f7/2 protons neutrons protons neutrons

  11. 32 68Ni low spin states ng9/2 40 nf5/2 • Collective structure in 68Ni? • Based on deformed excited states? np1/2 YES: Type II shell evolution Y.Tsunoda, T.Otsuka et al. arXiv[nucl-th] 23/9/2013 np3/2 pf5/2 neutrons pf7/2 28 protons

  12. Single Particle Strength in the odd, neutron-rich Ni isotopes • Persistence of customary magic numbers • Spin-isospin part of the nn interaction • Single particle strength in A-1Ni • components in the g.s. in ANi • comparison to shell model calculations • Provide the first gating transitions for GS data Dec 8 – 12 2012

  13. K500 Example: 82Se → 72Ni ion sources coupling line 82Se13+, 12 MeV/u K1200 A1900 focal plane p/p = 1% production target stripping foil 82Se34+, 140 MeV/u wedge fragment yield after target fragment yield after wedge fragment yield at focal plane 72Ni 72Ni 82Se 82Se 72Ni 82Se Figure courtesy A. Stolz

  14. TOF xfp Reaction product identificationS800 spectrograph 69Cu Reaction target 100-281mg/cm2 68Ni 67Co TOF obj A1900 fragment separator

  15. Reaction product identificationS800 spectrograph 75Zn 73Cu Reaction target 100-281mg/cm2 74Cu 72Ni A1900 fragment separator

  16. Reaction product identificationS800 spectrograph γ β ̴ 0.4c 68Ni 67Ni 67Ni* Reaction target 100-281mg/cm2 to focal plane S800 γ 9Be A1900 fragment separator

  17. Gated on 68Ni Reaction product identificationS800 spectrograph 67Ni 66Ni 65Co Reaction target 100-281mg/cm2 Velocity vector A1900 fragment separator

  18. Reaction product identificationS800 spectrograph Reaction target 100-281mg/cm2 K. Meierbachtol et al. NIM A 652 (2011) 668–670 A1900 fragment separator

  19. 68Ni is produced from 70Ni A surprise in 68Ni…

  20. Low-spin states in 68Ni 1770(30) 0+ Bacchus@IPNOrsay GIROD et al. 1988

  21. Low-spin states in 68Ni Lisol@KU Leuven Mueller et al. 2000 1770(30) 0+

  22. Low-spin states in 68Ni N=40 Z=40 1770(30) 0+ Predicted a new 0+ level at 2202 keV Pauwels et al. 2012

  23. Low-spin states in 68Ni EXOGAM-VAMOS@GANIL Dijon et al. 2012 2202 0+ 2p2h 1770(30) 0+

  24. Low-spin states in 68Ni EXOGAM-VAMOS@GANIL Dijon et al. 2012 2202 0+ 2p2h GAMMASPHERE@ANL Chiara et al. 2012 1770(30) 0+

  25. Reaction product identificationS800 spectrograph Reaction target 100-281mg/cm2 K. Meierbachtol et al. NIM A 652 (2011) 668–670 A1900 fragment separator Clean P-D coincidences 70Ni →68Ni

  26. 26 A surprise in 68Ni !! <511> in the hodoscope prompt

  27. Lifetime 350(50) ns ch

  28. GIROD PRC 1988

  29. 2nKO with GRETINA at NSCL… (a) CsI(Na) spectrum, 68Ni-gated; (b) GRETINA spectrum, gate on 511 and 68Ni

  30. DIS experiment • 440-MeV 70Zn + 208Pb DIS reaction at ATLAS • Stand-alone Gammasphere (100 Ge detectors) • Thick target stops all reaction products • Beam period 412 ns • Trigger on g fold ≥3 • DIS produces cross-coincident partner nuclei Analysis by CJ Chiara – University of Maryland/ANL

  31. Ge timing Prompt: t() in region 1 Delayed: t() in region 2 or 3 Coincidence cubes: PPP – all three ’s are prompt PPD– two prompt, one delayed PDD– one prompt, two delayed and within 50 ns of each other DDD – all three ’s are delayed 1 in 5 beam pulses allowed to hit the target 50 ns 412 ns  Time following an RF pulse Prompt  rays – emitted by excited states directly populated in the reaction Delayed  rays – emitted by isomeric states or in the b decay of the reaction products Analysis by CJ Chiara – University of Maryland/ANL

  32. DIS with Gammasphere at ATLAS… (delayed Po lines) (a,b) gate 662/Po; (c) gate 662/1139 Analysis by CJ Chiara – University of Maryland/ANL

  33. Measured branching ratios  relative B(E2)’s for decays to 0+1,2 and 2+1 states. * *W. F. Mueller et al., PRC61, 054308 (2000)

  34. B(E2) ratios, normalized at each level 50 g9/2 40 p1/2 m=2 (68%) m=4 (29%) f5/2 p3/2 m=2 (56%) m=4 (28%) 28 m=0 (42%) m=2 (43%) 2+2 decay favors 2+1(mixed) SM calcs with 56Ni core + nf5/2pg9/2 Generally good energies Small ‘tweak’  B(E2) ratios from 2+2 agree(0.4%) n(g9/2)m components...; 0+3 no good

