Spectroscopy and excited-state g factors in weakly collective Cd 111: Confronting collective and microscopic models

B. J. Coombes, A. E. Stuchbery*, A. Blazhev, H. Grawe, M. W. Reed, A. Akber, J. T.H. Dowie, M. S.M. Gerathy, T. J. Gray, T. Kibédi, A. J. Mitchell, T. Palazzo

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    10 Citations (Scopus)

    Abstract

    Background: The even cadmium isotopes near the neutron midshell have long been considered among the best examples of vibrational nuclei. However, the vibrational nature of these nuclei has been questioned based on E2 transition rates that are not consistent with vibrational excitations. In the neighboring odd-mass nuclei, the g factors of the low-excitation collective states have been shown to be more consistent with a deformed rotational core than a vibrational core. Moving beyond the comparison of vibrational versus rotational models, recent advances in computational power have made shell-model calculations feasible for Cd isotopes. These calculations may give insights into the emergence and nature of collectivity in the Cd isotopes. Purpose: To investigate the nature of collective excitations in the A≈100 region through experimental and theoretical studies of magnetic moments and electromagnetic transitions in Cd111. Method: The spectroscopy of Cd111 has been studied following Coulomb excitation. Angular correlation measurements, transient-field g-factor measurements and lifetime measurements by the Doppler-broadened line shape method were performed. The structure of the nucleus was explored in relation to particle-vibration versus particle-rotor interpretations. Large-scale shell-model calculations were performed with the SR88MHJM Hamiltonian. Results: Excited-state g factors have been measured, spin assignments examined, and lifetimes determined. Attention was given to the reported 5/2+ 753-keV and 3/2+ 755-keV states. The 3/2+ 755-keV level was not observed; evidence is presented that the reported 3/2+ state was a misidentification of the 5/2+ 753-keV state. Conclusions: It is shown that the g factors and level structure of Cd111 are not readily explained by the particle-vibration model. A particle-rotor approach has both successes and limitations. The shell-model approach successfully reproduces much of the known low-excitation structure in Cd111.

    Original languageEnglish
    Article number024322
    JournalPhysical Review C
    Volume100
    Issue number2
    DOIs
    Publication statusPublished - 14 Aug 2019

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