Parity Violating Electron Scattering at Jefferson Lab

路易斯安那理工大学应用物理研究中心（CAPS）的成员深入参与了杰斐逊实验室当前和未来的宇称违反实验。该小组的主要实验参与是作为G 0实验的成员研究质子的子结构，并作为新批准的Qweak实验的成员测试现代物理学的基本理论，标准模型。他们还正在开发自己的科学计划，作为E01-115实验的发言人，该实验将测量当质子被激发到其第一共振态Delta时反应中违反宇称的不对称性。该实验将使用G 0装置以其后向角模式进行，并将探测质子结构的一个重要组成部分，即被称为轴向矢量转换形状因子的量，这在其他反应中是无法实现的。这个形状因子测量质子的内在自旋对这种转变的动力学的贡献。为了便于G 0弹性和N-Delta实验的后向角测量，路易斯安那理工大学正在设计、安装和测试低温恒温器出口探测器（CED），其中还包括相关信号处理电子设备的开发。 G 0前向角测量的调试已经完成，下一组测量计划于2003年10月进行。后向角测量预计将于2005年初开始。该小组在Qweak实验中发挥了关键作用，该实验将通过测量质子的弱电荷来寻找标准模型之外的物理。自Qweak实验开始以来，CAPS小组一直致力于设计光谱仪和探测器系统的主要组件和属性。该小组对即将进行的实验的责任将是设计、测试、建造和安装前向跟踪系统的一个组成部分，该系统将在测量实验的运动学和背景方面发挥关键作用。这些新的探测器将基于欧洲核子研究中心最近开发的气体电子倍增（GEMS）创新技术。为了继续路易斯安那理工大学的宇称违反测量计划，该小组向JLab PAC提交了一份意向书，以扩展其自己的测量计划，即在前向角处测量N - Delta过渡中的宇称违反不对称性。该实验将测量强子弱相互作用动力学理论的基本耦合常数，并将测试在更高能量下发生的对称性破缺机制。CAPS在现代实验中的参与在北路易斯安那州并没有被忽视。这是动力和机会，在这个地区的各级学生参与最先进的科学。它还提供了一个机会，让当地高中教师参与前沿科学，并通过他们的参与，将现代科学和技术进一步传播到当地学生中。CAPS计划的这一组成部分被认为与他们的科学贡献一样重要。

The members of Louisiana Tech University's Center for Applied Physics Studies (CAPS) are deeply involved in the current and future parity violation experiments at Jefferson lab. The Group's primary experimental involvements are the study of the substructure of the proton as members of the G0 experiment, and testing the basic theory ofmodern physics, the Standard Model, as members of the newly approved Qweak experiment. They are also developing their own scientific program as spokespersons for the E01-115 experiment which will measure theparity violating asymmetry in the reaction when the proton is excited into its first resonant state, the Delta. The experiment will be performed using the G0 apparatus in its backward angle mode, and will probe an important component of the proton's structure, a quantity known as the axial vector transition form factor, inaccessible in other reactions. This form factor measures the contribution of the proton's intrinsic spin to the dynamics of this transition. To facilitate the backward angle measurements for both the G0 elastic and N -- Delta experiments, Louisiana Tech is working on the design, installation, and testing of the Cryostat Exit Detectors (CED's) which also includesdevelopment of the associated signal processing electronics. Commissioning for the G0 forward angle measurements has been completed, and the next set of measurements is scheduled to be run in October of2003. The backward angle measurements are expected to start early in 2005.The Group has taken on a crucial role in the Qweak experiment which will search for physics beyond the standard model by measuring the proton's weak charge. Since the inception of the Qweak experiment,the CAPS Group has been working on the design of major components and attributes of the spectrometer and detector systems. The Group's responsibilities for the upcoming experiment will be the design,testing, construction, and installation of a component of the forward tracking system which will play a crucial role in measuring the kinematics and background of the experiment. These new detectors will be based on the innovative technology of Gas Electron Multiplication (GEMs) which have been recently developed at CERN. To continue Louisiana Tech's program of parity violation measurements, the group submitted an Letter of Intent to the JLab PAC to extend its own program of measurements of the the parity violating asymmetry in the N -- Delta transition at forward angles. This experiment will measure a fundamental coupling constant of dynamic theories of the weak interaction of hadrons, and will also test symmetry breaking mechanisms which take place at higher energies.The involvement of CAPS in modern experiments is not unnoticed in North Louisiana. It is motivation and opportunity for students at all levels in this region to participate in state of the art science. It also provides an opportunity to involve local high school teachers in forefront science and, through their involvement, spread modern science and technology even further into the local student population. This component of the CAPS program is considered as important as their scientific contributions.