We report on the "safe" Coulomb excitation of neutron-rich Cd, Xe, and Ba isotopes in the vicinity of the doubly-magic nucleus 132 Sn. The radioactive nuclei have been produced by ISOLDE at CERN and postaccelerated by the REX-ISOLDE facility. The γ-decay of excited states has been detected by the MINIBALL array. The presented preliminary results for the B(E2) values are consistent with expectations from phenomenological systematics and will be compared with theoretical calculations.

We investigate the magnetic dipole moments in even-even self-conjugate nuclei from $$^{12}$$ 12 C to $$^{48}$$ 48 Cr. For these nuclei, the measured gyromagnetic factors of excited states turn out to assume the same value of $$g \approx + 0.5$$ g ≈ + 0.5 within statistical errors. This peculiar feature can be interpreted on the basis of collective excitations of $$\alpha $$ α -clusters. Analogously, the behaviour of the same observable is studied for all isotopes obtained by adding one or two neutrons to the considered self-conjugate nuclei. It is found that for the $$N = Z + 1$$ N = Z + 1 isotopes the $$\alpha $$ α -cluster structure hardly contributes to the observed negative g- factor value, corroborating molecular $$\alpha $$ α -cluster models. The addition of a further neutron, however, restores the original $$\alpha $$ α -cluster g-factors, except for the semi-magic isotopes, in which the deviations from $$g \approx + 0.5$$ g ≈ + 0.5 can be associated with the relevant shell closures. Secondly, we analyze the same observable in the framework of a macroscopic $$\alpha $$ α -cluster model on a finite lattice of side length L. We focus on the discretization effects induced in the magnetic dipole moments of the $$2_1^+$$ 2 1 + and the $$3_1^-$$ 3 1 - states of $$^{12}$$ 12 C at different values of the lattice spacing a.

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We investigate the magnetic dipole moments in even-even self-conjugate nuclei from 12 C to 44 Ti. For the latter, the measured gyromagnetic factors of excited states turn out to assume the same value of g ≈ +0.5 within statistical errors. This peculiar feature can be interpreted on the basis of collective excitations of α-clusters. Analogously, the behaviour of the same observable is studied for all isotopes obtained by adding one or two neutrons to the considered self-conjugate nuclei. It is found that for the N = Z + 1 isotopes the α-cluster structure hardly contributes to the observed negative g-factor value, corroborating molecular α-cluster models. The addition of a further neutron, however, restores the original α-cluster g-factors, except for the semi-magic isotopes, in which the deviations from g ≈ +0.5 can be associated with the relevant shell closures. Secondly, we analyze the same observable in the framework of a macroscopic α-cluster model on a finite lattice of side length L. We focus on the discretization effects induced in the magnetic dipole moments of the 2 + 1 and the 3 − 1 states of 12 C at different values of the lattice spacing a.