Nucleon Structure and Nuclear Force Studies

该奖项是为了支持肯特州立大学两名教授、他们的研究生和一名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。这个小组正在或即将在弗吉尼亚州的杰斐逊国家加速器设施(JLAB)和纽约长岛的相对论重离子对撞机(RHIC)进行实验。JLAB正在进行一项实验，以确定中子内部的电荷分布。中子虽然总体上是中性的，但已知是由带正电荷和带负电荷的物体组成的。这些天体被称为“夸克”。夸克通过被称为“胶子”的粒子交换而聚集在一起。夸克在中子内部的结合、运动和相互作用的确切方式尚不清楚。对电荷分布的精确测量，称为电子形状因数，将提供各种中子结构模型中最灵敏的测试之一。这些测量是最近才有可能的，需要JLAB目前可用的电子束特性，并涉及在过去十年在其他加速器设施进行的实验中使用该小组开发的大体积中子偏振仪。旋光仪的研制、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，以研究核内核子之间的短程关联。这样的短程关联是已知的，但这种关联的确切性质和强度只是很难确定。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与中子有关的这种关联。该小组最近加入了一项计划，利用RHIC(STAR代表RHIC的螺线管跟踪器)探测器来研究极化质子碰撞光束之间的相互作用。这项研究的目的是确定质子的固有角膜层或自旋的确切来源。自旋和电荷分布一样，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。到目前为止，只确定了夸克的贡献；这个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，有必要观测在碰撞中以相对较小的角度产生的强子喷流。该小组与印第安纳大学、阿贡国家实验室和其他研究人员的合作，将建造一个新的“端盖量热计”，安装在RHIC目前的STAR探测器的一端。该小组将负责为这种新型热量计中用于粒子检测的多阳极光电倍增管提供特性和校准。

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.