The Study of Intermediate Energy Photonuclear Physics with Polarized Beams and Targets

偏振光束和靶的中能光核物理研究

• 批准号: 0242159
• 负责人: C. Steven Whisnant
• 金额: $ 16.5万
• 依托单位: James Madison University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0242159&HistoricalAwards=false
• 关键词: Study; Intermediate; Energy; Photonuclear; Physics

This award will support continued study of the properties of the nucleon through the production of mesons and nucleon resonances.The dominant component of this program isthe use of polarization observables in photonuclear reactions. The experimental program is located at the Laser Electron Gamma Source (LEGS) atthe National Synchrotron Light Source (NSLS) at Brookhaven NationalLaboratory (BNL). Combining our novel polarized HD target, SPHICE, and thelarge acceptance SASY detector with the high quality polarized photon beamat LEGS, the initial experimental program concentrates on sum-rulemeasurements of the spin-dependent Compton amplitude for the nucleon toprovide a direct determination of the forward spin-polarizability andGerasimov Drell-Hearn sum rule integrals for the proton and the first suchmeasurement for the neutron. We will simultaneously measure the doublepolarization observables for pion photoproduction from the proton andneutron. The combination of SPHICE and SASY at LEGS makes measurement of acomplete set of observables possible, permitting the first model independentmultipole analysis. High quality double polarization data on thephotodisintegration of deuterium will also be obtained greatly expanding ourunderstanding of this fundamental reaction. The JMU group is responsible for producing the high purity HD gasrequired for the production of the polarized targets used for theseexperiments, the operation and mapping of the the superconducting magnet tobe installed as part of the SASY upgrade, and will participate in thecollection and analysis of the data. Five undergraduate students willparticipate in this project each year and gain experience in both on-campusand off-campus activities.

该奖项将支持通过介子和核子共振的产生继续研究核子的性质。该计划的主要组成部分是在光核反应中使用偏振可观测量。实验计划位于布鲁克海文国家实验室（BNL）的国家同步加速器光源（NSLS）的激光电子伽马源（LEGS）。结合我们的新型极化HD靶SPHICE和大接收SASY探测器以及LEGS上的高质量极化光子束，最初的实验计划集中在核子自旋相关康普顿振幅的求和规则测量上，以提供质子的前向自旋极化率和GerasimovDrell-Hearn求和规则积分的直接确定，以及中子的首次测量。我们将同时测量质子和中子光生π介子的双极化观测值。SPHICE和SASY在LEGS的结合使得测量完整的可观测量成为可能，允许第一个模型独立的多极分析。高质量的双偏振数据的氘光致衰变也将大大扩大我们的理解这一基本反应。 JMU小组负责生产用于这些实验的极化靶的生产所需的高纯度HD气体，作为SASY升级的一部分安装的超导磁体的操作和绘图，并将参与数据的收集和分析。每年将有五名本科生参加这个项目，并在校内和校外活动中获得经验。