Characterization of Systematic Effects in Ultracold Neutron Tests of Fundamental Symmetries

基本对称性超冷中子测试中系统效应的表征

• 批准号: 2310015
• 负责人: Adam Holley
• 金额: $ 23万
• 依托单位: Tennessee Technological University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2310015&HistoricalAwards=false
• 关键词: Characterization; Systematic; Effects; Ultracold; Neutron

One of the most-successful and best-studied physical theories is the Standard Model (SM), which describes how the universe functions at very small scales. This model has been verified in many different ways over the course of five decades. In principle, such a fundamental theory should be able to predict observations about the universe at large scales, but in a number of notable cases it fails to do so. This suggests an exciting possibility, that there are fundamental features about the universe of which we are unaware. Since these unknown properties have so far evaded detection, discovering them requires experiments with a new level of sensitivity, requiring innovative approaches. Two such experiments leverage recent progress in the production of very low energy “ultracold” neutrons. They are UCNtau, which measures the average time required for a free neutron to decay, and nEDM, a measurement of the charge distribution in an isolated neutron. This project focuses on the development of three techniques designed to enhance the sensitivity of these experiments. The research effort will assemble a cross-disciplinary team to strengthen the synergy between science and technology and will target early undergraduates and pre-college students to more effectively connect practical research experience with the students’ academic work.The first of three primary research activities to be carried out in this project is the inclusion of empirically-determined magnetic field maps of the UCNτ Halbach array and ab initio simulations of the loaded ultracold neutron (UCN) phase space distribution into a semiclassical spin-tracking Monte Carlo model developed to account for entanglement between spatial and spin degrees of freedom. This goal will ensure that the characterization of systematic effects associated with spin dynamics (depolarization) keeps pace with anticipated improvements in statistical precision. The second core activity is to develop a real-time monitor for the UCNτ effort that will place run-by-run empirical limits on the depolarization rate and serve as a cross-check of the computational model. The third objective is to develop a quantum sensor, based on Nitrogen-Vacancy defects in diamond, optimized to aid in the control and characterization of magnetic and electric fields for nEDM experiments, thereby enhancing the sensitivity with which the neutron electric dipole moment can be measured.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.

最成功和研究最充分的物理理论之一是标准模型（SM），它描述了宇宙如何在非常小的尺度上运行，这个模型在过去的五年里已经通过多种不同的方式得到了验证。这样的基本理论应该能够预测对大尺度宇宙的观测，但在许多值得注意的情况下它却未能做到这一点，这表明了一种令人兴奋的可能性，即宇宙存在我们不知道的基本特征。由于这些未知的属性迄今已被回避探测、发现它们需要更高灵敏度的实验，需要创新的方法，其中两个实验利用了极低能量“超冷”中子的最新进展，它们是 UCNtau，它测量自由中子产生的平均时间。衰变和 nEDM（孤立中子中电荷分布的测量）该项目重点开发旨在提高这些实验灵敏度的三种技术。该研究工作将组建一个跨学科团队，以加强科学之间的协同作用。和技术，并将针对早期本科生和预科学生，更有效地将实际研究经验与学生的学术工作联系起来。该项目将进行的三项主要研究活动中的第一项是纳入根据经验确定的磁场图UCNτ Halbach 阵列和加载超冷中子 (UCN) 相空间分布的从头开始模拟到半经典自旋跟踪蒙特卡罗模型中，该模型是为了解释空间自由度和自旋自由度之间的纠缠而开发的。目标将确保与自旋动力学（去极化）相关的系统效应的表征与统计精度的预期改进保持同步。第二个核心活动是为 UCNτ 工作开发实时监控器，该监控器将逐次运行经验。第三个目标是开发一种基于金刚石中氮空位缺陷的量子传感器，该传感器经过优化以帮助控制和表征磁场和电场。电火花加工该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。