Laser Excitation of the 229-Th Nuclear Isomer

第 229 个核异构体的激光激发

• 批准号: 1360546
• 负责人: Alexander Kuzmich
• 金额: $ 44万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1360546&HistoricalAwards=false
• 关键词: Laser; Excitation; 229; Th; Nuclear

While typical nuclear excitation energies are in the keV to MeV range, there are several exceptional cases where the excitation energies are much lower. The subject of this project is the thorium-229 isotope, which, uniquely, has an excited state in the UV optical spectrum. Several experimental searches for optical emission in this range undertaken in the past ten years were unsuccessful or inconclusive. In addition to searching in the wrong energy region, the searches were challenged by the narrow linewidth of the nuclear transition. In this work, an alternative electron-bridge transition will be employed for the initial laser excitation of the nuclear isomer level in thorium-229. The nuclear transition is likely to be exceptionally sensitive to the variation of fundamental constants, due to the interplay of the strong and electroweak interactions inside this nucleus. After the isomer level is found, the sensitivity of the nuclear transition to time variation of the fine structure constant will be determined.This research will have broad impact across several areas of physics and technology. Laser excitation and coherent manipulation of nuclear states would establish a new bridge between atomic and nuclear physics, with the promise of new levels of accuracy for frequency metrology. The project will involve extensive graduate and undergraduate student training and participation.

虽然典型的核激发能在 keV 到 MeV 范围内，但在一些特殊情况下，激发能要低得多。该项目的主题是钍 229 同位素，它在紫外光谱中具有独特的激发态。过去十年中对该范围内的光发射进行的几次实验研究均不成功或没有结论。除了在错误的能量区域中搜索之外，搜索还受到核跃迁窄线宽的挑战。在这项工作中，将采用替代的电子桥跃迁来对钍 229 中的核异构体能级进行初始激光激发。由于核内强相互作用和电弱相互作用的相互作用，核跃迁可能对基本常数的变化异常敏感。找到异构体水平后，将确定核转变对精细结构常数时间变化的敏感性。这项研究将在物理和技术的多个领域产生广泛的影响。核态的激光激发和相干操纵将在原子和核物理之间建立一座新的桥梁，并有望将频率计量的精度提高到新的水平。该项目将涉及广泛的研究生和本科生培训和参与。