Fundamental Studies in Nuclear Physics

PI将在三个不同的实验中对中子的物理性质进行精确测量。他的主要关注点将是通过寻找电偶极矩(EDM)来发展对中子电学性质的灵敏搜索。中子电火花加工可以发出新的物理学信号，超越我们目前对物理学的理解，并有助于解释为什么宇宙由物质主导，而不是由同等数量的物质和反物质(正如目前的物理定律所预测的那样)。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一大谜题。PI还将参与UCNtau(超冷中子寿命)实验，该实验的目标是捕获中子，以精确测量自由中子的寿命。这提供了有关弱核力的重要信息，这是理解宇宙开始时大爆炸的一部分，以及太阳中的核能产生。博士后学者、研究生和本科生参与这些实验，有助于为国家提供一支训练有素的核科学劳动力队伍，在医学、技术、国防和基础科学方面有应用。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进行捕获的超冷中子(UCN)的精确测量。他的团队最近完成了对UCNtau实验最新数据的三项独立分析中的一项，该实验使用了洛斯阿拉莫斯UCN设施的磁性/重力中子陷阱。这一数据提供了世界上最精确的中子寿命测量，与之前公布的结果相比，不确定度小了两倍。未来的数据采集将进一步提高实验的精度。该团队还在开发和建设一项新的实验方面发挥了主导作用，该实验将用于搜索自由中子的电偶极矩(EDM)。NEDM@SNS实验(在散裂中子源，ORNL)旨在将测量的灵敏度比以前的实验提高两个数量级。观测到的中子EDM发出了违反时间反转对称性的信号，并可能提供与物质起源有关的重要信息--宇宙的反物质不对称性，以及可能对此负责的新的物理现象。该实验的关键低温磁体和磁屏蔽将被委托，然后在SNS使用冷中子束进行安装和测试，以在本授权的时间范围内进行中子极化和传输研究。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。

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.