We study the role of configuration mixing in the heavier even-even isotopes of argon. We begin by limiting the configurations of the even-even Ar isotopes to $(d_{3/2}^2){}_{\pi }\hspace{0.5em}(f_{7/2}^n){}_{\nu }$. There, due to the particular location in this shell-model space of ${}^{40}\mathrm{Ar}$ and ${}^{44}\mathrm{Ar}$, we find that the spectra, $B(E2)$'s, and magnetic moments of these two nuclei are identical. Any deviation from this equality is direct evidence of configuration mixing. In a larger shell-model space there are significant differences between these two nuclei, with ${}^{44}\mathrm{Ar}$ being more collective. We also consider other even-even isotopes of argon and study how their nuclear structure effects evolve with N. We compare in the full $0\hslash \hspace{0.5em}\omega$ space $(\mathit{sd}){}_{\pi }\hspace{0.5em}(\mathit{fp}){}_{\nu }$ the results of calculations with the WBT interaction and with the newer SDPF, denoted SDPF-U, interaction.

• Received 15 December 2008

DOI:https://doi.org/10.1103/PhysRevC.79.054322