论文标题
$^{40} $ ca中从超级形式的频段过渡的电动单极过渡
Electric monopole transition from the superdeformed band in $^{40}$Ca
论文作者
论文摘要
连接第三个0 $^+$ Level的过渡，电动单极（$ e0 $）的过渡强度$ρ^2 $，它是“ SuperDeformed”频段的头部，与“球形” 0 $^+$ offer offer magic $^{40} $ ca中的“球形” 0 $^+$地面状态通过$ e^+e^+e^+e^+e^ - $ paigh-$ $ paigh-$ $ paigh-$ $ $ $ e^ - $ $ $ $ $ $ $ $。测量值$ρ^2（e0; 0^+_ 3 \ to 0^+_ 1）〜= 〜2.3（5）\ times10^{ - 3} $，是最小的$ρ^2（e0; 0^+\ to 0^to 0^+）$。相反，从第二个0 $^+$状态观察到的$ e0 $过渡强度是“正常”变形的频段负责人，是一个更大的数量级，$ρ^2（e0; 0^+_ 2 \ _ 2 \ to 0^+_ 1）进行了大规模的壳模型（LSSM）计算，以了解激发态的显微镜结构，并在它们之间进行构型混合； $^{40} $ CA中的实验$ρ^2 $值，而相邻的同位素是通过LSSM计算很好地复制的。异常小的$ρ^2（e0; 0^+_ 3 \至0^+_ 1）$值是由于形状折叠式结构的混合中的破坏性干扰，这些结构基于几种不同的多颗粒 - multihole激发。该观察结果超出了对$ E0 $强度的通常处理，在这种情况下，两态形状混合不会导致破坏性干扰。
The electric monopole ($E0$) transition strength $ρ^2$ for the transition connecting the third 0$^+$ level, a "superdeformed" band head, to the "spherical" 0$^+$ ground state in doubly magic $^{40}$Ca has been determined via $e^+e^-$ pair-conversion spectroscopy. The measured value, $ρ^2(E0; 0^+_3 \to 0^+_1)~=~2.3(5)\times10^{-3}$, is the smallest $ρ^2(E0; 0^+ \to 0^+)$ found in $A<50$ nuclei. In contrast, the $E0$ transition strength to the ground state observed from the second 0$^+$ state, a band head of "normal" deformation, is an order of magnitude larger, $ρ^2(E0; 0^+_2 \to 0^+_1)~=~25.9(16)\times~10^{-3}$, which shows significant mixing between these two states. Large-Scale Shell Model (LSSM) calculations were performed to understand the microscopic structure of the excited states, and the configuration mixing between them; experimental $ρ^2$ values in $^{40}$Ca and neighboring isotopes were well reproduced by the LSSM calculations. The unusually small $ρ^2(E0; 0^+_3 \to 0^+_1)$ value is due to destructive interference in the mixing of shape-coexisting structures, which are based on several different multiparticle-multihole excitations. This observation goes beyond the usual treatment of $E0$ strengths, where two-state shape mixing cannot result in destructive interference.
