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In-beam gamma-ray spectroscopy at RIBF

In-beam gamma-ray spectroscopy at RIBF. May 31, 2012 NN2012. AOI Nori RCNP Osaka Univ. 0. Introduction Deep inside (or beyond) island-of-Inversion -- South of Island-of-Inversion -- East of Island-of-Inversion Neutron rich Si isotopes N~28 Next step.

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In-beam gamma-ray spectroscopy at RIBF

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  1. In-beam gamma-ray spectroscopy at RIBF May 31, 2012NN2012 AOI NoriRCNP Osaka Univ. • 0. Introduction • Deep inside (or beyond) island-of-Inversion • -- South of Island-of-Inversion • -- East of Island-of-Inversion • Neutron rich Si isotopes N~28 • Nextstep

  2. Exotic structure in exotic nuclei Nuclear Strucuter shell closure p & n decoupling Astrophysics solar fusion explosive burning 16C: “egg” structure ? decoupled n-motion 32Mg: large deformation explosive hydrogen burning neutron skin Magic # (N=20) disappears. solar neutrino production 28O: particle unstable new magic #, N=16 neutron halo molecular structure neutron skin Magic # (N=8) disappears. heavy hydrogens

  3. Exotic structure in exotic nuclei Nuclear Strucuter shell closure p & n decoupling Astrophysics solar fusion explosive burning 16C: “egg” structure ? decoupled n-motion 32Mg: large deformation RIBF More exotic Heavier nuclei In beam-γ, First few years East and South of Island-of-inversion N~28  Intense 48Ca beam (~200pnA) explosive hydrogen burning neutron skin Magic # (N=20) disappears. solar neutrino production 28O: particle unstable new magic #, N=16 neutron halo molecular structure neutron skin Magic # (N=8) disappears. heavy hydrogens

  4. In-beamg-ray spectroscopy at RIBF • 2008 DayOnewith 48Ca • 32Ne, 31,33Na • H. Scheit, P. Doornenbal • Phys.Rev.Lett., 103:032501, 2009./Phys.Rev. C, 81:041305, 2010. • 201048Ca campaign • ~42Si S. Takeuchi, M. Matsushita • A>36Mg P. Doornenbal, H. Scheit • ~Al, P David Steppenbeck • 33Mg D. Bazin • 2011 U campaign (~3 pnA) • ~132Sn H. Wang, NA • 2012 Xe campaign • ~10xSn P. Doornenbal et al. • A. Obatelli et al.,

  5. Island-of-Inversion First proposed from masses Mass 31Na(Z=11, N=20) C. Thibault et al. PRC12(75)644 E.K. Warburton et al., PRC41(90)1147.

  6. Island-of-Inversion First proposed from masses Mass Ex(2+) moments … 31Na(Z=11, N=20) C. Thibault et al. PRC12(75)644 E.K. Warburton et al., PRC41(90)1147.

  7. Study of Island-of-Inversion via 2+, 4+ states in E-E nuclei Evolution of collectivity B(E2;0+2+) : Measure of Collectivity Ex(2+) : Alternative ∝　B(E2)(at least locally) R4/2 = Ex(4+) / Ex(2+) : Type of Collectivity ( Ex in odd-A nuclei ) ~

  8. Island-of-Inversion T. Motobayashi et al., Phys. Lett. B346, 9(95) Deformed (B(E2)) Deformed (Ex(2+))

  9. Island-of-Inversion before RIBF Deformed (B(E2)) Deformed (Ex(2+))

  10. Further into and beyond Island-of-Inversion ? Deformed (B(E2)) Deformed (Ex(2+))

  11. BigRIPS/ZeroDegree @ RIBF BigRIPS/ZeroDegree

  12. γ-ray spectroscopy setup @ BigRIPS/ZeroDegree Scheit et al. Takeuchi et al. Around the island of inversion (32Ne …), 42Si But unable to continue due to activation problem. SRC IRC Production Target F11 F5 F3 F1 F2 F7 F7 F8 F12 1st stage separation ZeroDegree analysis of 2ndary reaction products 2nd stage analysis

  13. γ-ray spectroscopy setup @ BigRIPS/ZeroDegree Scheit et al. Takeuchi et al. Around the island of inversion (32Ne …), 42Si But unable to continue due to activation problem. SRC IRC Production Target F11 F5 F3 F1 F2 F7 F7 F8 Target g F12 1st stage separation ZeroDegree analysis of 2ndary reaction products 2nd stage analysis

  14. 32Mg(p,p’) b~0.3 Energy (keV) 160° 20° H.Hasegawa, Master’s thesis, Rikkyo Univ., 2003 Emission angle of g rays

  15. Further into Island-of-Inversion ? ? Deformed (B(E2)) Deformed (Ex(2+))

  16. South of Island-of-Inversion ? ? Deformed (B(E2)) Deformed (Ex(2+))

  17. 32Ne : Ex (2+ ) 32Ne, 33Na + C  32Ne + g + X RIBF DayOne experiment • 29F : Ex (Jπ ), 30Ne + C  29F + g + X P. Doornenbal and H. Scheit et al., in preparation Phys.Rev.Lett., 103:032501, 2009.

