Identification of excited states in the deformed proton emitter La117 (travel and subsistence)

变形质子发射器 La117 中激发态的识别（旅行和生存）

• 批准号: ST/H003460/1
• 负责人: Edward Paul
• 金额: $ 0.51万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FH003460%2F1
• 关键词: Identification; excited; states; deformed; proton

Only about 300 of the predicted 7000 atomic nuclei are stable, yet most of our understanding of nuclear physics is based on the measured properties of the stable (and near-stable) nuclei. For example, the arrangement of nucleons in specific shells, in a manner analogous to electrons in atomic structure, is one of the concepts at the heart of nuclear structure physics. The introduction of the spin-orbit interaction by Mayer, Haxel, Suess, and Jenssen was able to explain the existence of shell gaps and magic numbers in nuclei. Recent observations, however, have challenged the accepted shell structure, and have suggested that the well-known sequence of single-particle states does not persist in exotic nuclei which lie far from the line of beta stability. Instead, shifts in the sequence of single-particle levels conspire to cause different shell gaps, producing new and unexpected phenomena. The reasons for these alterations are presently of paramount importance in the field of nuclear-structure physics. In order to understand the structure of exotic nuclei, it is important to measure the properties of nuclei far from stability, near and at the particle driplines. The driplines delimit the existence of nuclei. The neutron dripline lies 20 or 30 mass units away from stability, and is still far from being experimentally accessible. Conversely, the proton dripline lies closer to stability and, using state-of-the art experimental techniques, it is now possible to study nuclei at the proton dripline in experiments. The structure of the nuclei at the proton dripline will be used to test our models of the bahaviour of nucleus and its constituents, and to search for new phenomena caused by a severe excess of protons. Specifically the research proposed here will study a very proton-rich nucleus in the rare-earth region - La117. Nuclei in this region present ideal candidates to be studied because they are expected to possess novel structural phenomena, owing to the occupation of very similar orbitals by the the most energetic neutrons and protons. With the technique of recoil-decay tagging in this region, it is possible to study the exotic proton-rich rare-earth nuclei over a whole range of isotopes, not just in individual cases, so that systematic effects will be studied at the proton dripline. Our objective is to study the structure of La117 by identifying its low-lying excited states using gamma-ray spectroscopy. In addition, we will further investigate the proton-decay properties of La117; although this decay mode has been studied previously, the configuration of the proton-decaying state is still unclear. The experiment to study La117 has been approved by the Programme Advisory Panel at Jyvaskyla Accelerator Laboratory in Finland using the Jurogam gamma-ray spectrometer and the RITU recoil-mass spectrometer. Here, we request funds for travel and subsistence to carry out the experiment.

在预测的7000个原子核中，只有大约300个是稳定的，然而我们对核物理的大多数理解都是基于稳定（和近稳定）核的测量性质。例如，核子在特定壳层中的排列方式，类似于原子结构中的电子，是核结构物理学的核心概念之一。迈耶、赫尔斯、苏斯和詹森引入的自旋轨道相互作用能够解释核中壳层能隙和幻数的存在。然而，最近的观测结果对公认的壳层结构提出了挑战，并表明著名的单粒子态序列在远离β稳定线的奇异核中并不存在。相反，单粒子能级序列的变化会导致不同的壳层间隙，产生新的和意想不到的现象。这些变化的原因目前在核结构物理学领域具有极其重要的意义。为了了解奇异核的结构，测量远离稳定核、粒子滴线附近和滴线处的性质是非常重要的。滴线界定了原子核的存在。中子滴注线距离稳定状态还有20或30个质量单位，而且离实验上可达到的距离还很远。相反，质子滴注线更接近稳定，并且使用最先进的实验技术，现在可以在实验中研究质子滴注线上的原子核。质子滴注线上的原子核结构将被用来检验我们的原子核及其组分的平衡模型，并寻找由质子严重过剩引起的新现象。具体来说，这里提出的研究将研究稀土区域的一个非常富含质子的核-La 117。这一区域的原子核是理想的研究对象，因为它们被认为具有新的结构现象，因为能量最高的中子和质子占据了非常相似的轨道。在该区域使用反冲衰变标记技术，可以研究整个同位素范围内的奇异富质子稀土核，而不仅仅是个别情况，因此可以在质子滴注线上研究系统效应。我们的目标是研究La 117的结构，通过确定其低激发态使用γ射线光谱。此外，我们将进一步研究La 117的质子衰变性质，虽然这种衰变模式以前已经研究过，但质子衰变态的构型仍然不清楚。芬兰伊瓦斯基拉加速器实验室的方案咨询小组已核准利用Jurogam伽马射线光谱仪和RITU反冲质谱仪进行研究La 117的实验。在此，我们请求提供进行试验所需的旅费和生活费。