Precision Measurements and Fundamental Symmetries

精密测量和基本对称性

• 批准号: 1506021
• 负责人: Timothy Chupp
• 金额: $ 48万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506021&HistoricalAwards=false
• 关键词: Precision; Measurements; Fundamental; Symmetries

Precise experimental tests of fundamental particle properties are now a well-established way to search for new laws of nature beyond our current physical knowledge. The research presented in this proposal challenges precise Standard Model predictions and could provide solid signals of new physics by measuring the magnetic-moment anomaly of the muon, a known elementary particle that is produced in abundance at the Fermi National Accelerator Laboratory. The proposed research is also to study the detailed behavior of the radioactive decay of neutrons. This work addresses questions at the deepest level: what is matter made of, how did it come to be and how does it interact? At the same time, this research addresses the technical demands of the experiments by pushing the limits of magnetic field measurement to a higher level.The existing 3.6-sigma difference between the Standard-Model prediction and the experimental value of g-2 of the muon provides a persistent laboratory signal of new physics, and we have the opportunity to advance the precision and strengthen the signal to reach discovery level. As part of the Fermilab Muon g-2 collaboration, our goal is to improve the experimental precision by a factor of four, which would result in a 7-sigma signal if the central value does not change, or even larger if the theory error is reduced. The University of Michigan group has shifted its effort from fundamental neutron physics with expertise in neutron polarization and precision neutron polarimetry to the problem of measurement of the muon-storage ring magnetic field. This expertise and experience in precision spin-precession and NMR-based magnetometry with polarized 3He will be applied to the problem of absolute calibration of the magnetic field measurement system and determining the systematic errors on the field measurement. In particular, this research will fund: 1) development of NMR techniques and systematics of the NMR-based magnetic-field measurement system and 2) work towards an absolute measurement of the 3He magnetic moment in a Penning trap. Furthermore, the proposed research will complete the development of the SNS beam for the Nab experiment, specifically the determination of the residual polarization of the Fundamental Neutron Physics Beamline (FNPB) beam using a 3He spin filter.

对基本粒子性质的精确实验测试现在是一种行之有效的方法，可以在我们现有的物理知识之外寻找新的自然定律。 该提案中提出的研究挑战了精确的标准模型预测，并可以通过测量μ子的磁矩异常来提供新物理学的可靠信号，μ子是费米国家加速器实验室大量产生的已知基本粒子。 拟议的研究还将研究中子放射性衰变的详细行为。这项工作解决了最深层次的问题：物质是由什么组成的，它是如何形成的，以及它是如何相互作用的？与此同时，本研究通过将磁场测量的极限推向更高水平来解决实验的技术需求。μ子的g-2的标准模型预测与实验值之间存在3.6 σ的差异，这为新物理提供了持久的实验室信号，我们有机会提高精度并加强信号以达到发现水平。作为Fermilab Muon g-2合作的一部分，我们的目标是将实验精度提高四倍，如果中心值不变，则会产生7-sigma信号，如果理论误差减小，则会更大。密歇根大学的研究小组已经将其工作从具有中子极化和精确中子极化测量专门知识的基础中子物理学转移到测量μ子储存环磁场的问题上。这种专业知识和经验，在精密自旋进动和核磁共振为基础的磁力与极化3 He将被应用到磁场测量系统的绝对校准和确定的系统误差的问题，现场测量。特别是，这项研究将资助：1）NMR技术的发展和基于NMR的磁场测量系统的系统学，2）致力于在潘宁阱中绝对测量3 He磁矩。此外，拟议的研究将完成Nab实验的SNS束的开发，特别是使用3 He自旋过滤器确定基本中子物理束线（FNPB）束的剩余极化。