A beam physics model server (Art++) has been developed for the Jefferson Lab accelerator. This online model server is a redesign of the ARTEMIS model server. The need arose from an impedance mismatch between the current requirements and ARTEMIS capabilities. The purpose of the model server is to grant access to both static (machine lattice parameters) and dynamic (actual machine settings) data using a single programming interface. A set of useful optics calculations (R-matrix, orbit fit, etc.) has also been implemented and can be invoked by clients via the model interface. Clients may also register their own dynamic models in the server. The server interacts with clients using the CDEV protocol and data integrity is guaranteed by a relational database (Oracle8i) accessed through a persistence layer. By providing a centralized repository for both data and optics calculations, the following benefits were achieved: optimal use of network consumption, software reuse, and ease of maintenance.
The Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab comprise a unique facility for experimental nuclear physics. This facility is presently being upgraded, which will enable a new experimental program with substantial discovery potential to address important topics in nuclear, hadronic, and electroweak physics. Further in the future, it is envisioned that the Laboratory will evolve into an electron-ion colliding beam facility.
Long term plans for the investigation of the quark and gluon structure of matter have for some time focussed on the possibility of an electron-ion collider, with the nuclear physics communities associated with JLab and BNL being particularly active. We briefly outline the current thinking on this subject at Jefferson lab.
The Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab comprise a unique facility for experimental nuclear physics. This facility is presently being upgraded, which will enable a new experimental program with substantial discovery potential to address important topics in nuclear, hadronic, and electroweak physics. Further in the future, it is envisioned that the Laboratory will evolve into an electron-ion colliding beam facility.
A Relational Database Model for Managing Accelerator Control System Software At Jefferson Lab
Thomas Jefferson国家加速器设施的运营软件团队面临着许多挑战，这些挑战与管理大量内部开发软件的设施相同。开发人员包括软件组成员、操作员、硬件工程师和加速器物理学家。一个管理问题是确保所有软件都有一个确定的维护人员，他仍然在实验室工作。在某些情况下，定位“孤儿”软件的源代码也被证明是困难的。其他挑战包括执行版本和文档的最低标准，将测试软件与操作软件隔离，鼓励更好的代码重用，整合输入/输出文件存储和管理，以及跟踪软件依赖关系。本文将描述一个关系数据库模型，用于跟踪解决上述问题所需的信息。该数据库模型的实例化为各种提高生产力和一致性的工具提供了基础，这些工具用于自动化（或至少辅助）软件的构建、版本控制、文档编制和安装。
Jefferson Lab began a plasma processing program start-ing in the spring of 2019. Plasma processing is a common technique for removing hydrocarbons from surfaces, which increases the work function and reduces the sec-ondary emission coefficient. Unlike helium processing which relies on ion bombardment of the field emitters, plasma processing uses free oxygen produced in the plasma to break down the hydrocarbons on the surface of the cavity. The residuals of the hydrocarbons in the form of water, carbon monoxide and carbon dioxide are re-moved from the cryomodule as part of the process gas flow.…
Jefferson Laboratory（杰斐逊实验室）；Old Dominion University（奥多明尼昂大学）
We report on the development of machine learning models for classifying C100 superconducting radio-frequency (SRF) cavity faults in the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. CEBAF is a continuous-wave recirculating linac utilizing 418 SRF cavities to accelerate electrons up to 12 GeV through 5-passes. Of these, 96 cavities (12 cryomodules) are designed with a digital low-level RF system configured such that a cavity fault triggers waveform recordings of 17 RF signals for each of the 8 cavities in the cryomodule. Subject matter experts (SME) are able to analyze…
The Qweak experiment aims to measure the weak charge of the proton to 4% via the parity-violating asymmetry ($\sim$-200 ppb) in elastic e+p scattering. The scattering rate is largely influenced by five beam parameters: horizontal position (X), angle (X'), vertical position (Y), angle (Y'), and beam energy (E). Changes in these parameters when the beam polarization is reversed will create a false asymmetry. To measure the detector sensitivities, we modulate X, X', Y, Y' using four air-core dipoles in the Hall C beamline as well as beam energy with a superconducting RF cavity. Linear regression …
This report presents a brief summary of the science opportunities and program of a polarized medium energy electron-ion collider at Jefferson Lab and a comprehensive description of the conceptual design of such a collider based on the CEBAF electron accelerator facility.
The Continuous Electron Beam Accelerator Facility (CEBAF) was built with a thermionic electron source and the three original experimental hall lines reflected this. A few years after beam delivery began a parity violation experiment was approved and two polarimeters were installed in the Hall A beam line without consultation with the accelerator physics group. The beam raster system was placed after the new Compton polarimeter, before one accelerator quadrupole and four quadrupoles in the new Moller polarimeter. It was very difficult to meet experimental requirements on envelope functions and …
Using A Nameserver to Enhance Control System Efficiency
Thomas Jefferson National Accelerator Facility（Jefferson Lab）控制系统使用名称服务器来减少系统响应时间，并最大限度地减少客户端名称解析对前端计算机的影响。该控制系统基于实验物理和工业控制系统（EPICS），该系统使用基于名称的广播来启动数据通信。默认情况下，当客户端应用程序请求EPICS过程变量（PV）时，所有前端计算机都会接收广播并根据本地通道名称列表执行名称解析处理。名称服务器用于将名称解析任务卸载到单个节点。以前在所有前端计算机上进行的此处理现在仅由名称服务器完成。在具有重负载前端计算机和高峰值客户端连接负载的控制系统中，可以看到显著的性能改进。本文将更详细地描述名称服务器，并讨论使名称解析成为集中式服务的优点和缺点。
Precise and accurate measurements of the beam energy delivered to the experimental halls at the Thomas Jefferson Accelerator Facility (Jefferson Lab) is required by many experiments for proper data analysis and physics event reconstruction. During the 6 GeV era of Jefferson Lab, the energy delivered to experimental Hall A was determined to 2E-4 dE/E with multiple measurements; but after the machine was upgraded to 12 GeV, the accelerator's beam energy calculations needed to be re-calibrated. In order to link the 6 GeV era calibrations to the 12 GeV era, the Hall A ARC energy measurement system…
CEBAF, the Continuous Electron Beam Accelerator Facility, has been actively serving the nuclear physics research community as a unique forefront international resource since 1995. This CW electron linear accelerator (linac) at the U.S. Department of Energy's Thomas Jefferson National Accelerator Facility (Jefferson Lab) has continued to evolve as a precision tool for discerning the structure and dynamics within nuclei. Superconducting RF (SRF) technology has been the essential foundation for CEBAF, first as a 4 GeV machine, then 6 GeV, and currently capable of 12 GeV. We review the development…
