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This is a wiki page for references, information, and procedures about Fall 2015 work to match Twiss parameters and measure transverse beam emittances at many locations through the fully operational 12 GeV CEBAF accelerator. This approach leverages data from qsUtility that will be used for standard matching procedures in the accelerator as of Fall 2015.

Prerequisites at Each Measurement Location

  • 4-8 uA tune beam to first dumplette downstream of match point.
  • quad centering of BPM/quadrupole pairs for qsUtility scan quadrupoles.
  • clean steering in region of measurement and downstream to maximize aperture, minimize beam losses.
  • clean ORFP dispersion in region of measurement and correction. In particular, dispersion in both planes must be consistent with zero at scan quadrupoles and harp.


  • confirm harp is working and set harp parameters
  • perform zigzag measurements to establish scan quadrupoles and ranges
  • edit qsUtility configuration files if necessary
    • configuration files are in /a/opsdata/fiefdata/fileio/q/qsUtility/config/F3-0/GoldenTemplates
  • perform qsUtility scans
  • evaluate qsUtility data to get measured Twiss parameters and emittances
  • back-propagate measured Twiss parameters to start of upstream xS04 quadrupole with elegant
    • A script to do this is in ~satogata/backpropagate.pl
  • use qsUtility betatron match module to calculate xS04-xS10 match
    • configuration files are in /a/opsdata/fiefdata/fileio/q/qsUtility/match_config/F3-0
  • evaluate and install match
  • re-scan harp and evaluate match effectiveness
  • After match is installed, one has to set the recombiner quads back to design in order to proceed to the next arc.
  • perform confirmation fopt

Data and References

  • Fall 2015 Optics Spreadsheet (Google docs)
  • CEBAF energy calculation spreadsheet (toddsatogata.net)
  • 0L injector match (E=123.0 MeV, BDL=615.43*K1 for L=0.15m magnets)
  • 1E01 match (E=1213.0 MeV, BDL=6069.20*K1 for L=0.15m magnets, be careful MQN1S04 is L=0.30m, others are L=0.15m)
  • 1E03 match (E=1213.0 MeV, BDL=6069.20*K1 for L=0.15m magnets, be careful MQN1S04 is L=0.30m, others are L=0.15m)
  • 2E01 match (E=2303.0 MeV, BDL=23045.94*K1 for L=0.30m magnets)
  • 3E01 match (E=3393.0 MeV, BDL=33953.49*K1 for L=0.30m magnets)
  • 4E01 match (E=4482.8 MeV, BDL=44861.04*K1 for L=0.30m magnets)
  • 5E01 match (E=5572.4 MeV, BDL=55768.58*K1 for L=0.30m magnets)
  • 6E01 match (E=6661.3 MeV, BDL=66676.13*K1 for L=0.30m magnets)
  • 7E01 match (E=7749.1 MeV, BDL=77583.67*K1 for L=0.30m magnets)
  • 8E01 match (E=8835.1 MeV, BDL=88491.22*K1 for L=0.30m magnets)
  • 9E01 match (E=9918.4 MeV, BDL=99398.76*K1 for L=0.30m magnets)
  • AE01 match (E=10997.6 MeV, BDL=110306.31*K1 for L=0.30m magnets)
  • 5C00 match (E=12071.3 MeV, BDL=121213.86*K1 for L=0.30m magnets)
  • 1C match (E=10997.6 MeV, fifth pass, BDL=110306.31*K1 for L=0.30m magnets)
  • rayTrace data

Useful Tools

setquadstomachine: During the backpropagation or the matching calculation, if one wants to take into account quadrupoles that are off design, one can use the script ~roblin/tools/setquadstomachine which together with a snap file of the region in question produces a sdds file suitable for inclusion in the ELEGANT command file via load_parameters. usage is

 # ~roblin/tools/setquadstomachine <commandfile> <snapfile>

and it will make QUADparams.sdds ready for load_parameters. Read the comments in the script for further details (or page Yves).

analyzeZigZagRange.pl: Todd has written a tool to help analyze zigzag scans for quad scan ranges. Usage is, for example,

# ~satogata/tools/analyzeZigZagRange.pl IHA1E03.SA.02282015_00:28:42

This tool prints out the quadrupole that is being scanned, the list of scans and corresponding BDL and K values for that quad, and uses gnuplot to plot the zigzag scan data. One can then count the peaks and look up the corresponding BDL and K values for use in qsUtility configuration files.

zigzag2qsUtility: Dennis has a tool that converts zigzag scans to input files for qsUtility, though at present the qsUtility file that is generated needs to have the quadrupole K values added manually. An example for IHA3E01 is

# zigzag2qsUtility -scan_file=IHA3E01.SA.03032015_10:48:30 -show_plots -exclusion_zone=0.15 -plane=X -lattice_name=test -momentum=2200 -start_element=MQA3S10 -pass=2