Nuclear structure studies of the neutronrich Rubidium isotopes

Nuclear structure studies of the neutron-rich Rubidium isotopes using Coulomb excitation. G. Georgiev 1, J. M. Daugas 2, G. Simpson 3, D. L. Balabanski 4, A. Blazhev 5, D. Bucurescu 6, S. Das Gupta 7, T. Faul 2, D. Filipescu 6, E. Fiori 1, L. Gaudefroy 2, D. Ghita 6, M. Hass 8, K. Hauschild 1, D. Jenkins 9, U. Koester 10, T. Kroel 11, V. Kumar 8, G. Lo Bianco 7, N. Marginean 6, A. Lopez-Martens 1, C. Mihai 6, R. Lozeva 1, V. Meot 2, D. Mücher 5, P. Reiter 5, O. Roberts 9, O. Roig 2, M. Seidlitz 5, K. Singh 8, A. Stuchbery 12, D. Voulot 13, J. Van de Walle 13, N. Warr 5, F. Wenander 13, A. Wendt 5, R. Wadsworth 9 and REX-ISOLDE and Miniball collaborations 1. CSNSM, Orsay, France 2. CEA/DIF/DPTA/SPN, Bruyeres le Chatel, 91297 Arpajon, France 3. LPSC, Grenoble, France 4. INRNE, BAS, Sofia, Bulgaria 5. Institute for Nuclear Physics, Cologne, Germany 6. H. Hulubei, NIPNE, Bucharest, Romania 7. Dipartimento di Fisica, Universita di Camerino, Italy 8. Weizmann Institute of Science, Rehovot, Israel 9. University of York, United Kingdom 10. Institute Max von Laue-Paul Langevin, Grenoble, France 11. Physik-Department E 12, TU Muenchen, Garching, Germany 12. Department of Nuclear Physics, ANU, Canberra, Australia 13. ISOLDE, CERN, Geneva, Switzerland

From spherical to well deformed structures Neutron side W. Urban et al. , Eur. Phys. J. A 22, 241 (2004) n 9/2+[404], n 1/2 -[550], n 3/2 -[541], n 3/2+[411] Proton side C. Thibault et al. , Phys. Rev. C 23, 2720 (1981) p 3/2 -[312], p 3/2 -[301], p 3/2+[431]

Mean-field calculation • Hartree-Fock-Bogoliubov • D 1 S Gogny effective force • axial-symmetric hypothesis Much more gradual shape changes compared to the experimentally observed

93 Rb – last odd Rb with know excited states • Experimental information for excited states – only for 93 Rb • Theoretical approaches – shell model, quasi-particle-rotor model

Astrophysics interest n r-process path – according to one of the scenarios it can pass exactly through those Rb nuclei

Experimental details Beam impurities Beam monitor PPAC Beam Dump Ge Detector Bragg detector q j IC - Si telescope Particles • angles (16° – 53°) • energies DSSSD Beam from REX-ISOLDE @ » 3 Me. V/u

Previous experience for odd-mass Coulex (67 -73 Cu) 67 Cu 5/21/27/2104 Pd 2340 7/2 - 1670 1/25/2 - 1170 1115 67 Cu/total ~ 97 % 1. 2 x 105 pps during 30 hours 3/2 - 69 Cu 1/2104 Pd 7/2 - 5/2 - 7/27/2 - 1871 1711 69 Cu/total ~ 94 % 5/21/2 - 1213 1096 during 40 hours 1. 5 x 105 pps 3/2 - PRL 100, 112502 (2008)

(1/2 -) 71 Cu 454 ke. V 7/2 - (7/2 -) 1190 (7/2 -) 981 (5/2 -) (1/2 -) 104 Pd 534 454 71 Cu/total ~ 76 % 1. 5 x 105 pps during 20 hours (3/2 -) 71 Ga DC for A=71 73 Cu (7/2 -) 1010 961 73 Ga 7/2 - ~ 19 % 1. 5 x 104 pps (1/2 -) 5/2 - 73 Cu/total 166 135 (5/2 -) (1/2 -) (3/2 -) 120 Sn during 12 hours

Beam-time request 93 Rb (5. 8 s) 95 Rb (377 ms) 97 Rb (170 ms) 99 Rb (50 ms) ISOLDE yields [p/µC] Expected count SC PSB rate at Miniball [pps] 1 x 108 1 x 109 > 5 x 106 4 x 107 1 x 108 > 1 x 106 5 x 106 1 x 107 1 x 105 4 x 105 1 x 105 2 x 103 Shifts + 3 shifts for changing settings between the different isotopes Total 21 shifts requested 3 3 3 9

Coulomb excitation of polarized nuclei Me. V TF 51 V (Ip = 7/2 -), 13+ charge state 195 Me. V - Coulex on Pb 51 V@50 • 51 V beam intensity ~ 1 pn. A • left-right asymmetry • strong velocity dependence of the polarization observed: • PI = 1. 2(2)% at b = 6. 5% • PI > 10(1) % at b = 4. 6% J. Bendahan et al. , ZPA 331, 343 (88)