PM: Development Towards a Tabletop Experiment with Unprecedented Sensitivity to Hadronic CP Violation

PM：对强子 CP 破坏具有前所未有的敏感性的桌面实验的开发

• 批准号: 2208024
• 负责人: David DeMille
• 金额: $ 64.94万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2208024&HistoricalAwards=false
• 关键词: PM; Development; Towards; Tabletop; Experiment

Our understanding of fundamental physics still leaves many mysteries unsolved, such as the disappearance of antimatter after the big bang (when it was created in equal amounts with matter), and what yet-undiscovered new particles and forces may exist. Certain room-scale experiments are able to explore these questions in ways complementary to studies at large particle accelerators. The research under this grant aims to develop a new approach to such a small experiment, which would search for a tiny deformation in the distribution of electric charge in a nucleus, known as a Schiff Moment, that can only be caused by new particles carrying forces that could explain the cosmological matter-antimatter asymmetry. This new method promises to increase the sensitivity to this deformation by a factor of 1000 beyond the state of the art, and would probe the existence of certain particles hundreds of times heavier than any that could be produced at even the world's largest particle colliders today. Under this grant the group aims to perform two major steps needed to implement this method: create an ultracold gas of silver atoms, and develop a continuous source of francium-223 atoms. The grant will support training of two Ph.D. students in quantum science; it will also enable new initiatives to convey the excitement and accessibility of optical and quantum physics to underprivileged students on Chicago’s South Side. The proposed new measurement will use an optically-trapped, ultracold gas of the polar molecule 223FrAg to search for the Schiff Moment of francium-223. This approach combines many advantageous features at once, relying almost entirely on proven techniques. The 223Fr nucleus is pear-shaped, which enhances its Schiff Moment by a factor of nearly 1000. The FrAg molecule forms a strong polar bond that enhances the measurable signal by another factor of about 10,000. The simple structure of both Fr and Ag atoms has allowed them to be laser-cooled and trapped before. When trapped together, pairs of each atom can be assembled into FrAg molecules without heating, using methods applied to many other, similar atom pairs. The measurement precision relies on a long coherence time of a nuclear spin superposition, which has also been demonstrated in similar molecules under similar conditions. Creating this trapped sample of ultracold 223FrAg molecules will require forming a Bose-Einstein condensate (BEC) of both atoms, which in turn requires measuring the unknown ultracold scattering properties of both atoms. The group will make these measurements for silver atoms, then form the first BEC of silver. Because 223Fr has a short half-life, the group will in parallel develop a high-flux, continuous source of 223Fr atoms that will later be used to perform analogous steps for francium. To achieve the broader impacts in the community, the group will expand the existing SMART program of outreach to local schools, in part by initiating regular “lunch with a scientist” gatherings.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.

我们对基础物理学的理解仍然留下许多未解之谜，例如大爆炸后反物质的消失（当它与物质等量时），以及可能存在的尚未发现的新粒子和力。某些房间规模的实验能够以与大型粒子加速器研究互补的方式探索这些问题。这项研究旨在开发一种新的方法来进行这样一个小型实验，该实验将寻找原子核中电荷分布的微小变形，称为希夫矩，这只能由携带可以解释宇宙学物质-反物质不对称性的力的新粒子引起。这种新方法有望将这种变形的灵敏度提高1000倍，超过现有技术水平，并将探测某些粒子的存在，这些粒子比当今世界上最大的粒子对撞机所能产生的任何粒子都重数百倍。在这项资助下，该小组的目标是执行实施这种方法所需的两个主要步骤：创造一种银原子的超冷气体，并开发一种连续的<$-223原子源。 这笔赠款将支持两名博士的培训。量子科学的学生;它还将使新的倡议，传达光学和量子物理学的兴奋和可及性，以贫困学生在芝加哥的南区。这项新的测量方法将使用极性分子223 FrAg的光学捕获超冷气体来寻找Francium-223的希夫矩。这种方法同时结合了许多有利的功能，几乎完全依赖于成熟的技术。 223 Fr的核是梨形的，这将其希夫矩提高了近1000倍。FrAg分子形成强极性键，其将可测量信号增强约10，000倍。 Fr和Ag原子的简单结构使它们能够被激光冷却和捕获。当被捕获在一起时，每个原子对可以在不加热的情况下组装成FrAg分子，使用应用于许多其他类似原子对的方法。测量精度依赖于核自旋叠加的长相干时间，这也已经在类似条件下的类似分子中得到证明。创建这种被捕获的超冷223 FrAg分子样品将需要形成两个原子的玻色-爱因斯坦凝聚体（BEC），这反过来又需要测量两个原子的未知超冷散射特性。 该小组将对银原子进行这些测量，然后形成银的第一个BEC。由于223 Fr的半衰期很短，该小组将同时开发一种高通量、连续的223 Fr原子源，随后将用于对<$进行类似的步骤。为了在社区产生更广泛的影响，该组织将扩大现有的SMART计划，将其推广到当地学校，部分是通过定期发起“与科学家共进午餐”的聚会。该奖项反映了NSF的法定使命，并被认为是值得支持的，通过使用基金会的知识价值和更广泛的影响审查标准进行评估。