1 / 26

Heavy-Ion Binary Reactions as a Tool for Detailed Gamma Spectroscopy in Exotic Regions

Heavy-Ion Binary Reactions as a Tool for Detailed Gamma Spectroscopy in Exotic Regions Silvia Leoni University of Milano & INFN. LOI Collaboration. Milano University and INFN A. Bracco, G. Benzoni, N. Blasi, F. Camera, F. Crespi, S. Leoni, B. Million, O. Wieland et al.

kavanagh
Download Presentation

Heavy-Ion Binary Reactions as a Tool for Detailed Gamma Spectroscopy in Exotic Regions

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. Heavy-Ion Binary Reactions as a Tool for Detailed Gamma Spectroscopy in Exotic Regions Silvia Leoni University of Milano & INFN

  2. LOI Collaboration Milano University and INFN A. Bracco, G. Benzoni, N. Blasi, F. Camera, F. Crespi, S. Leoni, B. Million, O. Wieland et al. P.F. Bortignon, G.Colò, E. Vigezzi et al. Legnaro INFN Laboratory L.Corradi, G. DeAngelis, E. Fioretto, D. Napoli, A. Stefanini, J.J. Valiente-Dobon, et al. Padova University and INFN D. Bazzacco, E. Farnea, S. Lenzi, S.Lunardi, G. Montagnoli, D.Montanari, F.Scarlassara, C.Ur, et al. Torino University and INFN G. Pollarolo IFIC, CSIC-University of Valencia, Spain A. Gadea, … Krakow, Poland A. Maj, P. Bednarczyk, B. Fornal, M. Kmiecik, M. Ciemala et al., Ruder Boskovic Institute, Zagreb S. Szilner, T. Mijatovic et al. AGATA- PRISMA collaborations

  3. Multi-Nucleon Transfer Reactions as a TOOL tostudyn-rich nuclei 64Ni 66Ni 48Ca CLARA/AGATA–PRISMA campains @ LNL since 2004- … Structure of moderately n-rich nuclei using most n-rich beams by PIAVE-Tandem-ALPI (5-10 MeV/A) Multi-nucleon transfer A~50 48Ca + 64Ni @ 6MeV/A 96Zr 70Zn 82Se 40Ar 136Xe 64Ni 26Mg 48Ca 36S 46Ca

  4. CLARA (ex-EUROBALL)/AGATA – PRISMA setup Legnaro National Laboratory INFN (Italy) PRISMA ΔΩ = 80 msr ΔZ/Z  1/60 ΔA/A  1/190 Energy acceptance ±20% Bρ = 1.2 Tm CLARA (now AGATA) 25 EUROBALL HpGe Clover • ~3 % @ Eγ= 1.3 MeV • 2 p solid angle • 3 rings at 100°, 130°, 150° High-Efficiency g - particle coincidence Measurements

  5. FirstExcitedStatesofExotic Nuclei Shape Evolution in Cr and Fe isotopes A & Z identification +2p Fe (-2p) +1p -1p -2p+2n -2p -3p 64Ni + 238U @ 6.3 MeV/A -4p -5p Cr (-4p) -6p -4p Beams ~ 109 pps S. Lunardi et al., PRC76(2007)034303 N. Marginean et al., PLB633(2006)696

  6. Complete g-Spectroscopy: Ip and B(El) lifetime 48Ca + 64Ni @ 6 MeV/A Angular Distribution and Polarization Plunger E1 9/2+ 7/2- E2 Tentative Ip 7 Wu 3-p3/2: coupling octupole Phonon - single particle 49Ca 0.05 Wu MNT Reactions: Strong SPIN Alignment perpendicular to reaction plane D. Montanari et al., PLB697(2011)288 and J.J. Valiente-Dobon et al., PRL102(2009)242502

  7. FIRST EXAMPLE of Multi-Nucleon transfer with RIB 24Ne + 208Pb@ 7.9 MeV/A EXOGAM + VAMOS SPIRAL Beam 24Ne ~ 1.5 105 pps Study of Reaction Dynamics and First excited states mostly in ONE nucleon transfer channels G.Benzoni, F.Azaiez et al., EPJA45(2010)287 24Ne 25Ne +1n 23F -1p 25Ne +1n 24Ne 2+ 0+ Semiclassical model GRAZING gives reasonable agreement also for reactions with radioactive beams G. Pollarolo. A.Winther, Nucl.Phys.A594 (1995)203

  8. Physics Cases with 108-109pps 1 - gspectroscopy around 132Sn 2 - r-process nuclei beyond N=50 Multi-Nucleon transfer with SPES beams @ 5-10 MeV/A SIMILAR/BETTER quality as today experiments (with 109 pps)  factor  3 higher detection efficiency (CLARA GALILEO/AGATA)  factor 3 longer beam time (1 week 3 weeks)

