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

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) Nuclear Isospin Symmetry A=70 isobaric nuclei has an unusual behavior of the CED, a negative tendency with increasing spin. Strong Collective Effects (N p =N n ) Shape co-existence

Mirror Nuclei Properties Charge symmetry → pp  nn Charge independence → pp  nn  pn Ground state masses!!! i)n-p mass difference ii)Coulomb energy difference T=1 T=0 Isotriplets Isosinglet T z =+1 T z =0 T z =-1 All nucleons When the Coulomb interactions between protons are ignored, the nuclear force is perfectly charge-symmetric and charge- independent

Mirror Nuclei Properties Charge symmetry → pp  nn Charge independence → pp  nn  pn Ground state masses!!! i)n-p mass difference ii)Coulomb energy difference T=1 T=0 Isotriplets Isosinglet T z =+1 T z =0 T z =-1 All nucleons When the Coulomb interactions between protons are ignored, the nuclear force is perfectly charge-symmetric and charge- independent

Coulomb Energy Difference (CED) 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 D.D. Warner et al.,Nature Physics 2, 311 (2006) M.A. Bentley, S. Lenzi, Prog.Part.Nucl.Phys. (2006) T z > =T z< +1 CED(J π )=E Jπ (T z )

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

Calculated CED Values Deformed liquid drop model: If  2 changes from -0.3 to 0.35  CED  -7 keV Def. Shell Model Calculations: Stretch in  2 from 0.18 to 0.33  CED  -75 keV S.E. Larsson, Phys.Scri. 8,17 (1973) R.Sahu et al, JPG 13, 603 (1987) Assume that the shape changes in the analogue nuclei are the same

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

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

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

Excited Vampire Predictions B(E2) Values e 2 fm 4 J i  J f 70 Kr 70 Se 2 +    Exp. J. Ljungvall et al.

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

Beam Production LISE++ calculations: Primary beam 78 Kr 1.3x10 10 pps Be target 5000 mg/cm 2 Secondary beam 71 Kr ~ 100 pps at 170 MeV/u Be target 1000 mg/cm 2 AGATA

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

Lifetime determination 71 Kr on 56 Fe target d target =700 mg/cm 2 I beam =100 pps  =2.7 mb (for 1n knock-out)   =20% (1 MeV) N  =35 day

955 keV