The Study of Nuclear Physics with Intermediate Energy Probes

虽然普通物质质量的98%是由强核力造成的，但目前关于这种力的理论（量子色动力学）仍未得到充分理解。该奖项支持通过探索物质的亚结构来研究强核力。几乎一个原子的全部质量都集中在它微小的原子核上，原子核是由带正电（质子）或电中性（中子）的核子组成的。然而，这些亚原子粒子并不是基本粒子，而是由夸克和胶子组成的复合物体。核子的结构是强核力的一种表现，强核力是已知的最强的力。这项研究将有助于促进核物理的发现和理解，并促进教学、培训和学习。初级科学家的培养在支持的活动中起着中心作用。南卡罗来纳大学（USC）的核物理研究项目主要是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进行的。在那里，该小组使用高能电子束和光子束以及复杂的粒子探测器，这些探测器在某种程度上是由南加州大学开发的，作为强大的显微镜来研究亚原子世界。该小组还在瑞士的保罗·谢勒研究所准备MUSE实验。这个实验将通过将介子和电子从质子中散射出去来解决质子半径之谜。通过探测器的开发、模拟、复杂实验的管理和数据分析，他们将揭示一些最深刻的问题，比如：核子的结构是什么？我们如何激发它的内部自由度？一旦被激发，核子以何种方式衰减回原始状态？如果核子被嵌入致密的核物质中，它的结构会改变吗？对这些性质的实验研究使人们对强作用力的本质有了深入的了解，并允许对基本理论进行严格的测试。

Although ninety-eight percent of the mass of ordinary matter is due to the strong nuclear force, the present theory of that force (Quantum Chromodynamics) is still not fully understood. This award supports the study of the strong nuclear force by probing the substructure of matter. Almost the entire mass of an atom is concentrated in its tiny nucleus, which is made of nucleons that 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 glue particles (gluons). The structure of nucleons is a manifestation of the strong nuclear force, which is the strongest force known. This research will help advance discovery and understanding in nuclear physics, and promote teaching, training, and learning. The preparation of junior scientists plays a central role in the supported activities.The nuclear physics research program at the University of South Carolina (USC) is mainly based at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia. There, the group uses high-energy electron and photon beams along with sophisticated particle detectors that were developed, in part, at USC as powerful microscopes to study the subatomic world. The group is also preparing the MUSE experiment at the Paul Scherrer Institute in Switzerland. This experiment will address the proton-radius puzzle by scattering muons and electrons off the proton. Through detector development, simulations, management of complex experiments, and data analyses, they will shed light on some of the most profound 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? The experimental study of these properties gives insight into the nature of the strong force and allows for rigorous tests of the underlying theory.