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

1950年，在李和杨著名的左撇子和右撇子世界之间存在根本区别的断言六年前，珀塞尔和拉姆齐首次提出离散对称可能不是神圣的。具体地说，珀塞尔和拉姆齐提出，中子和电子可能具有与自旋成正比的电偶极矩(EDM)，这违反了时间反转对称性。虽然吴女士在钴-60的贝塔衰变中观察到的宇称破坏几乎立即证实了李和杨？S的断言，但珀塞尔和拉姆齐关于电偶极矩的提议发起了一项至今仍在进行的实验性探索。这个项目寻求继续我们的进展，以实现使用PBF的电子电火花加工的重要测量。非零的e-EDM将打破分子顺磁状态之间的正常简并，分子的顺磁状态仅在相对于外加电场的旋转方向上不同。这些分子强大的内部电场使得即使是一个小的电火花加工也能以相对较大的量打破这种简并。我们的实验概念是由6年的密集光谱指导的，这导致了对PBF分子的电子、振动、旋转、超精细、塞曼和斯塔克结构的详细了解，其中X1态的基态能级结构现在被理解为200赫兹的精度，而长寿命A态的能级结构被理解为10 MHz的精度。我们收集了大量关于这种分子的数据，这让我们进行了光学双共振实验，寻找偶偶宇称基态的电子电火花。这种分子状态是独特的，因为它对e-EDM很敏感，在实验的电场中具有小的磁性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。我们将使用略微改进的分子束装置和全光学双共振技术，集中讨论PBF光谱和几何相位效应中的必要细节。这项测量将测试几何相位的模型，这是系统误差的重要来源，以及我们整个数据收集系统。E-EDM搜索有着产生戏剧性更广泛影响的历史。例如，Ramsey开发了分离振荡器原子钟，它的计时非常精确，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，可能会引领分子指纹识别的新时代。最后，我们开发了一种高精度(5 MHz)的共振电离方案，它具有前所未有的分辨率和灵敏度的组合。这项名为PC-REMPI的新技术将用于一般光谱用途：例如，痕迹检测，包括爆炸物的远程检测，分子指纹，化学反应动力学。这项资助为研究生提供培训，以获得对未来科学工作至关重要的关键技能。

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.