Return to hallc_beam_energy_meas.tex CVS log | Up to [HallC] / Documents / Howtos |
File: [HallC] / Documents / Howtos / hallc_beam_energy_meas.tex
(download)
/
(as text)
Revision: 1.1, Tue Apr 1 22:17:33 2003 UTC (21 years, 5 months ago) by saw Branch: MAIN CVS Tags: mar2005, hks05 Hall C Beam Energy Measurement |
\documentclass{chowto} \title{Hall C Beam Energy Measurement} \howtotype{user} % ``expert'', ``user'', ``reference'' %\experiment{Name of experiment} % Optional \author{M. K. Jones} \category{beamline} % Subject area of this document %\maintainer{Name of person maintaining document} % Optional \date{\today} % Can use \today as the argument \begin{document} \begin{abstract} MCC does the beam energy measurement. It is important for the user to make an hclog entry as documentation. \end{abstract} \section{MCC energy measurement} MCC follows a standard \htlink{procedure}{http://opsntsrv.acc.jlab.org/ops_docs/online_document_files/MCC_online_files/HallC_energy_measure_proc.pdf} for doing the Hall C beam energy measurement. The basic idea is to setup a dispersive tune. Setting up a clean dispersive tune is usually what takes the most time. Then MCC adjusts the current of the arc dipole string (MBSY3C) to center the beam at the end of the arc on IPM3C17H. From the current one can calculate the beam energy assuming the beam follows the central path. By measuring the positions and angles at the entrance and exit of the dipole arc one can correct for small deviations for the central path. To measure these positions superharp scans are performed 3C07 and 3C17 positions. The beam current for the harp scans is 10~$\mu$A. \section{Making an hclog entry} It is important for the user to make an hclog entry. The user should log the following information. \begin{enumerate} \item The current of the arc dipole string MBSY3C. \item The Elog entry number of the {\it Hall C Energy Measurement} screen that MCC should make. An example is Elog entry \htlink{1134263}{http://opweb.acc.jlab.org/CSUEApps/elog02/elog_item.php?elog_id=1134263}. \item The Elog entry number of the {\it Hall C Superharp Analyzer} screen that MCC should make. An example is Elog entry \htlink{1134260}{http://opweb.acc.jlab.org/CSUEApps/elog02/elog_item.php?elog_id=1134260}. \item The uncorrected and corrected beam energies from the {\it Hall C Superharp Analyzer} screen. One can calculate the uncorrected beam energy using the current of the arc dipole string MBSY3C and the program {\it magnet} in the directory { \it Beam\_Energy } in the cdaq account on the cdaql1 machine. An example session is : \begin{verbatim} cdaql1.jlab.org> pwd /net/cdaqfs/hallc/home/cdaq/Beam_Energy cdaql1.jlab.org> magnet Include extrapolation uncertainty (<y> or <n>) ? : y do you want to do a calculation (<y> or <n>) ? : y enter current (amps) : 126.41194 Current: 126.41194 A Bdl = 756226.317 Gauss.cm P = (3.02898 +/- 0.00122) GeV/c do you want to do a calculation (<y> or <n>) ? : n \end{verbatim} \item The values for the epics variables {\it halla\_MeV} and {\it hallc\_MeV} . These values have been calibrated to previous energy measurements in Hall A and C and have been accurate in the past. To get the values do the following on a cdaq computer: \begin{verbatim} cdaql1.jlab.org> caget halla_MeV halla_MeV 5008.97 cdaql1.jlab.org> caget hallc_MeV hallc_MeV 3028.39 \end{verbatim} \end{enumerate} \end{document} % Revision history: % $Log: hallc_beam_energy_meas.tex,v $ % Revision 1.1 2003/04/01 22:17:33 saw % Hall C Beam Energy Measurement %
Analyzer/Replay: Mark Jones, Documents: Stephen Wood |
Powered by ViewCVS 0.9.2-cvsgraph-1.4.0 |