Coulomb excitation of the neutron-rich Cu Coulomb excitation of the neutron-rich Cu isotopes and isomers using RILISisotopes and isomers using RILIS

Irina Stefanescu1, O. Ivanov1, J. Van de Walle1, N. Patronis1, D. Pauwels1, T. E. Cocolios1, N. Bree1, M. Huyse1, P. Van Duppen1

G. Georgiev2, T. Kröll3, P. Maierbeck3, A. Blazhev4, N. Warr4, S. Franchoo5, J. Iwanicki6, P. Napiorkowski6, K. Wrzosek6, D. Balabanski7, K. Gladnishki7, G. Rainovski7,

G. Lo Bianco8, N. Blasi8, A. Lagoyannis9, T. Konstantinopoulos9, A. Ekström10

1IKS, KU Leuven2CSNSM Orsay, France

3TU München, Germany4IKP Köln, Germany

5IPN Orsay, France6Heavy Ion Laboratory, Warsaw University, Poland

7University of Sofia, Bulgaria8Universita di Camerino, Italy

9National Research Center Demokritos, Greece10Lund University, Sweden

Funded by IAP Belgium, BMBF, EURONS

Beyond 68Ni by Coulomb excitation with RIBs

68Ni

+2p

+2n

70Ni (68Ni+2n) and 70Zn (68Ni+2p) show large collectivity at low excitation energies;

tensor force: shifts and re-ordering of the single-particle orbits erosion of the Z=28 and N=40 gaps. (T. Otsuka, PRL 95, 232502 (2005)).

N=4

0 N=5

0

B(E2;2+0+) by Coulex

g9/2

f7/2

40

p3/2

f5/2

p1/2

2828

protons neutronsprotons

Beyond 68Ni by Coulomb excitation with RIBs

n-rich Cu isotopes provide an excellent means for testing the proton-neutron residual interaction in this mass -region;

n-rich Cu beams @ ISOLDE: p (1.4 GeV) +UCx + resonant laser ionization (RILIS).

N=4

0 N=5

0

B(E2;2+0+) by Coulex

2005: Coulomb excitation of odd-odd 68,70Cu;

2006: Coulomb excitation of odd-mass 67,69,71,73Cu.

g9/2

f7/2

40

p3/2

f5/2

p1/2

2828

protons neutronsprotons

The odd-odd The odd-odd 68,70 68,70CuCu

level schemes dominated by multiplets originating from the coupling of the odd proton with the odd neutron;

B(E2) values within the states of the p3/2 g9/2 multiplet offers important information about the p-n residual interaction across N=40.

p3/2 g9/2 = 3-, 4- , 5- , 6-

g9/2

f7/2

40

p3/2

f5/2

p1/2

2828

68Cu39

g9/2

f7/2

40

p3/2

f5/2

p1/2

2828

70Cu41

084

T1/2=31.1 sT1/2=7.84 ns

722778

956

1350

T1/2=3.75 min

0.7 ns <T1/2 <4 ns

-

1+

2+

6-

(3-)

(4-)

(5-)

p3/

2g

9/2

p3/

2p

1/2

68Cu39

0

228242

T1/2= 33 s

506

T1/2= 6.6 s

6-

3-

(4-)

1+

(5-)

70Cu41

-

-

T1/2= 45.5 s

101

68Cu: J.D. Sherman et al. PLB67 (77) 257; T. Ishii, JAERI-Review, 2002-029, 25.70Cu: J. Van Roosbroeck et al., PRL92(2004)112501, J. Van Roosbroeck et al., PRC69(2004)034313.

68,7068,70CuCu

Coulex with post-accelerated 6- isomeric beams !E

2

E2

Isomeric Isomeric 68,7068,70Cu beams @ IsoldeCu beams @ Isolde

6-

1+ (g.s.)

68Cu

6- (g.s.)

1+

70Cu 3-

technique based on in-source laser spectroscopy (Ü. Köster et al., NIM B, 160, 528(2000); L. Weissman et al., PRC65, 024315(2000)).

set the laser frequency to select and maximize the production of the isomer of interest.

