Isospin Symmetry test on the semimagic 44Cr

1
Isospin Symmetry test on the semimagic 44Cr

• Toward the dripline
• in the f7/2 shell

2
44Cr

• N20, 40Ca 4 protons
• Mid mass, Tz-2
• 36Ca_at_RISING

NZ
3
T1 and T2 mirror nuclei

• Shell evolution
• Gaps Z14 and N14
• No cross shell excitations

f7/2
f7/2
N,Z20
N,Z20
d3/2
d3/2
s1/2
s1/2
d5/2
d5/2
p
p
?
?
36S
36Ca
4
Cross conjugate nuclei
f7/2
f7/2
N,Z20
N,Z20
d3/2
d3/2
s1/2
s1/2
d5/2
d5/2
p
p
?
?
44Ca
44Cr
f7/2
f7/2
N,Z20
N,Z20
d3/2
d3/2
s1/2
s1/2
d5/2
d5/2
p
p
?
?
36S
36Ca
5
44Cr
f5/2
f5/2
p1/2
p1/2
p3/2
p3/2
f7/2
f7/2
N,Z20
N,Z20
p
p
?
?
44Cr
44Ca
1360
2
1248
2
1157
2
0
0
0
44Ca
Exp
kb3g
gxpf1a
104
9.8
10.3
B(E2)e2fm4
6
44Cr
p3/2
p3/2
f7/2
f7/2
N,Z20
N,Z20
d3/2
d3/2
s1/2
s1/2
p
p
?
?
44Cr
44Ca
2
1571
1360
2
1248
2
1157
2
0
0
0
0
44Ca
Exp
kb3g
gxpf1a
sdfp
104
9.8
10.3
105.6
B(E2)e2fm4
7
Particle-hole cross-shell excitations
2
1571
1360
2
1248
2
1157
2
0
0
0
0
44Ca
Exp
kb3g
gxpf1a
sdfp
104
9.8
10.3
105.6
B(E2)e2fm4
8
44Cr

• Isospin symmetric 44Ca

3307
3-
3285
6
Sp 2800 keV (SY)
2283
4
2
1157
0
0
44Ca
44Cr
9
f7/2 shell and INC nuclear forces
VCm,
VCM
VB
From the MED we extract information of nuclear
structure properties

• How the nucleus generates its angular momentum
• Evolution of the deformation along a rotational
  band
• Isospin non-conserving terms in the nuclear
  interaction
• Learn about the configuration of the states

10
36Ca from 40Ca
Fragmentation 40Ca ? 37Ca 38
µbarn Knock-out37Ca ? 36Ca 2 mbarn
11
44Cr from 50Cr
Fragmentation 50Cr ? 45Cr 1.5
µbarn Knock-out45Cr ? 44Cr 2 mbarn
12
44Cr from 58Ni
Fragmentation 58Ni ? 45Cr 0.6
µbarn Knock-out45Cr ? 44Cr 2 mbarn
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Feasibility fragmentation knock-out

• Comparison to 36Ca
• Cross section /50
• AGATA efficiency x5
• AGATA resolution x2
• Energy of the gamma (3.0? 1.2 MeV) x3
• Beam current x30 (3108?1010)
• 44Cr now is a factor 20 easier!

P. Doornenbal et al. Physics Letters B 647
(2007) 237242
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Feasibility fragmentation coulex

• Directly produced 44Cr 24 nbarn
• More than an order of magnitude lost
• Coulex on secondary target
• 2 predicted collective (2p2h, 4p4h)
• Enhanced B(E2)
• Good excitation cross section (200 mbarn)
• Factor of 10 in statistics for the 2

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B(E1) in T2

• Janecke
• EC (A,T,TZ) EC0(A,T) - Tz EC1(A,T)
  (3Tz2-T(T1))EC2(A,T)
• Warburton
• Corresponding E1 transition in conjugate nuclei
  have equal strength
• T2 Tz-2
• EC EC0 2 EC1(A,2) 6EC2(A,T)
• T2 Tz-1
• EC EC0 1 EC1(A,2) - 3EC2(A,T)
• T2 Tz0
• EC EC0 - 6EC2(A,T)
• T2 Tz1
• EC EC0 1 EC1(A,2) - 3EC2(A,T)
• T2 Tz2
• EC EC0 - 2 EC1(A,2) 6EC2(A,T)

WILKINSON - ISOSPIN IN NUCLEAR PHYSICS