Argon Crystals for the Electron Electric Dipole Moment (eEDM) Search with the EDM^3 Collaboration

通过 EDM^3 协作进行电子电偶极矩 (eEDM) 搜索的氩晶体

• 批准号: RGPIN-2022-04603
• 负责人: Storry, Cody
• 金额: $ 1.75万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=763109
• 关键词: Argon; Crystals; Electron; Electric; Dipole

The proposed research is toward the search for the permanent electron (e-) electric dipole moment (EDM). The e- is a point particle in the classical physics picture but physics predicts an asymmetry in the charge near it. Detecting the precession or wobble of the eEDM in an electric field, in polar molecules for example, will confirm the expected, yet elusive, eEDM. To probe for this effect, many e- (improved statistics) observed for long periods (characterized by precession time) are required. Measurements by the ACME II collaboration indicate an eEDM below 1.1*10^--29 e-cm. The challenge is that the physical size of the e EDM is tiny and its measurement will require development of new techniques. The projected sensitivity of our recently established EDM^3 (Electric Dipole Measurements using Molecules within a Matrix) collaboration will find the eEDM or limit it at a level of <10^-34 ecm, a 10^5 times improvement. My independent research contribution to the EDM^3 will provide the ideal substrate for Argon (Ar) crystal growth in which the polar molecules are fixed. Specifically, the short-term objectives of this Discovery application are to: (1) produce highly pure cryogenic Ar solids from liquified Ar in a crystal form; (2) make crystallographic measurements to confirm it is a monolithic crystal with the required low defect and impurity content; and (3) manipulate this cryogenic crystal transporting it into separate apparatus where the polar molecules are deposited during additional crystal growth on this idea substrate for EDM^3 goals. These objectives are toward EDM^3 goals where an apparatus is under development to observe the first polar molecules frozen in an Ar solid. Here argon is frozen on a sapphire substrate and freezes in an unknown, random orientation due to the sapphire surface potentials. A cylindrical, cm diameter, flawless, Ar crystal with embedded polar molecules is to be needed for EDM^3 objectives. Finding an asymmetry in the charge near the e would lead to a permanent eEDM, the discovery of which would be ground-breaking, narrowing the range of possible physics models describing the universe, and providing evidence of new particles or interactions that lead to the observed matter--antimatter asymmetry in the universe. Our new approach will increase the e number observed and the duration of time they are observed by fixing the molecules in a crystal of frozen Ar. Our small laboratory apparatus is novel: measurements that detect this tiny size probe energy scales beyond the reach of high energy accelerators, making our research competitive with LHC experiments at CERN but at a tiny fraction of the cost and housed at a Canadian University. This project will enable 10 undergraduates and 7 graduates to receive training in high tech fields ideal for careers in today's industries. The success of our research will cement the way to achieve the most sensitive measurement yet of the eEDM.

本研究的目的是寻找永久电子电偶极矩。在经典物理学中，电子是一个点粒子，但物理学预测它附近的电荷是不对称的。在电场中检测eEDM的进动或摆动，例如在极性分子中，将证实预期的，但难以捉摸的eEDM。为了探测这种效应，需要长时间（以进动时间为特征）观察到许多e-（改进的统计）。ACME II协作组的测量表明，eEDM低于1.1*10^-29 e-cm。挑战在于电火花加工的物理尺寸很小，其测量需要开发新技术。 我们最近建立的EDM^3（使用矩阵内分子的电偶极测量）合作项目的预计灵敏度将发现eEDM或将其限制在<10^-34 ecm的水平，提高了10^5倍。我对电火花加工的独立研究成果^[3]将为氩（Ar）晶体生长提供一种理想的基质，在这种基质中极性分子被固定。具体地说，这一发现应用的短期目标是：（1）从晶体形式的液态Ar生产高纯低温Ar固体;（2）进行晶体学测量，以确认它是具有所需低缺陷和杂质含量的单片晶体;以及（3）操作该低温晶体，将其输送到单独的装置中，在该装置中，在附加的晶体生长期间，这是EDM^3目标的思想基础。这些目标都是为了实现EDM ^[3]的目标，即研制一种仪器来观测冻结在Ar固体中的第一个极性分子。这里，氩被冻结在蓝宝石衬底上，并且由于蓝宝石表面电势而以未知的随机取向冻结。EDM物镜需要一个直径为厘米、无缺陷的圆柱形氩晶体，其中嵌入了极性分子^[3]。 在e附近发现电荷的不对称性将导致永久性的eEDM，这一发现将是突破性的，缩小描述宇宙的可能物理模型的范围，并提供新粒子或相互作用的证据，导致观察到的宇宙中的物质-反物质不对称性。我们的新方法将通过将分子固定在冷冻Ar晶体中来增加观察到的e数和观察它们的持续时间。我们的小型实验室设备是新颖的：检测这种微小尺寸的探测器能量尺度超出了高能加速器的范围，使我们的研究与欧洲核子研究中心的LHC实验竞争，但成本只有加拿大大学的一小部分。该项目将使10名本科生和7名毕业生接受高科技领域的培训，这些领域是当今行业的理想职业。我们研究的成功将巩固实现迄今为止最灵敏的eEDM测量的方法。