  18. 2+ states in 32Ne Phys.Rev.Lett., 103:032501, 2009.

  19. 2+ states in 32Ne Phys.Rev.Lett., 103:032501, 2009.

  20. Further south, south of 30Ne ? 28O Unbound 29F = 28O+p p p 28O 28O

  21. Excited states in 29F

  22. Excited states in 29F

  23. South of Island-of-Inversion ? Deformed (B(E2)) Deformed (Ex(2+))

  24. South of Island-of-Inversion ? Deformed (B(E2)) Deformed (Ex(2+))

  25. East of Island-of-Inversion ? Deformed (B(E2)) Deformed (Ex(2+))

  26. 36,38Mg : Ex (2+), Ex(4+) 37Al + C  36Mg + g + X 39Al, 40Si + C  38Mg + g + X • 36,38Mg : B(E2;0+2+1) Coulex (38Mg+Pb) s  B(E2) P. Doornenbal and H. Scheit et al., in preparation

  27. 2+ state in 36,38Mg P. Doornenbal, H. Scheit et al. C(37Al, 36Mg*) C(40Si, 38Mg*) C(37Al, 36Mg*) C(39Al, 38Mg*)

  28. 2+ state in 36,38Mg P. Doornenbal, H. Scheit et al.

  29. East of Island-of-Inversion ? Deformed (B(E2)) Deformed (Ex(2+))

  30. East of Island-of-Inversion Deformed (B(E2)) Deformed (Ex(2+))

  31. North-East of Island-of-Inversion ? Deformed (B(E2)) Deformed (Ex(2+))

  32. Spherical or deformed ? from R4/2 Si isotope A Shape Coex., C. Forceet al. PRL 105, 2010. ? R(4/2) R(4/2) S isotope 4+ ? Ex (MeV) Ex (MeV) 2+ N 4+ Deformed (B(E2)) 2+ Deformed (Ex(2+))

  33. Spherical or deformed ? from R4/2 Deformed (B(E2)) Deformed (Ex(2+))

  34. Spherical or deformed ? from R4/2 ? Deformed (B(E2)) Deformed (Ex(2+))

  35. What we know about 42Si. • b-decay experiment • Short half-life  Large deformation (possibly oblate), comparing with QRPA calculation. • S.Grevyet al., Phys. Lett. B 594, 252 (2004). • Mass measurement • Deformed/Spherical? • B.Jurado et al., Phys. Lett. B 694, 43 (2007). Two-proton removal reactions, 44S  42Si • NSCL case • A substantial Z=14 subshell closure • J.Fridmann et al., Phys. Rev. C 74, 034313 (2006) • GANIL case • Well-deformed oblate rotor • B.Bastin et al., Phys. Rev. Lett. 99, 022503 (2007).

  36. Exof 2+ and (4+) states in 38,40,42Si 40S + C  38Si + g + X 44S + C  40Si + g + X 44S + C  42Si + g + X S. Takeuchi and M. Matsushita et al. in preparation

  37. 42Si - g single spectrum - 44S + C  42Si + g + X GANIL exp. : 770(19) keV B.Bastin et al., Phys. Rev. Lett. 99, 022503 (2007). We confirmed g line observed at GANIL.

  38. 42Si - g single spectra - 44S + C  42Si + g + X g ray (2+0+): 742(8) keV new lines: 1431(11) keV 2032(9) keV 2357(15) keV *Widths are fixed to simulated values.

  39. 42Si - g-g spectra - 44S + C  42Si + g + X 1431 keV Partner of 1431 keV 742 keV 2032 keV? Partner of 742 keV 1431 keV 2032 keV? 2032 keV ? R4/2 = 2.9 742 keV 1431 keV (4+) 2173 keV ? 2032 keV ? 742 keV 1431 keV 2+ 0 keV 0+ *Widths are fixed to simulated values.

  40. Spectroscopy of 38Si and 40Si 40S + C  38Si + X + γ 44S + C  40Si + X + γ Gate on 1079keV 634(7) 1079(6) 988(6) • (8) : This Work • (4+2+) Gate on 988keV Gate on 1079keV • : This Work • ( Ex(4+) )

  41. Spectroscopy of 38Si and 40Si 40S + C  38Si + X + γ 44S + C  40Si + X + γ Gate on 1079keV 634(7) 1079(6) 988(6) • (8) : This Work • (4+2+) Gate on 988keV Gate on 1079keV • : This Work • ( Ex(4+) ) (4+) 2.21 1126 1.08 2+ (4+) 2.53 1084 1544 (1.62) 38Si 634 0.99 2+ 988 40Si

