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    Isospin dependence of electromagnetic transition strengths among an isobaric triplet
    (Elsevier, 2019) Boso, A.; Milne, S. A.; Bentley, M. A.; Recchia, F.; Lenzi, S. M.; Rudolph, D.; Labiche, M.; Aydın, Sezgin
    Electric quadrupole matrix elements, Mp, for the J? = 2+ ? 0+, T = 0, T = 1 transitions across the A = 46 isobaric multiplet 46Cr-46V-46Ti have been measured at GSI with the FRS-LYCCA-AGATA setup. This allows direct insight into the isospin purity of the states of interest by testing the linearity of Mp with respect to Tz . Pairs of nuclei in the T = 1 triplet were studied using identical reaction mechanisms in order to control systematic errors. The Mp values were obtained with two different methodologies: (i) a relativistic Coulomb excitation experiment was performed for 46Cr and 46Ti; (ii) a “stretched target” technique was adopted here, for the first time, for lifetime measurements in 46V and 46Ti. A constant value of Mp across the triplet has been observed. Shell-model calculations performed within the f p shell fail to reproduce this unexpected trend, pointing towards the need of a wider valence space. This result is confirmed by the good agreement with experimental data achieved with an interaction which allows excitations from the underlying sd shell. A test of the linearity rule for all published data on complete T = 1 isospin triplets is presented.
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    Isospin symmetry breaking in mirror nuclei 23mg-23Na
    (Jagiellonian University Press, 2017) Boso, A.; Lenzi, S. M.; Recchia, F.; Bonnard, J.; Aydin, S.; Bentley, M. A.; Cederwall, B.; Clement, E.; De France, G.; Di Nitto, A.; Dijon, A.; Doncel, M.; Ghazi-Moradi, F.; Gottardo, A.; Henry, T.; Huyuk, T.; Jaworski, G.; John, P. R.; Juhasz, K.; Kuti, I.; Melon, B.; Mengoni, D.; Michelagnoli, C.; Modamio, V.; Napoli, D. R.; Nyako, B. M.; Nyberg, J.; Palacz, M.; Valiente-Dobon, J. J.
    Mirror energy differences (MED) are a direct consequence of isospin symmetry breaking. Moreover, the study of MED has proved to give valuable information of several nuclear structure properties. We present the results of an experiment performed in GANIL to study the MED in mirror nuclei Mg-23-Na-23 up to high spin. The experimental values are compared with state-of-the-art shell model calculations. This permits to enlighten several nuclear structure properties, such as the way in which the nucleons alignment proceeds, the radius variation with J, the role of the spin-orbit interaction and the importance of isospin symmetry breaking terms of nuclear origin.
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    Neutron Skin Effects in Mirror Energy Differences: The Case of Mg-23-Na-23
    (American Physical Society, 2018) Boso, A.; Lenzi, Silvia M.; Recchia, Francesco; Bonnard, Jèrèmy; Zuker, Andrés P.; Aydın, Sezgin; Bentley, M. A.; Cederwall, Bo
    Energy differences between analogue states in the T = 1/2 Mg-23-Na-23 mirror nuclei have been measured along the rotational yrast bands. This allows us to search for effects arising from isospin-symmetrybreaking interactions (ISB) and/or shape changes. Data are interpreted in the shell model framework following the method successfully applied to nuclei in the f(7/2) shell. It is shown that the introduction of a schematic ISB interaction of the same type of that used in the f(7/2) shell is needed to reproduce the data. An alternative novel description, applied here for the first time, relies on the use of an effective interaction deduced from a realistic charge-dependent chiral nucleon-nucleon potential. This analysis provides two important results: (i) The mirror energy differences give direct insight into the nuclear skin; (ii) the skin changes along the rotational bands are strongly correlated with the difference between the neutron and proton occupations of the s(1/2) "halo" orbit.