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

该提案旨在通过使用快速定时技术测量低能激发态的寿命，提供100Zr附近奇a和奇奇核的新的和改进的光谱信息。目的是为中子和质子单粒子轨道在这一特定质量区域的演化获得更多的光谱证据。推导出的伽玛射线跃迁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结果进行比较，后者能够描述在接近100Zr的N = 60等音附近观察到的球体到变形的形状跃迁和形状共存现象。有兴趣测量的候选原子核是奇偶101Mo原子核、奇偶103Tc原子核和奇偶102Tc原子核。其他关于奇偶99Y核和N = 59奇偶98Y和100Nb同工同位素的实验数据最近已经获得，需要进行分析。要测量的富中子候选物质可以在热中子诱导的裂变中很好地产生，例如235U。实验将在法国格勒诺布尔的劳-朗格万研究所（ILL）的“Lohengrin”裂变碎片分离器上进行。IKP将与国际物理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）探测器将通过γ - γ或β - γ时差测量，用于皮秒级灵敏度的低能量伽马射线寿命测定。实验的安装、校准和监督将由IKP快速计时组完成。实验数据将在高速IKP服务器上分析，使用专门兼容ILL数据格式的软件，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（E2）和B（M1）跃迁率，用于集体研究或用作输入参数，以执行更多的现象学核结构计算。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与我们成功合作多年的理论核结构物理学家进行。我们的主要目标是对接近100Zr的原子核的形状跃迁和形状共存的演化作为质子和中子数（轨道）的函数有一个更好的认识，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.