Coulomb excitation of the neutron-rich Cu isotopes 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 Leuven 2CSNSM Orsay, France 3TU München, Germany 4IKP Köln, Germany 5IPN Orsay, France 6Heavy Ion Laboratory, Warsaw University, Poland 7University of Sofia, Bulgaria 8Universita di Camerino, Italy 9National Research Center Demokritos, Greece 10Lund University, Sweden Funded by IAP Belgium, BMBF, EURONS

Beyond 68Ni by Coulomb excitation with RIBs g9/2 f7/2 40 llllllll llll llllll ll p3/2 f5/2 p1/2 28 protons neutrons N=50 N=40 B(E2;2+0+) by Coulex 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)). +2p 68Ni +2n

Beyond 68Ni by Coulomb excitation with RIBs g9/2 f7/2 40 llllllll llll llllll ll p3/2 f5/2 p1/2 l 28 protons neutrons N=40 N=50 B(E2;2+0+) by Coulex 2005: Coulomb excitation of odd-odd 68,70Cu; 2006: Coulomb excitation of odd-mass 67,69,71,73Cu. 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).

The odd-odd 68,70Cu 70Cu41 68Cu39 p3/2  g9/2 = 3-, 4- , 5- , 6- f7/2 40 llllllll llll llllll l p3/2 f5/2 p1/2 28   70Cu41 ll g9/2 f7/2 40 llllllll llll llllll l p3/2 f5/2 p1/2 28   68Cu39 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.

68,70Cu 1+ 2+ 6- (3-) (4-) (5-) p3/2g9/2 p3/2p1/2 Coulex with post-accelerated 6- isomeric beams ! E2 1350 956 (5-) 506 778 0.7 ns <T1/2 <4 ns 722 T1/2=3.75 min 1+ 242 T1/2= 6.6 s - (4-) 228 84 101 T1/2=7.84 ns 3- T1/2= 33 s T1/2=31.1 s 6- T1/2= 45.5 s - - 68Cu39 70Cu41 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.

Isomeric 68,70Cu beams @ Isolde 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. 6- 1+ (g.s.) 68Cu 1+ 6- 722  6- (g.s.) 3- 70Cu 6- 1+ 242  3- 101 1+ + postacceleration by REX-ISOLDE

Experimental set-up for Coulex @REX-ISOLDE Miniball: 8 clusters, 3 X 6 fold segmented 4 quadrants 16 annular strips () 24 sector strips () DSSD detector (16o-53o) 68m,70gCu (6-) REX- ISOLDE E~2.83 MeV/u Beam dump detector PPAC 120Sn Beam ~2 mg/cm2 monitor

68Cu 70Cu Coulomb excitation of odd-odd 68,70Cu - first use of postaccelerated isomeric beams - 68,mCu (2.83 MeV/u) @ 120Sn (2.3 mg/cm2) 85 1+ (2+) 6- 4- (3-) 722 (5-) 956 178 (M1) 693 84 778 E2 coulex 68Cu 70Cu (2.83 MeV/u) @ 120Sn (2.3 mg/cm2) 6- (3-) 4- (5-) 101 228 506 127 (M1) E2 70Cu coulex I. Stefanescu et al., PRL 98, 122701(2007).

Comparison with shell-model calculations Shell-model calculations for the valence space outside the 56Ni core (e=1.5e, e=0.5e) . protons 28 p3/2 f5/2 p1/2 g9/2 f7/2 llllllll l neutrons llll llllll 40 ll *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). 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.

68Cu: releasing the energy of the 6- isomer 1+ 2+ 6- 4- (3-) 722 3.75 min 31.1 s 5- 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 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). instantaneous depopulation of isomers in odd-odd nuclei based on their multiplet structure possible scheme for triggered energy release in odd-odd nuclei I(I+1) Energy 6- E2 3- 4- 5- 1+ 2+ M1

2006: Coulomb excitation of 67,69,71,73Cu 28 g9/2 f5/2 40 p3/2 p1/2 ll l (f7/2)-1 3/2- 5/2- 1/2- 7/2- 67Cu38 Eex (MeV) 2 69Cu40 p3/22+ (A-1Ni) p1/2 71Cu42 1 f5/2 shell-model p3/2 73Cu44 75Cu46 g9/2 B. Zeidman et al., PRC 18, 2122(1978)/R. Grzywacz et al., PRL 81, 766 (1998) /S. Franchoo et al., PRL 81, 3100(1998). 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

Coulomb excitation spectra 67Cu (2.99 MeV/u) @ 104Pd (2 mg/cm2) 71Cu (2.95 MeV/u) @ 104Pd (2 mg/cm2) 5/2- 1/2- 7/2- 3/2- p3/22+(66Ni) p3/2 f5/2 p1/2 (1/2-) (1/2-) (5/2-) (7/2-) (3/2-) p3/22+(70Ni) 454 5/2- 7/2- 1/2- 7/2- 104Pd 104Pd 69Cu (2.97 MeV/u) @ 104Pd (2 mg/cm2) 73Cu (2.88 MeV/u) @ 120Sn (1.7 mg/cm2) 1/2- 5/2- 7/2- 3/2- p3/22+(68Ni) (1/2-) (1/2-) (5/2-) (7/2-) (3/2-) p3/22+(72Ni) 135 73Ga 1/2- 5/2- 5/2- 7/2- 120Sn 104Pd 7/2-

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) 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) 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 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)

Experimental results (1) 67Cu 7/2- 2340 (f7/2)-1 5/2- 7/2- 1670 p3/22+ (66Ni) 1/2- 7/2- 1/2- 1170 104Pd 5/2- 1115 67Cu38 DC for A=67 3/2- 1871 69Cu 7/2- p3/22+ (68Ni) (f7/2)-1 7/2- 1711 1/2- 5/2- 1213 5/2- 7/2- 104Pd 1/2- 1096 69Cu40 DC for A=69 3/2-

Experimental results (2) (1/2-) 71Cu 454 keV 7/2- (7/2-) 1190 p3/22+ (70Ni) (f7/2)-1 (7/2-) 981 104Pd 71Ga (5/2-) 534 DC for A=71 (1/2-) 454 71Cu42 71Cu (1/2-) (3/2-) 5/2- 120Sn DC for A=71

Experimental results (3) DC for A=73 (1/2-) 73Cu 5/2- Laser ON (7/2-) 1010 (f7/2)-1 73Ga 120Sn p3/22+ (72Ni) (7/2-) 961 7/2- (5/2-) 166 (1/2-) 135 73Cu44 Laser OFF (3/2-)

g9/2 f5/2 f7/2 protons neutrons j> = l+1/2 j< = l’-1/2

Radioactive beams of 67,69,71,73Cu @ISOLDE 1.4 GeV proton beam UCx target REX-ISOLDE Resonant laser ionization (RILIS) XCu+XGa ~2.95 MeV/u Miniball

68Cu 6- beam 68Cu 1+ beam