AP-CEBAF-Optics-2015-02-28
This is a wiki page for references, information, and procedures about Feb 27-Mar 1 work to transversely match CEBAF Twiss parameters at the injector (~0L07), 1E03, and xE01 locations.
Contents
Philosophy
The philosophy was developed at a 15:00 meeting in MCC, including Arne Freyberger, Mike Spata, Yves Roblin, Mike TIefenback, Jay Benesch, Todd Satogata, and Operations:
- use zigzag harp scans to identify quadrupole ranges for good optics/emittance measurements at each harp.
- modify qsUtility configuration files in the golden area and acquire optics/emittance measurements with traditional qsUtility scans.
- use qsUtility to analyze the scans and get measured horizontal/vertical Twiss parameters at the start of the respective scan quads.
- back-propagate measured Twiss parameters to the start of the upstream xS04 quadrupole.
- use the qsUtility betatron match module (which uses ced2elegant and elegant) to calculate the match, with match point at the harp, using xS04-xS10 quadrupoles for matching to distribute matching effort.
- evaluate and install the match.
- re-scan the harp and compare beam sizes to sqrt(emit_meas * beta_design)
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.
Procedure
- 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
- perform confirmation fopt
Data and References
- Spring 2015 Optics Spreadsheet
- 0L injector match (E=107.2 MeV, BDL=536.365*K1 for L=0.15m magnets)
- 1E03 match (E=1057.2 MeV, BDL=5289.659*K1 for L=0.15m magnets):
- 2E01 match (E=2007.2 MeV, BDL=20085.89*K1 for L=0.30m magnets):
- 2E01: zigzags -> MQC2S10 horizontal scan centered near 4600G, range +/-1000G (BDL 0.229+/-0.05)
- 3E01 match (E=2957.2 MeV, BDL=29592.47*K1 for L=0.30m magnets):
- 4E01 match (E=3907.2 MeV, BDL=39099.05*K1 for L=0.30m magnets):
- 5E01 match (E=4857.2 MeV, BDL=48605.63*K1 for L=0.30m magnets):
- 6E01 match (E=5807.2 MeV, BDL=58112.20*K1 for L=0.30m magnets):
- 8E01 match (E=7707.2 MeV, BDL=77125.36*K1 for L=0.30m magnets):
- 9E01 match (E=8657.2 MeV, BDL=86631.93*K1 for L=0.30m magnets):
- AE01 match (E=9607.2 MeV, BDL=96138.51*K1 for L=0.30m magnets):
- 5C00 match (E=10557.2 MeV, BDL=105645.09*K1 for L=0.30m magnets):
- 1C match (E=9607.2 MeV, fifth pass, BDL=96138.51*K1 for L=0.30m magnets):
- 2C match (E=2007.2 MeV, first pass, BDL=20085.89*K1 for L=0.30m magnets):
- rayTrace data: 3322485 H 3322488 H 3322490 V
Useful tools
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 me).