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Lifetime measurement in 74 Ni: probing the core polarisation around the double magic 78 Ni

Lifetime measurement in 74 Ni: probing the core polarisation around the double magic 78 Ni. G. de Angelis, D.R. Napoli, E. Sahin , J.J. Valiente-Dobon INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy S. Aydin, D. Bazzacco, E. Farnea, S. Lenzi, S. Lunardi, R. Menegazzo,

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Lifetime measurement in 74 Ni: probing the core polarisation around the double magic 78 Ni

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  1. Lifetime measurement in 74Ni:probing the core polarisation around the double magic 78Ni • G. de Angelis, D.R. Napoli, E. Sahin, J.J. Valiente-Dobon • INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy • S. Aydin, D. Bazzacco, E. Farnea, S. Lenzi, S. Lunardi, R. Menegazzo, • D. Mengoni, F. Recchia, C. Ur • Dipartimento di Fisica and INFN, Sezione di Padova, Padova, Italy P. Boutachkov, C. Domingo-Pardo, J. Gerl, M. Gorska, E. Merchan, S. Pietri, H.J. Wollersheim GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany • M. Bostan, N. Erduran, A. Kusoglu • University of Istanbul, Istanbul, Turkey M. Doncel, B. Quintana University of Salamanca, Spain A. Algora, A. Gadea, T. Huyuk, B. Rubio IFIC Instituto de Fisica Corpuscular, Valencia, Spain

  2. Scientific motivation • Study the tensor part of the (spin-isospin term of the) residual interaction. • Attraction between orbitals with antiparallel spin configuration. • Smaller Z=28 gap for protons in the pf-shell, and inversion of single-particle orbitals. j> N=50 g9/2 j< f5/2 Z=28 j> f7/2 Z=28 neutron proton Inversion of the single particle orbitals 78Ni 68Ni Particle-hole excitations across the shell gap (Z=28) neutrons in g9/2 T. Otsuka et al. PRL 95, 232502 (2005)‏

  3. Scientific motivation • Study the tensor part of the (spin-isospin term of the) residual interaction. • Attraction between orbitals with antiparallel spin configuration. • Smaller Z=28 gap for protons in the pf-shell, and inversion of single-particle orbitals. 0 2 4 6 8 10 g9/2 68Ni70Ni72Ni74Ni76Ni78Ni j> N=50 g9/2 j< f5/2 Z=28 j> f7/2 Zn neutron proton J.van de Walle et al., Phys. Rev. Lett. 99, 142501 (2008).

  4. 70,72Ni Isotopes at LN LegnaroCore polarization due to the tensor mechanism around 78Ni 72Ni B(E2:2+0+) ~200 e2fm4 ~2 ps O. Perru et al. PRL 96, 232501 (2006) O. Sorlin et al. PRL 88, 092501 (2002) A. Ansari, P. Ring, PRC 74, 054313 (2006) LNL, Multi-nucleon Transfer Reactions Lifetime measurement in neutron-rich Ni, Cu, and Zn isotopes 70Ni 72Ni Eda Sahin*, Maria Doncel**, Andreas Görgen*** et al. * INFN-LNL, Legnaro (PD), Italy ** LRI, University Salamanca, Spain ***CEA, Saclay,IRFU/SPhN, France • neutron polarization charge of 1.5 e is needed in the SM calculation in order to reproduce the experimental results!

  5. 74Ni at AGATA@GSICore polarization due to the tensor mechanism around 78Ni O. Perru et al. PRL 96, 232501 (2006) O. Sorlin et al. PRL 88, 092501 (2002) A. Ansari, P. Ring, PRC 74, 054313 (2006) 70Ni 74Ni 75Cu 75Cu 100 pps 74Ni* + p 86Kr 1x1010pps

  6. Line shape effect of first 2+ in 74Ni vs. lifetime 2+ 1024 keV 0+ 74Ni Realistic MC Simulation of a fragmentation experiment: DSAM Analysis 74Ni 75Cu @ 150 MeV/u t= ? Fe Target (500mg/cm2) t = 0.5 to 1.5 ps Zoom

  7. Summary & Outlook • The aim of the experiment at GSI would be to make one step further, compared to the present experimental programme at LNL (on the Ni, Cu and Zn isotopes), and measure the lifetime of 74Ni via the DSAM technique. • Such measurement will represent the closest measurement to 78Ni in the seniority parabola scheme of B(E2) vs. Neutron Number, and will allow for a more detailed undertanding of the core polarisation mechanism and the tensor component of the spin-isospin term in the residual interaction. • We think that this is a GSI-AGATA unique experiment, because of the high secondary beam intensities required to populate the 2+ in 74Ni, and because of the high angular sensitivity needed for the DSAM analysis.

