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9 A s an example of probing such valence occupations, here is work done a long time ago. We measured (d,p) cross sections in the 4 even Zn isotopes to all accessible final states. Phys. Rev. 164, 1374 (1967)

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12 (e,e’p) from Lapikas et al.

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52 (e,e’p) results by Lapikas et al.

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70 Comparison of ( 3 He,d) with ( ,t) for same transfer.

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75 Yale Spectrograph

Triton spectra at 6 0 Colors: g 7/2 h 11/2

78 * Using a single normalization for all 14 transitions. Target Ratio (  6  ) S 7/2 * S 11/2 * 112 Sn Sn Sn Sn Sn Sn Sn

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84 Similar trend in N=82 isotones There are 5 stable isotones (Sm, Nd, Ce, Ba, Xe) Fragmentation is known to be more significant than in Sn. Xe requires a gas cell Previous work done at Oxford in the 70’s Choose to explore the neutron-adding (α, 3 He) reaction.

85 Considerable fragmentation seen (mostly one additional state) ! Centroid of single-particle strength shifts. Estimated uncertainty: Absolute cross sections ~7% Relative cross section <5% Relative spectroscopic factors ~10% Other fragments? Confident to limit of 5% of strongest

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89 For Z=51 h 11/2 neutrons are filling in Sn REPULSIVE effect on πh 11/2. ATTRACTIVE effect on πg 7/2. Difference is~0.12 MeV per nucleon From (d,p) studies in the 1960's. Otsuka et al. [PRL95(2005)232502]

90 Expectations for Z=51 GT2: Gogny + tensor D1S: traditional Gogny Quantitative measurements  -spectroscopy only ‘ultra’ neutron rich (for the far future) neutron rich Mean field calculations now explicitly include a tensor term The trend in stable isotopes should flatten above N=82 Start reversing above N=90 Otsuka et al. [PRL97(2006)232501]

91 For N=83 From ( 3 He,d) work in 1960-s. πg 7/2 protons filling as Z increases (and N-Z decreases). ATTRACTIVE for i 13/2 REPULSIVE for h 9/2 ~0.18 MeV per nucleon

92 Interpretation (N=82) From tensor matrix elements provided by Otsuka, uncertainty arises from proton occupancies

93 Mean-field challenges The details of the filling of protons in the πg 7/2 and πd 5/2 orbitals matter. Recent HF calculations treated the filling of these orbits sequentially, and it does matter. G. Colo et al. Phys Lett. B 646(2007)227

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