Pair polarimeter for high-energy linearly polarized photons

智力优势：尽管有40年的历史，高能光子偏振测量是一个未开发的领域。在JLab能量下，所有已知的方法都具有低分析能力，并且绝对精度低于批准和预期的物理程序所需的精度。 目前，估计霍尔B中光子偏振程度的唯一方法是通过将理论计算拟合到准直光子能谱。在B厅和计划中的D厅的JLab物理程序将大大受益于这种新的偏振计，这将大大减少在所有批准和一些计划的实验中的主要系统实验误差。 建议的偏振计将有一个实验的不对称性约为1.7（分析功率26%）的能量范围从几十兆电子伏到几个GeV。这意味着对于每秒106个光子的光束强度，例如在JLab，偏振测量的1%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，并且其成本将低于根据任何其他可用方法制造的旋光仪。 在杜克、BNL、SPring 8和JLab建造并测试了三个原型。 在Spring-8的测试运行期间，等能量对的分析功效确定为19.2%，所有事件的分析功效确定为11.9%。该偏振计应用于JLab Hall B g8 B实验，并按预期工作，高光束强度和事件重建没有问题。由于预算减少了90%以上，工作范围将仅限于分配与旋光仪物理学相关的项目的学生的教育。由于缺乏支持，任何与旋光仪的研究或开发相关的计划工作都将无法执行。 更广泛的影响：拟议的研究和教育计划可以提高NCCU物理和科学课程的竞争力，并改善教师和学生招聘的条件。 研究和教育之间的整合可以通过新的课程和研究项目来扩展，以丰富现有的课程，并使更多的学生参与原始研究。然而，有限的资金将使我们只能开发学生的研究项目，这将创造一个环境，以加强本科计算程序在科学部门，最近批准的研究生课程的物理。该项目最重要的影响将是为高技能少数民族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始研究，以及计算机建模，可以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提供职业选择的灵活性，充分准备我们的学生进一步研究生学习，并突出我们的毕业生的就业机会。此外，我们预计，这一计划将刺激非洲裔美国研究生和本科生的培训不断扩大。

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.