Precision Electroweak Studies of the Standard Model

这项为期两年的桥梁计划将支持新聘请的PI(Deconinck)标准模型的三个精密电弱测量，标准模型是我们目前描述基本粒子及其相互作用的最佳理论。这一桥梁计划将确保正在进行的一个SAP项目(Moller)和未来两个SAP项目(BL3和EIC EW)的研究连续性，同时建立一个加拿大社区。所有三个项目都将在两年内过渡到亚原子物理包络-项目支持：Moller过渡到正在进行的SAP项目，该项目将于2021年更新，BL3和EIC EW过渡到新项目。 将通过精密测量确定的参数与理论预测进行比较，可以对标准模型进行精度测试。这一桥牌项目侧重于三种方法。 1)PI和1名博士生将为杰斐逊实验室的穆勒实验设计、建造和测试介子探测器系统，该实验是对电子微弱电荷的精确测量。 穆勒实验将测量液氢靶中纵向极化电子与未极化电子的散射中违反宇称的不对称性。非对称性测量的背景是光生粒子。我们将在主要的莫勒探测器之后增加一个铅吸收体，以测量大部分电子的范围，但让大部分介子通过。在这面铅墙的后面将是由光电倍增管读出的丙烯酸切伦科夫探测器。一名博士生将设计、制造和测试丙烯酸切伦科夫探测器的概念。 2)PI和1名博士生将为NIST的BL3精密中子寿命实验模拟和测试质子探测器。 自20世纪90年代以来，使用瓶子实验和束流实验两种实验技术测量中子寿命之间一直存在着差异。BL3实验的目的是将过去的“束”实验的不确定度从2.1%提高到0.3%。为了探测衰变质子，该实验将使用分段硅探测器。一名博士生将模拟质子在分段硅探测器上的后向散射，并在我们的质谱仪设备中测试它们的性能。 3)PI和1个共享的博士后将使用JLab已经开发的分布式模拟平台，完成电子离子对撞机(EIC)上的电弱精密测量研究。 核物理领域备受瞩目的努力之一是EIC。该设备将允许精确测量中性电流的弱电可观测值。作为EIC软件联盟的一部分，我们已经开发了一个分布式模拟工作流程，因此可以很好地重新审视具有新探测器设计的通用模拟。有一半的博士后，我们将更新基于为EIC设计的探测器系统的电弱混合角和形状因数提取的研究。 所有这三个组成部分确保在与亚原子物理计划相关的领域培训高素质的人员。

This 2-year bridge program will support the newly-hired PI (Deconinck) on three precision electroweak measurements of the Standard Model, our current best theory describing fundamental particles and their interactions. This bridge program will ensure research continuity in one ongoing SAP project (MOLLER) and in two future SAP projects (BL3 and EIC EW) while building a Canadian community. All three projects will transition to Subatomic Physics Envelope - Project support within 2 years: MOLLER onto the ongoing SAP project which will be due for renewal in 2021, and BL3 and EIC EW onto new projects. The comparison of parameters determined from precision measurements with theoretical predictions allow for precision tests of the Standard Model. This bridge program focuses on three approaches. 1) The PI and 1 PhD student will design, build, and test the pion detector system for the MOLLER experiment at Jefferson Lab, a precision measurement of the electron's weak charge. The MOLLER experiment will measure the parity-violating asymmetry in the scattering of longitudinally-polarized electrons from unpolarized electrons in a liquid hydrogen target. A background for the asymmetry measurement is photo-produced pions. We will add a lead absorber after the main MOLLER detectors to range out most of the electrons but letting through a large fraction of the pions. Behind this lead wall will be acrylic Cherenkov detectors read out by photo-multiplier tubes. One PhD student will design, build, and test the acrylic Cherenkov detector concept. 2) The PI and 1 PhD student will simulate and test the proton detectors for the BL3 precision neutron lifetime experiment at NIST. Since the 1990s there has been a persistent discrepancy between the neutron lifetime measurements using two experimental techniques: bottle and beam experiments. The BL3 experiment aims to improve the 2.1 s uncertainty of the past "beam" experiments to better than 0.3 s. To detect decay protons, the experiment will use a segmented silicon detector. One PhD student will simulate backscatter of protons on the segmented silicon detectors, and test their performance in our mass-spectrometer facility. 3) The PI and 1 shared postdoc will complete studies for electroweak precision measurements at the Electron-Ion Collider (EIC), using distributed simulation platforms already developed at JLab. One of the high profile efforts in nuclear physics is the EIC. This facility will allow for precise measurements of neutral-current electroweak observables. We have developed a distributed simulation workflow as part of the EIC software consortium, and thus well positioned to revisit generic simulations with new detector designs. With half of one postdoc, we will update studies of the electroweak mixing angle and form factor extractions based on the detector systems designed for the EIC. All three components ensure training of highly qualified personnel in areas relevant to the subatomic physics program.