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E. Sahin, G. de Angelis

Breaking of the Isospin Symmetry and CED in the A  70 mass region: the T z =-1 70 Kr. E. Sahin, G. de Angelis. N~Z A=70 Nuclei: 70 Se, 70 Br, 70 Kr Characteristic features can be extracted through CED?. Strong Collective Effects (N p =N n ) Shape co-existence.

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E. Sahin, G. de Angelis

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  1. Breaking of the Isospin Symmetry and CED in the A70 mass region: the Tz=-1 70Kr E. Sahin, G. de Angelis

  2. N~Z A=70 Nuclei:70Se, 70Br, 70KrCharacteristic features can be extracted through CED? • Strong Collective Effects (Np=Nn) • Shape co-existence • Strong Collective Effects (Np=Nn) (Shape co-existence) • Nuclear Isospin Symmetry • A=70 isobaric nuclei has an unusual behavior of the CED, a negative tendency with increasing spin.

  3. Coulomb Energy Difference (CED) CED(Jπ)=EJπ(Tz<)-EJπ(Tz>) Tz>=Tz<+1 But in reality, Isospin non-conserving interactions with Coulomb force break the isospin symmetry!! A plot of CED with increasing angular momentum will be a good tool to study the collective properties of the nuclei N/=Z M.A. Bentley, S. Lenzi, Prog.Part.Nucl.Phys. (2006) D.D. Warner et al.,Nature Physics 2, 311 (2006)

  4. Coulomb Energy Difference (CED) Negatif CED values in A=70 isobars CED(6+)=-37 keV CED(4+)=-36 keV CED(2+)=-11 keV Tz< Tz> N. Singh et al., Phys.Rev.C75, 061301 (2007) 70Br:G.de Angelis Eur. Phys.J.A.12,51 (2001) 70Se:J. Ljungvall et al., PRL 100, 102502 (2008)

  5. Excited Vampire Predictions Microscopic description of mirror nuclei in the A=70 mass region Shape coexistence and mixing Isospin symmetric G-matrix(A) + Coulomb Interaction between valence protons Mixing ratios p/o o/p 95/4 81/18 70/29 84/16 Exp. data 66As: G. de Angelis (to be submitted) 70Br:G.de Angelis Eur.Phys.J.A.12,51 (2001) A.Petrovici Nuc.Phy. A 728, 396 (2003) 70Se:J. Ljungvall et al., PRL 100, 102502 (2008)

  6. Excited Vampire Predictions Vampire Calculations: First minimum is predominantly prolate in 70Br First minimum is predominantly oblate in 70Se Mixing ratios p/o o/p 80/20 39/61 58/41 64/36 59/41 59/41 64/36 57/42 A.Petrovici Nuc.Phy. A 728, 396 (2003)

  7. Excited Vampire Predictions The comparison of the microscopic structure of the mirror nuclei 70Se and 70Kr The Coulomb interaction is included for the valence protons The mirror nuclei 70Se-70Kr have different shapes in their ground state A.Petrovici private comm.

  8. Excited Vampire Predictions B(E2) Values e2fm4 342 Exp. J. Ljungvall et al.

  9. Experiment 1neutron-knockout reaction: 71Kr + 9Be →70Kr Target 1neutron 70Kr 71Kr 9Be 56Fe Identification of the 2+→0+ transition : 71Kr + 9Be → 70Kr Lifetime measurement : 71Kr + 56Fe → 70Kr

  10. Beam Production LISE++ calculations Secondary beam 71Kr ~ 100 pps at 170 MeV/u AGATA Primary beam 78Kr 1.3x1010 pps LISE++ calculations: LISE++ calculations: Be target 5000 mg/cm2 Be target 1000 mg/cm2

  11. 71Kr on 9Be target dtarget=1 g/cm2 Ibeam=100 pps =2 mb (for 1n knock-out) =20% (1 MeV) N=200 day-1 Identification of the 2+ → 0+ transition 1-2 days of beamtime

  12. 71Kr on 56Fe target dtarget=700 mg/cm2 Ibeam=100 pps =2.7 mb (for 1n knock-out) =20% (1 MeV) N=35 day-1 Lifetime determination 2+ 950 0+

  13. 955 keV

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