AI 中文总结
该研究提出基于杰斐逊实验室新建成的超级大bite谱仪的物理计划，解决核子结构研究中小截面测量难题，其首批实验已完成，拟议升级将进一步拓展研究范围。
AI 中文摘要
核子结构是强相互作用物理非微扰区域的核心问题。事实上，宇宙中绝大多数已知物质由质子和中子构成，它们是量子色动力学的显著涌现现象。实验研究核子结构的关键方面是测量弹性核子形状因子等基本量，测量横向动量依赖分布函数也同样重要。然而，由于涉及的截面很小，尤其是在高动量转移下，通过实验获取这些量颇具挑战性。本文提出一项基于超级大bite谱仪（Super Bigbite Spectrometer, SBS）的物理计划，以应对这一挑战，该谱仪近期已在托马斯杰斐逊国家加速器装置建成。SBS提供70 msr的相对大立体角，可在高亮度和前向散射角下使用；其基于开放式结构的单个大型偶极磁铁，探测器组件可直接观测靶标，该方案仅通过采用能在极高计数率下运行且具备优异空间分辨率的探测器技术才能实现。对于小截面测量而言，立体角与亮度的乘积至关重要，在这方面，杰斐逊实验室（JLab）的谱仪系统中，SBS当前的能力独具特色。利用SBS开展的首批实验已成功完成，未来还计划开展更多实验。本文还讨论了一项拟议升级，该升级将把SBS的立体角提升至260 msr，从而为更广泛的物理研究计划开辟前景。
英文摘要
The structure of the nucleon is a central problem in strong interaction physics in the non-perturbative regime. Indeed, the vast majority of the known matter in the Universe is made of protons and neutrons which are a remarkable emergent phenomenon of quantum chromodynamics. A critical aspect of investigating nucleon structure experimentally is the measurement of fundamental quantities such the elastic nucleon form factors. Also important is the measurement transverse momentum dependent distribution functions. Accessing such quantities experimentally, however, is challenging because of the small cross sections involved, particularly at high momentum transfer. We present here a physics program that is addressing this challenge based on the Super Bigbite Spectrometer (SBS) that has recently been built at the Thomas Jefferson National Accelerator Facility. SBS provides a relatively large solid angle of 70 msr and can be used at high luminosities and forward-scattering angles. It is based on a single large dipole magnet in an open-geometry in which the detector package has a direct line of sight to the target. This approach is only possible through the use of detector technology that can operate at very high rates while providing excellent spatial resolution. It is the product of solid angle and luminosity that is critical when measuring small cross sections, and in this regard, among spectrometer systems at JLab, SBS is presently unique in its capability. The first set of experiments utilizing SBS has been successfully completed, and more experiments are planned for the future. We also discuss a proposed upgrade that would increase the SBS solid angle to 260 msr, thereby opening perspectives for an even broader physic program.
Comments21 pages, 9 fogures
