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.

Philosophy

The philosophy was developed at a 15:00 meeting in MCC, including Arne Freyberger, Mike Spata, Yves Roblin, Mike TIefenback, 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
• perform qsUtility scans
• evaluate qsUtility data to get measured Twiss parameters and remittances
• back-propagate measured Twiss parameters to start of upstream xS04 quadrupole with elegant
• use qsUtility betatron match module to calculate xS04-xS10 match
• evaluate and install match
• re-scan harp and evaluate match effectiveness
• perform confirmation fopt