Nuclear Structure and Reactions: Theory and Experiment

核结构和反应：理论与实验

基本信息

批准号：
ST/J000051/1
负责人：
Philip Malzard Walker
金额：
$ 279.6万
依托单位：
University of Surrey
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%2FJ000051%2F1
关键词：
Nuclear Structure Reactions Theory Experiment

项目摘要

Nuclear physics research is undergoing a transformation. For a hundred years, atomic nuclei have been probed by collisions between stable beams and stable targets, with just a small number of radioactive isotopes being available. Now, building on steady progress over the past 20 years, it is at last becoming possible to generate intense beams of a wide range of short-lived isotopes, so-called 'radioactive beams'. This enables us vastly to expand the scope of experimental nuclear research. For example, it is now realistic to plan to study in the laboratory a range of nuclear reactions that take place in exploding stars. Thereby, we will be able to understand how the chemical elements that we find on Earth were formed and distributed through the Universe. At the core of our experimental research is our strong participation at leading European radioactive-beam facilities: FAIR at GSI, Darmstadt, Germany; SPIRAL at GANIL, Caen, France; and ISOLDE at CERN, Geneva, Switzerland. While we are now contributing, or planning to contribute, to substantial technical developments at these facilities, the present grant request is focused on the exploitation of the capabilities that are now becoming available. To achieve our physics objectives, we also need to use other facilities, including stable-isotope accelerators, since these can provide complementary capabilities. Experimental progress is intimately linked with theory, where novel and practical approaches are a hallmark of the Surrey group. A key and unique feature (within the UK) of our group is our blend of theoretical and experimental capability. Our science goals are aligned with current STFC strategy for nuclear physics, as expressed in detail through the Nuclear Physics Advisory Panel. We wish to understand the boundaries of nuclear existence, i.e. the limiting conditions that enable neutrons and protons to bind together to form nuclei. Under such conditions, the nuclear system is in a delicate state and shows unusual phenomena. It is very sensitive to the properties of the nuclear force. For example, weakly bound neutrons can orbit their parent nucleus at remarkably large distances. This is already known, and our group made key contributions to this knowledge. What is unknown is whether, and to what extent, the neutrons and protons can show different collective behaviours. Also unknown, for most elements, is how many neutrons can bind to a given number of protons. It is features such as these that determine how stars explode. So, we need a more sophisticated understanding of the nuclear force, and we need experimental information about nuclei with unusual combinations of neutrons and protons to test our theoretical ideas and models. Therefore, theory and experiment go hand-in-hand as we push forward towards the nuclear limits. An overview of nuclear binding reveals that about one half of predicted nuclei have never been observed, and the vast majority of this unknown territory involves nuclei with an excess of neutrons. The focus of our activity addresses this 'neutron-rich' territory, exploiting the new capabilities with radioactive beams. Our principal motivation is the basic science, and we contribute strongly to the world sum of knowledge and understanding. Nevertheless, there are more-tangible benefits. For example, our radiation-detector advances can be incorporated in medical diagnosis and treatment. In addition, we provide an excellent training environment for our research students and staff, many of whom go on to work in the nuclear power industry, helping to fill the current skills gap. On a more adventurous note, our special interest in nuclear isomers (energy traps) could lead to novel energy applications. Furthermore, we have a keen interest in sharing our specialist knowledge with a wide audience, and we already have an enviable track record with the media.

核物理研究正在经历一场变革。一百年来，人们一直通过稳定束流与稳定目标之间的碰撞来探测原子核，而只能得到少量的放射性同位素。现在，在过去 20 年稳步进展的基础上，产生各种短寿命同位素的强束流（即所谓的“放射性束”）终于成为可能。这使我们能够极大地扩大实验核研究的范围。例如，现在计划在实验室研究爆炸恒星中发生的一系列核反应是现实的。因此，我们将能够了解我们在地球上发现的化学元素是如何形成并在宇宙中分布的。我们实验研究的核心是我们对欧洲领先放射性束设施的大力参与：德国达姆施塔特 GSI 的 FAIR；法国卡昂 GANIL 的 SPIRAL；以及瑞士日内瓦欧洲核子研究中心的 ISOLDE。虽然我们现在正在或计划为这些设施的实质性技术发展做出贡献，但目前的赠款请求侧重于利用现有的能力。为了实现我们的物理目标，我们还需要使用其他设施，包括稳定同位素加速器，因为它们可以提供互补的能力。实验进展与理论密切相关，新颖且实用的方法是萨里小组的标志。我们小组的一个关键且独特的特点（在英国）是我们的理论和实验能力的结合。我们的科学目标与当前 STFC 的核物理战略一致，正如核物理咨询小组详细阐述的那样。我们希望了解核存在的边界，即使中子和质子结合在一起形成原子核的限制条件。在这样的条件下，核系统处于脆弱的状态，并表现出不寻常的现象。它对核力的特性非常敏感。例如，弱束缚中子可以在非常远的距离上绕其母核运行。这是众所周知的，我们的团队对此知识做出了关键贡献。未知的是中子和质子是否以及在多大程度上可以表现出不同的集体行为。对于大多数元素来说，还未知的是有多少中子可以与给定数量的质子结合。正是这些特征决定了恒星如何爆炸。因此，我们需要对核力有更深入的了解，我们需要有关具有不寻常的中子和质子组合的原子核的实验信息来测试我们的理论思想和模型。因此，当我们向核极限迈进时，理论和实验是齐头并进的。对核结合的概述表明，大约一半的预测原子核从未被观察到，而这一未知领域的绝大多数涉及具有过量中子的原子核。我们活动的重点是解决这个“富含中子”的领域，利用放射性束的新功能。我们的主要动机是基础科学，我们为世界知识和理解做出了巨大贡献。尽管如此，还有更明显的好处。例如，我们的辐射探测器进步可以融入医疗诊断和治疗中。此外，我们还为研究生和员工提供优良的培训环境，其中许多人继续在核电行业工作，帮助填补当前的技能缺口。更具冒险精神的是，我们对核异构体（能量陷阱）的特殊兴趣可能会带来新的能源应用。此外，我们非常有兴趣与广大受众分享我们的专业知识，并且我们已经在媒体方面拥有令人羡慕的记录。