Nuclear Structure Studies of¹⁰⁶Pd and¹⁰⁶Cd with the (n,n′γ) Reaction

Abstract

Abstract. Excited states in 106 Pd and 106 Cd have been studied using the (n,n γ) reaction. The data include level lifetimes, spins, branching ratios, and multipole mixing ratios, and give a comprehensive view of excitations with spin ≤6 . The determined E2 strengths show serious discrepancies with the quadrupole phonon structure expected in these nuclei.

Proton-neutron symplectic model description of 106Cd

“…However, within the PNSM, the mixing of various states of different quadrupole deformations belonging to a single irrep is treated in the laboratory system without the need for performing a particle-number and angular-momentum restoration. The difference from the traditional WJ γ-unstable rotor interpretation is that, in the present approach, the quadrupole dynamics corresponds to the rigid-flow type instead of the irrotational-flow one assumed in the WJ limit of the BM model [1,2,33,44,45]; both types exhibit the γ-instability as a characteristic fea-− ture. As previously mentioned, the difference is easily understood by looking at the form of the excitation quadrupole operators in both traditional WJ and present PNSM approaches instead of solely examining the type of γband staggering.…”

“…This version provides an interesting and relevant shell-model symplectic-based framework to explore the nature of the observed nuclear collective dynamics. In particular, it has already been applied to the microscopic description of the rigid-flow quadrupole collectivity in some strongly deformed [42] and transitional [43] nuclei and as well to the microscopic shell-model description of the irrotational-flow dynamics observed in 106 106 some weakly deformed nuclei [44,45]. Thus, the purpose of the present study is to examine the low-lying (normal) collective states in Cd, where the latter is suggested as "an excellent laboratory to study the emergence of collectivity" [21], within the microscopic shell-model version of the BM model.…”

“…However, Refs. [44,45] indicate that by modifying them one is able to produce a γ-unstable odd-even staggering pattern for the states of the γ band that is a characteristic of the γ-unstable WJ model (see Fig. 1 for Cd).…”

“…1 for Cd). Thus, we follow [44,45] and use the following parametrization for the model parameter in Eq. (10).…”

“…The symplectic generators in large dimensional representations contract [93] to the standard quadrupole phonon operators in the original BM model and the traditional phonon-scheme picture can be naturally obtained. Such irrotational-flow excitation operators are represented by the shear momentum operators of the subgroup within the framework of the PNSM and have been used to describe the irrotational-flow rotations and the high-energy vibrations in Cd, Ru [44] and Pd [45]. ) symmetry ω, where A denotes the number of protons and neutrons of the nucleus.…”