Spectroscopy studies around 78 Ni and beyond N=50 via transfer and Coulomb excitation reactions J. J. Valiente Dobón (INFN-LNL, Padova,Italy) A. Gadea (IFIC, Valencia, Spain) E. Clement (GANIL, Caen, France) R. Orlandi (Japan Atomic Energy Agency, Japan) D. Verney (IPN Orsay, France) LoI SPES

“On closed shells in nuclei” J. Hans D. Jensen (1907 – 1973) PR75, 1766 (1949) Maria Goeppert Mayer PR75, 1969 (1949) NOBEL 1963 Mayer et al., PR75, 1969 (1949) & Jensen et al., PR (1949)

Ductu naturae fp g 9/2  fp  g 9/2 Magic numbers and their evolution as a direct consequence of the character of the nuclear force.

f 7/2 d 3/2 20 d 5/2 p 1/2 1d 1f s 1/2 2s 2p p 3/2 f 5/2 28 L.S H.O L2L2 N=2 N=3 1g N=4 2d d 5/2 1p N=1 p 3/2 p 1/ g 9/2 The “spin-orbit” magic numbers N=8 collapses at 12 Be Triggered by the  p 3/2 - p 1/2 interaction N=8 collapses at 12 Be Triggered by the  p 3/2 - p 1/2 interaction Reduction of N=20 triggered by  d 5/2 - d 3/2 Island of inversion, large collectivity Reduction of N=28 gap by tensor force  d 3/2 - f strongly deformed 42 Si Reduction of N=28 gap by tensor force  d 3/2 - f strongly deformed 42 Si Reduction of N=50 gap by tensor force  f 5/2 - g Behaviour of 78 Ni ? Reduction of N=50 gap by tensor force  f 5/2 - g Behaviour of 78 Ni ?

NNN in the Ca region Microscopic calculations with well-established two-nucleon NN, do not reproduce N=28. However NN and NN+3N forces predict the N=28 shell gap, but with quantitative differences. D. Steppenbeck et al., nature 502, 207 (10 october 2013) T. Otsuka et al., PRL105, (2010) J.D. Holt et al., JPG: NPP (2013) The changes due to 3N forces are amplified in neutron- rich nuclei and will play a crucial role for matter at the extremes

Evolution along Z= Ni K. Sieja et al., PRC81, (2010) O. Sorlin et al. PRL 88 (2002) O. Perru et al. PRL 96 (2006) G. Kraus et al. PRL 73 (1994) T. Marchi et al., submitted to PRL

Cu isotopes, Z=29  p 3/2  f 5/2  p 3/2  2 + ( A-1 Ni)  f 7/2 ) -1  p 5/2  2 + ( A-1 Ni) 3/2 - 5/2 - 1/ Cu Cu Cu Cu 48 7/2 - S. Franchoo et al., PRL 81, 3100(1998), I. Stefanescu et al., PRL 100, (2008), K. Flanagan PRL, 103, (2009), J. M. Daugas PRC 81, (2010) Collectivity of the 7/2 1 - state probe the B(0 +  2 + ) in 76 Ni Magnetic moment measurement confirmed the inversion of the f 5/2 with the p 3/2 in 75 Cu

Along the N=50 J. Hakala et al., PRL101, (2008) J. Van de Walle et al., PRL99, (2007) 80 Zn Coulex Highly precision mass measurements Two neutron shell gap energies

The N=50 isotones Shell Model calcuations: 2p-2h excitations across the N=50 shell to 2d 5/2 -1g 7/2 -3s 1/2 (Lisetsky) for 4.7 MeV of the shell gap value→No reduction of the shell gap 1g 9/2 1g 7/2 2d 5/2 3s 1/2 N=50 Z=31 E. Sahin et al. Nuclear Physics A 893 (2012). Y.H. Zhang PRC70, (2004).

Beyond N=50 - Deformation Coulex: 78,80,82 Ge E. Padilla-Rodal et al., PRL94, (2005) Relativistic Coulex + knockout: 82 Ge and 84 Se A. Gade et al., PRC81, (2010) (d,p): 83 Ge and 85 Se: J.S. Thomas et al., PRC76, (2007) Involvement of the quasi-SU(3) in the explanation of the deformation in the N=40 region 78,80,82 Ge Coulex 84 Se(d,p) 85 Se (N=51) Proton angular distributions for GS and 462keV Ex

Physics cases considered Coulomb excitation neutron-rich 86,88 Se and 84 Ge – Evolution of deformation quasi-SU(3). Coulomb excitation 75,77 Cu, population of collective states - Infer deformation on the Ni isotopes. (d,p) 81 Ga, 84 Se, 82 Ge, 80 Zn – single particle orbital beyond N=50 d 5/2, s 1/2, d 3/2, g 7/2 and h 11/2. Gap stability. Monopole evolution. (t,α) to selectively populate single proton states in odd-A 73,75,77 Cu isotopes- p 3/2, f 5/2 and f 7/2. Proton removal from the GS of Zn.

Beam rates in SPES 73 Cu: 1, – 75 Cu: 2, – 77 Cu: 1, Zn: 7, – 76 Zn: 2, – 78 Zn: 2, – 80 Zn: 1, Ga: 2, Ge: 2, – 84 Ge: 1, Se: 2, – 86 Se: 1, – 88 Se: 2, Reacelerated – 200 μA proton current

Detection systems AGATA TRACE Gamma ray arrays Charged particle/heavy ion detectors GALILEO SPIDER DANTE

Summary Study of the low-lying properties of isotopes near by 78 Ni and beyond N=50 with the SPES beams. Shell evolution in the region – NN and NNN interactions, rigidity of the gaps when going towards 78 Ni Changes due to 3N forces are amplified in neutron-rich nuclei and will play a crucial role for matter at the extremes. Experimentally: Use of Coulomb excitation, (d,p) and (t,α) reactions to study the region Apparata: Sensitive detection systems to be used like: AGATA, GALILEO, TRACE, DANTE, SPIDER There is no a universal technique to measure the physical properties along an isotopic chain Concerns: beam purity > 20%, intensity , energy 10MeV/u

List of collaborators

Systematic variation of effective single-particle energies due to the tensor interaction T. Otsuka et al. PRL 95, (2005) V T = (           2) Y (2   Z(r) Tensor interaction

Indication of three body forces NNN Evidence of NNN forces in the Binding Energies in light nuclei Courtesy of C. Pipier, Argonne National lab.

Overview Study of nuclei in the region of 78 Ni –Along Z=28 –Along N=50 –Beyond N=50 Physics cases for SPES Experimental apparatus Summary/Remarks