RUI: A Search for Long-Range Spin-Spin Interactions and Optical Forces in TlF

RUI：在 TlF 中寻找长程自旋-自旋相互作用和光学力

• 批准号: 1806297
• 负责人: Larry Hunter
• 金额: $ 48.06万
• 依托单位: Amherst College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1806297&HistoricalAwards=false
• 关键词: RUI; Search; Long; Range; Spin

Precision measurements of elementary particles' spins can provide new insight into the fundamental laws of nature. Elementary particles have an intrinsic property called spin which makes them act as if they are constantly rotating like mechanical tops. Just as tops precess in the presence of gravity, the spins of fundamental particles precess in a magnetic field. This precession is the basis of nuclear magnetic resonance which is the underlying physics used in the medical diagnostic known as magnetic resonance imaging (MRI). Recently developed precision optical techniques have allowed the study of interactions with particle spins with unprecedented fidelity. This project will use these precision techniques as tools to investigate the fundamental forces and symmetries of nature. At the most basic level, physicists' present understanding of nature is summarized by the "Standard Model" of particle physics. This model requires four fundamental forces (gravitational, electromagnetic, strong, and weak) to describe all of reality as it is presently known. In one experiment, the investigators will look for a new long-range force between particle spins that can't be described by the Standard Model. To optimize their search, they will measure the interaction of their laboratory spins with all of the aligned electron spins within the Earth. In their other experiment, the researchers hope eventually to see if the fundamental laws of nature might be asymmetric in time. This breaking of "time symmetry" can be studied by looking for the precession of a nuclear spin in an electric field. Here the experimental sensitivity is increased by using a beam of very cold molecules. Additional time asymmetry (beyond that which has already been observed) is believed to be necessary to explain the existence of our universe. Without time-reversal violation, our universe would have produced equal amounts of matter and anti-matter. Their mutual annihilation would not have allowed for the formation of galaxies, stars, planets and life. In 2013, the researchers created the first map of the electron-spin density within the Earth. These "geo-electrons" constitute the largest polarized spin source known. Precision measurement of spin-precession frequencies in laboratories at the surface of the Earth as a function of the magnetic-field direction, allows one to look for long-range spin-spin interactions (LRSSI) between the geo-electrons and the laboratory spins. In the first proposed experiment, a refined spin-precession apparatus will be constructed which is both well-calibrated and relatively immune to AC light effects. This should allow at least an order of magnitude improvement in the sensitivity of these LRSSI measurements. If an effect is seen it would suggest the existence of a new force of nature. In current models this force might be associated with an ultra-light vector meson, a "dark photon", the "unparticle", or torsion gravity. In the second proposed experiment, the researchers will continue their investigation of critical parameters that will ultimately determine the sensitivity of the thallium fluoride (TlF) electric-dipole moment (edm) experiment that is presently being constructed at Yale by the CeNTREX collaboration. Specifically, the researchers hope to continue to improve their measurements of optical cycling in TlF and to demonstrate that this cycling can be used to exert optical forces on TlF. These optical forces will be used to transversely cool a cryogenic molecular beam of TlF. This transverse cooling should increase the sensitivity of the TlF edm experiment by about an order of magnitude. With this additional sensitivity it is possible that a permanent nuclear edm will be discovered. If this edm is found, it would imply a violation of time symmetry and could help explain the existence of our matter-dominated universe.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.

基本颗粒的旋转的精确测量可以提供对自然基本定律的新见解。基本颗粒具有称为自旋的固有特性，它使它们的作用似乎像机械顶一样不断旋转。就像在重力存在下顶上的序曲一样，基本颗粒的旋转在磁场中。该动力是核磁共振的基础，核磁共振是被称为磁共振成像（MRI）的医学诊断中使用的基本物理。最近开发的精确光学技术允许研究与前所未有的保真度与粒子旋转的相互作用。该项目将使用这些精确技术作为研究自然力量和对称性的工具。在最基本的层面上，物理学家对自然的当前理解总结了粒子物理学的“标准模型”。该模型需要四个基本力（引力，电磁，强和弱）来描述目前已知的所有现实。在一个实验中，研究人员将寻找粒子旋转之间的新远程力，而标准模型无法描述。为了优化他们的搜索，他们将测量实验室旋转与地球内所有对齐电子旋转的相互作用。在他们的另一项实验中，研究人员希望最终了解自然的基本定律是否可能及时不对称。可以通过寻找电场中核旋转的进攻来研究“时间对称性”的破坏。在这里，使用非常冷的分子束通过实验灵敏度提高。认为额外的时间不对称性（超越已经观察到的时间）是解释我们宇宙存在的必要条件。没有时间逆转的情况，我们的宇宙将产生相等数量的物质和反物质。他们相互歼灭不允许形成星系，恒星，行星和生命。 2013年，研究人员创建了地球内电子旋转密度的第一张地图。这些“地理电子”构成已知最大的极化自旋源。磁场方向的函数的实验室中的自旋方向频率的精确测量，使人们可以在地球电和实验室旋转之间寻找远程自旋旋转相互作用（LRSSI）。在第一个提出的实验中，将构建一个精致的自旋细分设备，该设备既经过良好校准，又对AC光效应相对免疫。这应该至少可以提高这些LRSSI测量的灵敏度。如果看到效果，将表明存在一种新的自然力量。在当前模型中，该力可能与超光线媒介膜，“深色光子”，“非图案”或扭转重力有关。在第二次提出的实验中，研究人员将继续研究关键参数，这些参数最终将确定氟化物（TLF）电 - 偶极力矩（EDM）实验的灵敏度，该实验目前由Centrex Collabory在耶鲁大学构建。具体而言，研究人员希望继续改善其在TLF中光循环的测量值，并证明该循环可用于在TLF上发挥光力。这些光学将用于横向冷却TLF的低温分子束。这种横向冷却应大约将TLF EDM实验的灵敏度提高大约一个数量级。有了这种额外的敏感性，可能会发现永久性的核EDM。如果发现此EDM，这将意味着违反时间对称性，并可以帮助解释我们以物质为主的宇宙的存在。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛的影响评估标准来通过评估来获得支持的。

项目成果

Optical Cycling of TlF

TlF 的光循环

• 发表时间: 2019
• 期刊: The Gordon Conference on Atomic Physics
• 作者: Clayburn, N.B.;Delaveron, J.H.;DeMille, D.;Hunter, L.R.
• 通讯作者: Hunter, L.R.

Toward a Free Precession Hg-Cs Co-magnetometer for Measurements of Long-Range Spin-Spin Interactions

用于测量长距离自旋-自旋相互作用的自由进动 Hg-Cs 共磁强计

• 发表时间: 2020
• 期刊: DAMOP 2020
• 作者: Clayburn, N.B.;Carlin, C.C.;Peck, S.K.;Hunter, L.R.
• 通讯作者: Hunter, L.R.

Improved Understanding of Optical Cycling in TlF

加深对 TlF 中光循环的理解

• 发表时间: 2022
• 期刊: Molecular and Optical Physics
• 作者: Clayburn, N.;Gabiyev, I.;Grasdijk, O.;Kastelic, J.;Timgren, O.;DeMille, D.;Hunter, L.
• 通讯作者: Hunter, L.

Improved Optical Cycling of TlF

改进的 TlF 光学循环

• 发表时间: 2021
• 期刊: DAMOP 2021
• 作者: Clayburn, N.B.;Cullen, M.;DeMille, D.;Hunter, L.R.
• 通讯作者: Hunter, L.R.