Experiments Sensitive to the Electron's Electric Dipole Moment in PbF

对 PbF 中电子电偶极矩敏感的实验

• 批准号: 1307337
• 负责人: John Furneaux
• 金额: $ 2.5万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1307337&HistoricalAwards=false
• 关键词: Experiments; Sensitive; Electron; Electric; Dipole

In 1950, six years before Lee and Yang's famous assertion of a fundamental difference between a left- and right- handed world, Purcell and Ramsey first suggested that discrete symmetries may not be sacred. Specifically Purcell and Ramsey proposed that neutrons and electrons may possess an electric dipole moment (EDM) proportional to spin that violates time-reversal symmetry. Whereas Madam Wu's observation of parity violation in the Beta decay of Cobalt-60 almost immediately verified Lee and Yang?s assertion, Purcell and Ramsey's suggestion of an electric dipole moment launched an experimental hunt that is still ongoing today. This project seeks to continue our progress toward a significant measurement of the e-EDM using PbF. A non-zero e-EDM would break the normal degeneracy between paramagnetic states of molecules that differ only by the direction of rotation with respect to an applied electric field. The strong internal electric field of these molecules causes even a small e-EDM to break this degeneracy by a relatively large amount. Our experimental concept is guided by 6 years of intensive spectroscopy which has led to a detailed understanding of the electronic, vibrational, rotational, hyperfine, Zeeman, and Stark structures of the PbF molecule, with the ground state energy level structure of the X1 state now understood to an accuracy of 200 Hz and the energy level structure of the long-lived A state understood to an accuracy of 10 MHz. The large body of data we have collected on this molecule has led us to an optical double resonance experiment that searches for an e-EDM in the even parity ground state. This molecular state is unique in that it is sensitive to an e-EDM, it has a small magnetic g factor at the electric fields of the experiment, and has a spectroscopy that demonstrates focused (hyperfine resolved) spectra at high electric fields. We will concentrate on necessary details in PbF spectroscopy and the geometric phase effect using a slightly modified molecular beam apparatus with the full optical double resonance technique. This measurement will test models of the geometric phase, which is an important source of systematic error, and our entire data collection system. The e-EDM search has a history of making dramatic broader impacts. E.g. Ramsey developed the separated oscillator atomic clock that allows timing so accurate that a satellite-based global positioning system is feasible; Eric Cornell has developed a frequency-locked comb-based measurement system with both extremely high resolution and high scan range that may lead to a new era of molecular fingerprinting. Finally, we have developed a high-precision ( 5 MHz) resonant ionization scheme that has an unprecedented combination of resolution and sensitivity. This new technique, pc-REMPI, will be of general spectroscopic use: e.g. trace detection including remote detection of explosives, molecular fingerprinting, chemical reaction dynamics. This grant provides training for graduate students to acquire critical skills that are important for the future scientific work force.

1950年，在李和杨提出左手世界和右手世界的根本区别的著名论断的六年前，珀塞尔和拉姆齐首次提出离散对称性可能并不神圣。特别是珀塞尔和拉姆齐提出，中子和电子可能拥有与自旋成比例的电偶极矩（EDM），这违反了时间反演对称性。而吴女士在钴-60的β衰变中观察到宇称破坏，几乎立即证实了李和杨？在他的断言之后，珀塞尔和拉姆齐关于电偶极矩的建议引发了一场至今仍在进行的实验性搜寻。该项目旨在继续我们的进展，对一个显着的测量e-EDM使用PbF。非零e-EDM将打破分子的顺磁状态之间的正常简并性，所述顺磁状态仅在相对于所施加的电场的旋转方向上不同。这些分子的强内部电场导致即使是小的e-EDM也能相对大量地破坏这种简并性。 我们的实验概念是由6年的密集光谱学，这导致了详细了解的电子，振动，旋转，超精细，塞曼，和斯塔克结构的PbF分子，与基态能级结构的X1状态现在理解的精度为200赫兹和能级结构的长寿A状态理解的精度为10 MHz的指导。我们收集到的大量关于这种分子的数据使我们进行了光学双共振实验，该实验在偶宇称基态中搜索e-EDM。这种分子状态是独特的，因为它对e-EDM敏感，它在实验的电场下具有小的磁性g因子，并且具有在高电场下展示聚焦（超精细分辨）光谱的光谱。我们将集中在必要的细节，在PbF光谱和几何相位效应，使用一个稍微修改的分子束装置与全光学双共振技术。该测量将测试几何相位模型（这是系统误差的重要来源）以及我们的整个数据收集系统。e-EDM搜索有着产生巨大广泛影响的历史。例如，Ramsey开发了分离振荡器原子钟，其计时如此精确，以至于基于卫星的全球定位系统是可行的; Eric Cornell开发了一种基于频率锁定的梳状测量系统，具有极高的分辨率和高扫描范围，可能会导致分子指纹的新时代。最后，我们开发了一种高精度（5 MHz）的共振电离方案，具有前所未有的分辨率和灵敏度的组合。这种新技术，pc-REMPI，将具有一般的光谱用途：例如痕量检测，包括爆炸物的远程检测、分子指纹、化学反应动力学。该补助金为研究生提供培训，以获得对未来科学工作者至关重要的关键技能。