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Identification of a possible new island of inversion

Identification of a possible new island of inversion. Production of new neutron-rich isotopes @ NSCL  Two stage separation  76 Ge beam  82 Se beam Momentum distributions Production cross sections

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Identification of a possible new island of inversion

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  1. Identification of a possible new island of inversion Production of new neutron-rich isotopes @ NSCL Two stage separation 76Gebeam  82Sebeam Momentum distributions Production cross sections Exploration of a possibleisland of inversion Qg – systematics “Temperature” plots Summary Oleg B. Tarasov NCSL / MSU, USA 05 / 28 / 2012 11-th Conference on Nucleus-Nucleus Collisions 11th Conference on Nucleus-Nucleus Collisions

  2. Production of new isotopes O.T. et al.,Phys.Rev. C 75, 064613 (2007) T.Baumann et al.,Nature (London) 449, 1022 (2007) 44Si 40Mg, 42Al, 43Al • Two-stage separation • No detectors in beam line down to wedge selection slits (A1900 FP). • Position (Brho) measurement in the dispersive focal plane in the second stage (S800BL) • The first stage (A1900) of the system serves as a selector whereas the second stage (transfer hall line + S800BL) contains detectors and functions as analyzer • All new fragment separators BigRIPS, SuperFRS, A2400 are multi-stage separators. Figure.40Mg expected yield calculated for the A1900 fragment separator using extrapolation production cross section from the 44Si experiment 11th Conference on Nucleus-Nucleus Collisions

  3. 2009 : 76Ge(130 MeV/u) 50Cl, 53Ar, 55,56K, 57,58Ca, 59,60,61Sc, 62,63Ti, 65,66V, 68Cr, 70Mn Phys.Rev.Lett. 102, 142501 (2009) : New isotopes, indication of a new island of inversion Phys.Rev.C. 80, 034609 (2009) : Set-up, cross sections, momentum distributions NIM A 620, 578-584 (2010) : A new approach to measure momentum distributions 11th Conference on Nucleus-Nucleus Collisions

  4. 2009 : 76Ge (130MeV/u) - PID, resolution, new isotopes For all particles stopped in the Si-telescope in the production runs 11th Conference on Nucleus-Nucleus Collisions

  5. 2011 : Newly-developed82Se (139 MeV/u) Beam E (MeV/u) I(pna) N/Z 82Se 139 35 1.412 76Ge 130 20 1.375 64Ti, 67V, 69Cr, 72Mn 70Cr 1event & 75Fe 1event DN/DZ=2 will be submitted soon g g 11th Conference on Nucleus-Nucleus Collisions

  6. 82Se (139 MeV/u) + Be: New isotopes, PID Production runs All runs 64Cr 62Ti 11th Conference on Nucleus-Nucleus Collisions

  7. 2. Momentum Distributions Why? To obtain cross sections based on LISE++ transmission calculations with parameters of momentum distribution model obtained from the current experiment “Classic: way: Brho scanning thin target New method: Brho = const Target thickness variation A new approach to measure momentum distributions and production cross sections of neutron rich nuclei using fragment separators O.T. et al.,NIM A 620, 578-584 (2010) 11th Conference on Nucleus-Nucleus Collisions

  8. Momentum Distributions : Target scanning method 76Ge : 5 targets(max 3 isotopes for one element) 82Se : 7 targets (max 8 isotopes for one element) 76Ge analysis (2009) : point for fit in the middle of target or weights = const 2012 update : using weights F(vp,s) from the momentum distribution model with vp,s, ..which actually are fitted…… (!!!!) target middle More probable Based on vp & s 11th Conference on Nucleus-Nucleus Collisions

  9. 82Se (139 MeV/u) + Be : Momentum Distributions – u/u0 Borrel convolution DJM 11th Conference on Nucleus-Nucleus Collisions

  10. 82Se (139 MeV/u) + Be : Momentum Distributions – Widths 11th Conference on Nucleus-Nucleus Collisions

  11. Momentum distributions analysis results 11th Conference on Nucleus-Nucleus Collisions

  12. 76Ge (130 MeV/u) + Be, W : cross sections O.T. et al. Phys.Rev.C. 80, 034609 (2009) 11th Conference on Nucleus-Nucleus Collisions

  13. 82Se (139 MeV/u) + Be, W : cross sections 11th Conference on Nucleus-Nucleus Collisions

  14. 82Se (139 MeV/u) : W vs. Be targets New isotopes 76Ge+Be, 82Se+Be New isotopes 76Ge+W 11th Conference on Nucleus-Nucleus Collisions

