Nuclear Physics Consolidated Grant 2020

宇宙的大部分可见质量是由位于原子中心的原子核组成的。核物理学试图回答一些基本问题，例如：“当被推向极端时，物理定律是如何工作的？宇宙的基本成分和结构是什么？它们是如何相互作用的？宇宙是如何开始的？它是如何演化的？核物质和强子物质的性质是什么？”我们研究的目的是研究和测量原子核和热核物质的性质，以回答这些问题。对于远离稳定的奇异核系统，我们将探索原子核如何倾向于重新排列其形状，可以是球体、橄榄球等，以及它如何在可能的自由度中存储能量。我们将研究极少数情况下原子核可以呈梨形的性质，这可能是理解宇宙为什么有物质-反物质不平衡的关键。我们将探索质子和中子滴线区域，这是束缚核和非束缚核之间的边界，与理解原子核是如何在恒星中合成有关的。质子滴线以外的原子核具有如此多的电荷，因此它们非常不稳定，并试图通过质子发射过程获得更大的稳定性。我们将研究这一过程如何受到原子核的形状和结构的影响，并使用激光对这些基本性质进行精确测量。目前还没有人知道到底有多少中子和质子可以结合在一起。我们将研究可以在实验室中制造的最重的原子核，并确定它们的性质，这将使我们能够对“超重”做出更好的预测。我们还将研究原子核的性质是如何发展的，因为我们让它们自转得越来越快，确定重原子核中超高自旋态的确切性质，就在原子核因裂变而分裂之前。核物质可以以不同的相存在，类似于普通物质中的固、液、气和等离子体相。通过改变温度、密度或压力，核物质可以经历从一个相到另一个相的转变。在密度和温度的极端条件下(大约是太阳中心温度的10万倍)，应该会发生相变，夸克和胶子(构成质子和中子的物质)应该以一种新的物质状态存在，称为夸克-胶子等离子体。通过在欧洲核子研究中心的大型强子对撞机上以高能碰撞原子核，我们将研究这种新的物质状态的性质。这些信息不仅对核物理很重要，而且对理解中子星和其他致密天体也很重要。这一研究方案将采用各种各样的实验方法来探索核结构的许多方面和强相互作用物质的相，主要使用我们在几个世界领先的加速器实验室建造的仪器。这项工作将需要在一系列设施中进行一系列相关实验，以便我们深入了解上述问题的答案。这些实验将帮助理论家改进和测试他们的计算，这些计算试图预测原子核和核物质的性质，但结果往往大相径庭。这个问题的解决将有助于我们描述复杂的多体核系统，并更好地理解大爆炸后几分之一秒内我们宇宙中的情况。

The majority of visible mass of the universe is made up of atomic nuclei that lie at the centre of atoms. Nuclear physics seeks to answer fundamental questions such as: "How do the laws of physics work when driven to the extremes? What are the fundamental constituents and fabric of the universe and how do they interact? How did the universe begin and how is it evolving? What is the nature of nuclear and hadronic matter?" The aim of our research is to study and measure the properties of atomic nuclei and hot nuclear matter in order to answer these questions. For exotic nuclear systems lying far from stability we will explore how the nucleus prefers to rearrange its shape, which can be a sphere, rugby ball, etc. and how it stores its energy among the possible degrees of freedom. We will study the properties of the very few cases where nuclei can assume the shape of a pear, that may be key in understanding why the universe has a matter-antimatter imbalance. We will explore in the region of the proton and neutron drip lines, which are the borders between bound and unbound nuclei and are relevant to understanding how atomic nuclei are synthesised in stars. Nuclei beyond the proton drip line have so much electrical charge that they are highly unstable and try to achieve greater stability through the process of proton emission. We will investigate how this process is affected by the nucleus' shape and structure, and make precision measurements of these fundamental properties using lasers. No one yet knows just how many neutrons and protons can be made to bind together. We will study the heaviest nuclei that can be made in the laboratory and determine their properties which will allow better predictions to be made for the "superheavies". We will also investigate how the properties of nuclei develop as we make them spin faster and faster, determining the precise nature of ultra-high spin states in heavy nuclei, just before the nucleus breaks up due to fission. Nuclear matter can exist in different phases, analogous to the solid, liquid, gas and plasma phases in ordinary substances. By varying the temperature, density or pressure, nuclear matter can undergo a transition from one phase to another. In extreme conditions of density and temperature (about 100 thousand times more than the temperature at the heart of the sun!), a phase transition should occur and quarks and gluons (of which the protons and neutrons are made) should exist in a new state of matter called the Quark-Gluon Plasma. By colliding nuclei together at high energies at the Large Hadron Collider at CERN, we will study properties of this new state of matter. Such information is not only important for nuclear physics but also to understand neutron stars and other compact astrophysical objects. This programme of research will employ a large variety of experimental methods to probe many aspects of nuclear structure and the phases of strongly interacting matter, mostly using instrumentation that we have constructed at several world-leading accelerator laboratories. The work will require a series of related experiments at a range of facilities in order for us to gain an insight into the answers to the questions posed above. These experiments will help theorists to refine and test their calculations that have attempted to predict the properties of nuclei and nuclear matter, often with widely differing results. The resolution of this problem will help us to describe complex many-body nuclear systems and better understand conditions in our universe a few fractions of a second after the big bang.