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Device control at CEBAF

Description: CEBAF has undergone a major conversion of its accelerator control system from TACL to EPICS, affecting device control for the RF system, magnets, the machine protection system, the vacuum and valves, and the diagnostic systems including beam position monitors, harps, and the camera and solenoid devices (beam viewers, faraday cups, optical transition radiation viewers, synchrotron radiation monitor, etc.). Altogether these devices require approximately 125,000 EPICS database records. The majority of these devices are controlled through CAMAC; some use embedded microprocessors (RF and magnets), and newer interfaces are in VME. The standard EPICS toolkit was extended to include a driver for CAMAC which supports dual processors on one serial highway, custom database records for magnets and BPMs, and custom data acquisition tasks for the BPMs. 2 refs., 1 tab.
Date: August 1, 1996
Creator: Schaffner, S.; Barker, D. & Bookwalter, V.
Partner: UNT Libraries Government Documents Department

Information-Control Software for Handling Serial Devices in an EPICS Environment

Description: Each accelerator control system has a variety of measurement devices. One of the most common types of instrument interfaces used for their control is a serial (RS-232) bus. It is inexpensive and adequate for relatively simple measurement and control devices such as switchers, amplifiers, voltmeters, and stepper motors. Since the RS-232 specification is very broad and does not require uniformity above the basic communication protocol level, one of the major problems associated with the use of RS-232 is that a fundamental understanding of the details of each device's command protocol is required. This makes writing reliable control software difficult and also hampers efforts to design effective, generic troubleshooting methods for RS-232. This paper presents software developed at Jefferson Lab to handle serial devices in a generic manner. The software is based on the EPICS toolkit and uses a 3-tier architecture which includes a common serial driver at the bottom, a top-level protocol to specify individual device commands in a generic manner, and a mid-level of software to glue the two together.
Date: November 1, 2001
Creator: Chevtsov, P. & Schaffner, S.
Partner: UNT Libraries Government Documents Department

Software engineering practices for control system reliability

Description: This paper will discuss software engineering practices used to improve Control System reliability. The authors begin with a brief discussion of the Software Engineering Institute's Capability Maturity Model (CMM) which is a framework for evaluating and improving key practices used to enhance software development and maintenance capabilities. The software engineering processes developed and used by the Controls Group at the Thomas Jefferson National Accelerator Facility (Jefferson Lab), using the Experimental Physics and Industrial Control System (EPICS) for accelerator control, are described. Examples are given of how their procedures have been used to minimized control system downtime and improve reliability. While their examples are primarily drawn from their experience with EPICS, these practices are equally applicable to any control system. Specific issues addressed include resource allocation, developing reliable software lifecycle processes and risk management.
Date: April 1, 1999
Creator: Schaffner, S. K. & White, K. S
Partner: UNT Libraries Government Documents Department

PLC Support Software at Jefferson Lab

Description: Several Automation Direct (DirectNet) Programmable Logic Controllers (PLCs) have been integrated into the accelerator control system at Jefferson Lab. The integration is based on new software that consists of three main parts: a PLC driver with a state machine control block, a device support module, and a common serial driver. The components of new software and experience gained with the use of this software for beam dump systems at Jefferson Lab are presented.
Date: October 1, 2002
Creator: Chevtsov, P.; Higgins, S.; Schaffner, S. & Seidman, D.
Partner: UNT Libraries Government Documents Department

Correction of dispersion and the betatron functions in the CEBAF accelerator

Description: During the commissioning of the CEBAF accelerator, correction of dispersion and momentum compaction, and, to a lesser extent, transverse transfer matrices were essential for robust operation. With changing machine conditions, repeated correction was found necessary. To speed the diagnostic process the authors developed a method which allows one to rapidly track the machine optics. The method is based on measuring the propagation of 30 Hz modulated betatron oscillations downstream of a point of perturbation. Compared to the usual methods of dispersion or difference orbit measurement, synchronous detection of the beam displacement, as measured by beam position monitors, offers significantly improved speed and accuracy of the measurements. The beam optics of the accelerator was altered to decrease lattice sensitivity at critical points and to simplify control of the betatron function match. The calculation of the Courant-Snyder invariant from signals of each pair of nearby beam position monitors has allowed one to perform on-line measurement and correction of the lattice properties.
Date: October 1, 1996
Creator: Lebedev, V. A.; Bickley, M.; Schaffner, S.; van Zeijts, J.; Krafft, G. A. & Watson, C.
Partner: UNT Libraries Government Documents Department

Tools for application management at Jefferson Lab

Description: The Software Controls Group at Thomas Jefferson National Accelerator Facility (Jefferson Lab) is responsible for slow controls for many Jefferson Lab facilities. The Experimental Physics and Industrial Control System (EPICS) is used as the basis of these control systems. The Controls Group developed and maintains over 150 control applications running on over 100 I/O controllers (IOCs). With so many applications, it becomes increasingly difficult to maintain and upgrade older applications and still produce new applications. The difficulties became especially apparent this year as a major effort was undertaken to upgrade all control system applications to the newest versions of EPICS and VxWorks. Over the past few years, the Controls Group has worked on constructing a framework within which to develop and maintain applications more efficiently. As the framework has matured and applications have been structured to fit the framework, a number of tools have been developed to help with software maintenance and upgrades. This paper will describe some of these tools and how they are used to enhance the maintainability and reliability of the control system.
Date: October 1, 1999
Creator: Schaffner, S.; Bickley, M.; Hoffler, A.; Keesee, M.; Wetherholt, D. & White, K.
Partner: UNT Libraries Government Documents Department

Data processing in AGS Experiment 780

Description: Experiment 780 is a search for the rare K decays K/sub L//sup 0/ ..-->.. ..mu..e and K/sub L//sup 0/ ..-->.. e/sup +/e/sup -/. We will be sensitive to these decays if the branching ratio is above 10/sup -10/. To achieve this in a 1000 hr experiment will require an intense beam with about 2 x 10/sup 5/ K decays/sec in the three meter decay region and over 10/sup 7/ counts/m/sup 2//sec in the apparatus. We will need a multilevel event selection sequence which will accept good events with high efficiency but quickly reject most of the background events. 1 ref.
Date: January 1, 1985
Creator: Morse, W.M.; Jastrzembski, E.; Larsen, R.C.; Leipuner, L.B.; Adair, R.K.; Greenlee, H. et al.
Partner: UNT Libraries Government Documents Department

Status and first results of Brookhaven Experiment 780: A search for K/sub L//sup 0/. -->. mu + e and K/sub L//sup 0/. -->. e + e

Description: We report on the progress of a search for the rare decays K/sub L//sup 0/ ..-->.. ..mu.. + e and K/sub L//sup 0/ ..-->.. e + e underway at the Brookhaven National Laboratory AGS. Analysis of data collected in February and May of 1987 yields the preliminary limit: BR(K/sub L//sup 0/ ..-->.. ..mu.. + e), BR(K/sub L//sup 0/ ..-->.. e + e) < 7 x 10/sup -9/. Prospects are discussed for the running period scheduled to begin in January of 1988.
Date: October 1, 1987
Creator: Greenlee, H.B.; Kasha, H.; Mannelli, E.; Mannelli, M.; Schaffner, S.; Schmidt, M.P. et al.
Partner: UNT Libraries Government Documents Department