RUI: Search for Anomalous Proton Spin Interactions with A Dual-Isotope Rubidium Magnetometer

RUI：用双同位素铷磁强计寻找反常质子自旋相互作用

• 批准号: 0969666
• 负责人: Derek Kimball
• 金额: $ 31.03万
• 依托单位: California State University, East Bay Foundation, Inc.
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0969666&HistoricalAwards=false
• 关键词: RUI; Search; Anomalous; Proton; Spin

This award supports continuation of a research program using a dual-isotope rubidium (Rb) magnetometer to search for a hypothetical long-range coupling between Rb nuclear spins and the mass of the earth. It will also support research to explore use of the dual-isotope Rb magnetometer and related experimental techniques to search for anomalous intermediate-range (over distance scales of about one meter) and short-range (over distance scales of about one nanometer) spin-spin couplings. The dual-isotope Rb magnetometer is particularly sensitive to non-magnetic, spin-dependent interactions of the proton so that anomalous interactions of the proton spin produce a differential shift between the Rb spin-precession frequencies, whereas most sources of systematic error produce common-mode shifts of the spin-precession frequencies which can be controlled through auxiliary measurements. The majority of recent searches for similar effects limit anomalous couplings of either the neutron or electron spin, so the proposed experiment searches a parameter space to some degree, depending on the theoretical model, orthogonal to that constrained by previous experiments. The optimized dual-isotope Rb magnetometer has sufficient shot-noise-projected sensitivity to improve experimental limits on long-range spin-mass couplings by an order of magnitude in general and by two orders of magnitude for the proton spin in particular, and improve limits on anomalous spin-spin couplings by over an order of magnitude.There is renewed interest in scalar-tensor theories of gravity with massless scalar/pseudoscalar fields since they can explain the recent observation of "dark energy" over cosmological distances. The pseudoscalar component of such a field generates a long-range interaction between spins and the gravitational field of the Earth. This interaction in the simplest scalar-tensor theory causes a shift of the spin precession frequencies smaller than present limits but just within the range of this experiment. Detection of this type of interaction would be evidence that gravity violated parity and time-reversal symmetries, as well as the equivalence principle which underlies the theory of general relativity. A result consistent with general relativity would still provide new tests of numerous alternative theories, such as torsion gravity, that hypothesize anomalous spin-mass and spin-spin couplings. As the only externally funded physics experiment in the history of California State University / East Bay, this research program has led to tripling the number of physics majors in the past three years and sixteen students, including four women and nine underrepresented minority students, have made meaningful contributions to the project.

该奖项支持继续使用双同位素铷（Rb）磁力计的研究计划，以寻找Rb核自旋和地球质量之间的假设远程耦合。它还将支持开展研究，探讨如何使用双同位素Rb磁力计和相关实验技术来寻找异常的中程（距离尺度约为1米）和短程（距离尺度约为1纳米）自旋-自旋耦合。双同位素Rb磁力计对质子的非磁性、自旋相关的相互作用特别敏感，使得质子自旋的异常相互作用产生Rb自旋进动频率之间的差分移位，而大多数系统误差源产生可以通过辅助测量控制的自旋进动频率的共模移位。最近对类似效应的大多数搜索限制了中子或电子自旋的异常耦合，因此拟议的实验在某种程度上搜索了一个参数空间，这取决于理论模型，与以前实验所约束的参数空间正交。优化的双同位素Rb磁力计具有足够的散粒噪声投影灵敏度，以将长程自旋-质量耦合的实验极限一般提高一个数量级，特别是提高质子自旋的两个数量级，并将反常自旋-自旋耦合的极限提高了一个数量级以上。赝标量场，因为它们可以解释最近在宇宙学距离上观察到的“暗能量”。这种场的赝标量分量产生自旋和地球引力场之间的长程相互作用。在最简单的标量-张量理论中，这种相互作用导致自旋进动频率的移动小于目前的极限，但正好在本实验的范围内。这种类型的相互作用的检测将是引力违反宇称和时间反演对称性以及作为广义相对论基础的等效原理的证据。一个与广义相对论一致的结果仍然会为许多替代理论提供新的检验，比如扭转引力，它假设了反常的自旋-质量和自旋-自旋耦合。作为加州州立大学/东湾历史上唯一一个外部资助的物理实验，这个研究项目在过去三年中使物理专业的学生人数增加了两倍，16名学生，包括4名女性和9名代表性不足的少数民族学生，为该项目做出了有意义的贡献。