  35. B(E2) ratios, normalized at each level d5/2 50 g9/2 40 40 p1/2 p1/2 f5/2 f5/2 p3/2 p3/2 28 28 f7/2   • pfp + nf5/2pg9/2d5/2 • 0+3 is p excitation • B(E2)’s reproduced • B(E2)2+1→0+2is 16 times B(E2)2+2→0+2 2+2 decay favors 2+1(mixed)

  36. 36 MC Shell Model N. Shimuzu, T. Otsukaet al. Prog. Theor. Exp. Phys. (2012) 01A205

  37. 37 MC Shell Model N. Shimuzu, T. Otsukaet al. Prog. Theor. Exp. Phys. (2012) 01A205 Tsunoda JPG (2013), [nucl-th] 1309.5851v1 (2013)

  38. Conclusions • 68Ni studied via 2nKO with GRETINA at NSCL and via DIS with Gammasphere at ATLAS • Energy of 0+2 isomer firmly established • Mixing of configurations for low-lying states supports picture of shape coexistence • What comes next? • 68Ni: • Absolute lifetimes / B(E2)’s needed! • Study of the branchings with larger statistics • 2 proton transfer cross sections • More 2+ levels • Heavier Ni isotopes

  39. Thankyou! Experiment:C. J. Chiara, R. V. F. Janssens, D. Weisshaar, A.Gade, W. B.Walters, M. Albers, M. Alcorta, V.M.Bader, T. Baugher, D.Bazin, J. S. Berryman, P.F. Bertone, B. A. Brown, C. M.Campbell, M.P.Carpenter, J. Chen, H. L. Crawford, H.M.David, D. T. Doherty, C. R. Hoffman, F. G.Kondev, A. Korichi, C. Langer, N. Larson, T. Lauritsen, S. N. Liddick, E. Lunderberg, A. O. Macchiavelli, S. Noji, C. Prokop, A. M. Rogers, D. Seweryniak, S. R. Stroberg, S. Suchyta, S. Williams, K. Wimmer, S. Zhu Theory:B.A.Brown

  40. Available online 2 weeks ago!

  41. GRETINA Experiments at NSCL • Nuclear Shell Evolution • N=Z Mirror Spectroscopy  • Structure in 221,223Rn  • 50-52Ca neutron knock-out  • Neutron-rich Ti  • Odd neutron-rich Ni  • 34Si Bubble nucleus?  • Neutron-rich Si  • GRETINA commissioning  • Neutron-rich N=40 nuclei  • Normal and intruder configurations in the Island of Inversion • Nuclear Astrophysics • Excitation energies in 58Zn  • Measurement of the 56Ni(d,n)57Cu transfer reaction 23 Expts 3360 hrs • Collective Nuclear Structure • Transition matrix elements in 70,72Ni • Quadrupole collectivity in light Sn • γ-γ spectroscopy in neutron-rich Mg • Neutron-rich C lifetime measurement  • Collectivity at N=Z via RDM lifetime measurements  • B(E2:2→0) in 12Be  • 71-74Ni excited-state lifetimes  • Inelastic excitations beyond 48Ca Triple configuration • coexistence in 44S • GT strength distributions in 45Sc and 46Ti  • Search for isovector giant monopole resonance  done through February 2013 Prepared by H. Crawford, LBNL

  42. The new interaction in the fpgd space LNPS interaction: renormalized realistic interaction + monopole corrections 48Ca core protons: full pf shell neutrons: p3/2,f5/2, p1/2, g9/2, d5/2 d5/2 g9/2 40 f5/2 p1/2 p3/2 28 28 f7/2 • KB3gr for the pf-shell; • monopole corrections to reproduce the Z=28 and N=50 gaps in 78Ni based on data of neighboring nuclei 48Ca S. M. Lenzi, F. Nowacki, A. Poves, and K. Sieja, PRC82, 054301 (2010)

  43. E (2+) The N=40 isotones A change of structure is observed along the isotonic chain in good agreement with the available data Occupation of intruder orbitals and percentage of p-h configurations B(E2;2+0+) S.M. Lenzi, F. Nowacki, A. Poves and K. Sieja, PRC 82, 054301 (2010)

  44. Neutron-rich Cr and Fe isotopes results and shell-model calculations The energy levels at N=40 cannot be described within the fp or fpg space S. Lenzi, F. Nowacki, A. Poves and K. Sieja 2010 d5/2 g9/2 68Ni p1/2 f5/2 1131 p3/2 48Ca 420 f7/2 π ν

  45. Cr Fe Ni Cr-Fe-Ni isotopes E (2+) β~0.35 β~0.3 B(E2) S.M. Lenzi, F. Nowacki, A. Poves and K. Sieja, PRC 82, 054301 (2010)

More Related