Abstract
The interpretation of nuclear observables in the laboratory frame in terms of the intrinsic deformation parameters and is a classical theme in nuclear structure. Here we use the quadrupole invariants, calculated within the framework of the configuration-interaction shell model, to clarify the meaning and limitations of nuclear shapes. We introduce a novel method that enables us to calculate accurately higher-order invariants and, therefore, the fluctuations in both and . We find that the shape parameter often has a non-negligible degree of softness and that the angle is usually characterized by large fluctuations, rendering its effective value not meaningful. Contrary to common belief, we conclude that doubly magic nuclei are not spherical, because the notion of a well-defined shape does not apply to them.
- Received 18 June 2019
- Revised 19 February 2020
- Accepted 26 March 2020
DOI:https://doi.org/10.1103/PhysRevC.101.054307
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