Signatures for a nuclear quantum phase transition from E0 and E2 observables in Gd isotopes

• Main Authors: Wiederhold, J., Kern, R., Lizarazo, C., Pietralla, N., Werner, V., Jolos, R.V., Bucurescu, D., Florea, N., Ghita, D., Glodariu, T., Lica, R., Marginean, N., Marginean, R., Mihai, C., Mihai, R., Mitu, I.O., Negret, A., Nita, C., Olacel, A., Pascu, S., Stroe, L., Toma, S., Turturica, A.
• Format: Conference Proceeding
• Language: English
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1023/1/012024

Nuclei are complex quantum objects due to complex nucleon-nucleon interactions. They can undergo rather rapid changes in structure as a function of nucleon number. A well known region of such a shape transition is the rare-earth region around N = 90, where accessible nuclei range from spherical nuclei at the closed neutron shell at N = 82 to deformed nuclei. For a better understanding of this phenomenon, it is of interest to study empirical signatures like the E2 transition strength B(E2;21+→01+) or the E0 excitation strength ρ2(E0;01+→02+). The nuclide 152Gd with 88 neutrons is located close to the quantum phase transition at N = 90. The lifetime τ(02+) of 152Gd has been measured using fast electronic scintillation timing (FEST) with an array of HPGe- and LaBr3- detectors. Excited states of 152Gd were populated via an (α,n)-reaction on a gold-backed 149Sm target. The measured lifetime of τ(02+)=96(6)ps corresponds to a reduced transition strength of B(E2;02+→21+)=111(7) W.u. and an E0 transition strength of ρ2(E0) = 39(3) · 10−3 to the ground state. This result provides experimental support for the validity of a correlation between E0 and E2 strengths that is a novel indicator for a quantum phase transition. This work was published as J. Wiederhold et al., Phys. Rev. C 94, 044302 (2016).