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

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部分理解是基于稳定（和接近稳定）原子核的测量性质。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。梅尔、哈克塞尔、苏斯和詹森引入的自旋轨道相互作用能够解释原子核中壳层间隙和幻数的存在。然而，最近的观察对公认的壳结构提出了挑战，并提出，在远离稳定线的奇异原子核中，众所周知的单粒子态序列并不存在。相反，单粒子能级序列的变化共同导致不同的壳隙，产生新的和意想不到的现象。这些变化的原因是目前在核结构物理领域最重要的。为了了解奇异核的结构，对原子核在远离稳定线、近粒子线和近粒子线处的性质进行测量是非常重要的。这些条纹划定了原子核的存在。中子滴线距离稳定状态有20到30个质量单位的距离，而且还远远不能在实验上得到。相反，质子滴线更接近稳定，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线下的原子核。质子滴线处的原子核结构将被用来检验我们的原子核及其组成部分的行为模型，并寻找由质子严重过剩引起的新现象。具体地说，这里提出的研究将研究稀土区的一个质子非常丰富的原子核- La117。这个区域的原子核是理想的研究候选者，因为它们被期望具有新颖的结构现象，因为最有能量的中子和质子占据了非常相似的轨道。利用该区域的反冲衰变标记技术，可以在整个同位素范围内研究富含质子的奇异稀土核，而不仅仅是在个别情况下，从而在质子滴线上研究系统效应。我们的目的是通过伽玛射线光谱识别La117的低洼激发态来研究它的结构。此外，我们将进一步研究La117的质子衰变性质；虽然这种衰变模式以前已经被研究过，但质子衰变态的构型仍然不清楚。研究La117的实验已得到芬兰Jyvaskyla加速器实验室方案咨询小组的批准，该小组使用Jurogam伽玛射线光谱仪和RITU反冲质谱仪。在此，我们要求提供进行实验的旅费和生活费。

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.