  15. Qg- systematics 48Ca(140MeV/u) + W,Be A simple systematic framework was found to describe the production cross sections based on thermal evaporation from excited prefragments that allows extrapolation to other weak reaction products. O.T. et al., Phys.Rev. C 75, 064613 (2007) Compilation with data from M. Mocko et al.,Phys. Rev. C 74, 054612 (2006) Figure. The variation of the cross sections for the production of neutron rich nuclei as a function of the two-body Q values [Qgg, left panels (a), (b)] and as a function of the one-body Q value [Qg, right panels (c), (d)]. Upper panels (a), (c) show data for W (Ta), lower panels (b), (d) for Be targets. 11th Conference on Nucleus-Nucleus Collisions

  16. 76Ge (130MeV/u) + W,Be : Qg- systematics O.T. et al. Phys.Rev.C. 80, 034609 (2009) The fact that the cross sections of the most neutron-rich nuclei with Z = 19 to 22 are enhanced relative to the lighter isotopes may indicate that these nuclei and their precursors are more bound than predicted and is reminiscent of the discovery of the island of inversion at N = 20. B.A. Brown, Prog. Part. Nucl. Phys. 47, 517 (2001). 11th Conference on Nucleus-Nucleus Collisions

  17. Islands of inversion • Particle-hole excitations across a shell gap into the next higher oscillator shell can become energetically favored if stabilized by deformation and pairing correlations [1]. [1] “Isotope Science Facility at Michigan State University”,MSUCL-1345, 11-2006 • Strong quadrupole deformations have been observed in the neutron-rich nuclei around N = 20 [2,3], [2] D. Guillemaud-Mueller et al., Nucl. Phys. A426, 37 (1984). [3] T. Motobayashi et al., Phys. Lett. B 346, 9 (1995). • and around N = 8 [4,5]. [4] A. Navin et al., Phys. Rev. Lett. 85, 266 (2000). [5] H. Iwasaki et al., Phys. Lett. B 481, 7 (2000). Figure: Measured 12Be (N = 8) and 31Na (N = 20) and predicted (N=40) islands of inversion across the neutron-rich side of the nuclear chart. [1]. • Such an anomalous deformation is suggested to appear in the heavier region around N = 40 (62Ti [6], 64Cr [7]). [6] B.A. Brown, Prog. Part. Nucl. Phys. 47, 517 (2001) [7] S.M. Lenzi et al., Phys. Rev. C 82, 054301 (2010) 11th Conference on Nucleus-Nucleus Collisions

  18. Search for the new island of inversion The observation of low-energy 2+ states in 60,62Cr suggests that these isotopes are strongly deformed O. Sorlin et al., Eur. Phys. J. A 16, 55 (2003) The large experimental R4/2 ratio of 62Cr is an indication for the development of deformation: N. Aoi et al., PRL 102, 012502 (2009) Evidence for increased collectivity at N = 40 in neutron-rich 64Cr A.Gade et al., Phys. Rev. C 81, 051304 (2010) 11th Conference on Nucleus-Nucleus Collisions

  19. Possible new island of inversion? (76Ge) O.T. et al., Phys.Rev.Lett. 102, 142501 (2009) O.T. et al., Phys.Rev.C. 80, 034609 (2009) 11th Conference on Nucleus-Nucleus Collisions

  20. 82Ge (139MeV/u) + Be : Qg- systematics 11th Conference on Nucleus-Nucleus Collisions

  21. 82Ge (139MeV/u) + Be : Qg- systematics 11th Conference on Nucleus-Nucleus Collisions

  22. Inverse slope parameter T O.T.. et al., Phys.Rev.C. 80, 034609 (2009) Will be submitted soon 11th Conference on Nucleus-Nucleus Collisions

  23. “Next” Calcium isotopes 76Ge approved proposal from MSU @ RIKEN Intensity factor 2 Target thick. factor 10 Secondary reactions factor 55 (for 60Ca)? 11th Conference on Nucleus-Nucleus Collisions

  24. 82Se (140MeV/u) + Be : cross section new record? *reduced, assuming 100% transmission, 100% time just for one production run 11th Conference on Nucleus-Nucleus Collisions

  25. Summary & Outlook for Possible Island of inversion ○ More than two dozens of neutron-rich isotopes (12 ≤ Z ≤ 26) have been observed in the first time ○ Evidence for a Change in the Nuclear Mass Surface in two experiments with different primary beams 76Ge & 82Se : new island of inversion (62Ti)? ○ Measurement of cross sections and momentum distributions in wide regionwith different beam-target combinations ○ A new approach to measure momentum distributions Incoming experiments ○Time-of-Flight Mass Measurements of Neutron Rich Nuclei (MSU) -- done ○ Gamma-ray spectroscopy of neutron-rich isotopes (MSU and …) ○ Exploration of the possible new island of inversion with the discovery of neutron rich nuclei (RIKEN) 11th Conference on Nucleus-Nucleus Collisions

