We report on the measurement of the first 2 + and 4 + states of 66 Cr and 70,72 Fe via in-beam γ-ray spectroscopy. The nuclei of interest were produced by (p, 2p) reactions at incident energies of 260 MeV/nucleon. The experiment was performed at the Radioactive Isotope Beam Factory, RIKEN using the DALI2 γ-ray detector array and the novel MINOS device, a thick liquid hydrogen target combined with a vertex tracker. A low-energy plateau of 2 + 1 and 4 + 1 energies as a function of neutron number was observed for N≥38 and N≥40 for even-even Cr and Fe isotopes, respectively. State-of-the-art shell model calculations with a modified LNPS interaction in the pf g 9/2 d 5/2 valence space reproduce the observations. Interpretation within the shell model shows an extension of the Island of Inversion at N=40 for more neutron-rich isotopes towards N=50. Atomic nuclei are the place of a complex interplay between single-particle configurations and correlations which strongly determine their quantum coherent wavefunctions. All over the nuclear chart, the so-called magic numbers of nucleons define boundaries of large areas of deformation. This picture, mainly established for stable nuclei and neighbors, is re-examined at the light of new available nuclei with an unbalanced proton-to-neutron ratio, with the underlying question of the persistence or evolution of magic numbers [1,2]. Specific terms of the nuclear interaction can induce the formation of shell gaps or the lowering of relative orbital energies which, combined with correlations, sometimes lead to energetically favored intruder states as the ground state configuration [3][4][5][6][7][8]. Regions where two-particle two-hole (2p2h) configurations are favored over normally-filled orbitals by quadrupole correlations have been termed as Islands of Inversion (IoI) [9][10][11]. The N=20 IoI in the vicinity of 32 Mg has provided unique information on shell evolution [12]. This IoI does not show any decrease in collectivity for Mg isotopes at N > 24 and merges with the N=28 deformation region [8,13]

We report on the first γ-ray spectroscopy of low-lying states in neutron-rich ^{98,100}Kr isotopes obtained from ^{99,101}Rb(p,2p) reactions at ∼220  MeV/nucleon. A reduction of the 2_{1}^{+} state energies beyond N=60 demonstrates a significant increase of deformation, shifted in neutron number compared to the sharper transition observed in strontium and zirconium isotopes. State-of-the-art beyond-mean-field calculations using the Gogny D1S interaction predict level energies in good agreement with experimental results. The identification of a low-lying (0_{2}^{+}, 2_{2}^{+}) state in ^{98}Kr provides the first experimental evidence of a competing configuration at low energy in neutron-rich krypton isotopes consistent with the oblate-prolate shape coexistence picture suggested by theory.

We report on the measurement of new low-lying states in the neutron-rich 81,82,83,84Zn nuclei via in-beam γ -ray spectroscopy. These include the View the MathML source41+→21+ transition in 82Zn, the View the MathML source21+→0g.s.+ and View the MathML source41+→21+ transitions in 84Zn, and low-lying states in 81,83Zn were observed for the first time. The reduced View the MathML sourceE(21+) energies and increased View the MathML sourceE(41+)/E(2+1) ratios at N=52N=52, 54 compared to those in 80Zn attest that the magicity is confined to the neutron number N=50N=50 only. The deduced level schemes are compared to three state-of-the-art shell model calculations and a good agreement is observed with all three calculations. The newly observed 2+2+ and 4+4+ levels in 84Zn suggest the onset of deformation towards heavier Zn isotopes, which has been incorporated by taking into account the upper sdg orbitals in the Ni78-II and the PFSDG-U models