Investigating the Structure of Exotic Nuclei with Lifetime Measurements of Excited Nuclear States

通过激发核态的寿命测量来研究奇异核的结构

• 批准号: 418937767
• 负责人: Professor Dr. Alfred Dewald
• 金额: --
• 依托单位: Institut für Kernphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/418937767?language=en
• 关键词: Investigating; Structure; Exotic; Nuclei; Lifetime

The aim of the project is the investigation of the evolution of nuclear structure far from the valley of stability from absolute transition strengths. The latter will be determined from level lifetimes which will be measured with the recoil distance Doppler-shift method (RDDS). The main focus of this work lies on the appearance of collectivity in the close vicinity of nuclear (sub-)shell closures and on changes in the shell structure of nuclei with extreme ratios of protons and neutrons leading, e.g. to shape coexistence. Such phenomena were already found in several exotic nuclei and investigated successfully in the last project of our group and also within another project. The present grant application aims for a continuation of this successful work to extend the existing data significantly and, therefore, to achieve a general picture in different mass regions missing so far and spanning from neutron-rich nuclei close to the Z = 28 shell closure to neutron deficient nuclei around shell closures at Z=50 and Z=82. As a continuation of another project we aim to examine the structural evolution of light neutron rich nuclei around Z=28 and close to exotic doubly-magic 78Ni by investigating odd 59,61,63Mn and 75−79Cu. Further, the neutron deficient isotopes 112,116Te are in the focus of our interest: we want to solve the conundrum that even the transition strengths between the lowest yrast states cannot be explained with model approaches so far. However, new shell model calculations for the neighboring Sn isotopes in a very large valence space performed by the group of T. Otsuka were able to reproduce E2 transition strengths for the first time that could not be understood before. Here we plan to perform similar calculations for the Te isotopes in collaboration with T. Otsuka to solve the aforementioned conundrum and answer the question, if proton excitations over the Z=50 shell closure can explain the observations, similar to Pt and Hg isotopes (excitation over the Z=82 shell closure). We also aim to measure yrast transition strengths in 174,178W and 176Pt as existing experimental data are contradictory and do not allow a conclusion on the structure, e.g., with respect to an expected shape coexistence in 176Pt.

该项目的目的是研究远离绝对跃迁强度稳定谷的核结构的演变。 后者将确定从水平的寿命，这将是测量与反冲距离多普勒频移法（RDDS）。这项工作的主要重点在于集体的外观在附近的核（子）壳封闭和变化的壳结构的核与极端比例的质子和中子导致，例如形状共存。这种现象已经在几个奇异核中发现，并在我们小组的最后一个项目和另一个项目中成功地进行了研究。目前的资助申请旨在继续这项成功的工作，以显着扩展现有的数据，因此，在不同的质量区域，实现一个一般的图片失踪到目前为止，从富中子核接近Z = 28壳关闭周围壳关闭Z=50和Z=82的中子缺乏核。作为另一个项目的延续，我们的目标是通过研究奇数59，61，63 Mn和75− 79 Cu来研究Z=28和接近奇异双魔78 Ni的轻中子丰核的结构演化。此外，缺中子同位素112，116 Te是我们感兴趣的焦点：我们想解决的难题，即使是最低的yraast状态之间的过渡强度不能用模型方法解释到目前为止。然而，由T。大冢首次能够再现E2跃迁强度，这是以前无法理解的。在这里，我们计划与T. Otsuka解决了上述难题，并回答了这个问题，如果质子激发超过Z=50壳层封闭可以解释观察，类似于Pt和Hg同位素（激发超过Z=82壳层封闭）。我们还旨在测量174，178 W和176 Pt中的yraast跃迁强度，因为现有的实验数据是矛盾的，并且不允许对结构做出结论，例如，相对于176Pt中预期的形状共存。