Nuclear Structure and Reactions: Theory and Experiment

核物理研究正在经历一场变革。一百年来，原子核一直是通过稳定光束和稳定目标之间的碰撞来探测的，只有少量的放射性同位素可用。现在，在过去20年稳步发展的基础上，终于有可能产生各种短寿命同位素的强光束，即所谓的“放射性光束”。这使我们能够极大地扩大实验核研究的范围。例如，现在计划在实验室里研究发生在爆炸恒星中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在国际领先的放射性束流设施中的积极参与。虽然我们现在正在或计划对这些设施的重大技术发展作出贡献，但目前的赠款请求的重点是利用现在可用的能力。实验进展与理论密切相关，其中新颖和实用的方法是萨里小组的标志。一个突出的特点是我们强大的理论和实验能力的结合，这是我们小组研究计划的关键，在英国是独一无二的。我们的科学目标与核物理咨询小组详细阐述的当前STFC核物理战略保持一致。我们希望了解核存在的界限，即使中子和质子结合在一起形成原子核的极限条件。在这种情况下，核系统处于微妙状态，并出现异常现象。它对核力的性质非常敏感。例如，弱束缚的中子可以绕母核运行很远的距离。这是已知的，我们的团队对这一知识做出了关键贡献。目前尚不清楚的是，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，同样未知的是给定数量的质子能结合多少中子。正是这些特征决定了恒星如何爆炸。为了解决这些问题，我们需要对核力有更复杂的理解，我们需要关于中子和质子不寻常组合的原子核的实验信息，以检验我们的理论思想和模型。因此，当我们向核极限推进时，理论和实验是齐头并进的。对核结合的概述表明，预测的原子核中约有一半从未被观察到，而这一未知领域的绝大多数涉及中子过剩的原子核。我们的大部分活动都是针对这个“中子丰富”的领域，利用放射性光束的新能力。我们的主要动机是基础科学，我们为世界知识和理解的总和做出了巨大贡献。然而，还有更切实的好处。例如，我们的辐射探测器的进步可以被纳入医疗诊断和治疗。此外，我们为我们的研究生和工作人员提供了一个良好的培训环境，其中许多人继续在核电行业工作，帮助填补目前的技能空白。更大胆地说，我们对核异构体（能量陷阱）的特殊兴趣可能会导致新的能源应用。此外，我们对与广大受众分享我们的专业知识有着浓厚的兴趣，我们在媒体方面已经有了令人羡慕的记录。

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 international radioactive-beam facilities. 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.Experimental progress is intimately linked with theory, where novel and practical approaches are a hallmark of the Surrey group. An outstanding feature, which is key to our group's research plans and is unique in the UK, is our powerful 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. To tackle these problems, 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. Much 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.