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Decay Studies

Decay Studies. María José García Borge Instituto de Estructura de la Materia, CSIC. Near the drip lines. Overview. Desintegration  + -EC Desintegration  - Desintegration  Fission. Halo structure Disappearance of magic numbers Exotic decays Asymmtries Order to Chaos.

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Decay Studies

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  1. Decay Studies María José García Borge Instituto de Estructura de la Materia, CSIC M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  2. Near the drip lines Overview Desintegration +-EC Desintegration - Desintegration  Fission • Halo structure • Disappearance of magic numbers • Exotic decays • Asymmtries • Order to Chaos M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  3. Beta-delayed Particle Emission • 1916 Rutherford & Wood [Philos. Mag. 31 (1916) 379] • 1963Barton &Bell identified 25Si as p • The intensity of the particle depends of: • 1-Beta intensity of the precursor • 2-Probability of particle emission versus  E,  Level density Spin, Isospin -decay properties M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  4. 6Li 7Li 8Li 9Li 11Li Tanihata, 1985 Halo nuclei • Energy threshold effect • Highlight by nuclear reactions • Effects in beta decay M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  5. Even a neutron rich- nuclei emit charged particles 20.6 - 3/2- 1996 17.916 T1/2 = 8 ms 1983 9Li+d 1966 9Li 15.721 8Li+t 10.59 p 1980 d 8.82 8.982 1979 2+3n 7.315 9Be+2n 0.320 ½- 1974 Energías (MeV) g 0.504 0.320 ½+ 10Be+n 11Be 11Be Beta decay of an exotic nuclei M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  6. Qd = 3.007 – S2n MeV M.V. Zhukov et al., PRC47 (1993) 2937 D. Baye et al., Prog. Th. Phys. 91 (1994) 271 F.C. Baker, Phys. Lett. B 322 (1994) 17 Beta-delayed deuterons b- 6He a+d M.J.G. Borge et al., Nucl. Phys. A560 (1993) 664 Anthony et al., PRC 65 (2002) 034310 10-4 6Li Intensity (decay-1 MeV-1) 10-5 10-6 Exploring w.f.  10 fm 500 1000 0 0 Ed (keV) M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  7. 11Li, gamma rays 320 keV ½- g ½+ 11Be Q = 20.62 MeV, T 1/2= 8.2 ms b(320) = 6.3(6) % log ft = 5.73 M.J.G. Borge et al., PRC55 (97) R8 N. Aoi et al., NPA616 (97) 181c D. Morrisey et al., NPA627 (97) 222 (1s1/2)2/(0p1/2)2 ~1 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  8. 11Li (284 MeV/u) + C 9Li + n @ GSI H. Simon et al., PRL 83 (1999) 496 See presentation of Thomas Nilsson 10Li 10Li 9Li n2 n1 (1s 1/2)2 = 45(10) % in the 11Li g.s Single-particle momentum distributions, Hankel functions M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  9. - 11Li Energy, spin & T1/2 from -line shapes in 11Li decay 11Li Controversial interpretation of n in 11Li  New Method 8.8 3/2,5/2 8 6.7 5.958 11Be 2.6 MeV 3.4 MeV 10Be Doppler broaden -lines (n) • Decay of exotic neutron rich light nuclei • Depends of energy of neutron • T1/2 of the bound state Fynbo, NPA 736 (2004) 39 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  10. 11Li Polarized radioactive beams: 11Li @ TRIUMF 8.8 8 3/2 7 6.179 3/2 11Be 5 5.958 2.6 MeV 3.4 MeV 10Be • Spin polarized 11Li beam • , n, n coincidences • Spin and parities of 7 levels in 11Be assigned. Hiriyama, Phys. Lett. B 611 (2005)239 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  11. b+ : p→n + e+ +  d = 4.8 (4) % b- : n→p + e- +  E.C. : p + e-→n +  ft- ft+ n p n p Mirror Asymmetry & Systematics  = nuc + SCC Thomas et al., AIP Conf. Proc 681, p. 235 • Allowed Gamow-Teller transitions (log(ft)<6) • 17 couples of nuclei • 46 mirror transitions Average asymmetry d : 11 (1) % in the 1p shell (A<17) 0 (1) % in the (2s,1d) shell (17<A<40) M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  12. 