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Reminder

Reminder. Dilution kicker system MKB is staged (2H, 2V) Limits extracted intensity at 7 TeV to 50% of nominal For 25ns spacing, this is a limit on single bunch intensity , NOT on total in LHC

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Reminder

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  1. Reminder • Dilution kicker system MKB is staged (2H, 2V) • Limits extracted intensity at 7 TeV to 50% of nominal • For 25ns spacing, this is a limit onsingle bunch intensity, NOT on total in LHC • Not an issue for “Stage I” : could safely dump full beam intensity up to about 2 TeV – (no interlock - rather unlikely to be needed in first few months…) Allowed dumped intensity (staged MKB) BTVDD trace – full dilution BTVDD trace – staged MKB

  2. Safety critical aspects of the LBDS • Signal from beam interlock system (test in HWC/RR) • No trigger = no beam dump • Energy tracking • Potentially catastrophic (whole beam at “any” amplitude) • MKD retriggering (test in HWC/RR) • No retriggering could put whole 7 TeV beam at ~10s • TCDQ setting • Wrong w.r.t. orbit exposes LHC arc / triplets / collimators. • System self-tests and post-mortem • Undetected ‘dead’ MKD severely reduces reliability • Aperture, optics and orbit • Dump with bad orbit could damage extraction elements MSD, TCDS or MKB • MKD – MKB connection and sweep form • Insufficient dilution could damage TDE, BTVDD and TDE entrance window • Abort gap ‘protection’ • Beam in the abort gaps risks quench, or TCT/LHC damage if TCDQ position error • Fault tolerance with 14/15 MKD • The system is designed to operate safely with only 14 out of the 15 MKDs Nearly all aspects need beam commissioning (validation or optimisation)

  3. Before first extraction… Circulating beam, 1 pilot at 450 GeV • Rough timing and revolution frequency • Adjust RF synch  MKD kick delay, S signal from IR6 BPM (UA access for each delay trim!) • Optics and other measurements in IR6 • Beta, dispersion, orbit correction, stability • Commission dedicated LBDS BDI for circulating beam • Synch BPM, BLMs (MKD, MSD, TCDS, TCDQ), check direct LBDS interlock BLM • Aperture measurement with circulating beam • MSD, TCDS, MKD, TCDQM Opening for circulating beam (H plane) at TCDS and MSD 15.3 mm (n1=6.5) 20.8 mm (n1=7.0)

  4. Before first pilot ramp…i Extracted beam: 1 pilot @ 450 GeV (inject & dump) • First extraction • Into “Inject & Dump” mode • Check of extraction timing with extracted beam • Commission extraction line BDI • BTV (SE, D, DD), BPM (SE, D), BLMs, BCTs Any major problems will be apparent at this stage!

  5. Before first pilot ramp…ii Extracted beam: 1 pilot @ 450 GeV (inject & dump) • Verification of extraction trajectory and aperture • Vary orbit in IR6 and measure aperture at TCDS/MSD/TD line • Optimise extraction trajectory (orbit, MKD, MSD); define ‘reference’ (UA access for MKD trim!) Opening for extracted beam (H plane) at TCDS and MSD Extracted beam aperture vs IR6 orbit { MKD sweep

  6. Before first pilot ramp…iii Extracted beam: 1 pilot @ 450 GeV (inject & dump) • Logging and fixed displays • Checks that the beam related data is being correctly acquired and displayed • XPOC basic functionality (trajectory, BLMs, BCT, kickers, BTVDD, …) • Check that XPOC validation is working correctly for pilot setup • Issue: safe change of configuration when changing beam. With MCS/SIS/sequencer? • BDI Post-Mortem data • Check that all beam-dependant transient signals from the LBDS systems are being PM’d

  7. Before first pilot ramp…iv 89 ms MKD kick waveform measurements • Important for aperture at TCDS/MSD • BPMD, BTVDD and BLMs. inject & dump, vary injected bunch bucket (5 meas. points) MKB sweep measurements • Important for MKB and TD line aperture • BPMD and BTVDD. inject & dump, vary injected bunch bucket (≈10 meas. points) Extracted beam: 1 pilot @ 450 GeV (inject & dump) MKD kicker waveforms (current signal) BTVDD ‘screenshot’ bunch 1300

