Qweak: Measurement of the Proton's Weak Charge

十多年来，弗吉尼亚州纽波特纽斯的杰斐逊实验室一直在寻找超越基本相互作用标准模型的物理学。Qweak实验已经产生了世界上第一个质子弱电荷的测量结果，这是一个决定质子如何响应弱相互作用的基本属性。在接下来的两年里，我们将完成对2010-12年期间获得的超过180 TB数据的细致分析，并准备发布对电子-质子散射中宇称违反不对称性的最精确测量，确定质子的弱电荷精确度提高5倍，并为标准模型之外可能存在的新力介导亚原子粒子设定新的限制。自2001年首次提出这一大胆倡议以来，加拿大集团一直是这一倡议的主要参与者。在NSERC，CFI，TRIUMF，Jefferson Lab和我们的家庭机构的支持下，我们设计，建造，测试并负责Qweak磁谱仪，主探测器阵列，康普顿偏振计反冲电子探测器，石英扫描仪探测器的安装，调试和成功实施，以及用于主检测器和束线/极化源诊断设备的所有低噪声电流模式电子器件和数字读出。我们在实验中领导了螺旋度相关系统误差的评估，并在Qweak的调试和运行阶段的评估中发挥了重要作用。在这场密集的运动中，我们培养了许多本科生、研究生和研究生研究人员。我们目前的拨款申请将支持该小组正在进行的工作，包括一名研究助理，他是蒙特卡罗模拟和粒子跟踪分析方面的专家，以完成数据分析的最后阶段并准备发表结果。

A search for physics beyond the Standard Model of fundamental interactions has been underway at Jefferson Laboratory in Newport News, VA, for over a decade. The Qweak experiment has already produced the world’s first measurement of the proton’s weak charge, a fundamental property that determines how a proton responds to the weak interaction. Over the next two years we will complete our meticulous analysis of over 180 Terabytes of data acquired during 2010-12 and be ready to publish the most precise measurement of a parity-violating asymmetry in electron-proton scattering, determining the proton’s weak charge to 5x higher precision, and setting new limits on the possible existence of new force-mediating subatomic particles beyond the Standard Model. The Canadian group has been a major player in this bold initiative since it was first proposed in 2001. With support from NSERC, CFI, TRIUMF, Jefferson Lab, and our home institutions, we designed, built, tested and took responsibility for the installation, commissioning and successful implementation of the Qweak magnetic spectrometer, the main detector array, the Compton polarimeter recoil electron detectors, the quartz scanner detector, and all of the low-noise current mode electronics and digital readout for the main detector and beamline / polarized source diagnostic devices. We led the evaluation of helicity-correlated systematic errors in the experiment and played a major role in their assessment during the commissioning and running phases of Qweak. We have trained numerous undergraduate, graduate, and postgraduate researchers during the course of this intensive campaign. Our present grant request will support the group’s ongoing efforts, including one research associate who is an expert in Monte Carlo simulations and particle tracking analysis, to complete the final stages of the data analysis and prepare results for publication.