17Ne 18Ne 19Ne 16F 17F Asymmetry Halo Structure First identification of a proton-halo state Rolfs, NPA217(73)29 Beam-on 1.65(16) % Beam-off 1.56(20)%, Ogawa et al., J. Phys. G24 (1998) 143 600 = ft+/ft- - 1 = -0.55(09) Borge et al., PLB317(93)25 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  13. 33Ar p-spectrum free of -summing 0 2 3 4 Ep (MeV) Electron-Neutrino Correlations • Study of the proton line shape • Physics beyond the SM (see presentation of O. Naviliat-C) • Isospin mixing in Fermi decays • Configuration mixing • Level interferences • Spin assignment • Excitation energies 32Ar Schardt & Riisager, Z. Phys. A 345 (1993) 265 Adelberger & Garcia, Hyp. Int 129 (2000) 237 0 2.5 3.5 Ep (MeV) M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  14. Zn Ni Fe Exotic Radioactivities 1p-radioactivity (Z,N)  p + (Z-1,N) 2p-radioactivity (Z,N)  2p + (Z-2,N) M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  15. 57(6) % 2p E2p = 1.154(16) MeV Status of 2p-radiaoctivity GANIL Fragmentation reactions 58Ni-beam 45Fe 45Fe Giovinazzo et al., PRL 89 (2002) 102501 Agreement with 3-body model for p-wave emission Dossat, PRC, submitted • Next Steps: • Search for new two-proton emitters • 48Ni , 59Ge ….. • Detailed study of the decay process Measurement of proton-proton correlation: • p-p angle • Individual proton energies • Modelling of the 2p resonance 87(13) % 2p E2p = 1.48(2) MeV 54Zn 54Zn Blank et al., PRL 94 (2005) 232501 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  16. Beta delayed particle emitters B.Jonson & K. Riisager, NPA693 (2001) 77 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  17. Decay of IAS through 2p emission Diagonal from decays via single intermediate state from many initial states fed in beta-decay 1p-spectrum. 31Ar -2p emitter 2p-spectrum M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  18. ? Best candidate for correlated 2p-emission • Search at the limit of 0.01% for • direct 2p emission and 3p –emission Improvements in comparison to previous ISOLDE experiment: • Double coincidences a factor of 30 better • Triple coincidence a factor 70 better • Energy cut-off down to 100 keV M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  19. Why to Study Light Nuclei ? • Exact” A-body calculations possible for A12 • Green Funtion Monte-Carlo methods • Non-core Shell-model • Crucialfor bridging A=5 and A=8 gaps in • Big Bang and Stellar nuclear synthesis • The (n,)9Be + 9Be(,n)12C • Competes with triple- in n-rich scenarios • Importance of the +n5He(, )9Be • Experimentally -decay provides • Clean way to feed unbound states • Break-up mechanism not fixed by kinematics M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  20. Data Sequential Direct 3 break up of the 12.71 MeV state in 12C 12N  12.7 1+ 3 8Be 2+ 8Be 0+ 12C Break-up mechanism ? Sequential or Direct ... mainly sequential + Coulomb int. between the 3  Fynbo et al, Phys. Rev. Lett. 91(2003) 082502 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  21. Large asymmetries δ ≈ 3 δ=1.2±0.5 A = 9 Isobar δ ≈ 0 Nyman et al., NPA 510 (1990) 189 Mikolas et al., PRC 37 (1988) 766 F. Ajzenberg-Selove, NPA 490 (1988) 1 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  22. 9B States fed in -decay of 9C • Sequential Decay of 12.2 MeV State via 8Be(gs), 8Be(2+), 5Li(gs) and 5Li(1/2) • R-Matrix-formalism applied. • MC-simulations to account for efficiencies of each channel • Results E: 12.19(4) MeV • : 450(20) keV • J: 5/2 • BGT: 1.20(15) • UC Bergmann, NPA 692 (2001)427 IAS Esum (MeV) Ep,,(keV) M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  23. 