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，但我们对核物理的大部分理解都是基于稳定(和近稳定)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。Mayer，Haxel，Suess和Jenssen的自旋-轨道相互作用的引入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，并表明众所周知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共同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领域是至关重要的。为了了解奇异核的结构，重要的是测量远离稳定性的核的性质，在粒子垂线附近和在粒子垂线上。滴线划定了原子核的存在范围。中子滴线距离稳定性有20或30个质量单位，而且还远远不能在实验上达到。相反，质子滴线更接近稳定，使用最先进的实验技术，现在可以在实验中研究质子滴线上的原子核。质子滴线上的原子核结构将被用来测试我们的原子核及其成分的行为模型，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域中一个非常富含质子的原子核-La117。由于最外层的中子和质子占据着非常相似的轨道，这一区域的原子核是理想的研究对象，因为它们有望具有新的结构现象。利用这一区域的反冲衰变标记技术，有可能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，以便在质子滴线上研究系统效应。我们的目标是通过利用伽马能谱识别La117的低激发态来研究其结构。此外，我们还将进一步研究La117的质子衰变性质；虽然这种衰变模式已经被研究过，但质子衰减态的组态仍然不清楚。芬兰Jyveskyla加速器实验室方案咨询小组批准了使用Jurogam伽马射线光谱仪和Ritu反冲质谱仪研究La117的实验。在这里，我们要求提供开展试验的旅费和生活费。

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 behaviour 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 outermost 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.