Fundamental symmetry tests with the francium laser trap facility at ISAC

自然的基本力量是一个迷人的主题，可以在ISAC，加拿大的放射性束设施在TRIUMF研究。特别是，导致原子核β衰变的弱力在显示宇称违反现象方面是独一无二的：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提供了一个独特的可能性，研究原子宇称不守恒在<$（Fr），一个元素结合了一个非常重的核（Z=87）与简单的，基本上是氢，价结构的碱金属。在元素周期表的前103种元素中，Fr核是最不稳定的，寿命最长的同位素衰变仅需23分钟。为了最大限度地利用微小的样品，Fr原子被激光减慢并被捕获到磁光激光阱中，悬浮在比室温低数百万倍的自由空间中。与来自美国和墨西哥的研究人员，包括3名研究生，一名博士后研究员和几名本科生研究生一起，我们在ISAC建立了一个Francium捕获设施，并对被捕获的Fr原子进行了首次测量，涉及一系列同位素中原子核内部的磁化分布。下一步，我们现在正在建立使用精确激光和微波光谱的实验，以最终研究<$中的原子宇称不守恒。微波实验将测量原子核内部的宇称非守恒效应，称为阿那普尔矩。到目前为止，只有铯和铊的一种同位素的测量已经完成，更多的数据对于更好地理解核物质中强子宇称不守恒是至关重要的。激光实验将在迄今为止非常成功的粒子物理标准模型之外，通过测量不依赖于核自旋的原子宇称不守恒来寻找“新”物理。该项目为广泛培训高素质人员提供了极好的机会。

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.