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DA measurements: second session. Participants: S. Fartoukh, M. Giovannozzi, E. Maclean, S. Redaelli, F. Roncarolo, F. Schmidt, E. Todesco, R. Tomás, W. Venturini Delsolaro, F. Zimmermann Contributions by: W. Höfle, J. Uythoven, V. Senaj
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DA measurements: second session Participants: S. Fartoukh, M. Giovannozzi, E. Maclean, S. Redaelli, F. Roncarolo, F. Schmidt, E. Todesco, R. Tomás, W. Venturini Delsolaro, F. Zimmermann Contributions by: W. Höfle, J. Uythoven, V. Senaj Goal: Benchmarking of DA computations; non-linear modelling and resonances. LHC Studies WG - MG
What is new since last presentation • MKA issues: • Variation in kicker strength observed access required to fix it. • Access request already put in: 2 hours needed. • Hopefully this can take place before the MD (in the shadow of another access request). • Otherwise, it could take place right after the ramp down from previous MD (some access time could be absorbed in the 2 hours assumed for ramp down). • MP issues: • MKA should be enabled/disabled before and after the MD: about 0.5 hour needed. • A pre-cycle should be performed after the second access and before switching to next MD: about 1 hour needed. • All collimators opened, except primaries at 12 s is acceptable. Decision on whether the MKA will be used to be taken just before the MD block • Transverse damper to blow-up the beam: • Confirmed to be available by Wolfgang (at least for Beam 1)! LHC Studies WG - MG
Procedure - I • Nominal machine (Beam 1) • crossing bumps ON • coupling well corrected • collimators: all opened, primaries at 12 sigma (to shadow machine aperture) • Then • Inject a single bunch of about 1010 p, standard emittance (FWS measurement) • Blow-up transversely (H/V) using the transverse damper (FWS measurement and BSRT) • Measure intensity decay with time • Change settings and go to 1 • Configurations to be tested: • Nominal (including MOs) • MOs set to zero (manual de-Gaussing) • Scan over MCDs • Scan over MCOs with alternating signs between sectors to minimise off-momentum effects. New option successfully tested in MD#3 To have another reference measurement Already planned in previous MD, but skipped due to hardware problem. Order of scan to be defined. LHC Studies WG - MG
Procedure - II • Nominal machine (Beam 2) • crossing bumps ON • coupling well corrected • collimators: all opened, primaries at 12 sigma (to shadow machine aperture) • Then • Inject a single bunch of not more than 1010 p, standard emittance (FWS measurement) • Kick with aperture kicker to determine directly DA • Change settings (or repeat to gather statistics) and go to 1 • Configurations to be tested: • Nominal (including MOs) • MOs set to zero (manual de-Gaussing) • Scan over MCOs and MCDs • Scan over MCOs with alternating signs between sectors. • Driving terms and detuning measurements will be also performed. If MKA measurements are dropped, DA for Beam 2 will be dropped, but driving term and detuning measurements will be performed with AC dipole. Upgrade of aperture kicker allows reaching 12 s at injection LHC Studies WG - MG