  8. 1g9/2 N=40 2p1/2 1f5/2 2p3/2 71Cu Z=28 (f7/2)-1 7/2- 73Cu 1f7/2  7/2-  p3/22+ (A-1Ni)‏ 75Cu p1/2 1/2- f5/2 5/2- f5/2-p3/2 inversion 3/2- p3/2 71Cu42 67Cu38 69Cu40 73Cu44 75Cu46 g9/2 Cu IsotopesEvolution of the Z=28 shell closure 82Se + 238U @ 515 MeV CLARA-PRISMA ΘPRISMA=ΘGrazing=64˚ Deep-inelastic and multi-nucleon transfer reactions Nuclear spin and magnetic moment measurements @ ISOLDE proved the inversion K.T. Flanagan et. al, PRL 103, 142501 (2009)

  9. (f7/2)-1 p3/22+ f5/22+ ~2ps Cu Ni 73Cu 71Cu ~2 ps N-50 Z=28 Cu IsotopesEvolution of the Z=28 shell closure Coulomb excitation with radioactive beams at REX-ISOLDE ~10ps p3/22+ ~2ps ~25ps B(E2) values are essential in order to characterize the levels. Single-particle excitations across the Z=28 shell gap will provide the information on the Z=28 shell gap size and therefore, its evolution.

  10. Zn isotopesShape and collectivity Mf 2+ 0+ 74Zn 20 ps 25 ps 28.5 ps • excitation probability depends on • transitional matrix element 2+M(E2)0+ B(E2;0+→2+) • diagonal matrix element 2+M(E2)2+ Qs(2+) • Coulomb excitation of radioactive Zn at ISOLDE • integral measurement of excitation probability • relative to target excitation • combine Coulomb excitation and lifetimes • find correct B(E2) value • AND quadrupole moment B(E2) values extracted under the assumption that Qs(2+) = 0 J. Van de Walle et al., PRL 99, 142501 (2007) PRC 79, 014309 (2009)

  11. Proposed Experiment AIM: To measure the lifetime of the excited states in 70,72Ni, 71,73Cu, and 72-76Zn isotopes using RDDS technique Multi-nucleon transfer reactions 76Ge + 238U @ E(76Ge)=500 MeV SETUP: AD coupled to PRISMA (at 59) + Köln Plunger beam target degrader

  12. AGATA Demonstrator vs. CLARA Comparison between the Diff.plunger lifetime experiment performed with CLARA and with the AGATA D. A novel technique that combines the RDDS method with CLARA-PRISMA has been successfully performed using deep-inelastic reactions 48Ca 310MeV + 208Pb AGATA CLARA for lifetime measurement gain ~5 M.C. Simulations (by D. Mengoni)

  13. Distances Energy of the Projectile-like ions <E>= 320 MeV =28.5 m/ps  =9.5% Lifetimes (ps) Distances (m) 2 30, 60, 120, 250* 25 500, 1000, 2000

  14. Rate Evaluation ~100 counts 70Zn+238U 76Ge+238U (-4p) (-3p,-2n) (-3p) (-2p,+2n) 66Fe 65Co 67Co 70Ni 72Ni 71Cu 73Cu 76Zn Distance (m) 30 60 120 250 500 1000 2000 Short Long 70Zn + 238U @ 460 MeV CLARA-PRISMA ΘPRISMA=ΘGrazing=64˚ Thanks to S. Lenzi Total Gain Factor : 8

  15. Beam Time Request • Beam :76Ge at 500 MeV provided from the Tandem-ALPI complex • Target :2 mg/cm2 238U • Degrader : 4 mg/cm2 natural Mg • Beam Intensity:2 pnA • Cross sections from the GRAZING code (N. Pollarolo et. al) • (72Ni) ~ 100 µb  (66Fe) ~ 100 µb • (73Cu) ~ 750 µb • (71Cu) ~ 250 µb • (76Zn) ~ 2000 µb 14 days of beam time (2 days per distance) 

  16. Thank you …

  17. RDDS experiment in inverse kinematics: VAMOS  EXOGAM – Plunger beam: 238U, 6.5 MeV/u target: 64Ni, 1.5 mg/cm2 degrader: Mg, 4.7 mg/cm2 6 distances: 40 – 750 μm ~18 hours per distance 62Fe 64Fe J. Ljungvall et al., to be published

  18. AGATA Demonstrator vs. EXOGAM Exogam AGATA Demo. 3135 14.5 cm AD at 14cm 1180 11 cm GEANT 4 simulation and AGATA tracking (J. Ljungvall) EXOGAM data gain: factor 3 in  singles  more exotic reaction channels factor 10 in - coinc.  higher precision in strong channels

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