  9. CASE 1: gspectroscopyaround132Sn • STUDY OF • Single particle states • particle-phonon couplings • high spins • Ip, B(El) Z=50 • Complementary to • Fission and b-decay • Coulomb excitation • Transfer with light targets • (d,p), (d,t), … N=82 SPES Beams 10 mb 1 mb GRAZING calculations Conservative estimates for more than 1 nucleon transfer

  10. FOCUS on Particle-PhononCoupledStates Favourable population by Heavy-Ion Reactions excited core (phonon) • Coupling with 1 particle • - effective single particle levels • - coupling strength • Coupling with 2 particles • -core + 2 particles model • - physics of pairing M.B. Tsang et al. PRL102(2009)062501 Near DOUBLY MAGIC nuclei Ni (EXP) ±40% ±40% • Key Ingredients for understanding of • Quenching of Spectroscopic Factors • Anharmonicity of vibrational spectra • Damping of Giant Resonances, … (Theory) SOURCE OF DISCREPANCY with SHELL MODEL: CORE Excitations  Need of CORRELATIONS only partially included in Shell Model

  11. 132Sn – 133Sn 208Pb 132Sn Spectroscopic factors CollectivePropertiesof132Sn: 2+: E = 4041 keV, B(E2) = 7.2 Wu 3-: E = 4352 keV, B(E3) > 7 Wu Complemenary INFOs from MNT Single particle states in 133Sn: Low beam Intensity: ~ 105 pps Extraction of SF (~ 30% error) (d,p): 132Sn + CD2 K.L. Jones et al., Nature, 465(2010)454

  12. 131In – proton hole states 132Sn pure hole states G.Colò and P.F.Bortignon M.Gorska et al., PLB672(2009)313

  13. 130Cd – 2 proton holes states 220 ns • Tentative Ip assignment • Tentative B(El) values • Missing levels • Strength of PAIRINGinteraction • SHELL quenching below 132Sn GSI: Projectile fragmentation 136Xe (750 MeV/A) + Be A. Jungclaus et al., PRL99(2007)132501

  14. RESEARCH LINE: • SystematicStudy of PVC states • aroundmagic/doubly-magic nuclei • Couplingstrength • Dependence on Fermi SurfaceAsymmetry (N/Z) Up to now: Scarce Information Mostly in Heavy-Masses 209Bi: Bohr & Mottelson, Vol. II. 209Pb: P. Kleinheinz et al.,PRL48(1982)1457 207Pb: N. Pietralla et al., PLB681(2009)134 A ~ 200 A ~ 150 147Gd, 147Tb: P. Kleinheinz et al.,PRL48(1982)1457; P. Kleinheinz, Physica Scripta 24(1981)236. More recently: Evidence for PVC in A~50 Nuclei 49Ca:9/2+ @ 4017 keV = 3- p3/2 47Ca:11/2+ @ 3999 keV = 3- f-17/2 … Robustness of Collectivity of magic (light) core …

  15. Experimental Signature 3- 4.507 • Multiplet of States: |l-j|  I  l+j • B(El) of phonon 7/2+ 5/2+ 3/2+ 4 9/2+ Energy Split: Coupling strength Nuclear Force 3-  p3/2 E [MeV] B(E3) 6.8 ± 1.0 Wu 7 Wu 3 48Ca 49Ca 48Ca (Z=20,N=28) 2 (n,g) proposal at ILL Grenoble  3/2+ and 5/2+ 0+ 0.0 3/2- 0.0 0 Phys. Lett. B697(2011)288 Phys. Rev. C85(2012)044301

  16. Theoretical Description PHENOMENOLOGICAL Particle-phonon WEAK couplingcalculations (Bohr & Mottelson) 48Ca: 3- RPA calculations 3-  p3/2 [l  j1]I 49Ca MultipletofStates 9/2+, 7/2+, 5/2+, 3/2+ Energy Shift SLy5 - LNS p 1d3/2 1f7/2 0.82 0.64 2s1/2 1f7/2 0.13 0.29  1f7/2 1g9/2 0.01 0.02 Lowest order Perturbative Contributions TransitionDensities • wl, B(El) • → Exp. Values • s.p. Energies • e(j1), e(j2) • → HF – SkX “SIMPLE”  MACROSCOPIC CORE Vibration

  17. Theoretical Description RPA microscopicVph PHENOMENOLOGICAL Particle-phonon WEAK couplingcalculations (Bohr & Mottelson) MICROSCOPIC Calculations based on SELF-CONSISTENT Scheme Energy Density Functional 3-  p3/2 [l  j1]I 49Ca MultipletofStates 9/2+, 7/2+, 5/2+, 3/2+ Energy Shift • Hartee-Fock with Veff • → short-rangecorrelationsincluded • Particle-Vibrationcoupling on top • → sameHamiltonian or EDF • NO approximation in the vertex • EXACT treatment of COUPLING • use of WHOLE phononwavefunction Lowest order Perturbative Contributions • wl, B(El) • → Exp. Values • s.p. Energies • e(j1), e(j2) • → HF – SkX Need of More Experimental Input G. Colò, H. Sagawa, P.F. Bortignon, PRC 82, 064307 (2010).

