论文标题
Isscalar Monopole和Dipole Transitions以$^{24} $ mg，$^{26} $ mg和$^{28} $ si
Isoscalar monopole and dipole transitions in $^{24}$Mg, $^{26}$Mg and $^{28}$Si
论文作者
论文摘要
$ SD $ shell中的核表现出了群集和平均场现象的显着相互作用。 $ n = z $ nuclei，例如$^{24} $ mg和$^{28} $ si，一直是这些现象的理论研究的重点。可以通过在等尺颗粒（例如杜特龙或$α$颗粒）散射等轴心单极和偶极状态的激发来探测簇和涡流平均现象。 在南非开普敦的Ithemba Labs的K600磁性光谱仪中，不分散的$α$颗粒是动量的。在两个多线漂移室中检测到散射的颗粒，并将两个塑料闪烁体放置在K600的焦平面上。在理论讨论中，使用了QRPA和AMD+GCM。 QRPA的计算使我们得出结论：i）平均场涡度主要出现在$ k = 1 $，ii）偶极子（单子）状态应具有强大变形的八振长（Quadrupole）副反应（Quadrupole）副反应和III的偶极状态，以及在$α$ -Article cutemi untely的情况下，$ -Artely（iii）$ -Artely and Completi $ k = 0 $ k = 0 $ k = 1 $ n nuclerate nuclei）具有令人印象深刻的八极强度。 AMD + GCM计算的结果表明，某些观察到的状态可能具有混合（平均场 +群集）字符或对应于特定的群集配置。 从QRPA和AMD+GCM建立了观察到的状态与理论状态之间的暂定对应关系。 QRPA和AMD+GCM分析表明，低能量等速膜偶极状态结合了簇和平均场特性。 QRPA计算表明，低能量涡度的定位良好，以$^{24} $ mg，碎片为$^{26} $ mg，在$^{28} $ si中不存在。
Nuclei in the $sd$-shell demonstrate a remarkable interplay of cluster and mean-field phenomena. The $N=Z$ nuclei, such as $^{24}$Mg and $^{28}$Si, have been the focus of the theoretical study of both these phenomena in the past. The cluster and vortical mean-field phenomena can be probed by excitation of isoscalar monopole and dipole states in scattering of isoscalar particles such as deuterons or $α$ particles. Inelastically scattered $α$ particles were momentum-analysed in the K600 magnetic spectrometer at iThemba LABS, Cape Town, South Africa. The scattered particles were detected in two multi-wire drift chambers and two plastic scintillators placed at the focal plane of the K600. In the theoretical discussion, the QRPA and AMD+GCM were used. The QRPA calculations lead us to conclude that: i) the mean-field vorticity appears mainly in dipole states with $K=1$, ii) the dipole (monopole) states should have strong deformation-induced octupole (quadrupole) admixtures, and iii) that near the $α$-particle threshold, there should exist a collective state (with $K=0$ for prolate nuclei and $K=1$ for oblate nuclei) with an impressive octupole strength. The results of the AMD+GCM calculations suggest that some observed states may have a mixed (mean-field + cluster) character or correspond to particular cluster configurations. A tentative correspondence between observed states and theoretical states from QRPA and AMD+GCM was established. The QRPA and AMD+GCM analysis shows that low-energy isoscalar dipole states combine cluster and mean-field properties. The QRPA calculations show that the low-energy vorticity is well localized in $^{24}$Mg, fragmented in $^{26}$Mg, and absent in $^{28}$Si.
