Pair polarimeter for high-energy linearly polarized photons

用于高能线偏振光子的对旋光计

• 批准号: 0653424
• 负责人: Branislav Vlahovic
• 金额: $ 6万
• 依托单位: North Carolina Central University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0653424&HistoricalAwards=false
• 关键词: Pair; polarimeter; energy; linearly; polarized

Intellectual Merits: In spite of 40 years of history, high energy photon polarimetry is an undeveloped field. At JLab energies all known methods have low analyzing power, and the absolute accuracy is below that required for the approved and anticipated physics programs. Currently, the only way to estimate the degree of photon polarization in Hall B is by fitting theoretical calculations to the collimated photon energy spectrum. The JLab physics program in Hall B and planned Hall D will significantly benefit from this new polarimeter, which will significantly reduce a major systematic experimental error in all approved and some planned experiments. The proposed polarimeter will have an experimental asymmetry of approximately 1.7 (analyzing power 26%) for an energy range from a few tens of MeV up to several GeV. This implies that for a beam intensity of 106 photons per second, such as at the JLab, a 1% statistical accuracy of the polarization measurement will require less then one hour of data taking. The polarimeter is simple in construction, compact, and its costs will be lower than for polarimeters built according to any other available method. Three prototypes were built and tested at Duke, BNL, SPring8 and JLab. The analyzing power was determined to be 19.2% for equal-energy pairs and 11.9% for all events during the test run at the Spring-8. The polarimeter was applied at JLab Hall B g8b experiment and it worked as predicted, there was no problem with high beam intensity and reconstruction of the events. Since the budget is reduced for more then 90% the scope of the work will be limited only to the education of the students that will have assigned projects related to the polarimeter physics. Any work planned related to the research or development of the polarimeter will be no performed, because of the lack of the support. Broader Impact: The proposed research and education program could result in increased competitiveness of the NCCU physics and science programs, and improved conditions for the faculty and student recruitment. The integration between research and education could be expanded with new courses and research programs designed to enrich current curriculum and bring more students into the original research. However the limited funding will allow us only to develop student research projects that will create an ambient for enhancing undergraduate computational program in science department, and recently approved graduate program in physics. The most significant impact of the project will be in providing highly qualified work force with highly skilled minorities and socially underrepresented groups. The original research in the fields of nuclear and computational physics, and computer modeling, could increase production of more competitive students. Emerging scientific advances and opportunities could also provide flexibility in career choices, adequately prepare our students for further graduate studies, and highlight the job opportunities for our graduates. Furthermore, we expect that this program will stimulate continuing expansion of training for African American graduate and undergraduate students.

智力优势：尽管高能光子偏振测量已经有40年的历史，但它仍然是一个未开发的领域。在JLab Energy，所有已知的方法分析能力都很低，绝对精度低于批准和预期的物理计划所需的精度。目前，估计B大厅中光子偏振度的唯一方法是将理论计算与准直光子能谱进行拟合。B展厅和计划中的D展厅的JLab物理项目将大大受益于这种新的偏振仪，它将显著减少所有已批准和计划中的实验中的主要系统实验误差。在几十MeV到几个GeV的能量范围内，建议的旋光计将有大约1.7的实验不对称性(分析功率26%)。这意味着对于每秒106光子的光束强度，例如在JLab，1%的偏振测量的统计精度将需要不到一个小时的数据采集。该旋光仪结构简单、紧凑，其成本将低于按照任何其他可用的方法制造的旋光仪。在Duke、BNL、SPring8和JLab制造了三个原型并进行了测试。在Spring-8的试运行期间，等能对的分析能力被确定为19.2%，所有事件的分析能力被确定为11.9%。偏振仪在JLab Hall B g8b实验中得到了应用，并达到了预期的效果，在高束强和重现事件方面没有问题。由于预算减少了90%以上，这项工作的范围将仅限于对那些将指定与偏振物理有关的项目的学生进行教育。由于缺乏支持，任何与旋光仪研究或开发相关的计划工作都将无法进行。更广泛的影响：拟议的研究和教育计划可能会提高NCCU物理和科学计划的竞争力，并改善教师和学生招聘的条件。可以通过设计新的课程和研究计划来扩大研究和教育之间的整合，以丰富现有的课程，并将更多的学生带入最初的研究。然而，有限的资金将只允许我们开发学生研究项目，这些项目将为加强科学系本科生计算课程和最近批准的物理学研究生课程创造环境。该项目最重要的影响将是为高技能少数群体和社会代表性不足的群体提供高素质的劳动力。在核物理和计算物理领域的原创研究，以及计算机建模，可能会增加更具竞争力的学生的产量。新兴的科学进步和机会也可以为职业选择提供灵活性，为我们的学生为进一步的研究生学习做好充分的准备，并为我们的毕业生提供就业机会。此外，我们预计这一计划将刺激继续扩大对非裔美国研究生和本科生的培训。