LEAPS-MPS: Precision Measurements of Neutron Beta Decay to Test Fundamental Symmetries

LEAPS-MPS：精确测量中子 Beta 衰变以测试基本对称性

• 批准号: 2213411
• 负责人: Jason Fry
• 金额: $ 21.12万
• 依托单位: Eastern Kentucky University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2213411&HistoricalAwards=false
• 关键词: LEAPS; MPS; Precision; Measurements; Neutron

This award supports Dr. Fry at Eastern Kentucky University in a project that will impact science and society through research activities aimed at precisely determining the neutron lifetime and two of its decay parameters (known as “a” and “b”), as well as training and mentoring undergraduate students in technical areas that will prepare them for careers in STEM fields. Precisely determining the neutron’s decay parameters can provide sensitive tests of the Standard Model and achieving that has been identified as a high priority in the current Long-Range Plan for Nuclear Science by the Nuclear Science Advisory Committee. Exciting preliminary results have already generated public interest and will continue to do so with further results from this work. The scales of the neutron “a” and “b” (Nab) experiment and the Beam Lifetime 3 (BL3) and its use of techniques from many subfields of physics lends itself to hands-on student participation and the development of a broad understanding of physical principles and experimental techniques. The project will help train motivated students at EKU, provide research opportunities in larger scale collaborations, and conduct team-based science. The award will employ students at a living wage at EKU, which will help retain students and increase future student success by keeping them engaged in activities in their major, therefore further adding to the scientific workforce.One of the cornerstones of the Standard Model of physics is the unitarity of the quark mixingmatrix (CKM matrix). This symmetry can be tested by combining precise measurements of the ratio of the axial-vector and vector coupling constants, and the neutron lifetime. Currently, measurements of the neutron lifetime using different methods are in conflict with each other and resolving this discrepancy is of high intellectual priority. Additionally, the neutron lifetime has cosmological implications as it was a key factor in the formation of the light elements during Big Bang Nucleosynthesis (BBN). The uncertainty in the neutron lifetime is the largest contribution to the uncertainty in the primordial helium abundance, YP. In these cosmological models, YP is related to important parameters such as the expansion of the universe and the number of effective neutrino species; resolving the neutron lifetime puzzle is top priority in nuclear science with implications in the interplay of cosmology and particle physics. The award will involve students in hands-on experiences in the lab at Eastern Kentucky University and at Oak Ridge National Lab. Student-centered projects will include addressing an important systematic effect in the Nab experiment by conducting an in-situ timing study to characterize silicon detectors to less than or equal to 1 ns, developing complex Monte Carlo simulations for systematic studies in the Nab and BL3 experiments, and to develop a data analysis server for the BL3 experiment. This work will give students an extraordinary experience at a regional university, travel to a national lab and experience with a larger collaboration and help them carve out meaningful roles in the scientific workforce. This project is jointly funded by the Division of Physics within the Mathematical and Physical Sciences Directorate and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该奖项支持东肯塔基州大学的Fry博士的一个项目，该项目将通过旨在精确确定中子寿命及其两个衰变参数（称为“a”和“B”）的研究活动来影响科学和社会，并在技术领域培训和指导本科生，为他们在STEM领域的职业生涯做好准备。精确地确定中子的衰变参数可以提供标准模型的敏感测试，并已被核科学咨询委员会确定为当前核科学长期计划的高度优先事项。 令人兴奋的初步结果已经引起了公众的兴趣，并将随着这项工作的进一步成果继续引起公众的兴趣。 中子“a”和“B”（Na B）实验和束寿命3（BL 3）的尺度及其对物理学许多子领域技术的使用有助于学生动手参与和对物理原理和实验技术的广泛理解的发展。 该项目将有助于培养EKU的积极学生，提供更大规模合作的研究机会，并进行基于团队的科学。该奖项将在EKU以生活工资雇用学生，这将有助于留住学生，并通过让他们参与专业活动来提高未来学生的成功，从而进一步增加科学劳动力。物理学标准模型的基石之一是夸克混合矩阵（CKM矩阵）的酉性。 这种对称性可以通过结合轴向矢量和矢量耦合常数之比的精确测量以及中子寿命来测试。 目前，使用不同的方法测量中子寿命是相互冲突的，解决这种差异是高智力优先级。 此外，中子寿命具有宇宙学意义，因为它是大爆炸核合成（BBN）期间形成轻元素的关键因素。 中子寿命的不确定性是原始氦丰度YP不确定性的最大贡献。在这些宇宙学模型中，YP与宇宙膨胀和有效中微子种类的数量等重要参数有关;解决中子寿命之谜是核科学的首要任务，涉及宇宙学和粒子物理学的相互作用。 该奖项将涉及学生在实验室在东肯塔基州大学和橡树岭国家实验室的实践经验。以学生为中心的项目将包括通过进行原位定时研究来表征硅探测器小于或等于1 ns，为Nab和BL 3实验中的系统研究开发复杂的Monte Carlo模拟，并为BL 3实验开发数据分析服务器，从而解决Nab实验中的重要系统效应。这项工作将为学生在地区大学提供非凡的体验，前往国家实验室并体验更大的合作，并帮助他们在科学劳动力中发挥有意义的作用。 该项目由数学和物理科学理事会物理部和刺激竞争性研究的既定计划（EPSCoR）共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。