Collaborative Research: Development of a Fast Muon Trigger to Study the Quark-Gluon Structure of the Proton

我们知道核子--质子和中子--是原子核和中子星的基本组成部分。核子本身是一个复合物体，具有复杂的子结构，夸克和胶子束缚在质子或中子内部。核子中夸克和胶子之间的相互作用由强核力的量子场论：量子染色体动力学（QCD）描述。自1969年Friedman、Kendall和Taylor在斯坦福大学直线加速器上首次实验观测到电子-质子深度非弹性散射中的夸克亚结构以来，对核子中夸克和胶子结构的认识取得了重大进展。然而，许多重要的问题仍然悬而未决，特别是我们仍然只留下了初步的了解质子spin.We的起源提出了研究质子自旋结构使用一个真正新颖的科学技术：观测的W-玻色子在高能极化质子-质子碰撞与PHENIX探测器在相对论重离子对撞机（RHIC）在布鲁克海文国家实验室（BNL）。宇称破坏W的产生将导致上夸克和下夸克以及它们相应的反夸克对质子自旋的贡献的单独测量。该测量方法将以极高的统计精度和系统精度分辨夸克和反夸克自旋分布与夸克相对动量的函数关系。PHENIX的快速μ子触发器将基于电阻板计数站（RPC），它们的前端电子设备用于读出，以及用于实现算法的大型快速可编程门阵列，该算法可以在p+p碰撞中发出W玻色子的罕见形成的信号。由于W信号预期每十亿次p+p碰撞仅发生一次，因此触发器允许选择和存储这些感兴趣的罕见事件并拒绝丰富的背景事件。RPC是紧凑的，相对便宜的设备，当电离粒子通过它们的主体时，它们将产生电子脉冲。发出W玻色子产生信号的电子设备由定制设计的电路板组成，这些电路板放大和处理来自RPC所有单个元件的原始电脉冲，随后是电子学分析来自单个元素的信号，以确定它们是否与W玻色子的产生一致。拟议的项目为研究生和本科生以及年轻人提供了一个出色的培训基地。研究人员，他们将在核物理的前沿进行分析，并将获得设计，建造和测试最先进的探测器和读出电子设备的经验。目前，该项目共有13名本科生、8名研究生和9名博士后研究员。在未来，该项目将强烈依赖于本科生团队在BNL进行RPC探测器的组装。为BNL的16名本科生提供的暑期支助已编入预算。目前，来自13个国家的80多名研究生和67名博士后研究人员在PHENIX上工作，一旦完成，很大一部分人将使用新设备。从历史上看，大量的女性作为本科生和研究生参与了PHENIX的研究，为科学和工程劳动力的多样性做出了贡献。PHENIX μ子触发小组由伊利诺伊大学厄巴纳尚潘分校的核物理实验室领导，并与阿比林基督教大学，科罗拉多大学博尔德分校，哥伦比亚大学纽约分校，位于艾姆斯的爱荷华州州立大学、日本的京都大学、中国北京的北京大学、位于布鲁克海文国家实验室的美日理研BNL联合研究中心以及位于滨江的加州大学。

We know the nucleon - proton and neutron - as the fundamental building blocks of nuclei in atoms and neutron stars. The nucleon itself is a composite object having complex sub-structure with quarks and gluons bound inside the proton or neutron. The interactions between quarks and gluons in the nucleon are described by the quantum field theory of the strong nuclear force: quantum chromo dynamics (QCD). Since Friedman, Kendall and Taylor's first experimental observation of quark sub-structure in deep inelastic electron-proton scattering at the Stanford Linear Accelerator in 1969 significant progress in understanding the quark and gluon structure of the nucleon has been made. However, many important questions remain open; in particular we are still left with only rudimentary understanding of the origin of the proton spin.We propose to study proton spin structure using a truly novel scientific technique: the observation of W-bosons in high energetic polarized proton-proton collisions with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Parity violating W production will lead to separate measurements of the spin contributions from up- and down-quarks and their corresponding anti-quarks to the proton spin. The proposed measurement will resolve the quark and anti-quark spin-distributions as a function of the relative quark momentum to the proton with excellent statistical precision and systematic accuracy.The fast muon trigger for PHENIX will be based on resistive plate counter stations (RPCs), their front-end electronics for read-out, and large fast programmable gate arrays for the implementation of algorithms that can signal the rare formation of a W-boson in a p+p collision. Since a W signal is expected to occur only about once per billion p+p collisions, the trigger allows selection and storage of these interesting rare events and rejection of abundant background events. The RPCs are compact, relatively inexpensive devices that will produce an electronic pulse when an ionizing particle passes through their bulk. The electronics to signal the creation of a W boson consists of custom designed circuit boards that amplify and process the raw electrical pulses from all of the individual elements of the RPCs, followed by electronics to analyze the signals from the individual elements to determine if they are consistent with the creation of a W boson.The proposed project offers an outstanding training ground for graduate and undergraduate students as well as young researchers, who will do analysis at the frontier of nuclear physics and will gain experience in the design, construction, and testing of state-of-the-art detectors and readout electronics. 13 undergraduate students, eight graduate students and nine postdoctoral fellows work on the project now. In the future, the project will strongly rely on teams of undergraduate students to carry out the assembly of the RPC detectors at BNL. Summer support for 16 undergraduate students at BNL has been budgeted. More than 80 graduate students and 67 postdoctoral researchers from 13 countries currently work on PHENIX, and a large fraction will utilize the new equipment once completed. Historically, a large number of women have been involved in PHENIX research as both undergraduate and graduate students, contributing to the diversity of the science and engineering workforce.The PHENIX muon trigger group is lead by the Nuclear Physics Laboratory at University of Illinois at Urbana Champaign and has collaborators from Abilene Christian University, the University of Colorado at Boulder, Columbia University in New York, Iowa State University at Ames, Kyoto University in Japan, Peking University in Beijing, China, the joint US-Japanese Riken BNL Research Center at Brookhaven National Laboratory and the University of California at Riverside.