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

该奖项将支持通过产生介子和核子共振来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观测数据。该实验计划位于布鲁克海文国家实验室(BNL)国家同步加速器光源(NSLS)的激光电子伽马源(LEGS)。将我们的新型极化HD靶SPHICE和大接收SASE探测器与高质量的极化光子束束腿相结合，最初的实验计划集中于核子与自旋相关的康普顿振幅的和规则测量，以提供对质子的前向自旋极化率和Gerasimov Drell-Hain和规则积分的直接确定，并首次对中子进行这样的测量。我们将同时测量质子和中子光生π介子的双偏振观测数据。SPHICE和SSIE的结合使完整的观测集合的测量成为可能，从而使第一个模型独立于多极分析成为可能。我们还将获得高质量的双偏振数据，这将极大地扩展我们对这一基本反应的理解。JMU小组负责生产用于这些实验的极化靶材的生产所需的高纯度高清气体，以及将作为SISE升级的一部分安装的超导磁体的操作和测绘，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。

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.