Transcript the Tz=-1

Breaking of the Isospin Symmetry and CED in the
A70 mass region: the Tz=-1 70Kr
E. Sahin, G. de Angelis
N~Z A=70 Nuclei: 70Se, 70Br, 70Kr
Characteristic features can be extracted through CED?
Strong Collective Effects (Np=Nn)
Strong Collective Effects (Np=Nn)
 Shape co-existence
(Shape co-existence)
Nuclear Isospin Symmetry
A=70 isobaric nuclei has an unusual
behavior of the CED, a negative tendency
with increasing spin.
Coulomb Energy Difference (CED)
CED(Jπ)=EJπ(Tz<)-EJπ(Tz>)
Tz>=Tz<+1
But in reality, Isospin nonconserving 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)
Coulomb Energy Difference (CED)
Negatif CED values in A=70 isobars
CED(6+)=-37 keV
CED(4+)=-36 keV
CED(2+)=-11 keV
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)
Tz<
Tz>
Excited Vampire Predictions
Microscopic description of mirror nuclei in the A=70 mass region
Shape coexistence and mixing
Mixing ratios
p/o
Isospin symmetric G-matrix(A) +
Coulomb Interaction between valence
protons
o/p
95/4
81/18
70/29
84/16
Exp. data 66As: G. de Angelis (to be submitted)
70Br:G.de
A.Petrovici Nuc.Phy. A 728, 396 (2003)
70Se:J.
Angelis Eur.Phys.J.A.12,51 (2001)
Ljungvall et al., PRL 100, 102502 (2008)
Excited Vampire Predictions
Vampire Calculations:
Mixing ratios
p/o
80/20
o/p
39/61
58/41
64/36
59/41
59/41
64/36
57/42
First minimum is predominantly prolate in 70Br
First minimum is predominantly oblate in 70Se
A.Petrovici Nuc.Phy. A 728, 396 (2003)
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.
Excited Vampire Predictions
B(E2) Values
e2fm4
Ji Jf
70Kr
2+ 0+
603
70Se
492 342
Exp.
J. Ljungvall et al.
4+ +
864
713
6+ +
933
779
Experiment
1neutron-knockout reaction:
71Kr
+ 9Be →70Kr
Target
1neutron
71Kr
9Be
70Kr
56Fe
Identification of the 2+→0+ transition :
Lifetime measurement
:
+ 9Be → 70Kr
71Kr + 56Fe → 70Kr
71Kr
Beam Production
Primary beam
78Kr 1.3x1010 pps
Secondary beam
71Kr ~ 100 pps at
170 MeV/u
LISE++ calculations:
Be target
5000 mg/cm2
Be target
1000 mg/cm2
AGATA
Identification of the
transition
71Kr
on 9Be target
dtarget=1 g/cm2
Ibeam=100 pps
=2 mb (for 1n knock-out)
=20% (1 MeV)
N=200 day-1
1-2 days of beamtime
+
2
→
+
0
Lifetime determination
2+
950
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
0+
955 keV