Precision Measurements and Fundamental Symmetries

该奖项支持的研究将测试精确的标准模型预测，并通过1）测量μ子的磁性特征提供新物理学的坚实信号，μ子是费米国家加速器实验室大量产生的一种奇异基本粒子，2）研究中子衰变时的详细行为。这项工作解决了我们可以问的最深层次的问题：物质是由什么组成的，它是如何形成的，以及它如何相互作用。同时，这项工作通过推动磁场测量的极限来解决两个实验的技术要求。 这些技术的许多潜在的额外应用可能会扩展到生物学，神经科学和医学。 这项研究为密歇根大学的研究生和本科生提供了具有挑战性的研究项目。 一个不同的研究生群体正在从事这项研究的各个方面，并将加入以前的学生在促进国家利益作为教师，研究人员在物理学和生物医学领域和领导人在industry.This研究包括推进两个精密测量：μ子磁矩异常g - 2和β-中微子不对称参数在中子衰变.这些解决了基本粒子和核物理学中最深层次的问题，即标准模型之外的东西，通过在对新物理最敏感的系统中测试精确的预测。 密歇根大学的这个小组正在为费米实验室Muon g-2实验做出贡献，该实验正在完成第一次生产数据运行，目标是通过更好地控制和理解系统误差来等同于先前测量的实验精度，并为即将到来的数据运行做准备，目标是将实验精度提高四倍。 更具体地说，该团队开发了磁场精确测量及其绝对校准的关键创新，以及场测量数据分析中最具挑战性的方面的创新，即在校准运行之间进行插值，以跟踪磁场及其空间变化的变化。 该小组还将完成调试并开始Nab，这是一种新的精确测量中子衰变中β中微子不对称性参数a的方法，它还通过冗余测量参数lambda（轴向矢量与矢量耦合常数之比）来探索标准模型之外的物理学，该参数也由β不对称性（A）决定。在密歇根州设计和建造的中子自旋翻转器已被转移到ORNL的SNS的基本中子物理束（FNPB）。这将用于确定剩余中子束极化，这将对测量结果进行主要的系统校正。 由该小组开发和建造的He-3绝对校准磁力计已全面投入使用，灵敏度为ppb（十亿分之一），将可能影响从地质学到医学到物理学的精确磁场测量。 这项研究将继续播种一些推广机会，包括物理学及其应用的公开讲座，本科课程开发，为专业学生举办讲座，如国家核物理暑期学校。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

The research supported by this award will test precise Standard Model predictions and can provide solid signals of new physics by 1) measuring the magnetic signature of the muon, an exotic elementary particle that is produced in abundance at the Fermi National Accelerator Laboratory and 2) studying the detailed behavior of neutrons as they decay. This work addresses the deepest questions that we can ask: what is matter made of, how did it come to be, and how does it interact. At the same time this work addresses the technical demands of the two experiments by pushing the limits of magnetic field measurements. Many potential additional applications of these techniques may be extended into biology, neuroscience and medicine. This research provides challenging research projects for graduate and undergraduate students at the University of Michigan. A diverse cohort of graduate students are working on aspects of this research and will join former students in contributing to the National interest as teachers, researchers in physics and biomedical fields and leaders in industry.This research consists of advancing two precision measurements: the muon magnetic moment anomaly g - 2 and the beta-neutrino asymmetry parameter in neutron decay. These address the deepest question in elementary particle and nuclear physics, namely what lies beyond the Standard Model, by putting precise predictions to the test in systems most sensitive to new physics. This University of Michigan group is contributing to the Fermilab Muon g-2 experiment, which is completing the first production data run with the goal of equaling the experimental precision of the previous measurement with much better control and understanding of the systematic errors, and preparing for the upcoming data runs with the goal of improving the experimental precision by a factor of four. More specifically, the group has developed critical innovations for precision measurement of the magnetic field and its absolute calibration, and innovations in the most challenging aspect of the analysis of the field-measurement data, namely interpolating between calibration runs to track changes in the magnetic field and its spatial variations. The group will also complete commissioning and begin Nab, a new precision measurement of the beta-neutrino asymmetry parameter a in neutron decay that also probes physics Beyond the Standard Model by way of redundantly measuring the parameter lambda, the ratio of axial vector to vector coupling constants, which is also determined by the beta asymmetry (A). The neutron spin flipper designed and built at Michigan has been moved to the Fundamental Neutron Physics Beam (FNPB) at the SNS at ORNL. This will be used in determining the residual neutron beam polarization that would present a major systematic correction to the measurements. The He-3 magnetometer for absolute calibration developed and built by this group is fully operational, has sensitivity of sub ppb (part-per-billion) and will potentially impact precision magnetic field measurements from geology to medicine to physics. This research will continue to seed a number of outreach opportunities including public lectures on physics and its applications, undergraduate course development, lectures for specialist students such as the National Nuclear Physics Summer schools.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.