E. Sahin, G. de Angelis

Breaking of the Isospin Symmetry and CED in the A70 mass region: the T

z=-1 70Kr

N~Z A=70 Nuclei: 70Se, 70Br, 70KrCharacteristic features can be extracted through CED?

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.

Strong Collective Effects (Np=Nn)

Shape co-existence

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)

Tz>=Tz<+1CED(Jπ)=E

Jπ(T

z<)-E

Jπ(T

z>)

Negatif CED values in A=70 isobars

CED(2+)=-11 keV

CED(4+)=-36 keV

CED(6+)=-37 keV

Tz< Tz>70Br:G.de Angelis Eur. Phys.J.A.12,51 (2001)

N. Singh et al., Phys.Rev.C75, 061301 (2007)

Coulomb Energy Difference (CED)

70Se:J. Ljungvall et al., PRL 100, 102502 (2008)

Excited Vampire Predictions Microscopic description of mirror nuclei in the A=70 mass region

Shape coexistence and mixing

70/29

p/o o/p

81/18

95/4

84/16

Mixing ratios

A.Petrovici Nuc.Phy. A 728, 396 (2003)70Br:G.de Angelis Eur.Phys.J.A.12,51 (2001)

Isospin symmetric G-matrix(A) + Coulomb Interaction between valence protons

70Se:J. Ljungvall et al., PRL 100, 102502 (2008)

Exp. data 66As: G. de Angelis (to be submitted)

Excited Vampire Predictions

Vampire Calculations:

First minimum is predominantly prolate in 70BrFirst minimum is predominantly oblate in 70Se

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 70Se-70Kr have different shapes in their ground state

The comparison of the microscopic structure of the mirror nuclei 70Se and 70Kr

A.Petrovici private comm.

Excited Vampire Predictions

B(E2) Values B(E2) Values ee22fmfm44

Ji J

f

70Kr 70Se

2+ 0+ 603 492

4+ + 864 713

6+ + 933 779

342 Exp.J. Ljungvall et al.

Experiment1neutron-knockout reaction: 71Kr + 9Be →70Kr

71Kr 9Be70Kr

1neutronTarget

56Fe

Identification of the 2+→0+ transition : 71Kr + 9Be → 70Kr Lifetime measurement : 71Kr + 56Fe → 70Kr

Beam Production

LISE++ calculations: LISE++ calculations: Primary beam78Kr 1.3x1010 pps

Be target5000 mg/cm2

Secondary beam 71Kr ~ 100 pps at 170 MeV/u

Be target1000 mg/cm2

AGATA

Identification of the 2+ → 0+ transition

71Kr on 9Be targetd

target=1 g/cm2

Ibeam

=100 pps=2 mb (for 1n knock-out) =20% (1 MeV) N=200 day-1

1-2 days of beamtime

Lifetime determination

71Kr on 56Fe targetd

target=700 mg/cm2

Ibeam

=100 pps=2.7 mb (for 1n knock-out) =20% (1 MeV) N=35 day-1

2+

0+

950

955 keV