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Isospin Symmetry test on the semimagic 44 Cr. Toward the dripline in the f7/2 shell. 44 Cr. N=20, 40Ca +4 protons Mid mass, Tz=-2 36 Ca@RISING. N=Z. T=1 and T=2 mirror nuclei. Shell evolution Gaps Z=14 and N=14 No cross shell excitations. f7/2. f7/2. N,Z=20. N,Z=20. d3/2. d3/2. - PowerPoint PPT Presentation
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Isospin Symmetry test on the semimagic 44Cr
Toward the dripline
in the f7/2 shell
44Cr
• N=20, 40Ca +4 protons
• Mid mass, Tz=-2
• 36Ca@RISING
N=Z
T=1 and T=2 mirror nuclei
• Shell evolution• Gaps Z=14 and N=14• No cross shell excitations
ν36S
d3/2
d5/2
s1/2
f7/2
πν36Ca
d3/2
d5/2
s1/2
f7/2
π
N,Z=20N,Z=20
ν44Ca
d3/2
d5/2
s1/2
f7/2
πν44Cr
d3/2
d5/2
s1/2
f7/2
π
N,Z=20N,Z=20
Cross conjugate nuclei
ν36S
d3/2
d5/2
s1/2
f7/2
πν36Ca
d3/2
d5/2
s1/2
f7/2
π
N,Z=20N,Z=20
ν
p3/2
f5/2
p1/2
f7/2
πν44Cr
p3/2
f5/2
p1/2
f7/2
πN,Z=20N,Z=20
44Cr
44Ca
B(E2)[e2fm4] 104 9.8 10.3
2+
0+
1157
44Ca Exp kb3g gxpf1a
2+
0+
1248 2+
0+
1360
ν
d3/2
p3/2
s1/2
f7/2
πν44Cr
d3/2
p3/2
s1/2
f7/2
π
N,Z=20N,Z=20
44Cr
44Ca
B(E2)[e2fm4] 104 9.8 10.3 105.6
2+
0+
1157
44Ca Exp kb3g gxpf1a sdfp
2+
0+
1248 2+
0+
13602+
0+
1571
Particle-hole cross-shell excitations
B(E2)[e2fm4] 104 9.8 10.3 105.6
2+
0+
1157
44Ca Exp kb3g gxpf1a sdfp
2+
0+
1248 2+
0+
13602+
0+
1571
44Ca44Cr
44Cr
• Isospin symmetric: 44Ca
0+
2+
4+
6+
0+
3-
1157
2283
32853307
Sp = 2800 keV (SY)
f7/2 shell and INC nuclear forces
25Mn24 24Cr2549 49
VB
VCm,
VCM
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
From the MEDwe extract informationof nuclear structure properties
36Ca from 40Ca
Fragmentation: 40Ca → 37Ca 38 µbarn
Knock-out:37Ca → 36Ca 2 mbarn
44Cr from 50Cr
Fragmentation: 50Cr → 45Cr 1.5 µbarn
Knock-out:45Cr → 44Cr 2 mbarn
44Cr from 58Ni
Fragmentation: 58Ni → 45Cr 0.6 µbarn
Knock-out:45Cr → 44Cr 2 mbarn
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 (3*108→1010)
• 44Cr now is a factor 20 easier!
P. Doornenbal et al. Physics Letters B 647 (2007) 237–242
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+
knock-out coulex45Cr 46Cr 44Cr
primary 1.00E+10 1.00E+10 1.00E+10thickness 2.00E+00 2.00E+00 2.00E+00 gNa 6.00E+23 6.00E+23 6.00E+23Atarget 9.00E+00 9.00E+00 9.00E+00moli 2.22E-01 2.22E-01 2.22E-01cs 6.00E-04 1.50E-02 2.50E-05 mbarncs 6.00E-31 1.50E-29 2.50E-32 cm-2
yield 8.00E+02 2.00E+04 3.33E+01transmission 3.30E-01 3.30E-01 3.30E-01transmitted 2.64E+02 6.60E+03 1.10E+01thickness 7.00E-01 7.00E-01 7.00E-01 gNa 6.00E+23 6.00E+23 6.00E+23moli 7.78E-02 7.78E-02 7.78E-02cs 1.40E+00 4.00E-02 2.00E+02 mbarncs 1.40E-27 4.00E-29 2.00E-25 mbarn
yield 1.72E-02 1.23E-02 1.03E-01 Hz6.21E+01 4.44E+01 3.70E+02 per hour1.49E+03 1.06E+03 8.87E+03 per day
B(E1) in T=2• Janecke:
EC (A,T,TZ)= EC0(A,T) - Tz EC
1(A,T)
+ (3Tz2-T(T+1))EC
2(A,T)• Warburton
“Corresponding E1 transition in conjugate nuclei have equal strength”• T=2 Tz=-2
EC = EC0 + 2 EC
1(A,2) + 6EC2(A,T)
• T=2 Tz=-1 EC = EC
0 + 1 EC1(A,2) - 3EC
2(A,T) • T=2 Tz=0
EC = EC0 + - 6EC
2(A,T)• T=2 Tz=+1
EC = EC0 + 1 EC
1(A,2) - 3EC2(A,T)
• T=2 Tz=+2 EC = EC
0 - 2 EC1(A,2) + 6EC
2(A,T)
WILKINSON - ISOSPIN IN NUCLEAR PHYSICS