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

RUI：偏振光束和靶材的中能光核物理研究

• 批准号: 0650924
• 负责人: C. Steven Whisnant
• 金额: $ 18.55万
• 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: 2007
• 资助国家: 美国
• 起止时间: 2007-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0650924&HistoricalAwards=false
• 关键词: RUI; Study; Intermediate; Energy; Photonuclear

The proposed research uses photon scattering and meson production to investigate the properties of the nucleon and nucleon resonances using polarized beams and targets. The experimental program is located at the High Intensity Gamma Source (HIGS) facility at the Duke Free Electron Laser Laboratory laboratory at Duke University, Jefferson Laboratory (JLab) in Newport News, VA and the National Institute for Standards and Techonology (NIST) in Gaithersburg, MD.The HIGS facility opens a new window to the study of nucleon structure through elastic scattering of gamma-rays from both polarized and unpolarized nucleon and nuclear targets. This program will measure quantities that chacterize the response of the nucleon to the fluctuating electric and magnetic fields of the gamma-rays. This data will allow for precision tests of effective field theories, numerical calculations of the strong interaction as well as calculations and predictions of the standard model of particle physics. JMU is working with HIGS collaborators to build an active polarized proton target ideal for photon scattering experiments at low energies.Although approved experiments at JLab using a polarized butanol target now under development will constrain fits to meson photoproduction, these experiments alone are insufficient. A collaboration has been assembled to measure beam-target asymmetries for five meson production channels simultaneously with polarized neutrons in the Strongly Polarized HD Ice (SPHICE) target using the CEBAF Large Acceptance Spectrometer (CLAS). This will provide the first (over-)determination of a pseudoscalar meson photo-production amplitude and will be free of the ambiguities that have plagued this field for decades. This experiment, E06-101, was reviewed in August 2006, was approved with an ``A'' rating and alloted the entire beam-time request.Although the frozen spin HD target, SPHICE, is ideal for use in secondary beams, to use the target in a primary beam either the depolarizing effects of beam must be demonstrated to be small or new methods of operation must be found. The JMU group will, with collaborators from UVA, investigate the possibility of operating a dynamically polarized HD target. Target irradiation will be done at NIST using the Medical-Industrial Radiation Facility on high purity HD distilled at JMU. A dynamically polarized HD target with a high polarization would represent a significant advance in polarized target technology.JMU undergraduate students will be involved in both on- and -off campus activities. The on-campus activities will include distillation of HD for SPHICE targets, polarizable scintillator target material fabrication and NaI detector assembly and testing, and for the more senior students, data analysis. These activities foster connections among the various research groups in the department, form the basis for the continued development of a new nuclear physics lab at JMU and allow the expansion of new outreach initiatives. The off-campus work will introduce the students to ``large'' physics done at state-of-the-art facilities and expose them to the experts in photonuclear physics that are attracted to these facilities. The College of Science and Mathematics at JMU currently has four NSF REU programs funded (Materials, Chemistry, Biology and Mathematics). These programs cooperatively produce a vibrant summer research community spanning the college. The program outlined here will bring off-campus experiences back to enrich the experience of not only the more junior students in this group but also those in the other REU programs. Research and teaching at JMU are recognized as two facets of the same process. This integration of research and education continues to be one of the hallmarks of the highly rated undergraduate experience at JMU.

该研究利用光子散射和介子产生来研究核子和核子共振的性质，使用偏振光束和目标。实验计划位于杜克大学杜克自由电子激光实验室实验室的高强度伽马源（HIGS）设施、弗吉尼亚州纽波特纽斯的杰斐逊实验室（JLab）和盖瑟斯堡的国家标准与技术研究所（NIST），MD. HIGS设施为通过γ-射线弹性散射研究核子结构打开了一个新的窗口，来自极化和非极化核子和核目标的射线。这个程序将测量改变核子对伽玛射线波动电场和磁场的响应的量。这些数据将允许有效场论的精确测试，强相互作用的数值计算以及粒子物理标准模型的计算和预测。JMU正在与HIGS合作者合作，建立一个理想的低能光子散射实验的活性极化质子靶。尽管JLab批准的实验使用极化丁醇靶，目前正在开发中，将限制介子光生，这些实验本身是不够的。一个合作已经组装，以测量五个介子生产通道的束靶不对称性，同时在强极化HD冰（SPHICE）的目标使用CEBAF大型接受光谱仪（CLAS）的极化中子。这将提供赝标介子光生振幅的第一个（过）确定，并将摆脱困扰这一领域几十年的模糊性。该实验E06-101于2006年8月接受审查，获得“A”评级，并分配了整个束流时间请求。尽管冷冻自旋HD靶SPHICE非常适合用于次级束流，但要在初级束流中使用该靶，要么必须证明束流的去极化效应很小，要么必须找到新的操作方法。JMU小组将与来自UVA的合作者，研究操作动态极化HD目标的可能性。将在NIST使用医疗工业辐射设施对JMU蒸馏的高纯度HD进行靶辐照。一个高极化的动态极化高清目标将代表极化目标技术的重大进步。JMU的本科生将参与校园内外的活动。校内活动将包括SPHICE目标的HD蒸馏，可极化闪烁体目标材料制造和碘化钠探测器组装和测试，以及更高年级的学生，数据分析。这些活动促进了该部门各研究小组之间的联系，为JMU新的核物理实验室的持续发展奠定了基础，并允许扩大新的外联活动。校外工作将向学生介绍在最先进设施中完成的“大型”物理学，并使他们接触被这些设施所吸引的光核物理学专家。JMU的科学与数学学院目前有四个NSF REU项目（材料，化学，生物学和数学）。这些项目合作产生了一个充满活力的夏季研究社区跨越学院。这里概述的计划将带来校外的经验回来，以丰富不仅在这个组中，但也在其他REU程序的更低年级的学生的经验。JMU的研究和教学被认为是同一过程的两个方面。这种研究和教育的整合仍然是JMU高度评价的本科生经验的标志之一。