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High-spin states have been investigated in the mirror pair nuclei 49 Cr (Z 24, N 25) and 49 Mn ͑Z 25, N 24͒. Mirror symmetry up to the band termination at about 10.7 MeV has been established. A comparison of the corresponding energy levels of the pair shows, for the first time, that the Coulomb energy difference approaches zero as the band termination is approached. This is explained intuitively in terms of a pure f 7 2 shell framework. For 49 Cr, excellent agreement is found between the data and recent full pf-shell calculations. [S0031-9007(97)04648-6] PACS numbers: 23.20. Lv, 21.10.Sf, 27.40. + z, 29.30.Kv

Many-body nuclear theory utilizing microscopic or chiral potentials has developed to the point that collectivity might be dealt with in an ab initio framework without the use of effective charges; for example with the proper evolution of operators, or alternatively, through the use of an appropriate and manageable subset of particle-hole excitations.We present a precise determination of E2 strength in 22 Mg and its mirror 22 Ne by Coulomb excitation, allowing for rigorous comparisons with theory. No-core symplectic shell-model calculations were performed and agree with the new B(E2) values while in-medium similarity-renormalization-group calculations consistently underpredict the absolute strength, with the missing strength found to have both isoscalar and isovector components.

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