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