A Guided-Beam Measurement of the Electron's Electric Dipole Moment

该基金支持Ramsey双共振装置的开发，该装置使用PbF的相干激发分子束来搜索电子的电偶极矩（e-EDM）。当前阶段的工作涉及将用于e-EDM搜索的PbF分子的跃迁和状态的精确光谱-基态X1（nu=0，J=1/2,+,|M|=1，F=1）和激发态A（nu=0，J=1/2,+，M=0，F=1）之间的超精细分辨跃迁。具体地说，我们正在精确地确定这个跃迁的能量，以及外加电场对这个跃迁的影响。后一种测量方法将以比目前已知的更高的精度确定PbF分子电偶极矩。我们还利用双原子同位素130-碲分子的精确特征吸收谱线来提高激光系统的稳定性。该项目的未来步骤包括通过构建具有可调节几何相位的分子束，测试我们的整个测量系统以及我们对几何相位的理解，几何相位是我们提出的测量中的一个重要系统误差。然后，我们将展示，我们可以预测，产生和测量特定电场结构的几何相位。与我们对宇宙的理解相关的一个深刻的谜题是观察到的物质和反物质之间的不对称性。为什么我们的宇宙是由物质而不是反物质构成的？影响这种不对称性的一个因素是通过测量电子的电偶极矩（e-EDM）来确定的电子形状。这种e-EDM的可能性最早是由Purcell和Ramsey（物理学家）提出的。Rev. 78,807(1950)) 60多年前。最近，伦敦帝国理工学院的一个研究小组在Nature， 473,493（2011）上报道了e-EDM的新限制。我们正在进行一个类似的、更灵敏的实验，要么为这个重要常数设定一个更低的极限，要么用PbF更精确地测量它。我们正处于计划实验的初步阶段，这笔拨款资助了重要的光谱测量和设备开发，使最终的e-EDM测量成为可能。

This grant supports the development of a Ramsey double resonance apparatus using a coherently excited molecular beam of PbF to search for the electron's electric dipole moment (e-EDM). The current phase of the work involves precise spectroscopy of the transitions and states of the PbF molecule that will be used in the e-EDM search -- the hyperfine-resolved transition between the ground state X1(nu=0,J=1/2,+,|M|=1,F=1) and the excited state A(nu=0,J=1/2,+,M=0,F=1)). Specifically, we are making precision determinations of the energy of this transition and the effect of an applied E field to this transition. The latter measurement will determine the PbF molecular electric dipole moment to higher accuracy than currently known. We are also improving the stability of our laser system by using precisely characterized absorption lines in diatomic isotopic 130-Tellurium molecule. Future steps in this project include testing our entire measurement system along with our understanding of the Geometric Phase, an important systematic error in our proposed measurement, by constructing a molecular beam with an adjustable geometric phase. We will then show that we can predict, produce and measure this geometric phase for a specific configuration of electric fields.One of the profound puzzles associated with our understanding of the universe is the asymmetry between matter and anti-matter that is observed. Why is our universe made of matter and not anti-matter? A factor that affects this asymmetry is the shape of the electron as determined by measuring the electron's electric dipole moment (e-EDM). The possibility of such an e-EDM was first proposed by Purcell and Ramsey (Phys. Rev. 78, 807 (1950)) over 60 years ago. A new limit on the e-EDM was recently reported in Nature, 473,493 (2011) by a group at Imperial College, London. We are working on a similar, more sensitive, experiment to either set an even lower limit on this important constant or to more precisely measure it using PbF. We are in the preliminary phases of the planned experiment and this grant funds important spectroscopic measurements and equipment developments making an eventual e-EDM measurement possible.