Fundamental Studies in Nuclear Physics

PI将在三个独立的实验中对中子的物理性质进行精确测量。他的主要重点将是通过寻找电偶极矩（EDM）来开发对中子电特性的灵敏搜索。中子EDM可以发出超越我们目前对物理学理解的新物理学信号，并有助于解释为什么宇宙由物质而不是等量的物质和反物质（如目前物理学定律所预测的那样）主导。物质和反物质之间的不对称性仍然是我们理解宇宙演化的最大难题之一。PI还将参与UCNTau（超冷中子寿命）实验，其目标是捕获中子以精确测量自由中子的寿命。这提供了关于弱核力的重要信息，这是理解宇宙开始时大爆炸以及太阳核能产生的一部分。由博士后学者、研究生和本科生参与的这些实验有助于为国家提供训练有素的核科学人才，在医学、技术和国防以及基础科学方面都有应用。PI将使用新开发的技术，在洛斯阿拉莫斯和橡树岭国家实验室对捕获的超冷中子（UCN）进行精确测量。他的团队最近完成了对UCNTau实验最新数据的三项独立分析之一，该实验使用了洛斯阿拉莫斯UCN设施的磁/重力中子阱。这些数据提供了世界上最精确的中子寿命测量，与以前公布的结果相比，不确定性小了两倍。未来的数据采集将进一步提高实验的精度。 该团队还在一项新实验的开发和建设中发挥了主导作用，该实验将用于寻找自由中子的电偶极子矩（EDM）。nEDM@SNS实验（在SparkleNeutron Source，ORNL）旨在将测量的灵敏度提高两个数量级。对中子EDM的观测表明违反了时间反演对称性，并可能提供与宇宙物质-反物质不对称性的起源有关的重要输入以及可能对此负责的新物理现象。实验的临界低温磁体和磁屏蔽将被委托，然后在SNS上安装和测试，使用冷-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。

The PI will make precise measurements of the physical properties of the neutron in three separate experiments. His main focus will be to develop a sensitive search for the electrical properties of the neutron by searching for an electric dipole moment (EDM). A neutron EDM could signal new physics beyond our current understanding of physics and help to explain why the universe is dominated by matter rather than equal amounts of matter and antimatter (as predicted by the present laws of physics). The asymmetry between matter and antimatter remains one of the great puzzles in our understanding of the evolution of the universe. The PI will also participate in the UCNtau (Ultra-Cold Neutron Lifetime) experiment where the goal is to trap neutrons to make a precise measurement of the lifetime of a free neutron. This provides important information about the weak nuclear force that is part of understanding the Big Bang at the beginning of the universe as well as nuclear energy generation in the sun. Participation in these experiments by postdoctoral scholars, graduate students, and undergraduates helps provide the nation with a highly trained workforce in Nuclear Science, with applications in medicine, technology, and national defense as well as basic science.The PI will use newly developed techniques to perform precision measurements with trapped Ultra-Cold Neutrons (UCN) at Los Alamos and Oak Ridge National Laboratory. His group has recently completed one of three independent analyses of the latest data from the UCNtau experiment which uses a magnetic/gravity neutron trap at the Los Alamos UCN facility. This data provides the world’s most precise measurement of the neutron lifetime, with a factor of two smaller uncertainty compared to previously published results. Future data taking will further improve the precision of the experiment. The team also plays a leading role in the development and construction of a new experiment which will be used to search for the Electric Dipole Moment (EDM) of the free neutron. The nEDM@SNS experiment (at the Spallation Neutron Source, ORNL) is designed to improve the sensitivity of the measurement by two orders-of-magnitude compared to previous experiments. The observation of a neutron EDM signals a violation of time-reversal symmetry and could provide important input related to the origin of the matter-antimatter asymmetry of the universe and new physical phenomena that may be responsible for it. The critical cryogenic magnets and magnetic shielding of the experiment will be commissioned and then installed and tested at the SNS using a cold-neutron beam to perform neutron polarization and transmission studies during the time frame of this grant.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.