Nucleon Structure and Nuclear Force Studies

核结构和核力研究

• 批准号: 0099387
• 负责人: Bryon Anderson
• 金额: $ 60万
• 依托单位: Kent State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-06-01 至 2005-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0099387&HistoricalAwards=false
• 关键词: Nucleon; Structure; Nuclear; Force; Studies

This award is to support the research activities of two professors,their graduate students and a Senior Research Associate at Kent StateUniversity in the area of experimental medium-energy nuclear physics. The general objectives are the study of the structure of the nucleon(neutron or proton) and the nature of the nuclear force. This group isinvolved in experiments being performed, or to be performed at theJefferson National Accelerator Facility (Jlab) in Virginia and at theRelativistic Heavy-Ion Collider (RHIC) on Long Island, New York. Anexperiment is in progress at Jlab to determine the charge distributioninside the neutron. The neutron, while neutral overall, is known toconsist of objects with both positive and negative charges. Theseobjects are called "quarks". The quarks are held together by theexchange of particles called "gluons". Exactly how the quarks combine,move, and interact inside the neutron is not known. A precisemeasurement of the charge distribution, called the Electric Form Factor,will provide one of the most sensitive tests available of various modelsof the neutron structure. These measurements are only recently possibleand require the electron beam characteristics now available at Jlab andinvolve the use of a large-volume neutron polarimeter developed by thisgroup in experiments performed during the last decade at otheraccelerator facilities. The development, installation, calibration, andoperation of the polarimeter represents the unique contribution of thisgroup to this important experiment. This group plans also to performanother experiment at Jlab to study short-range correlation betweennucleons inside nuclei. Such short-range correlations are known toexist, but the exact nature and strength of such correlations are onlypoorly determined. This group will bring its expertise with neutrondetectors to help study such correlations involving neutrons.This group has recently joined an effort planned to study interactionsbetween colliding beams of polarized protons using the "STAR" detectorat RHIC (STAR stands for Solenoidal Tracker at RHIC). The object ofthis study is to determine the exact origin of the intrinsic angularmomentum, or spin, of the proton. The spin, like the chargedistribution, arises from the existence, interactions and movements ofthe constituents of the proton, generally believed to be the quarks andgluons. To date, only the contributions from the quarks has beendetermined; this project offers the possibility of determining thecontribution to the spin of the proton due to gluons. In order tomeasure these contributions, it is necessary to observe hadronic jetsproduced at relatively small angles in the collisions. This group,together with a collaboration of other researchers from IndianaUniversity, Argonne National Laboratory, and others, will construct anew "end-cap calorimeter" to be installed at one end of the present STARdetector at RHIC. It will be this group's responsibility to providecharacterizations and calibrations of the multi-anode photomultipliertubes used for particle detection in this new calorimeter.

该奖项旨在支持肯特州立大学的两位教授、他们的研究生和一位高级研究员在实验中能核物理领域的研究活动。总体目标是研究核子（中子或质子）的结构和核力的性质。 该小组参与了弗吉尼亚州杰斐逊国家加速器设施 (Jlab) 和纽约长岛相对论重离子对撞机 (RHIC) 正在进行或即将进行的实验。 Jlab 正在进行一项实验，以确定中子内部的电荷分布。 中子虽然总体呈中性，但已知由带有正电荷和负电荷的物体组成。 这些物体被称为“夸克”。 夸克通过称为“胶子”的粒子交换而结合在一起。 夸克究竟如何在中子内部结合、移动和相互作用尚不清楚。 电荷分布的精确测量（称为电形状因数）将为各种中子结构模型提供最灵敏的测试之一。 这些测量最近才成为可能，需要 Jlab 现有的电子束特性，并涉及使用该小组在过去十年在其他加速器设施进行的实验中开发的大体积中子旋光计。 旋光计的开发、安装、校准和操作代表了该小组对这一重要实验的独特贡献。 该小组还计划在 Jlab 进行另一项实验，研究原子核内核子之间的短程相关性。 众所周知，这种短程相关性是存在的，但这种相关性的确切性质和强度却很难确定。 该小组将利用其在中子探测器方面的专业知识来帮助研究涉及中子的此类相关性。该小组最近加入了一项计划，利用 RHIC 的“STAR”探测器（STAR 代表 RHIC 的螺线管跟踪器）来研究偏振质子碰撞束之间的相互作用。 这项研究的目的是确定质子的固有角动量或自旋的确切起源。 自旋与带电分布一样，源于质子成分的存在、相互作用和运动，通常认为质子成分是夸克和胶子。 迄今为止，仅确定了夸克的贡献； 该项目提供了确定胶子对质子自旋的贡献的可能性。 为了测量这些贡献，有必要观察碰撞中以相对较小角度产生的强子射流。 该小组将与印第安纳大学、阿贡国家实验室和其他机构的其他研究人员合作，建造一种新的“端盖量热计”，安装在 RHIC 现有 STAR 探测器的一端。 该小组的责任是提供用于这种新型量热计中粒子检测的多阳极光电倍增管的表征和校准。