Precision Measurement of Parity Non-Conserving, Weak-force Induced Transitions in Atomic Cesium

原子铯中宇称非守恒、弱力诱导跃迁的精确测量

• 批准号: 1912519
• 负责人: Daniel Elliott
• 金额: $ 108.21万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-15 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1912519&HistoricalAwards=false
• 关键词: Precision; Measurement; Parity; Non; Conserving

We understand the universe in which we live through four fundamental forces: gravitational, electromagnetic, weak (responsible for radioactivity and beta decay), and strong (which provides the force that binds atomic nuclei together). A theoretical framework that unifies three of these forces (electromagnetic, weak and strong) is known as the standard model, and has been very successful at explaining a broad range of observables and predicting others. There are, however, several notable effects that the standard model has not been able to explain, including the preponderance of regular matter in the universe (but very little anti-matter), and the existence and nature of dark matter and dark energy. The evidence of the existence of dark matter is provided by observations of the rotation of galaxies. From this, we know that the universe contains much more matter than we have been able to observe. But we know very little about what this "dark" matter is, or how, other than through gravity, it interacts with the matter that we can observe. In this project, the principal investigator and his team will use precision measurements of extremely weak optical interactions of a laser field with cesium atoms to test the standard model, and to search for signatures of physical effects that lie outside the realm of the standard model. The Principal Investigator and his research team are developing two measurement techniques to probe the weak force interactions in atomic cesium. Each measurement technique is a variant of two-color coherent control, in which the amplitudes for two transitions in the optical or radio-frequency range interfere with one another. One measurement, based on the 6s 2S1/2 → 7s 2S1/2 transition, is designed to provide an improved value of the weak charge of the cesium nucleus. The second, based on the 9.19 GHz transition between the hyperfine components of the ground state, is due solely to nuclear-spin dependent contributions such as the anapole moment of the nucleus. Atomic cesium was, of course, the choice of Wieman for his 1997 work, and that group's measurement is still the most precise measurement of the weak charge in any atomic species. Cesium is also the only species in which the nuclear anapole moment has been observed. The degree to which the measurement of the weak charge agrees with the standard model prediction will place constraints upon various models of physics beyond the standard model. The coherent control technique is expected to result in a reduction of the susceptibility of the measurement to systematic errors, critical for the success of these measurements.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.

我们了解我们通过四个基本力量生活的宇宙：重力，电磁，弱（负责放射性和β衰变）和强（提供将原子核结合在一起的力）。统一这些力的三个（电磁，弱和强）的理论框架被称为标准模型，并且非常成功地解释了广泛的可观察物和预测其他模型。 但是，标准模型无法解释的几种值得注意的效果，包括宇宙中常规物质的优势（但很少有反物质），以及暗物质和暗能量的存在和性质。 通过观察星系旋转的观察，存在暗物质存在的证据。 从中，我们知道宇宙所包含的物质比我们能够观察到的要多得多。 但是，我们对“黑暗”的问题是什么，或者除了通过重力之外，它与我们可以观察到的问题相互作用。 在该项目中，主要研究人员及其团队将使用激光场与剖子原子的极弱的光学相互作用的精确测量来测试标准模型，并搜索在标准模型领域之外的物理效果的签名。首席研究员和他的研究团队正在开发两种测量技术，以探测原子剖宫产中的弱力相互作用。 每种测量技术都是两色相干控制的变体，其中光学或射频范围中两个过渡的幅度相互交流。 一种测量，基于6S 2S1/2＆＃8594; 7S 2S1/2转变旨在提供核核弱电荷的改进值。第二个基于基态超精细成分之间的9.19 GHz转变，仅是由于核旋转依赖性贡献（例如核的Anapole矩）。 当然，原子剖宫产是Wieman在1997年的工作中的选择，该小组的测量仍然是对任何原子物种中弱电荷的最精确测量。 剖宫产也是唯一观察到核方矩矩的物种。 弱电荷测量与标准模型预测一致的程度将对超出标准模型的各种物理模型构成约束。 预计相干控制技术将降低测量对系统错误的敏感性，这对于这些测量的成功至关重要。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点评估来获得支持的，并具有更广泛的影响标准。