Bochum 2018 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 33: Structure and Dynamics of Nuclei VII

HK 33.3: Talk

Wednesday, February 28, 2018, 14:45–15:00, HZO 80

¹⁴⁸Ce as a good X(5) candidate from EXILL&FATIMA campaign — •Pavlos Koseoglou^1,2, V. Werner^1,3, N. Pietralla¹, S. Ilieva¹, M. Thürauf¹, R. B. Cakirli⁴, J. Jolie⁵, T. Kröll¹, J.-M. Régis⁵, and N. Saed-Samii⁵ — ¹IKP TU-Darmstadt, Germany — ²GSI, Germany — ³Yale University, USA — ⁴MPIK Heidelberg, Germany — ⁵IKP University of Cologne, Germany

The structure of the neutron-rich nuclide ¹⁴⁸Ce was studied at the high-flux reactor of the Institut Laue Langevin, Grenoble, within the EXILL&FATIMA campaign. A hybrid spectrometer consisting of the EXILL (high-resolution HPGe) and the FATIMA (fast LaBr₃) detectors was used to investigate fission fragments of ²³⁵U and ²⁴¹Pu. Lifetimes in the ps range were measured due to the fast LaBr₃ detectors and both the slope- and generalized centroid difference method. This kind of analysis serves as preparation for the FATIMA experiments at FAIR. ¹⁴⁸Ce sits on the low-Z boundary of the N=90 phase transitional region. The even-even N=90 isotones undergo a first order quantum phase transition which is characterized by a sudden change of the shape of the nucleus. Sensitive signatures of these kind of changes are the R_4/2=E(4₁⁺)/E(2₁⁺) and the B_4/2=B(E2;4₁⁺ → 2₁⁺)/B(E2;2₁⁺ → 0₁⁺) ratios. The experimentally measured ratios will be compared with the theoretical predictions of the X(5) symmetry. The analysis of ¹⁴⁸Ce will be presented together with the indicators which highlight this nucleus as a good X(5) candidate.