Shape coexistence and collective low-spin states in Sn112,114 studied with the (p,p′γ) Doppler-shift attenuation coincidence technique
Shape coexistence and collective low-spin states in Sn112,114 studied with the (p,p′γ) Doppler-shift attenuation coincidence technique
复制标题
使用 (p,p−2Y) 多普勒频移衰减符合技术研究 Sn112,114 中的形状共存和集体低自旋态
DOI：
10.1103/physrevc.97.054319
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发表时间：
2018
影响因子：
3.1
通讯作者：
Zilges, A.
中科院分区：
文献类型：
--
作者：
Spieker, M.;Petkov, P.;Litvinova, E.;Müller-Gatermann, C.;Pickstone, S. G.;Prill, S.;Scholz, P.;Zilges, A.
背景：半幻 Sn () 同位素已受到许多核结构研究的影响。已经观察到形状共存的特征，并将其归因于壳闭合过程中的双质子-双孔（2p-2h）激发。此外，还观察到了许多低位核结构特征，这些特征在过去有效地约束了理论模型。一个例子是由集体四极和八极声子耦合引起的所谓四极-八极耦合态（QOC）。目的：在科隆大学核物理研究所进行了质子散射实验和重合射线光谱，以激发低自旋态并确定其寿命并提取减少的跃迁强度。方法：组合光谱装置 SONIC@HORUS 已用于检测散射的质子和激发态的发射射线同时发生。采用新颖的多普勒频移衰减（DSA）符合技术来测量亚皮秒核能级寿命。结果：确定了七十四（74）个能级寿命。此外，还推导了支化比，从而可以研究两个核中的入侵者构型。这里添加了 IBM-2 混合计算，支持两种配置的共存。此外，预期的 QOC 五胞胎成员也是首次被提议。该候选物完全符合对其他稳定 Sn 同位素观察到的系统学。结论：对所谓的入侵者带的低自旋成员观察到的跃迁强度支持形状共存的存在。这种构型中的集体性与在 Pd 原子核（即 0p-4h 原子核）中观察到的集体性相当。可以观察到正常配置和入侵者配置的状态之间的强烈混合。QOC 状态的普遍存在得到了对 QOC 候选者的观察的支持。
Background:The semimagic Sn () isotopes have been subject to many nuclear-structure studies. Signatures of shape coexistence have been observed and attributed to two-proton–two-hole (2p-2h) excitations across theshell closure. In addition, many low-lying nuclear-structure features have been observed which have effectively constrained theoretical models in the past. One example are so-called quadrupole-octupole coupled states (QOC) caused by the coupling of the collective quadrupole and octupole phonons.Purpose:Proton-scattering experiments followed by the coincident spectroscopy ofrays have been performed at the Institute for Nuclear Physics of the University of Cologne to excite low-spin states inandto determine their lifetimes and extract reduced transition strengths.Methods:The combined spectroscopy setup SONIC@HORUS has been used to detect the scattered protons and the emittedrays of excited states in coincidence. The novelDoppler-shift attenuation (DSA) coincidence technique was employed to measure sub-ps nuclear level lifetimes.Results:Seventy-four (74) level lifetimesof states withwere determined. In addition, branching ratios were deduced which allowed the investigation of the intruder configuration in both nuclei. Here,IBM-2 mixing calculations were added which support the coexistence of the two configurations. Furthermore, members of the expected QOC quintuplet are proposed infor the first time. Thecandidate infits perfectly into the systematics observed for the other stable Sn isotopes.Conclusions:Thetransition strengths observed for the low-spin members of the so-called intruder band support the existence of shape coexistence in. The collectivity in this configuration is comparable to the one observed in the Pd nuclei, i.e., the 0p-4h nuclei. Strong mixing between thestates of the normal and intruder configuration might be observed in. The general existence of QOC states inis supported by the observation of QOC candidates with.