  18. WORK in PROGRESS: Study of PVC states around Ni isotopes Multiplet of States 9/2+, 7/2+, 5/2+, 3/2+ 3-  p3/2 [l  j1]I 3- B(E3)~15Wu • 64,66Ni • (Z=28,N=36,38) • Superfluid Core in n • p coupling pp3/2- Approved Experiment 64Ni(7Li,)65Cu Tandem-Bucarest S. Leoni et al. FAST TIMING B(E3)~???Wu Existing Data 64Ni(,p)67Cu N. Marginean et al. FAST TIMING t(9/2+)~150 ps B(E3)~17(2)Wu

  19. 66Ni(Z=28,N=38) : Superfluid Core • Single Particle Levels • Pairing Strength Including Pairing … • Coupling with proton WORK in PROGRESS … S. Bottoni, G. Colò, P.F. Bortignon, …

  20. CASE 2: r-process nuclei beyond N=50 Shape changes with N number subshell N=56 N=50 SPES Beams r-process - 2p - 1p 94-96Kr - 3p 90-92Br Only masses 87-90Se - 4p 86-88As

  21. Importance of Nuclear Deformation for r-process b-decay half-lives and neutron emission probabilities are different in DEFORMED and SPHERICAL nuclei tb SPH ~ 7 x tbDEF PnSPH ~ 0.5 x PnDEF • Large uncertainty in • r-process location • difficoult to extrapolate • to more exotic regions P. Moller et al., Phys. Rev. C67, 055802 (2003) and ref. therein.

  22. APPROVED REX-ISOLDE Proposal Gamma spectroscopy of n-rich 95,96,97Rb nuclei by the incomplete fusion reaction of 94Kr on 7Li Spokepersons: B. Fornal and S. Leoni particleemission 94Kr + 7Li → 97Rb + a ELAB = 3 MeV/nucleon Sa 2.5 MeV Production of the excited 97Rb Subsequent evaporation of one or two neutrons 96Rb and 95Rb population of only one state at ~14.5 MeV  factor of 10-20 more expected  35-75 mb for 97Rb (and 95Rb) 232 MeV 7Li a 6Li t MINIBALL + Si Telescope • TEST ofreactionmechanism • Spectroscopyofn-rich95-97Rb •  expectedpopulationofNON-yraststates

  23. CONCLUSIONS • Multi-Nucleon Transfer at 5-10 MeV/A • are powerfool tool to reach exotic nuclei • with most intense SPES beams 130-132Sn and 90-92Rb • gspectroscopy around 132Sn (PVC states) • r-process nuclei beyond N=50 • WORK in Progress: • Systematic investigation of Particle-Phonon Couplings • in different MASS regions: Ca, Ni, … • Theoretical Investigation by Phenomenological/Microscopic Models • Complementary to SHELL MODEL • Comparison with Other Rection Mechanisms • to populate Highly-excited dipole states •  preparatory work is needed • excitation function with stable beams5-10-15 MeV/A

  24. Thank you for the attention

  25. Spectroscopic Factors • Nature and Occupancy of single-particle orbits • Interplay Single-Particle and Collectivity •  Crucial test of Shell Model and Interactions M.B. Tsang et al. PRL102(2009)062501 A. Gade et al. PRC77(2008)044306 Ni (EXP) ±40% ±40% (Theory) Dependence on Fermi Surface EnhancedCORRELATIONS in Stronglyboundvalencenucleons • Source of discrepancies • Core excitations • State fragmentation

  26. Evolution of Shell Structure with N/Z • Search for Shell closures, Magic Numbers • Nature Effective Nuclear Force: 2-body, 3-body, … • Doubly Magic Nuclei • Near to Magic Nuclei • (1 and 2 nucleons away) • Among EXPERIMENTAL TOOLS • Coulex • Collectivity B(E2), B(E3), … • Knock-out, transfer reactions, … • Spectroscopic Factors • Purity of nuclear states • Single particle (SF 1) • Correlations (SF <1) HOT topic in Nuclear Physics

More Related