Developing a Radium Toolset for New Physics

这项工作将把离子俘获技术(利用电场抓住并保持一个缺少电子的原子)应用到一种异常重的、具有放射性的原子：镭。这种原子对于研究早期宇宙的条件特别重要。部分原因是它含有一个变形的原子核，特别是一个梨形的原子核，这使得它对某些影响比具有更圆的原子核的更轻的元素更敏感。然而，由于镭是放射性的，研究它是具有挑战性的。这项工作解决了这一挑战，在一个实验中使用了一个小的镭样本，在这个实验中，激光被用来冷却和捕获镭离子，并将它们保持很长一段时间进行研究。这项工作将首次测量镭离子的一些基本性质。它还将创造和研究含有镭的分子离子。这项工作将提高对这种元素及其解决长期存在的物理问题的潜力的理解。在这个项目中，Pi和他的同事们的目标是首次测量基本的Re离子性质，并研究基于Re的分子离子。对于镭离子，他们将测量7P_3/2态的分支分数，7P_1/2，7P_3/2，6D_3/2和6D_5/2态的寿命。除了6D_5/2寿命的下限外，这些值以前都没有测量过。这些值对于基本理解镭离子很重要，对于高级工作，如宇称非守恒测量，也是必不可少的。该小组将进一步研究基于镭的分子离子，如RaOH，这些离子很有希望用于研究电荷宇称破坏。他们计划在离子陷阱中创建分子离子，用共捕获的Ra对其进行交感冷却，然后用光解离谱来探测分子离子，以提供对其能级结构的基本了解。这一奖项反映了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。

This work will deploy ion trapping techniques (in which electric fields are used to grab onto and hold an atom which has a missing electron) to an unusually heavy, and radioactive, atom: radium. This atom is particularly important for the study of the conditions in the early universe. Part of the reason is that it contains a deformed nucleus, specifically one with a pear shape, which makes it more sensitive to some effects than lighter elements with a more round nucleus. Because radium is radioactive, however, it is challenging to study. This work addresses this challenge by using a small radium sample in an experiment in which lasers are used to cool and trap radium ions and hold them for extended periods of time to study. This work will produce the first measurements of some basic properties of the radium ion. It will also create and study molecular ions that contain radium. This work will improve understanding of the element and its potential to address long-standing physics questions.In this project the PI and his colleagues aim to make first measurements of basic radium ion properties and study radium-based molecular ions. For the radium ion they will measure the branching fractions of the 7P_3/2 state, the lifetimes of the 7P_1/2, 7P_3/2, 6D_3/2, and 6D_5/2 states. Besides a lower bound on the 6D_5/2 lifetime none of these values have been previously measured. The values are important for a basic understanding of the radium ion, and essential for advanced work, such as parity nonconservation measurements. The group will further study radium-based molecular ions, such as RaOH+, which are promising for studying charge-parity violation. They plan to create the molecular ions in the ion trap, sympathetically cool them with co-trapped Ra+, and then probe the molecular ions with photodissociation spectroscopy to provide a basic understanding of their energy level structure.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.