RUI: Testing Fundamental Symmetries with Muon g-2

该奖项将支持PI和来自雷吉斯大学的本科生，使他们能够为费米实验室的Muon g-2实验做出贡献，该实验旨在发现超出当前标准模型的新粒子和相互作用。亚原子物理的标准模型提供了一个重要的理论框架，它描述了除引力以外的所有已知力。它经过了广泛的测试，它成功地预测了粒子加速器实验中观察到的几乎每一种现象。然而，众所周知，它是不完整的，因为它无法解释暗物质或暗能量，也没有解释物质相对于反物质的不对称性，正是这种不对称性使得我们的宇宙结构得以形成。µ子在许多方面与电子相似，但质量大约是电子的207倍，而且它们不稳定，在几微秒内衰变；它们在自然界中以宇宙射线的形式出现。Muon g-2实验测量了Muon在磁场中运行时的自转速度。这种旋转可能是由于介子与新粒子的耦合而产生的。该实验已经搭建完成，并完成了第一年的数据收集。在PI和其他合作者的密切指导下，学生们将维护和升级粒子探测器，协助在费米实验室获取数据，并分析数据。他们将有机会在会议和协作会议上展示他们的工作。这些学生的专业发展是这个项目的主要关注点。进入雷吉斯大学上课的学生继续保持着种族和社会经济多样性增加的趋势，因此该奖项支持的学生代表了目前在物理学研究中代表性不足的群体的参与范围扩大。Muon g-2实验测量了Muon的反常磁矩。之前对这个量的测量与理论预测相差约3.5标准差。费米实验室的新测量将记录到比布鲁克海文国家实验室的实验821多20倍的介子衰变。系统的不确定性也将减少，预期的精度为十亿分之140。因此，该实验有可能发现新粒子和相互作用的间接影响，具有非常高的统计意义。可能出现的新物理学的范围很广；它可能包括超对称性、来自“暗扇区”的弱相互作用轻粒子、类轴子粒子或额外维度等概念。相反，如果结果与标准模型一致，它将对所有这些新的物理模型提供强有力的约束。该实验测量了弱聚焦1.5特斯拉储存环磁体中一束介子束的飞行自旋进动速率。几种束流动力学效应直接导致了系统误差，其中包括部分由CBO驱动的相干Betatron振荡(CBO)和介子损耗。纤维竖琴经过翻新，由Regis集团进行维护，用于表征CBO并将其降至最低。实验的预期精度假设来自CBO和Muon损失的系统误差将分别减少2.3和4.5倍。REGIS小组参与了光纤竖琴数据的分析，以了解这些光束动力学效应；它还为分析工作的其他部分做出了贡献，包括数据质量控制和运行选择。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。

This award will support the PI and undergraduate students from Regis University to enable them to contribute to the Muon g-2 Experiment at Fermilab, which aims to discover new particles and interactions that are beyond the current Standard Model. The Standard Model of subatomic physics provides an overarching theoretical framework that describes all known forces except gravity. It has been extensively tested, and it successfully predicts almost every phenomenon that has ever been observed in experiments at particle accelerators. Nevertheless, it is known to be incomplete, since it does not have a way to explain dark matter or dark energy, and it does not account for the asymmetry of matter over antimatter that allowed the structures of our universe to form. Muons are in many ways similar to electrons, but with a mass approximately 207 times higher, and they are unstable, decaying in a few microseconds; they appear in nature as cosmic rays. The Muon g-2 Experiment measures the rate at which the of muons rotate as they orbit in a magnetic field. That rotation could arise from the coupling of muons to new particles. The experiment has been constructed and has completed its first year of data collection. With close mentoring from the PI and other collaborators, students will maintain and upgrade particle detectors, assist with taking data at Fermilab, and analyze data. They will have opportunities to present their work at conferences and collaboration meetings. The professional development of these students is a primary focus of this project. Entering classes at Regis University are continuing a trend of increasing ethnic and socioeconomic diversity, so the students supported by this award represent a broadening in the participation by groups that are currently underrepresented in physics research.The Muon g-2 experiment measures the muon's anomalous magnetic moment. Previous measurements of this quantity differ from theoretical predictions by about 3.5 standard deviations. The new measurement at Fermilab will record 20 times more muon decays than experiment 821 at Brookhaven National Laboratory. Systematic uncertainties will also be reduced, leading to an expected precision of 140 parts per billion. Consequently, the experiment has the potential to discover the indirect effects of new particles and interactions with very high statistical significance. The range of possible new physics is wide; it could include ideas such as supersymmetry, light weakly-interacting particles from a "dark sector," axion-like particles, or extra dimensions. Conversely, if the result turns out to agree with the Standard Model, it would provide a strong constraint on all of these new physics models. The experiment measures the rate of spin precession in flight for a muon beam in a weak-focusing 1.5 Tesla storage ring magnet. Several beam dynamics effects directly contribute to the systematic error, including coherent betatron oscillations (CBO) and muon losses, which are partly driven by the CBO. The fiber harps, which were refurbished and are maintained by the Regis group, are used to characterize and to minimize the CBO. The anticipated precision of the experiment assumes that the systematic errors from CBO and muon losses will be reduced by factors of 2.3 and 4.5, respectively. The Regis group participates in the analysis of fiber harp data in order to understand these beam dynamics effects; it also contributes to other parts of the analysis effort, including data quality control and run selection.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.