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

该奖项支持东肯塔基大学的弗莱博士的一个项目，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，以及在技术领域对本科生进行培训和指导，为他们在STEM领域的职业生涯做准备，从而影响科学和社会。精确地确定中子的衰变参数可以提供对标准模型的敏感测试，并实现这一点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。令人振奋的初步结果已经引起了公众的兴趣，并将继续引起公众的兴趣，这项工作将产生更多的结果。中子“a”和“b”(NAB)实验和束寿命3(BL3)实验的规模及其对物理学许多子领域的技术的使用有助于学生的实际参与和对物理原理和实验技术的广泛理解的发展。该项目将帮助EKU培养有积极性的学生，在更大范围的合作中提供研究机会，并开展基于团队的科学。该奖项将以最低工资聘用EKU的学生，这将有助于留住学生，并通过让他们参与专业活动来提高学生未来的成功，从而进一步增加科学工作。标准物理模型的基石之一是夸克混合矩阵(CKM矩阵)的统一性。这种对称性可以通过精确测量轴向矢量和矢量耦合常数的比率以及中子寿命来测试。目前，用不同的方法测量中子寿命是相互矛盾的，解决这一差异具有重要的理论意义。此外，中子寿命具有宇宙学意义，因为它是大爆炸核合成(BBN)期间轻元素形成的关键因素。中子寿命的不确定性是原始氦丰度yp不确定的最大原因。在这些宇宙学模型中，yP与宇宙的膨胀和有效中微子物种的数量等重要参数有关；解决中子寿命之谜是核科学的重中之重，涉及宇宙学和粒子物理学的相互作用。该奖项将让学生在东肯塔基大学和橡树岭国家实验室的实验室中亲身体验。以学生为中心的项目将包括通过进行现场计时研究来解决NAB实验中的重要系统效应，以表征小于或等于1 ns的硅探测器，为NAB和BL3实验中的系统研究开发复杂的蒙特卡罗模拟，以及为BL3实验开发数据分析服务器。这项工作将让学生在地区性大学获得非凡的体验，前往国家实验室，并与更大的合作伙伴一起体验，帮助他们在科学劳动力中开拓出有意义的角色。该项目由数学和物理科学局内的物理部和既定的激励竞争性研究计划(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智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.