E. Sahin, G. de Angelis

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Breaking of the Isospin Symmetry and CED in the
A?70 mass region the Tz-1 70Kr
E. Sahin, G. de Angelis
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NZ A70 Nuclei 70Se, 70Br, 70KrCharacteristic
features can be extracted through CED?

• Strong Collective Effects (NpNn)
• Shape co-existence

• Strong Collective Effects (NpNn) (Shape
  co-existence)
• Nuclear Isospin Symmetry

• A70 isobaric nuclei has an unusual behavior of
  the CED, a negative tendency with increasing spin.

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Mirror Nuclei Properties
Charge symmetry ?pp?nn Charge independence ?
pp?nn?pn Ground state masses!!! i)n-p mass
difference ii)Coulomb energy difference
When the Coulomb interactions between protons are
ignored, the nuclear force is perfectly
charge-symmetric and charge-independent
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Mirror Nuclei Properties
Charge symmetry ?pp?nn Charge independence ?
pp?nn?pn Ground state masses!!! i)n-p mass
difference ii)Coulomb energy difference
When the Coulomb interactions between protons are
ignored, the nuclear force is perfectly
charge-symmetric and charge-independent
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Coulomb Energy Difference (CED)
CED(Jp)EJp(Tzlt)-EJp(Tzgt)
TzgtTzlt1
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)
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Coulomb Energy Difference (CED)
Negatif CED values in A70 isobars
CED(6)-37 keV
CED(4)-36 keV
CED(2)-11 keV
Tzlt
Tzgt
N. Singh et al., Phys.Rev.C75, 061301 (2007)
70BrG.de Angelis Eur. Phys.J.A.12,51 (2001)
70SeJ. Ljungvall et al., PRL 100, 102502 (2008)
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Calculated CED Values
Deformed liquid drop model
S.E. Larsson, Phys.Scri. 8,17 (1973)
If ?2 changes from -0.3 to 0.35 ?CED ? -7 keV
R.Sahu et al, JPG 13, 603 (1987)
Def. Shell Model Calculations Stretch in ?2 from
0.18 to 0.33 ?CED ? -75 keV
Assume that the shape changes in the analogue
nuclei are the same
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Excited Vampire Predictions
Microscopic description of mirror nuclei in the
A70 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)
70BrG.de Angelis Eur.Phys.J.A.12,51 (2001)
A.Petrovici Nuc.Phy. A 728, 396 (2003)
70SeJ. Ljungvall et al., PRL 100, 102502 (2008)
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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)
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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.
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Excited Vampire Predictions
B(E2) Values e2fm4
Ji ?Jf 70Kr 70Se
2 ????0 603 492
4 ????? 864 713
6 ????? 933 779
342
Exp.
J. Ljungvall et al.
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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
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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
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Identification of the 2 ? 0 transition

• 71Kr on 9Be target
• dtarget1 g/cm2
• Ibeam100 pps
• ?2 mb (for 1n knock-out)
• ??20 (1 MeV)
• N?200 day-1

1-2 days of beamtime
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Lifetime determination
2
950

• 71Kr on 56Fe target
• dtarget700 mg/cm2
• Ibeam100 pps
• ?2.7 mb (for 1n knock-out)
• ??20 (1 MeV)
• N?35 day-1

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955 keV
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