  8. During ramp with pilot… Extracted beam: 1 pilot @ 450-7000 GeV (dump in ramp) • MKD, MKB kicker and MSD septum energy tracking • Extract single pilot at pre-defined energies in the ramp (calibrated points) – 1 TeV intervals. • Adjustment of kicker lookup tables means UA access • Time-consuming if done as dedicated measurement….need to organise in a quasi-parasitic way • Extraction with 2 pilots during the ramp is also needed to verify the abort gap timing…combine MKD lookup table calibration data

  9. Before moving to unsafe beams…i bunch 1 turn n 270 mrad kick bunch 2808 turn n-1 3 mrad kick Extracted beam: 2 pilots @ 450 GeV (inject & dump) MKD kicker “fine” timing adjustment • Inject 2 pilots into positions 1 and 2808 (3.0 ms spacing) • Fine adjustment of MKD timing (IR6 synch BPMs and RF frequency) • Acquire last turn of bunch 2808 in LHC to verify MKD kick (0.5 s or 3 mrad) MKD kick waveform 3.0 ms Note: this also needs to be checked through the ramp…

  10. Before moving to unsafe beams…ii Circulating beam: safe beam @ 450 GeV • Abort gap “watchdog” • Fine timing between IR6 and injections needs to be adjusted with beam • Abort gap monitoring and cleaning commissioning • Interlock BPMs for IR6 maximum orbit • Interlocked to around ±3.6 mm. Threshold setting and tests • SW interlock for beam position at TCDQ • Beam stability with orbit feedback at TCDQ and MSD

  11. Before moving to unsafe beams…TCDQ Circulating beam: 1 pilot @ 450 GeV • Adjustment of TCDQ/TCS jaws to 450 GeV position (≈10 s) • Beam axis wrt jaw, adjustment of jaw tilt, movement cross-calibration • TCS – 2 jaws - more accurate movement - tighter setting (by ≈0.5 s) • Needs BLMs and collimator controls • Orbit at TCDQ • Measurement of beam axis • Check that LHC aperture is protected…… Circulating beam: safe beam @ 450-7000 GeV • Establish TCDQ movement function during ramp • Interdependence with collimation system • Check of interlock functions and chain Circulating beam: safe beam @ 7 TeV • Establish TCDQ movement function during squeeze • Accurate adjustment of TCDQ and TCS jaws in final position • Establish reference settings for target b* during next phase of commissioning • Interdependence with collimation system  Interdependency on collimation settings, and on orbit feedback  Iterations (changes of orbit, b-beat, b*) to finalise TCDQ reference function

  12. Before first 43b ramp… Extracted beam: 43b @ 450 GeV (inject, fill & dump?) • Start with 43 pilots, to keep below the damage threshold…..? • When this is OK, move to 43 bunches of 41010 for validation • Losses in extraction channel and along the dump line • Reduced sweep with staged MKB means generous TD aperture • Check BDI response – new gains etc. maybe needed • Logging, PM and XPOC validations • Establish new reference data for XPOC… • Check abort gap monitoring and cleaning BPMD BTVDD

  13. Before first 156b ramp… Extracted beam: 156b @ 450 GeV (inject, fill & dump?) • As per 43b activities… • Plus….. • Specific check of TDE thermal behaviour (nominal 10 kW load)? • Could load with ≈4 kW with repeated inject, fill & dump of 156 bunches…

  14. LBDS beam commissioning – pilot beam

  15. LBDS beam commissioning – 43b

  16. LBDS beam commissioning – 156b This is the same list of activities as from pilot to 43b. It will be essentially the same list for all major changes in LHC beam (filling pattern, significant intensity steps, optics, emittance, …) It will also be repeated in detail when the full MKB kicker system installed

  17. Some issues/questions • Presently difficult to make 1:1 mapping between full system commissioning, MP aspects commissioning and overall LHC commissioning…. • Inconsistencies and different assumptions • Incomplete stages • Do NOT want to write and maintain 3 separate sets of procedures!!! • How do we assure that only the ‘authorised’ beam is used • Operational states and allowed LHC beam conditions – MCS, SIS and sequencer? • Acceptance criteria need more explicit definition – but some of these are more ‘fuzzy’… • Will try to add these in the ‘test’ document

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