Investigation on shape transitions and shape coexistences in neutron-rich odd-A and odd-odd nuclei around 100Zr

该提议的目的是提供新的和改进的光谱信息，主要是通过使用快速计时技术测量低能激发态的寿命，来提供关于100Zr附近的奇A核和奇奇核的光谱信息。目标是获得更多关于这一特定质量区域内中子和质子单粒子轨道演化的光谱证据。推导的伽马射线跃迁速率将与基于微观导出的能量密度泛函的解析集体模型的预测进行比较，这些泛函能够描述在N=60同位素附近观察到的球状到形变的形变相变和形状共存现象。需要测量的候选原子核是奇偶101Mo核、奇偶103Tc核和奇奇102Tc核。最近还获得了关于奇偶99Y核和N=59奇奇98Y和100Nb同位素的其他实验数据，需要进行分析。要测量的丰中子候选者是在热中子诱发的裂变中很好地产生的，例如235U。这些实验将在法国格勒诺布尔劳厄-朗之万研究所(ILL)的“罗亨格林”裂变碎片分离器上进行。IKP将与该研究所和其他国际科学家合作，组织3-4次快速计时运动。IKP Köln高性能LaBr3(Ce)探测器将用于通过伽马-伽马或贝塔-伽马时间差测量，利用低能伽马射线进行皮秒灵敏寿命测定。实验的安装、校准和监督将由IKP快速计时小组完成。实验数据将在高速IKP服务器上使用专门兼容病态数据格式的软件进行分析，并针对快速时序分析进行优化。得到的新的和改进的寿命结果将用于计算B(E_2)和B(M_1)跃迁率，用于集体研究或用作输入参数进行更唯象的核结构计算。在相互作用玻色子-费米子(-费米子)模型框架内的新计算将由理论核结构物理学家执行，我们已经成功地与他们合作了多年。我们的主要目标是更好地了解100Zr附近原子核的形状转变和形状共存随质子数和中子数(轨道)的变化，并发表结果和理论解释。

The proposal aims to provide new and improved spectroscopic information on odd-A and odd-odd nuclei in the vicinity of 100Zr mainly by lifetime measurements of low-energy excited states using fast-timing techniques. The goal is to obtain more spectroscopic evidences for the evolution of the neutron and proton single-particle orbitals in this particular mass region. The deduced gamma-ray transition rates will be compared with predictions using analytic collective models based on microscopically derived energy-density functionals which are able to describe the spherical-to-deformed shape transition and shape-coexistence phenomena observed in the vicinity of N = 60 isotones close to 100Zr. The candidates of interest to be measured are the even-odd 101Mo, the odd-even 103Tc and the odd-odd 102Tc nuclei. Other experimental data on the odd-even 99Y nucleus and the N = 59 odd-odd 98Y and 100Nb isotones have recently been acquired and requires to be analyzed. The neutron-rich candidates to be measured are well produced in thermal-neutron induced fission of, e.g. 235U. The experiments will be performed at the “Lohengrin” fission-fragment separator of the Institut Laue-Langevin (ILL) in Grenoble, France. In collaboration with the ILL and other international scientists, 3-4 fast-timing campaigns will be organized by the IKP. The IKP Köln high-performance LaBr3(Ce) detectors will be used for picosecond-sensitive lifetime determination with low-energy gamma rays via gamma-gamma or beta-gamma time-difference measurements. Installation, calibration and surveillance of the experiment will be done by the IKP fast-timing group. The experimental data will be analyzed on the high-speed IKP server using software specially compatible to the ILL data format and optimized for fast-timing analyzes. The new and improved lifetime results obtained will be used to calculate B(E2) and B(M1) transition rates for investigation on collectivity or for being used as input parameters to perform more phenomenological nuclear structure calculations. The new calculations within the framework of the Interacting-Boson-Fermion (-Fermion) model will be performed by theoretical nuclear structure physicists with whom we are successfully collaborating for many years. Our major objective is to obtain an improved insight on the evolution of shape transition and shape coexistence in nuclei close to 100Zr as a function of the proton and neutron number (orbitals) and to publish results and theoretical interpretations.