11.81 MeV state  91±10% 11.28 MeV state  9 % (e,p)-scattering on 9Be assumed J = 7/2 Only the participation of the 11.81 MeV state in 9Be for the beta feeding is considered Beta feeding to the 11-12 MeV region in 9Be Fit of the high energy peak gating on the 5He(3/2-) channel M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  24. 13.257 =0.45 5/2-  = 3.4(7) δ ≈ 3 5/2- δ=1.2±0.5 54.1(15)%  = 0.032(3) δ ≈ 0 PLB576 (2003)55 NP A692(2001)427 A = 9 isobar 3/2- (1/2,5/2)- (1/2)- 3/2- 3/2- Nyman et al., NPA 510 (1990) 189 Mikolas et al., PRC 37 (1988) 766 F. Ajzenberg-Selove, NPA 490 (1988) 1 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  25. N=20 Energy(MeV) Z=12 BaF2-2 Island of Inversion Fast timing technique Beta Ge-1 H. Mach, ENAM2004 32Na beam BaF2-1 T1/2(2+) = 16.0(4.2) ps B(E2; 01+  21+) = 327(87) e2fm4 Beta-Ge-BaF2(t) B(E2) vs N Mg 31Mg 1p1h B(E2;7/2-3/2-) = 67(6) e2fm4 Mach, EPJA25,s01(2005)149 30Mg normal B(E2; 2+ 0+) = 40(9) e2fm4Scheit, PRL 94(2005) 172501 Fast Timing Rex-Isolde M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  26. Nummela etal., PRC63(2001)044316 Intruder states & shape coexistence Nummela et al., PRC63(2001)044316 Position of 3/2- state in N = 21 isotones • Shell Model describe well by intruder states the Island of Inversion and the deformed region around 32Mg. • Predicts vulnerability of N= 28 closure for 44S, 42Si and 40Mg  • confirmed for 44S (Sohler, PRC66 (2002) 054302)) Fix the single particle energy for the effective sd-pf interaction M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  27. b-feeding E2 NaI g2 g1 E1 g1 g2 Ib N E2 E Deformation & Gamow-Teller distribution QEC oblate 76Sr prolate QEC BGT Total Absorption spectrometry Sarriguren NPA 691(2001)631 High resolution spectroscopy 76Sr  p Dessagne EJPA20 (2004) 405 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  28. 74Kr, shape admixture Mass 70 : Strong Deformation & Shape Coexistence 76Sr clearly prolate 76Sr 74Kr Oblate Prolate Poirier et al., PRC 69 (2004) 034307 Nácher et al., PRL 92 (2004) 232501 M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  29. Transition from order to Chaos Middle Z  High Density Narrow States Fluctuations  Porter Thomas Distribution Low Z  Narrow States Direct structure information Very low Z  Broad States R-Matrix description: E,  M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  30. Decay mechanism: 2H, 2He, 3p, halo-core Exotics decays Asymmetries: 9C, 9Li Unknown 17Ne, 17N halo structure Shapes, island of inversion Sign of deformation from GT-distribution Level densities Fluctuations Chaos Relevant for astrophysics Summary M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  31. Outlook • Shell structure @ drip lines • Changes in the (effective) interaction • New “islands” of inversion • Proton drip line and N=Z nuclei • Spectroscopy beyond the drip line • Proton-neutron pairing • Isospin Symmetry • Isospin Mixing • GT and Fermi -decays • Order to chaos • p / ratios N=Z • Production of new isotopes • New s.p. energies at large N/Z • T1/2 and Pn-values of new isotopes M.J.G. Borge, IEM, CSIC, Madrid (Spain)

  32. Many Thanks to all colleagues that generouslysend me some recent talks or papers Bertram Blank Alejandro García Björn Jonson Henryk Mach Alfredo Poves Karsten Riisager Berta Rubio Jean C. Thomas Piet Van Duppen..... October 1492 Thanks for your Attention!! M.J.G. Borge, IEM, CSIC, Madrid (Spain) October 1492

  33. M.J.G. Borge, IEM, CSIC, Madrid (Spain)

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