Spectroscopy of the 7s-8s highly forbidden transition in laser-trapped francium

激光捕获钫中 7s-8s 高度禁戒跃迁的光谱

• 批准号: 422682-2012
• 负责人: Gwinner, Gerald
• 金额: $ 10.75万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Research Tools and Instruments
• 财政年份: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=515837
• 关键词: Spectroscopy; 7s; 8s; highly; forbidden

The fundamental forces of nature are one of the fascinating subjects that can be studied at the ISAC radioactive beam facility at TRIUMF, Canada's national laboratory for nuclear and particle physics. In particular, the weak force, causing the beta-decay of nuclei, is unique in exhibiting the phenomenon of parity-violation: the mirror images of physical processes mediated by the weak force are not observed in nature. ISAC offers the possibility to study atomic parity-violation in francium (Fr), an element combining a very heavy nucleus (Z=87) with the simple, essentially hydrogenlike, valence structure of an alkali. Fr nuclei are the least stable among the first 103 elements in the periodic table, the longest-lived isotope decays in only 23 minutes. To make optimum use of the minute sample, the Fr atoms are slowed down with laser light and captured into a `magneto-optical' laser trap, suspended in free space at temperatures millions of times colder than room temperature. We have established a francium trapping facility at ISAC; in collaboration with researchers from the United States, Mexico, and China, we are now using this francium source to carry out a series of precision experiments using laser and microwave spectroscopy. In one of them, we will use the laser equipment requested in this application to excite an exceedingly faint electronic transition in francium, and study its properties in detail. The strength of this transition is very sensitive to relativistic effects in the francium atom and its measurement allows a comparison to state-of-the-art atomic theory. In addition, the 7s-8s transition in Fr is the basis for a possible, future atomic parity-violation experiment.

自然界的基本力是可以在加拿大国家核与粒子物理实验室TRIUMF的ISAC放射性束设施中研究的迷人课题之一。特别是，导致原子核β衰变的弱力在显示宇称破坏现象方面是独一无二的：由弱力介导的物理过程的镜像在自然界中是观察不到的。ISAC提供了研究<$（Fr）中原子宇称破坏的可能性，<$是一种将非常重的核（Z=87）与简单的、基本上类似氢的碱金属价结构结合在一起的元素。在元素周期表的前103种元素中，Fr核是最不稳定的，寿命最长的同位素衰变仅需23分钟。为了最大限度地利用微小的样品，Fr原子被激光减速，并被捕获到一个“磁光”激光阱中，悬浮在比室温低数百万倍的自由空间中。我们已经在ISAC建立了一个<$捕获设施;与来自美国、墨西哥和中国的研究人员合作，我们现在正在使用这种<$源，利用激光和微波光谱进行一系列精密实验。在其中一个项目中，我们将使用本申请所要求的激光设备来激发<$中非常微弱的电子跃迁，并详细研究其性质。这种跃迁的强度对<$原子中的相对论效应非常敏感，它的测量可以与最先进的原子理论进行比较。此外，Fr的7s-8 s跃迁是未来可能的原子宇称违反实验的基础。