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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A study of the β + /EC decay of 110 In into levels of 110 Cd is combined with a reanalysis of data from a previous study of 110 Cd with the (n, n ′ γ) reaction with monoenergetic neutrons. The γγ coincidences from the 110 In decay leads to many new assignments of γ rays observed in the (n, n ′ γ) reaction, permitting the observation of weak low-energy transitions, and setting stringent upper limits on unobserved decay branches. The uncertainties on many of the lifetimes from the (n, n ′ γ) reaction are significantly reduced, and limits are established for the lifetimes of levels too long for a direct measurement. The absence of enhanced transitions between the previously assigned phonon states and the deformed intruder states strongly suggests that mixing between the configurations is generally weak, refuting the strong-mixing scenario as an explanation of the decay pattern of the excited 0 + states in 110 Cd. The decay pattern of the non-intruder states is suggestive of a γ-soft rotor, or O(6) nucleus, rather than a vibrational, or U (5) pattern. The existence of a 4p − 6h proton excitation in 110 Cd is also suggested.

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