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E. Fiori, G. Georgiev, R. Lozeva : CSNSM, orsay L. Gaudefroy : CEA, Bruyères -Le- Chatel

Exploring life-time of low-lying states in neutron-rich nuclei towards 78Ni with the plunger technique at GANIL B. Mouginot (IPN-Orsay). E. Fiori, G. Georgiev, R. Lozeva : CSNSM, orsay L. Gaudefroy : CEA, Bruyères -Le- Chatel

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E. Fiori, G. Georgiev, R. Lozeva : CSNSM, orsay L. Gaudefroy : CEA, Bruyères -Le- Chatel

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  1. Exploring life-time of low-lying states in neutron-rich nuclei towards 78Ni with the plunger technique at GANIL B. Mouginot (IPN-Orsay) E. Fiori, G. Georgiev, R. Lozeva : CSNSM, orsay L. Gaudefroy : CEA, Bruyères-Le-Chatel M. Amthor, M.Assie, G.Burgunder, L. Caceres, E. Clément, G. De France, F. de Oliveira, A. Dijon, S. Grevy, M. Harakeh, C. Stodel, J.C. Thomas, P. Ujic : GANIL, Caen C. Borcea, A. Buta M. Catalin, F. Negoita, D. Pantelica, F. Rotaru : IFIN-HH, Bucharest P. Bednarczyk, M. Kmiecik, A. MAJ, S. Myalski : IFJ PAN, Krakovi L. Coquard, O. Moeller : IKP, Darmstadt A. Dewald, C. Fransen, G. Friessner, M. Hackstein, T. Pissula, W. Rother, : IKP, Universitätzuköln F. Azaiez, S. Franchoo, F. Ibrahim, I. Matea, B. MOUGINOT, M. Niikura, L. Perrot, J. A. Scarpaci, I. Stefan, D. Verney : IPN, Orsay G. de Angelis : LNL INFN, Legnaro A. Burger : University of Oslo

  2. 74Zn h11/2 g9/2 g7/2 d3/2 p1/2 s1/2 d5/2 p3/2 50 f5/2 28 g9/2 n p p1/2 f7/2 Se74 Se76 Se77 Se78 Se80 Se82 Se84 As75 As83 Ge70 Ge72 Ge73 Ge74 Ge76 Ge78 Ge80 Ge82 Ga69 Ga71 Ga81 Zn66 Zn67 Zn68 Zn70 Zn76 Zn78 Zn80 Zn72 Zn74 Cu65 Cu79 28 Ni66 Ni68 Ni70 Ni72 Ni74 Ni76 Ni78 Ni64 50 EURORIB 2010

  3. Evolution of the neutron orbital energy as fonction of the deformation parameter b Present Knowledge : K quantum number: 1/2 3/2 5/2 7/2 9/2 2+ energy (from Z=26 to 34) Region of possible deformation 74Zn Fermi Level E(2+) flatness B(E2) strength (from Z=28 to 34) Enhance collectivity with Z number Prolate Oblate Proton core polarisation J Van de Walle et al PhysicalReviewLetters 99, 142501 (2007) PhysicalReview C 79, 014309 (2009) O Perru et al PhysicalReviewLetters 96, 232501 (2006) N.J. Stone, Atomic Data and Nuclear Data Tables 90 (2005) 75-176 EURORIB 2010 B.MOUGINOT, IPNO

  4. Known Quadrupole Moment : Q Moment b Deformation parameter N.J. Stone, Atomic Data and Nuclear Data Tables 90 (2005) 75-176 How the Q/bwillevolve in more neutron rich Zn isotopes? In thispresentation I will focus on 74Zn EURORIB 2010 B.MOUGINOT, IPNO

  5. 74Zn secondary beam Production with LISE @GANIL : EXOGAM Selection Selection Br2 Br1 …To D6 74Zn @ 34MeV/u 1.5e5pps 76Ge @ 60MeV/u Cocktail beam Be 580um production-target Be 450um Degrader Plunger Slits Slits Beam selection D3->D4 PRODUCTION IDENTIFICATION D4->D6 D4 EXOGAM MCP MCP From D4… dE E Br3 Br3 Ionisation Chamber Plastic Plunger TOF D4-D6

  6. EXOGAM EXOGAM and PLUNGER : CD2 34mg/cm2 Be54mg/cm2 74Zn* 74Zn 74Zn* Identification b’ =0.2 b = 0.25 g g’ D Cologne PLUNGER 8 EXOGAM Clovers : 4 at 45° and 4 at 135° EURORIB 2010 B.MOUGINOT, IPNO

  7. Experimental Spectrum : Spectrum Doppler corrected forward angle CD2 Be 74Zn* 74Zn 74Zn* b’ =0.2 b = 0.25 g g’ D Emission rate before and after degrader Rate before degrader Energy [keV] 72Zn Contamination After Degrader Before Degrader 74Zn component Rate after degrader B.MOUGINOT, IPNO

  8. Determination of Intensity : Doppler corrected Spectrum for b2 (EXOGAM forward angle) after degrader component 74Zn before degrader component after degrader component 72Zn before degrader component >Peak deconvolution : fit with 4 gaussians : - 2 components for 74Zn (before and after degrader) - 2 components for 72Zn (...) EURORIB 2010 B.MOUGINOT, IPNO

  9. First Result : Preliminary • = 24(2)ps • B(E2,0+->2+) = 0.209(17)e2b2 EURORIB 2010 B.MOUGINOT, IPNO

  10. Quadrupole Moment : Prolate Oblate 0.28 0.24 Our preliminary result 0.20 0.209(17)e2b2 Coulex Measurement 0.16 From J.Van De Walle Ph.D 0.12 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 b=0,04(11) >> Qs= -0.09(25)b2 EURORIB 2010 B.MOUGINOT, IPNO

  11. Results : Our measurement is consistent with the coulex estimation in 74Zn² EURORIB 2010 B.MOUGINOT, IPNO

  12. Comparison with model B(E2) strength b Deformation parameter N=40 N=40 J.-P Delaroche Physical Review C -HFB calculation reproduces well N~44 the experimental data where it is supposed to be collective (mid-shell) -Still too much collectivity around N=40 & N=50 EURORIB 2010 B.MOUGINOT, IPNO

  13. Conclusion : • Feasibility of plunger technique using in-flight secondary beams and secondary reactions • with LISE spectrometer • ->Preliminary Life-time measurement of 2+ state in 74Zn : 24(2)ps • -> Constraint on the beta deformation parameter : Beta = 0.04(11) • -Result for 72Zn is under analysis. • -More accurate value of the Q moment will be extracted for 74Zn • and compared to model predictions (HFB and shell model calculations). EURORIB 2010 B.MOUGINOT, IPNO

  14. THANK YOU EURORIB 2010 B.MOUGINOT, IPNO

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