PM: Cold Radioactive Molecules for Precision Measurements.

PM：用于精密测量的冷放射性分子。

• 批准号: 2309361
• 负责人: Nicholas Hutzler
• 金额: $ 64.31万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2309361&HistoricalAwards=false
• 关键词: PM; Cold; Radioactive; Molecules; Precision

The fact that the Universe is made from matter, yet contains no anti-matter, is a mystery. Nobody knows which physical process was responsible for generation of matter in the early Universe, but we do know that it can manifest itself in some unusual ways. One way is by modifying the electromagnetic properties of nuclei, which can be studied precisely in a table-top setting using laser-controlled and atoms and molecules. Some nuclei are more sensitive than others to these effects, and it has been known for decades that polar molecules containing certain heavy, unstable nuclei in the last row of the periodic table amplify the effects of this new physics by around a million times compared to current state-of-the-art experiments. However, these gains remain unrealized; the complexity of even the simplest molecule, combined with the limited amounts of unstable nuclei which can be obtained and handled in the laboratory, made this research very challenging. Indeed, the first precise laser-based measurement of any radioactive molecule was first performed a few years ago. For this present study, the PI will lead a team of students to develop and demonstrate a new method to synthesize, cool, and precisely study the structure and properties of molecules containing radium – one of the nuclei with the highest sensitivity to new fundamental physics. The research team will combine laser-driven chemical reactions, cryogenic helium gas cooling, and new approaches to precision spectroscopy to study polyatomic radium-containing molecules, whose chemical structures are tuned to enable advanced quantum control to study these exotic nuclei. Furthermore, the method will be widely applicable to molecules containing unstable or rare nuclei for studies in nuclear structure, radiochemistry, and nuclear astrophysics.Molecules containing heavy, octupole-deformed nuclei, such as radium, offer extreme enhancement of hadronic CP-violation. The combination of the intermolecular electromagnetic environment and the shape deformation of the nucleus result in around a million-fold enhancement in sensitivity to CP-violating nuclear Schiff moments compared to state-of-the-art experiments using atoms with spherical nuclei. Furthermore, many radium-containing molecules are predicted to be laser-coolable, meaning that they offer an avenue to advanced quantum control for highly sensitive measurements. However, the difficulty of working with these species has stifled their study; indeed, only in the last few years has precision spectroscopy been performed on any short-lived radioactive molecular species. The goal of this research program is to synthesize, cool, and spectroscopically study radium-containing polyatomic molecules, including RaOH, by combining laser-driven chemical synthesis, cryogenic buffer gas cooling, and new approaches to both broadband and narrowband spectroscopy with very small quantities of material. The method will produce molecules which are rotationally and translationally cooled to around 4 K in a static buffer gas cell, thereby placing them at a starting point for spectroscopy, laser cooling, and precision measurements. Furthermore, the methods will be very general, and can be applied to a wide variety of molecules containing exotic nuclei or otherwise available only in trace amounts.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.

宇宙是由物质组成的，但不包含反物质，这是一个谜。 没有人知道是哪个物理过程导致了早期宇宙中物质的产生，但我们知道它可以以一些不寻常的方式表现出来。 一种方法是通过修改原子核的电磁特性，这可以在桌面上使用激光控制原子和分子进行精确研究。 一些原子核对这些效应比其他原子核更敏感，几十年来人们已经知道，与当前最先进的实验相比，在周期表的最后一行含有某些重的不稳定原子核的极性分子将这种新物理学的效应放大了大约一百万倍。 然而，这些成果仍然没有实现;即使是最简单的分子的复杂性，加上实验室中可以获得和处理的不稳定核的数量有限，使得这项研究非常具有挑战性。 事实上，第一次精确的基于激光的放射性分子测量是在几年前。 在本研究中，PI将带领一个学生团队开发和演示一种新的方法来合成，冷却和精确研究含镭分子的结构和性质-镭是对新基础物理学具有最高灵敏度的原子核之一。 研究小组将结合联合收割机激光驱动的化学反应，低温氦气冷却和精密光谱学的新方法来研究多原子含镭分子，其化学结构经过调整，使先进的量子控制能够研究这些奇异的原子核。 此外，该方法还可广泛应用于含不稳定核或稀有核的分子的核结构、放射化学和核天体物理研究。含重八极形变核的分子，如镭，可极大地增强强子CP破坏。 分子间电磁环境和核的形状变形的组合导致对CP违反核希夫矩的灵敏度比使用具有球形核的原子的最先进实验提高了大约一百万倍。 此外，许多含镭分子被预测是可激光冷却的，这意味着它们为高灵敏度测量提供了先进的量子控制途径。 然而，与这些物种合作的困难扼杀了他们的研究;事实上，只有在过去的几年里，才对任何短寿命的放射性分子物种进行了精确的光谱分析。 这项研究计划的目标是合成，冷却和光谱研究含镭的多原子分子，包括氢氧化镭，通过结合激光驱动的化学合成，低温缓冲气体冷却，以及新的方法来宽带和窄带光谱与非常少量的材料。 该方法将产生在静态缓冲气室中旋转和冷却至约4 K的分子，从而将它们置于光谱学，激光冷却和精密测量的起点。 此外，该方法将是非常普遍的，并可以应用于各种各样的分子含有外来核或以其他方式提供只有在微量。这一奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。