  42. 42Si: well deformed N=28 isotones Z=14 isotopes A A R(4/2) R(4/2) 4+ 4+ Ex (MeV) Ex (MeV) 2+ 2+ N Z R(4/2) = 2.93 36Si: ref: X.Liang et al., PRC74,014311(2006) 46Ar: ref: Zs.Dombradiet al., NPA 727(2003)195 44S: ref: D.Santiago-Gonzalez et al., PRC 83,061305R(2011)

  43. North East of Island-of-inversion ? Deformed (B(E2)) Deformed (Ex(2+))

  44. North East of Island-of-inversion Deformed (B(E2)) Deformed (Ex(2+))

  45. p3/2 Otsuka, Suzuki and Utsuno, Nucl. Phys. A805, 127c (2008) exp. N =28 (4+)： RIBF data 2011 f7/2 d3/2 doubly magic ? neutron s1/2 Z =14 d5/2 repulsive 4214Si28 proton attractive Potential Energy Surface full 42Si Tensor force removed from cross-shell interaction Strong oblate Deformation 42Si 2+: Bastin, Grévy et al., PRL 99 (2007) 022503 Other calculations (RMF, Gogny) show oblate shape. Otsuka-san’s talk (Wed)

  46. Systematics of the 2+ and 4+ states in Si Present exp. -- without tensor force  spherical min. -- with tensor force  oblate min. T.Otsuka et al., NPA 805 (2008) 127c

  47. In-beamg-ray spectroscopy at RIBF • 2008 DayOnewith 48Ca • 32Ne, 31,33Na • H. Scheit, P. Doornenbal • Phys.Rev.Lett., 103:032501, 2009./Phys.Rev. C, 81:041305, 2010. • 201048Ca campaign • ~42Si S. Takeuchi, M. Matsushita • A>36Mg P. Doornenbal, H. Scheit • ~Al, P David Steppenbeck • 33Mg D. Bazin • 2011 U campaign (~3 pnA) • ~132Sn H. Wang, NA • 2012 Xe campaign • ~10xSn P. Doornenbal et al. • A. Obatelli et al.,

  48. In-beamg-ray spectroscopy at RIBF • 2008 DayOnewith 48Ca • 32Ne, 31,33Na • H. Scheit, P. Doornenbal • Phys.Rev.Lett., 103:032501, 2009./Phys.Rev. C, 81:041305, 2010. • 201048Ca campaign • ~42Si S. Takeuchi, M. Matsushita • A>36Mg P. Doornenbal, H. Scheit • ~Al, P David Steppenbeck • 33Mg D. Bazin • 2011 U campaign (~3 pnA) • ~132Sn H. Wang, NA • 2012 Xe campaign • ~10xSn P. Doornenbal et al. • A. Obatelli et al.,

  49. 86Kr/136Xe/238U 1pμA 86Kr/136Xe/238U 1pμA Z=82 Z=82 N=82 N=82 N=50 N=50 Z=50 Z=50 N=28 N=28 N=126 N=126 N=20 N=20 Z=28 Z=28 Z=20 Z=20 r-process waiting points corresponding to r-process abundance peak • Calculation uses • 86Kr + Be Fragmentation EPAX2 • 136Xe + Be Fragmentation EPAX2 • 238U + Be Fragmentation EPAX2 • Fission DATA@GSI (limited) • 238U + Pb Fragmentation EPAX2 • Fission ABLABRA Approved γ-ray spectroscopy experiments at BigRIPS 86Kr/136Xe/238U 1pμA 86Kr/136Xe/238U 1pμA r-process Nov07 Spiral2 • Calculation uses • 86Kr + Be Fragmentation EPAX2 • 136Xe + Be Fragmentation EPAX2 • 238U + Be Fragmentation EPAX2 • Fission DATA@GSI (limited) • 238U + Pb Fragmentation EPAX2 • Fission ABLABRA

  50. 86Kr/136Xe/238U 1pμA 86Kr/136Xe/238U 1pμA Z=82 Z=82 N=82 N=82 N=50 N=50 Z=50 Z=50 N=28 N=28 N=126 N=126 N=20 N=20 Z=28 Z=28 Z=20 Z=20 r-process waiting points corresponding to r-process abundance peak • Calculation uses • 86Kr + Be Fragmentation EPAX2 • 136Xe + Be Fragmentation EPAX2 • 238U + Be Fragmentation EPAX2 • Fission DATA@GSI (limited) • 238U + Pb Fragmentation EPAX2 • Fission ABLABRA Approved γ-ray spectroscopy experiments at BigRIPS 86Kr/136Xe/238U 1pμA 86Kr/136Xe/238U 1pμA r-process Nov07 Spiral2 • Calculation uses • 86Kr + Be Fragmentation EPAX2 • 136Xe + Be Fragmentation EPAX2 • 238U + Be Fragmentation EPAX2 • Fission DATA@GSI (limited) • 238U + Pb Fragmentation EPAX2 • Fission ABLABRA

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