The Precision Frontier at FRIB: Masses, Radii, Moments, and Fundamental Interactions

原子核的基本力量和组成成分是什么？这个问题的答案是通过物质的基本核性质，如质量、电荷半径和原子向其他原子的衰变来揭示的。FRIB的精密测量小组将进行实验，以确定原子质量、核半径，并扩展对原子核奇异衰变的研究。这些测量的目的是提取原子核的基本性质，这些原子核具有较大的中子与质子比，这种情况只可能发生在自然界的极端天体物理事件中。该研究对核结构物理、核天体物理和多信使天体物理信号的解释具有重要意义。这里提出的工作也将通过测量提高对多信使天体物理事件中观测到的信号的解释，为美国国家科学基金会的大构想“宇宙之窗”做出重大贡献。精密测量小组将利用稀有同位素光束设施（FRIB）前所未有的能力来创建不寻常的同位素光束并测量其特性。该项目主要有三个重点。首先，测量原子质量。这些测量对于理解极端天体物理环境中的核合成和作为稳定边缘的核结构探针具有直接的重要性。此外，通过足够精确的测量，pi可以测试核物理和粒子物理中的基本对称性。第二，核半径和电磁矩。对镜像核性质的测量将有助于我们对核状态方程的理解，这对理解双中子星的合并尤其重要。此外，基态测量在各种系统测试核结构理论。第三，外来的相互作用。对奇异核、极化核和正电子的测量将测试基本的对称性。此外，这些测量测试了基本核理论的极端情况。测量将在FRIB停束线上进行，例如使用Penning陷阱和本地激光设备。这些工具也将提供给FRIB设施的其他用户。该奖项反映了美国国家科学基金会的法定使命，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。

What are the underlying forces and constituents of atomic nuclei? An answer to this question is revealed through the basic nuclear properties of matter such as the mass, charge radius, and decay of atoms into other atoms. The Precision Measurements group at FRIB will perform experiments to determine atomic masses, nuclear radii, and extend the search for exotic decays of nuclei. The measurements are designed to extract the fundamental properties of nuclei, with large neutron to proton ratios, which can only occur in Nature during extreme astrophysical events. The research has implications for nuclear structure physics, nuclear astrophysics and the interpretation of multi-messenger astrophysical signals. The work proposed here will also provide significant contributions to the NSF Big Idea “Windows on the Universe” through measurements that improve the interpretation of signals observed in multi-messenger astrophysical events.The Precision Measurements group will take advantage of the unprecedented capabilities of the Facility for Rare Isotope Beams (FRIB) to create beams of unusual isotopes and to measure their properties. There are three main thrusts in the project. First, measuring atomic masses. These measurements are of direct importance for understanding nucleosynthesis in extreme astrophysical environments and as probes of nuclear structure at the edge of stability. In addition, with adequately precise measurements, the PIs can test fundamental symmetries in Nuclear and Particle Physics. Second, nuclear radii and electromagnetic moments. Measurements of the properties of mirror nuclei will contribute to our understanding of the nuclear equation of state, which is particularly relevant for the understanding the merging of binary neutron stars. In addition, ground-state measurements in a variety of systems test nuclear-structure theory. Third, exotic interactions. Measurements with exotic nuclei, polarized nuclei, and positronium will test fundamental symmetries. In addition, these measurements test the extremes of basic nuclear theory.The measurements will be performed on the FRIB stopped-beam line using, for example, a Penning Trap and local laser facilities. These tools will also be made available to other users of the FRIB facility.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.