Fundamental symmetry tests with the francium laser trap facility at ISAC

使用 ISAC 的钫激光陷阱设施进行基本对称性测试

• 批准号: SAPPJ-2018-00027
• 负责人: Gwinner, Gerald
• 金额: $ 12.38万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Project
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718938
• 关键词: Fundamental; symmetry; tests; francium; laser

The fundamental forces of nature are one of the fascinating subjects that can be studied at ISAC, Canada's radioactive beam facility at TRIUMF. 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 a unique possibility to study atomic parity non-conservation 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-optic laser trap, suspended in free space at temperatures millions of times colder than room temperature. Together with researchers from the United States and Mexico, including 3 graduate students, one postdoctoral fellow, and several undergraduate research students, we have established a francium trapping facility at ISAC and have carried out first measurements with trapped Fr atoms, concerning the distribution of magnetization inside the nucleus in a string of isotopes. In a next step, we are now setting up experiments using precise laser and microwave spectroscopy to ultimately study atomic parity non-conservation in francium. The microwave experiment will measure a parity non-conserving effect inside the nucleus known as the anapole moment. To date, only measurements in one isotope of cesium and thallium each have been performed, and more data is crucial for a better understanding of hadronic parity non-conservation in nuclear matter. The laser experiment will search for 'new' physics outside the - so far very successful - Standard Model of particle physics by measuring nuclear-spin independent atomic parity non-conservation in francium. The project offers outstanding opportunities for the broad training of highly qualified personnel.

自然的基本力量是一个迷人的主题，可以在ISAC，加拿大的放射性束流设施在TRIUMF研究。特别是，引起原子核β衰变的弱力，在显示宇称违反现象方面是独一无二的：在自然界中没有观察到由弱力介导的物理过程的镜像。ISAC为研究钫（Fr）的原子宇称不守恒提供了独特的可能性，钫是一种结合了非常重的原子核（Z=87）和碱的简单的、本质上类似氢的价结构的元素。Fr是元素周期表前103个元素中最不稳定的，寿命最长的同位素衰变时间只有23分钟。为了充分利用微小的样品，用激光减慢Fr原子的速度，并将其捕获到磁光激光阱中，在比室温低数百万倍的温度下悬浮在自由空间中。我们与来自美国和墨西哥的研究人员（包括3名研究生、1名博士后和几名本科生）一起，在ISAC建立了一个钫捕获装置，并首次对捕获的Fr原子进行了测量，研究了一系列同位素中原子核内部的磁化分布。下一步，我们正在建立实验，使用精确的激光和微波光谱，最终研究钫的原子宇称不守恒。微波实验将测量原子核内部的宇称非守恒效应，即赝极矩。到目前为止，只对铯和铊的一种同位素进行了测量，更多的数据对于更好地理解核物质中的强子宇称不守恒至关重要。激光实验将通过测量钫中与核自旋无关的原子宇称不守恒，来寻找粒子物理学标准模型之外的“新”物理——迄今为止非常成功。该项目为广泛培训高素质人才提供了极好的机会。