Fundamental symmetry tests with cold, trapped francium at ISAC

自然的基本力量是可以在ISAC研究的令人着迷的学科之一，ISAC是加拿大在TRIUMF的放射性束设施。特别是，导致原子核β衰变的弱力，在呈现宇称破坏现象方面是独一无二的：在自然界中，没有观察到由弱力中介的物理过程的镜像。ISAC为研究Fr中的原子宇称破坏提供了独特的可能性，Fr是一种将非常重的核(Z=87)与简单的、基本上类似氢的碱的价态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，寿命最长的同位素只在23分钟内衰变。为了最大限度地利用微小样品，Fr原子将被激光减速，并被捕获到一个“磁光”激光陷阱中，该陷阱悬浮在自由空间中，温度比室温低数百万倍。我们将在ISAC建立一个采集乳香的设施；然后，我们将与来自美国和墨西哥的研究人员合作，利用这个乳香来源，利用激光和微波光谱学进行一系列精确的实验。首先，我们将测量一串法郎同位素中的超精细异常，让我们深入了解核磁矩在原子核内的分布。另一项目标是通过观察一系列铀同位素中的核极点矩来研究破坏宇称的核子-核子相互作用；迄今为止，只对铯和铊的两种单一同位素进行了测量，更多的数据对于更好地理解核物质中的强子宇称破坏至关重要。最终，我们想通过测量原子核自旋独立的原子宇称破坏来寻找粒子物理标准模型之外的“新”物理--到目前为止非常成功。

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-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 will be 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 will establish a francium trapping facility at ISAC; in collaboration with researchers from the United States and Mexico, we will then use this francium source to carry out a series precision experiments using laser and microwave spectroscopy. First we will measure what is known as the hyperfine anomaly in a string of francium isotopes, giving us insight into the distribution of the nuclear magnetic moment within the nucleus. Another goal is to study parity-violating nucleon-nucleon interactions in francium by observing the nuclear anapole moments in a chain of francium isotopes; to date, only measurements in two single isotopes of cesium and thallium have been performed, and more data is crucial for a better understanding of hadronic parity violation in nuclear matter. Ultimately, we want to search for `new' physics outside the - so far very successful - Standard Model of particle physics by measuring nuclear-spin independent atomic parity-violation in francium.