The Study of Nuclear Physics with Intermediate Energy Probes

我们在南卡罗来纳大学的研究项目设在弗吉尼亚州纽波特纽斯的托马斯·杰斐逊国家加速器设施。在那里，我们使用高能电子束和光子束以及复杂的粒子探测器作为强大的显微镜来研究亚原子世界。我们试图回答这样的问题：核子的结构是什么？什么是什么，我们如何才能激发它的内在自由度？一旦被激发，核子以哪种方式衰变回其原始状态？如果核子嵌在致密的核物质中，核子的结构会改变吗？如果其他亚原子粒子是在致密的核物质中产生的，它们是否会改变其性质？对这些性质的实验研究使我们能够洞察强力的本质，并允许对潜在的理论进行严格的测试。几乎一个原子的整个质量都集中在它的微小原子核中。原子核是由带正电荷(质子)或电中性(中子)的核子组成的。然而，这些亚原子粒子不是基本粒子，它们本身是由夸克组成的复合体，夸克通过胶粒(胶子)的交换被强大的力结合在一起。核子结构是人类已知的最强力的一种表现。虽然普通物质98%的质量是由强力造成的，但目前关于强力的理论(量子色动力学)仍然没有完全被理解。这项研究将有助于增进我们的理解。初级科学家的准备工作在所支持的活动中发挥着核心作用。

Our research program at the University of South Carolina is based at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia. There, we use high-energy electron and photon beams along with sophisticated particle detectors as powerful microscopes to study the subatomic world. We try to answer questions like: What is the structure of the nucleon? What are and how can we excite its internal degrees of freedom? Once excited, in which way does the nucleon decay back to its original state? Does the structure of the nucleon change if it is embedded in dense nuclear matter? Do other subatomic particles change their properties if they are produced in dense nuclear matter? The experimental study of these properties gives insight into the nature of the strong force and allows for rigorous tests of the underlying theory.Almost the entire mass of an atom is concentrated in its tiny nucleus. The atomic nucleus is made of nucleons, which are either positively charged (protons) or electrically neutral (neutrons). These subatomic particles, however, are not elementary but are themselves composite objects made of quarks held together by the strong force via the exchange of glue particles (gluons). The structure of nucleons is a manifestation of that strongest force known to mankind. Although ninety-eight percent of the mass of ordinary matter is due to the strong force, the present theory of that force (Quantum Chromodynamics) is still not fully understood. This research will help to advance our understanding. The preparation of junior scientists plays a central role in the supported activities.