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.

现在，基本粒子特性的精确实验测试是一种良好的方法，可以在我们当前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，可以通过测量MUON的磁性异常来提供新物理学的固体信号，Muon是一种已知的基本粒子，在Fermi National Accelerator实验室中产生了丰富的基本粒子。 拟议的研究还旨在研究中子放射性衰减的详细行为。这项工作在最深的层面上解决了问题：什么是构成的，它是如何产生的，它是如何互动的？同时，这项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。现有的标准模型预测与MUON G-2的实验值之间现有的3.6 sigma差异提供了新物理学的持续实验室信号，并且我们有机会提高信号和增强信号的范围。作为Fermilab Muon G-2协作的一部分，我们的目标是将实验精度提高四倍，如果中心值不变，则会导致7- sigma信号，甚至如果理论误差降低，则会导致更大的信号。密歇根大学集团已将其努力从具有中子极化和精确中子极化法专业知识的基本中子物理学转变为Muon-Storage环磁场的测量问题。具有极化3HE的精确自旋细分和基于NMR的磁力计的专业知识和经验将应用于磁场测量系统的绝对校准问题，并确定现场测量的系统误差。特别是，这项研究将资助：1）基于NMR的磁场测量系统的NMR技术和系统学的开发，以及2）致力于在笔陷阱中绝对测量3HE磁矩。此外，提出的研究将完成NAB实验的SNS束的开发，特别是确定了使用3HE自旋滤波器确定基本中子物理束线（FNPB）束的残余极化。