  26. 82Se experiment participants A.M.Amthor2, L.Bandura 2, T.Baumann 1, D.Bazin1, J.S.Berryman1, G.Chubarian3, N.Fukuda4, A.Gade 1,5, T.N.Ginter 1, M.Hausmann 2, N.Inabe 4, T.Kubo4, D.J.Morrissey1,6, J.Pereira 1, M.Portillo 2, B.M.Sherrill1,2,5, A.Stolz 1, C.Sumithrarachchi 1, O.B.T. 1, M.Thoennessen1,5, and D.Weisshaar 1 1National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA 2Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824-1321, USA 3Cyclotron Institute, Texas A&M University, 3366 TAMU, College Station, TX, 77843-3366, USA 4RIKEN Nishina Center, RIKEN, Wako-shi, Saitama 351-0198, Japan 5Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA 6Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA The authors would like to acknowledge the operations staff of the NSCL for developing the intense 76Ge and 82Se beams necessary for this study This work was supported by NSF #PHY-06-06007 grant. 11th Conference on Nucleus-Nucleus Collisions

  27. NSCL Friday evening game: Connect points! v.4 (A=3Z+c) Circle – 62Ti N=40 11th Conference on Nucleus-Nucleus Collisions

  28. 1. Production of new isotopes. Exploring the limits of nuclear existence 11th Conference on Nucleus-Nucleus Collisions

  29. 82Se (139 MeV/u) : W vs. Be targets 11th Conference on Nucleus-Nucleus Collisions

  30. 82Se (139 MeV/u) +Be -> N-2Z 11th Conference on Nucleus-Nucleus Collisions

  31. Exploration of unknown neutron-rich region 2009: RIBF @ RIKEN238U 345 MeV/u, 109pps @ 2009 2011: 238U 345 MeV/u, 1010 pps @ 2011 2017?: GSI – new isotope production with preseparator, 1.5 GeV/u, 1012pps 2020?: FRIB @ MSU 200-250 MeV/ u , 400 kW 11th Conference on Nucleus-Nucleus Collisions

  32. Yields per 1 second A total of 47 primary beams were used for FRIB yield analysis. These cover nearly 90% of the optimum primary beams for the production of all isotopes. RIBF @ RIKEN (2011)238U 345 MeV/u, 2pnA GSI ,1.5 GeV/u, 1012pps F-RIB @ MSU 200-250 MeV/ u , 400 kW 11th Conference on Nucleus-Nucleus Collisions

  33. FRIB Estimated rates Java version Excel version http://groups.nscl.msu.edu/frib/rates/ Readme file : http://groups.nscl.msu.edu/frib/rates/FRIB_rates_readme.pdf 11th Conference on Nucleus-Nucleus Collisions

  34. FRIB : new isotopes per 1 week 11th Conference on Nucleus-Nucleus Collisions

  35. v.2. # e09016 : W-target Qg-systematics (Z=14-19) 11th Conference on Nucleus-Nucleus Collisions

  36. # e09016 : W-target Qg-systematics (Z=20-25) 11th Conference on Nucleus-Nucleus Collisions

  37. # e09016 : W-target Qg-systematics (Z=26-28) 11th Conference on Nucleus-Nucleus Collisions

  38. Connect points! v.1 (Z-line) 11th Conference on Nucleus-Nucleus Collisions

  39. Connect points! V.2 (N-line) 50 25 30 49 11th Conference on Nucleus-Nucleus Collisions

  40. Connect points! V.3 (a-line) 11th Conference on Nucleus-Nucleus Collisions

  41. Supplemented slides 11th Conference on Nucleus-Nucleus Collisions

  42. Limiting temperature (A) 11th Conference on Nucleus-Nucleus Collisions

  43. Targets vs Energies 11th Conference on Nucleus-Nucleus Collisions

  44. LISE++ Abrasion-Dissipation-Ablation model (ADA) Under construction • A-A : two step process, A-D-A : three step process** • Dependence from projectile energy, N/Z target ratio, target nucleus size.Advantage of heavy targets to produce neutron-rich nuclei. • Mass prediction for unknown isotopes becomes very crucial ** -- “Universal parameterization”: three step projectile fragmentation model has been already used in LISE++ to describe momentum distributions. O.T., Nucl.Physics A734 (2004) 536-540 11th Conference on Nucleus-Nucleus Collisions

  45. Statistics issue 11th Conference on Nucleus-Nucleus Collisions

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