Coexisting structures in ${}^{105}\mathrm{Ru}$

New positive-parity states, having a bandlike structure, were observed in ${}^{105}\mathrm{Ru}$. The nucleus was produced in an induced fission reaction, and the prompt $\gamma$-rays, emitted from the fragments, were detected by the EUROBALL III multidetector array. The partial scheme of excited ${}^{105}\mathrm{Ru}$ levels is analyzed within the triaxial-rotor-plus-particle approach.

Figure 1

Left-hand side: $\gamma$-ray spectra, gated on (a) 365- and 569-keV transitions; (b) 1836- and 898-keV transitions; (c) 209- and 1836- or 209- and 898-keV transitions; (d) 209- and 2079-keV or 209- and 1309-keV transitions; (e) 209- and 235-keV transitions; (f) 209- and 440-keV transitions. The $\gamma$lines belonging to the ${}^{88}\mathrm{Sr}$ level scheme are denoted with a star symbol *. The $\gamma$lines belonging to the ${}^{89}\mathrm{Sr}$ level scheme are denoted with the hash symbol #. Right-hand side: Partial level schemes of ${}^{88}\mathrm{Sr}$ and ${}^{89}\mathrm{Sr}$ according to Refs. [16] and [15].

Figure 2

Partial level scheme of ${}^{105}\mathrm{Ru}$ as observed in the present study. Level and $\gamma$-ray energies are rounded values from Table 1. Spin and parity assignments to the levels, observed in the present work, are only tentative. Arguments for these assignments are given in the text.

Figure 3

Experimental and theoretical ${}^{105}\mathrm{Ru}$ level schemes. The ${\epsilon }_2=0.24$, ${\epsilon }_4=-0.013$, $\gamma ={20}^{\circ }$, and $E_{2^{+}}=0.2$ MeV parameters were used to obtain the rigid-triaxial-rotor-plus-particle model (RTRPM) spectrum. The empirical shell-model calculations within the $\nu d_{5/2}^3$ coupling scheme are parametrized with respect to the ${}^{104}\mathrm{Ru}$ data.

Figure 4

Evolution of the low-lying positive-parity states in ${}^{105}\mathrm{Ru}$ as a function of the rigid-triaxial-rotor-plus-particle model parameters (a) ${\epsilon }_2$, (b) ${\epsilon }_4$, (c) $\gamma$, and (d) $E_{2^{+}}$. In each subfigure, the unfitted parameters were held fixed to the values given in Fig. 3.