B(E2) strength in ${}^{36,38}$Ca and in mirror nuclei 36S, 38Ar

Abstract

Recently, $B(E2,0_1^{+}\to 2_1^{+})$ transition strength have been measured in ${}^{36}$Ca and ${}^{38}$Ca. Surprisingly, the measured value in ${}^{36}$Ca: $B(E2\uparrow )=131(20)$ e${}^2$fm${}^4$, is significantly larger than in ${}^{38}$Ca, where $B(E2\uparrow )=101(11)$ e${}^2$fm${}^4$, whereas an opposite tendency of $B(E2)$ values is seen in the mirror nuclei ${}^{36}$S and ${}^{38}$Ar. The resonance $2_1^{+}$ in ${}^{36}$Ca lies 465 keV above the proton emission threshold and its description requires inclusion of the coupling to the continuum. In this work, we are analyzing $B(E2\uparrow )$ values in ${}^{36}$Ca, ${}^{36}$S, ${}^{38}$Ca, and ${}^{38}$Ar using the real-energy continuum shell model, the so-called shell model embedded in the continuum, in the $(1s_{1/2}0d_{3/2}0f_{7/2}1p_{3/2})$ model space with the monopole adjusted effective interaction ZBM-IO.

Comments: 12 pages, 5 figures