beam measurement programme in 2007

1. beam measurement programme in 2007 Frank Zimmermann, LHCCWG 31.01.2007

2. baseline • orbit - R. Steinhagen, LCWG#8, J. Wenninger, LCWG#6 • linear optics (Q, b, k, D, Qs) - R. Tomas (TBT) LCWG#8, R. Steinhagen, LCWG#6, J. Wenninger (ORM) LCWG#9,… • injection & injection matching - G. Arduini & A. Butterworth LCWG#2, F. Zimmermann LCWG#3 • apertures (arcs & IR) - S. Redaelli LCWG#11, Y. Papaphilippou LCWG#13, R. Steinhagen, LCWG#6 • nonlinear optics - F. Zimmermann, LCWG#12(also separation dipoles) • behavior on ramp (beam loss etc.) - M. Lamont LCWG#7, L. Bottura LCWG#14, J. Wenninger LCWG#17

3. brief recollection 1st turn ORM: polarity errors, BPM errors, strength errors to a few %, average phase advance, possibly b3 closed orbit ORM, 4-20 CODs/plane: BPM quality & calibration, COD calibration , optics? excite each COD; also bumps at TCDQ, TDI TBT BPM readings after kick→ f beating orbit with radial steering → D combined correction off and D/b1/2 TBT data → measure & correct local coupling K modulation at key locations? global aperturewith COD pairs, controlled blow up or kick (wire scan or BCT), momentum aperture w. radial steering, center frequency, local closed bumps or sliding bumps with pre-scraped beams local dispersion bumps, or groups of p bumps, or off-momentum TBT data to check b3 correction Q’ measurement & correction,rad. steering or phase modulation or HT mon. off-momentum coupling → a3 correction separate tunes, minimize Q’’ with b4 s.p., verify detuning

4. brief recollection cont’d minimize Q’’’ for b5 correction triplet alignment optics, K modulation of triplets, 2-beam IR orbit correction for D1/D2 transfer function question ramp: capture “flash” losses, continuous losses, bunch length evolution, effect of rf noise, commission PLL based feedback for Q, k, Q’? tracking errors, dispersion measurement by rf modulation or ramping with different frf , beta beating, continuous emittance measurement injection failure studies:find loss locations check IR apertures for later squeeze, IR bumps commissioning of separation bumps and crossing angle cross-calibration fast BCTs and DCTs measure dispersion & IR apertures with separated beams, for IR2 ad IR8 with spectrometer dipoles at 7-TeV collision strength effect of experimental magnets on orbit, coupling and tune identify IR triplet nonlinear errors with 3-bumps local impedance masurements with bumps at difference beam currents measurement of long-range beam-beam effect

5. any time spent on 2007 beam measurements is well invested the following shut down can be used to address all problems found → include measurements aimed at pre-empting possible problems which may be encountered at 7-TeV and/or at higher intensity

6. “forward-looking” measurements 1 nonlinear optics • scan beam lifetime & background vs. Q & Q’ • detuning with amplitude up to 6 s • nonlinear resonant driving terms • off-momentum measurements stability • orbit and optics stability with & w/o feedback • BPM & orbit feedback performance below and abovegain-switching threshold • effect ofground motion & tides • emittance growth with and w/o transverse damper

7. “forward-looking” measurements 2 diagnostics • calibration wire scanner-IPM-SRM; luminosity collimation • efficiency, operation, loss rates, background • understand beam loss patterns, BLM calibration? higher-intensity & beam-beam effects • single-bunch tune shift vs. bunch current with collimators open and closed (impedance) • beam-beam effects: head-on; lifetime & background vs crossing angle & transverse offset; variation with tunes, Q’, transverse damper, IR1-5 phase advance • inject short train which could give rise to e-cloud? • M. Ferro-Luzzi