E0 transition strengths as a tool to constraint model parameters. Application to even-even Xe isotopes

Abstract

Background: In any nuclear structure model, the accurate description of E0 transition rates constitutes a significant challenge; at the same time, these observables provide a stringent constraint on the admissible parameter space of the model. Purpose: This work pretend to study the value of certain $ρ^2(E0)$ values or ratios over the whole parameter space of the interacting boson model. As an application, the case of the even-even Xe isotopes will be explored. Method: The interacting boson model will be considered for the calculation of $ρ^2(E0)$ values for some key transitions and to explore how these observables change over the parameter space of the model. Results: Several key $ρ^2(E0)$ values or ratios are considered and contour plots in the parameter space of the interacting boson model (Casten triangle) are computed. The results for even-even Xe isotopes are superimposed on the contour plots. Conclusions: The presented analysis confirms that $ρ^2(E0)$ values and, in particular, certain ratios allow to constraint the parameter space of the interacting boson model. There are certain regions where the $ρ^2(E0)$ values cannot be altered by the fine tuning of the Hamiltonian parameters.

Figures (9)

• Figure 1: a) Energy ratio $E(4_1^+)/E(2_1^+)$ and b) $B(E2: 4_1^+\rightarrow 2_1^+)/B(E2: 2_1^+\rightarrow 0_1^+)$ as a function of A. The dynamical symmetry limits are given as a reference.
• Figure 2: Experimental excitation energy systematics. Black lines for the yrast band, red lines for excited $0^+$ states and gray lines for the rest of levels.
• Figure 3: Experimental excitation energies (panel a)) and the theoretical results (panel b)), obtained from the IBM.
• Figure 4: Comparison of the absolute $B(E2)$ reduced transition probabilities along the yrast band, given in W.u. Panel a) corresponds to experimental data and panel b) to the theoretical IBM results.
• Figure 5: Same as Fig. \ref{['fig-be2-1']} but for few intraband transitions.