+ postacceleration by REX-ISOLDE

1+

6-

0

722

6-

1+

0

242

3-

101

Experimental set-up for Coulex @REX-ISOLDEExperimental set-up for Coulex @REX-ISOLDE

Miniball:

8 clusters, 3 X 6 fold segmented

120Sn

REX-ISOLDE

68m,70gCu (6-)E~2.83 MeV/u

PPACBeam

monitor

DSSD detector

~2 mg/cm2

Beam dump detector

(16o-53o)

• 4 quadrants

• 16 annular strips ()

• 24 sector strips ()

68,mCu (2.83 MeV/u) @ 120Sn (2.3 mg/cm2)

70Cu (2.83 MeV/u) @ 120Sn (2.3 mg/cm2)

851+

(2+)

6-

4-

(3-)722

(5-)

0

956178 (M1)

693

84

778E2

6-

(3-)

4-

(5-)

0

101

228

506

127 (M1) E2

Coulomb excitation of odd-odd 68,70Cu- first use of postaccelerated isomeric beams -

68Cu

70Cu

I. Stefanescu et al., PRL 98, 122701(2007).

coulex

coulex

*B(E2;6-4-) in 72Cu from R. Grzywacz et al., PRL 81, 766 (1998).

68,70Cu: I. Stefanescu et al., PRL 98, 122701(2007).

Comparison with shell-model calculationsComparison with shell-model calculations

protons

28p3/2

f5/2

p1/2

g9/2

f7/2

neutrons

28p3/2

f5/2

p1/2

g9/2

f7/2

40

Shell-model calculations for the valence space outside the 56Ni core (e=1.5e, e=0.5e) .

collectivity in 70Cu influenced by the stabilizing effect of 68Ni;

the poor agreement between the experiment and theory for 68,72Cu points to the importance of proton excitations across the Z=28 shell gap.

1+

2+

6-

4-

(3-)722

0

3.75 min

31.1 s

5-

178Hf: A.B. Hayes et al, PRL 89(2002)/PRL 96(2006);

180Ta: C. Schlegel et al., PRC 50, 2198(1994),

D. Belic et al., PRC 65, 035801(2002).

triggered -emission of high K-isomers extensively investigated by Coulomb depopulation, irradiation with bremsstrahlung, synchrotron radiation or X-rays

depopulation scheme based on K-mixing

instantaneous depopulation of isomers in odd-odd nuclei based on their multiplet structure

possible scheme for triggered energy release in odd-odd nuclei

6868Cu: releasing the energy of the 6Cu: releasing the energy of the 6-- isomer isomer

I(I+1)

En

ergy

6-

E23-

4-

5-

1+

2+

M1

2006: Coulomb excitation of 2006: Coulomb excitation of 67,69,71,73 67,69,71,73CuCu

B. Zeidman et al., PRC 18, 2122(1978)/R. Grzywacz et al., PRL 81, 766 (1998) /S. Franchoo et al., PRL 81, 3100(1998).

Eex

(M

eV)

0

1

2

p3/2

f5/2

p1/2

p3/22+ (A-1Ni)

3/2-

5/2-

1/2-

7/2-

67Cu38

7/2-(f7/2)-1

69Cu4073Cu44

71Cu42

rapid decrease of the energy of the f5/2 orbital beyond N=40 (monopole migration) systematic study of the evolution of collectivity across N=40 by Coulomb excitation

28

g9/2

f5/2

40

p3/2

p1/2

75Cu46

shell-model

g9/2

104Pd

7/2-

104Pd

104Pd

1/2-

5/2-

7/2-

5/2-

1/2-

7/2-

Coulomb excitation spectraCoulomb excitation spectra

120Sn

7/2-

(1/2-)

5/2- (1/2-)(5/2-)

(7/2-)

(3/2-)

p3/22+(72Ni)

1/2-

5/2-

7/2-

3/2-

p3/22+(68Ni)

(1/2-)(5/2-)

(7/2-)

(3/2-)

p3/22+(70Ni)

5/2-

1/2-

7/2-

3/2-

p3/22+(66Ni)

p3/2

f5/2

p1/2454

135

(1/2-)

