Research and Education with GlueX

弗吉尼亚州纽波特纽斯的杰斐逊实验室的核物理实验项目的一个目标是寻找新的共振，或在特定能量下得到强化的状态，这种状态可能存在于原子核最深处的网络状胶子场中，胶子是原子核中的初级能量储存。目前，胶子共振存在的最好证据是理论上的，但PI和他在康涅狄格大学的学生正在寻找胶子共振存在的实验证据，他们与一个由150名物理学家组成的团队在杰斐逊实验室D厅进行GlueX实验。康涅狄格州大学的小组负责偏振伽马射线的来源，偏振伽马射线是由杰斐逊实验室加速器发出的12GeV电子束通过精心制作和定向的钻石晶体产生的。来自源的偏振伽马射线被引导到液氢目标上，在那里产生共振，随后的衰变在目标周围的GlueX光谱仪中被拾取和识别，以揭示关于质子和其他原子核中夸克组织的新信息。GlueX实验旨在澄清胶子自由度在轻夸克强子激发光谱中所起的作用。为实现这一目标而收集的数据还阐明了核物理中的一些其他专题，包括接近阈值的J/psi光产生、ETA(550)介子的罕见衰变、ETA和ETA质子的2伽马衰变宽度，以及带电介子和中性介子(CPP、NPP)的极化率。GlueX现已完成其批准的GlueX第二阶段数据收集的30%，并正在迅速达到系统效应取代统计学成为许多研究实验不确定度的主要来源的地步。除了支持光子光束线和标记器的持续运行外，康涅狄格州大学的小组还在量化和减少与光子束特性相关的系统学方面发挥着关键作用。这笔资助使PI和两名博士生能够为D厅实验提供和提高钻石散热器的质量，维护和操作标记显微镜，并领导GlueX实验的物理模拟的持续发展。在这些努力的同时，康涅狄格州大学的学生还将在混合光谱学和相关主题方面根据主要的GlueX物理计划进行物理分析。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

One goal of the experimental program in nuclear physics at Jefferson Lab in Newport News, Virginia is to look for new resonances, or states reinforced at certain energies, that may exist at the deepest level of the nucleus within the web-like fields known as gluons, which are the primary energy stores in the nucleus. At present, the best evidence for the existence of gluonic resonances is theoretical, but the PI and his students at the University of Connecticut are seeking experimental proof of their existence, working together with a team of 150 physicists on the GlueX experiment in Hall D at Jefferson Lab. The UConn group is responsible for the source of polarized gamma rays, which are produced by passing the 12 GeV electron beam from the Jefferson Lab accelerator through a carefully crafted and oriented diamond crystal. Polarized gamma rays from the source are directed onto a liquid hydrogen target where resonances are produced, whose subsequent decays are picked up and identified in the GlueX Spectrometer, an apparatus surrounding the target, to uncover new information about the organization of quarks inside the proton and other nuclei.The GlueX experiment aims at clarifying the role played by gluonic degrees of freedom in the excitation spectrum of light-quark hadrons. Data collected in pursuit of this goal also shed light on a number of additional topics in nuclear physics, including near-threshold J/psi photoproduction, rare decays of the eta(550) meson, the 2gamma decay width of the eta and eta prime mesons, and the polarizability of the charged and neutral pions (CPP, NPP). GlueX has now completed 30% of its approved data collection for GlueX Phase 2, and is quickly reaching the point where systematic effects take over from statistics as the primary source of experimental uncertainty for many studies. The UConn group is playing a critical role in quantifying and reducing systematics related to the properties of the photon beam, in addition to supporting the ongoing operation of the photon beamline and tagger. Support under this grant enables the PI and two PhD students to provide and enhance the quality of diamond radiators for Hall D experiments, maintain and operate the tagger microscope, and lead the ongoing development of the physics simulation for the GlueX experiment. In parallel with these efforts, UConn students will also carry out physics analysis in line with the primary GlueX physics program in hybrid spectroscopy and related topics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.