Birmingham Nuclear Physics Consolidated Grant 2016

我们建议的研究有三个广泛的主题，建立在我们世界领先的专业领域。第一个项目是在世界上能量最高的粒子加速器——大型强子对撞机上研究高能核碰撞。ALICE实验的目的是研究核物质，因为它在大爆炸后大约百万分之一秒存在，当时宇宙非常热，密度非常大，原子核不存在。在原始状态下，核物质由处于等离子态的基本成分（夸克和胶子）组成。我们在实验中重建了这种物质的新状态，我们正在开发研究这些高能核碰撞的方法，以发现夸克-胶子等离子体的特性。这在技术上具有挑战性，研究小组开发了一种复杂的电子触发系统来控制实验。夸克-胶子等离子体具有显著的特性，比如大量的奇异夸克和近乎完美的流动性。在这个提议中，我们试图通过寻找仍然保留这些特性的最小的等离子体滴来确定尺寸是否重要。我们利用掠射碰撞来探索高能核的内部结构。我们正在观察夸克和胶子的碎片，它们有时会从碰撞中散射出来，在我们的探测器中产生一束粒子，也就是所谓的喷流，以研究等离子体内部的情况。我们还在研发基于硅像素探测器的新型探测器技术，其中读出电子元件包含在像素内。第二条线超出了夸克尺度延伸到原子核尺度。这里的挑战是理解强相互作用的本质是如何在核而不是亚核子尺度上发挥作用的。在这里，强作用力是高度复杂的，这在相关性中表现出来。这些可以是配对关联或更高阶的关联，从而导致α粒子簇的形成。团簇的几何排列产生了动态对称性，这反过来又给出了量子力学状态的指纹。伯明翰小组的工作表明，12C中存在三角形排列的α粒子。我们建议将这些技术和想法扩展到预计会受到四面体结构强烈影响的16O的研究中。当粒子从团核中加入或移除时，α粒子团簇发生的变化是极其重要的，因为这与滴线处的核结构密切相关。我们将研究一些系统，这些系统将提供对核分子等现象的更深入的了解。最后，我们计划开发一个实验程序，利用伽马射线束通过其电磁特性来高精度地探测聚簇核的结构。到目前为止，这个工具已经为我们提供了一些关于轻核结构的最佳见解，我们计划将这些研究扩展到团簇衰变阈值以上的奇异团簇状态。这个项目将产生测量来约束最先进的理论。这项拨款也认识到通过各种应用应用核物理知识的重要性。在同时使用核裂变和核聚变的能源生产领域，需要对各种核反应进行更精确的测量。我们计划使用伯明翰大学的MC40回旋加速器进行核数据研究。此外，回旋加速器可以用来创造一个高辐射环境，模仿反应堆或退役环境。我们将开发一个设备，用于测试在这种环境中使用的仪器和检测系统。

Our proposed research has three broad themes that build upon our world leading areas of expertise. The first of these involves the study of high-energy nuclear collisions at the Large Hadron Collider, the world's highest energy particle accelerator. The aim of the ALICE experiment is to study nuclear matter, as it would have existed about a millionth of a second after the Big Bang when the Universe was so hot and so dense that nuclei did not exist. In its primordial state nuclear matter consists of its fundamental constituents (quarks and gluons) in a plasma state. We recreate this novel state of matter in our experiment and we are developing ways of studying these high-energy nuclear collisions to discover the properties of the quark-gluon plasma. This is technically challenging and the group has developed a sophisticated electronic trigger system that controls the experiment. The quark-gluon plasma has remarkable properties, such as an abundance of strange quarks and near-perfect fluidity. In this proposal, we are trying to determine whether size matters by finding the smallest drop of plasma that still retains these properties. We are using grazing collisions to explore the internal structure of nuclei at high energy. And we are looking at the debris of quarks and gluons that are sometimes scattered out of the collision, producing a shower of particles in our detector known as a jet, to study the conditions inside the plasma. We are also performing R&D into new detector technologies based on silicon pixel detectors in which the readout electronics is contained within the pixel. The second strand extends beyond the quark scale to the scale of nuclei. Here the challenge is to understand how the nature of the strong interaction plays out on the nuclear, rather than the sub-nucleon scale. Here the strong force is highly complex, which is manifest in correlations. These can be pairing correlations or correlations of higher order, which results in the formation of alpha-particle clusters. The geometric arrangement of clusters produces dynamical symmetries, which in turn gives a fingerprint of quantum mechanical states. The work performed by the Birmingham group has indicated the presence of a triangular arrangement of alpha particles in 12C. We propose to extend the techniques and ideas to a study of 16O that is predicted to be strongly influenced by a tetrahedral structure. What happens to alpha-particle clustering as particles are either added or removed from the cluster cores is extremely important as this is intimately connected with the structure of nuclei at the drip-lines. We will be studying a number of systems that will provide a deeper insight into phenomena such as nuclear molecules. Finally, we plan to develop an experimental programme to exploit gamma-ray beams to probe with great precision the structure of clustered nuclei via their electromagnetic properties. To-date this tool has provided us with some of the best insights into the structure of light nuclei and we plan to extend these studies to exotic cluster states above the cluster decay threshold. This programme will produce measurements to constrain state-of-the-art theory.This grant also recognises the importance of applying nuclear physics knowledge through a variety of applications. In the field of energy production using both nuclear fission and fusion there is a need for more precise measurements of a variety of nuclear reactions. We plan to use the University of Birmingham's MC40 cyclotron for nuclear data studies. Moreover, the cyclotron may be used to create a high radiation environment that mimics either reactor or decommissioning environments. We will develop a facility that will be used to test instrumentation and detection systems for use in such environments.