67Cu (2.99 MeV/u) @ 104Pd (2 mg/cm2)

69Cu (2.97 MeV/u) @ 104Pd (2 mg/cm2)

71Cu (2.95 MeV/u) @ 104Pd (2 mg/cm2)

73Cu (2.88 MeV/u) @ 120Sn (1.7 mg/cm2)

73Ga

Experimental results (preliminary)Experimental results (preliminary)

rapid decrease of the energy of the 5/2- state beyond N=40 followed by a decrease in collectivity;

rapid decrease of the energy of the ½- state beyond N=40 followed by an increase in collectivity.

low energy, high B(E2). Deformation?

R.L. Robinson et al., Phys. Rev. 134, B567, 1964.

Experimental results (preliminary)Experimental results (preliminary)

B(E2; 7/2- 3/2-) B(E2; 2+ 0+) in agreement with the proposed p3/2 2+ nature for the 7/2- states;

B(E2; 7/2- 3/2-) : minimum collectivity at N=38;

trend in the odd-Cu isotopes similar to that shown by the even-even Zn isotopes.

Experimental results (preliminary)Experimental results (preliminary)

B(E2; 7/2- 3/2-) B(E2; 2+ 0+) in agreement with the proposed p3/2 2+ nature for the 7/2- states;

B(E2; 7/2- 3/2-) : minimum collectivity at N=38;

trend in the odd-Cu isotopes similar to that shown by the even-even Zn isotopes.

strong polarization of the 66Ni core by the p3/2 proton.

Summary and outlookSummary and outlook

2005: REX-ISOLDE postaccelerates first isomeric beams;

postaccelerated isomeric beams to be used for transfer reactions, magnetic moment measurements, etc;

68Cu: first clear evidence for instantaneous depopulation of a nuclear isomer;

measured B(E2; 6- 4-) indicate a fragile stabilizing effect of the Z=28 and N=40 gaps;

2006: systematic study of the evolution of collectivity across N=40 by Coulomb excitation with beams of 67,69,71,73Cu;

71,73Cu: coexistence of a deformed ½- state with a single-particle-like 5/2- level.

Summer 2007: beamtime accepted for Coulex of 72,75Cu @ REX-ISOLDE

new experimental set-up for transfer reactions, HIE-ISOLDE (5-10 MeV/u)

104Pd

104Pd

69Cu

1/2-

5/2-

7/2-

67Cu

5/2-

1/2-

7/2-

Experimental results (1)Experimental results (1)

3/2-

5/2-

1/2-

7/2-

7/2-

67Cu38

69Cu403/2-

5/2-

1/2-

7/2-

7/2-

DC for A=67

DC for A=69

2340

1670

1170

1115

1096

1213

1711

1871

(f7/2)-1

(f7/2)-1

p3/22+ (66Ni)

p3/22+ (68Ni)

71Cu(1/2-)5/2-

120Sn

Experimental results (2)Experimental results (2)

104Pd

7/2-

71Cu

71Ga

(1/2-)454 keV

(3/2-)

(5/2-)

(1/2-)

(7/2-)

(7/2-)

71Cu42

DC for A=71

DC for A=71

454

534

981

1190

(f7/2)-1

p3/22+ (70Ni)

Experimental results (3)Experimental results (3)

73Cu

73Ga

Laser ON

Laser OFF(3/2-)

(5/2-)

(1/2-)

(7/2-)

(7/2-)

73Cu44

DC for A=73

120Sn

7/2-

135

166

961

1010

(1/2-)

5/2-

(f7/2)-1

p3/22+ (72Ni)

protons neutrons

j> = l+1/2

j> = l’+1/2

j< = l’-1/2g9/2

f7/2

f5/2

1.4 GeV proton beam

Miniball

REX-ISOLDEXCu+XGa ~2.95 MeV/u

Resonant laser ionization (RILIS)

Radioactive beams of Radioactive beams of 67,69,71,7367,69,71,73Cu @ISOLDECu @ISOLDE

UCx target

68Cu1+ beam

68Cu 6- beam