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Birmingham Nuclear Physics Consolidated Grant

伯明翰核物理综合拨款

基本信息

批准号：
ST/J000140/1
负责人：
Martin Freer
金额：
$ 215.31万
依托单位：
University of Birmingham
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FJ000140%2F1
关键词：
Birmingham Nuclear Physics Consolidated Grant

项目摘要

The project is an exploration of the nature of strongly interacting matter. The research will probe the nature of matter at extreme temperature and density where the nucleons inside a nucleus loose their individual identity and dissolve into their constituents of quarks and gluons - the state of matter which it is believed existed an instant after the Big Bang. Using the ALICE experiment at CERN (in which the Birmingham group have played a leading role building the trigger electronics), and collisions between Lead nuclei, the nature of this state of strongly interacting matter will be characterised in detail for the first time. The study of this exotic state of matter, known as a quark-gluon plasma, will help physicists understand more about the nature of the strong force and the evolution of the very early Universe. Nucleons in nuclei are bound via the strong interaction. On the nuclear scale, the interaction is complex and has yet to be fully characterised. Nevertheless, despite the complexity rather simple patterns emerge, such as shell structure and magic numbers or geometric arrangements of nucleons as clusters within nuclei. Due to the very high stability of the alpha-particle it is most often alpha-clusters that precipitate within the nucleus. The role of clusterisation in nuclei is central to understanding the structure of light-nuclei. For example, the famous Hoyle-state in 12C, through which carbon is synthesised in stars, has a structure which is composed of three alpha-particle. The characterisation of such systems forms a key element of the programme. As one adds more and more neutrons to a nucleus the limit of stability is reached where the last neutron no-longer 'sticks' to the nucleus, a point called the neutron drip-line. Studying nuclei close to this limit provides a unique test of our understanding of the nature of the strong interaction. One rather interesting possibility is that nuclei at the drip-line will have a rather exotic structure and behave as clusters embedded in a sea of neutrons. Part of the current programme will study how clusterisation changes as the drip-line approaches. One of the most precise tests of the structure of nuclei comes from an indirect technique. The energy levels of the electrons in an atom are largely determined by the properties of the nucleus; its overall charge, the nuclear shape and radius, the charge distribution and the magnetic moment of the nucleus. Hence, rather fundamental properties of a nucleus may be determined through an interrogation of the electronic energy levels using laser techniques. The Birmingham group has nearly 20 years accumulated experience in using laser-spectroscopy techniques to determine nuclear properties with high precision. The current work will focus on the cerium isotopes which lie at the edge of a region of shape transition due to the weakening of the Z=64 proton sub shell. To measure these isotopes new transitions using a metastable state populated by optical pumping will be needed as well as a more efficient light collection region.

该项目是对强相互作用物质本质的探索。这项研究将探索物质在极端温度和密度下的性质，其中核内的核子失去了它们的个体身份，并溶解成夸克和胶子的成分-物质的状态被认为是大爆炸后瞬间存在的。使用欧洲核子研究中心的ALICE实验（伯明翰小组在其中发挥了主导作用，建立了触发电子学），以及铅核之间的碰撞，这种强相互作用物质状态的性质将首次被详细描述。对这种奇特的物质状态的研究，被称为夸克胶子等离子体，将有助于物理学家更多地了解强作用力的性质和早期宇宙的演化。原子核中的核子是通过强相互作用束缚在一起的。在核尺度上，相互作用是复杂的，尚未完全确定。然而，尽管复杂，但出现了相当简单的模式，如壳结构和幻数或核子的几何排列作为原子核内的簇。由于α粒子非常高的稳定性，最常见的是α团簇在核内沉淀。原子核团簇化的作用是理解轻原子核结构的核心。例如，12 C中著名的霍伊尔态，通过它在恒星中合成碳，具有由三个α粒子组成的结构。这种系统的特点构成了该方案的一个关键要素。当一个原子核中加入越来越多的中子时，最后一个中子不再“粘”在原子核上，这一点被称为中子滴线。研究接近这一极限的原子核为我们理解强相互作用的本质提供了一个独特的测试。一个相当有趣的可能性是，在滴线处的原子核将具有相当奇特的结构，并表现为嵌入中子海洋中的原子团。目前的计划的一部分将研究如何集群变化的滴水线的方法。对原子核结构的最精确的测试之一来自一种间接技术。原子中电子的能级在很大程度上取决于原子核的性质;它的总电荷，原子核的形状和半径，电荷分布和原子核的磁矩。因此，原子核的相当基本的性质可以通过使用激光技术询问电子能级来确定。伯明翰小组在使用激光光谱技术以高精度确定核特性方面积累了近20年的经验。目前的工作将集中在铈同位素的形状转变，由于Z=64质子子壳层的弱化区域的边缘。为了测量这些同位素，将需要使用由光泵浦填充的亚稳态的新跃迁以及更有效的光收集区域。