富中子硅同位素向N = 28的快速结构演化
Rapid structural evolution of neutron-rich silicon isotopes toward N = 28
AI总结：
研究富中子硅同位素向N = 28的结构演化，通过对$^{40}$Si和$^{41}$Si进行寿命测量及重离子非弹性散射测量，结果表明其向扁球形演化，与壳模型预测一致。
AI中文摘要：
富中子硅同位素代表了壳层演化的独特情况，在N = 20处有稳定的壳层闭合，在N = 28处有明显的四极集体性。我们报告了对$^{40}$Si激发态寿命的测量以及对$^{41}$Si首次同时进行的寿命和重离子非弹性散射测量。在$^{40}$Si中，提取的$2_1^+$和$(2_2^+)$态寿命表明在N = 26处有适度的四极集体性以及三轴性特征。在$^{41}$Si中，570和658 keV处的两个近简并态表现出从非弹性散射提取的可比$B(E2)$强度，而测量的寿命表明主要是$M1$衰变。综合的寿命和非弹性散射结果表明向扁球形演化，与大规模壳模型预测一致。
英文摘要：
Neutron-rich Si isotopes represent a unique case of shell evolution, exhibiting a robust shell closure at $N=20$ and pronounced quadrupole collectivity at $N = 28$. We report lifetime measurements of excited states in $^{40}$Si and the first simultaneous lifetime and heavy-ion inelastic-scattering measurements in $^{41}$Si. In $^{40}$Si, the extracted lifetimes for the $2_1^+$ and $(2_2^+)$ states indicate moderate quadrupole collectivity at $N=26$, together with signatures of triaxiality. In $^{41}$Si, two near-degenerate states at 570 and 658~keV exhibit comparable $B(E2)$ strengths as extracted from inelastic scattering, while the measured lifetimes indicate dominant $M1$ decays. The combined lifetime and inelastic-scattering results suggest an evolution toward oblate shape, consistent with large-scale shell-model predictions.
