Nuclear Structure & Reactions: Theory & Experiment

一百年来，对原子核的探测或多或少都是通过研究稳定光束与稳定目标之间的碰撞来实现的。这就限制了可以被研究的原子核只占那些被认为存在的原子核的一小部分。大多数对制造所有元素（在各种恒星过程中）很重要的原子核都无法进行实验。世界范围内核物理学的主要推动力，以及英国计划的一个关键优先事项，是通过使用由短寿命放射性同位素产生的光束来接触和研究这些奇异的原子核。这反过来又揭示了原子核的结构并不总是像稳定原子核看起来的那样，原子核的稳定性和不同的形状会影响恒星和超新星内部的反应速率。在萨里/布莱顿，我们非常重视这些英国的优先事项和新的机会，我们在世界上最好的设施中寻找并领导项目，以制造这些放射性光束。制造这些光束很困难，而且这些设施——以及研究工作——都是国际规模的。萨里/布莱顿在这些设施中建造和运行创新的实验设备。目前的拨款请求侧重于在最好的实验室开发这些能力。实验进展与理论密切相关，开发新颖、更好的理论方法是萨里小组的标志。整个小组的一个突出特点是我们强大的理论和实验能力，这是我们研究计划的关键，被认为是一种罕见而宝贵的力量。我们的科学目标与核物理咨询小组路线图中详细阐述的当前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。目前尚不清楚中子和质子是否以及在多大程度上能表现出不同的集体行为，甚至不知道有多少中子能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。为了解决这些问题，我们需要对核力有更复杂的理解，我们需要更强大的理论来将这种理解建立在计算中，我们需要关于中子相对于质子数量异常的原子核的实验信息，这样我们才能检验我们的理论观点。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，利用放射性光束带来的新能力，利用计算能力和分析理论的进步，为最新的观测带来优越的新理论工具。我们的主要动机是基础科学和STFC的“大问题”，我们为世界知识和理解的总和做出了巨大贡献。辐射探测器的进步，使我们的工作驱动，可以纳入医疗诊断和治疗，并在环境管理。我们与国家物理实验室在这些主题上进行了密切合作。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。此外，我们有兴趣与广大读者分享我们的专业知识，并积极推行公众参与议程。

For a hundred years, atomic nuclei have been probed more or less exclusively by studying collisions between stable beams and stable targets. This restricted the nuclei that could be studied to just a just a small fraction of those that are thought to exist. Most of the nuclei important to making all of the elements (in various stellar processes) have been inaccessible to experiment. The major thrust in nuclear physics worldwide, and a key priority in the UK's programme, is to reach out and study these exotic nuclei by using beams produced from short-lived radioactive isotopes. This in turn reveals that nuclear structure is not always like it seems to be for the stable nuclei, and nuclei are found to have surprising trends in stability and to have different shapes that will affect reaction rates inside stars and supernovae. At Surrey/Brighton we take these UK priorities and the new opportunities very much to heart, and we seek out and lead programmes at the world's best facilities for making these radioactive beams. To make the beams is difficult and the facilities - as well as the research effort - are international in scale. Surrey/Brighton builds and runs innovative experimental equipment at these facilities. The present grant request is focused on the exploitation of these capabilities at the best laboratories.Experimental progress is intimately linked with theory, and the development of novel and better theoretical approaches are a hallmark of the Surrey group. An outstanding feature of the group as a whole, which is key to our research plans and acknowledged as a rare and valuable strength, 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's road map. 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. It is unknown whether, and to what extent, the neutrons and protons can show different collective behaviour or even 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, we need more powerful theories that can build this understanding into the calculations, and we need experimental information about nuclei with unusual numbers of neutrons relative to protons so that we can test our theoretical ideas. 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 made possible with radioactive beams and exploiting advances in computational power and analytical theories to bring superior new theoretical tools to bear on the latest observations.Our principal motivation is the basic science and the STFC "big questions", and we contribute strongly to the world sum of knowledge and understanding. The radiation-detector advances that our work drives can be incorporated in medical diagnosis and treatment and in environmental management. We engage strongly with the National Physical Laboratory on these topics. 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. Furthermore, we have a keen interest in sharing our specialist knowledge with a wide audience, and actively pursue a public engagement agenda.