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Proposed tests with beam

Proposed tests with beam. Massimo Giovannozzi Acknowledgements: G. Arduini, B. Goddard, M. Lamont, S. Redaelli , N. Sammut, J. Uythoven , J. Wenninger. Evolution of sector test proposals. 2006: Detailed analysis presented at the Chamonix Workshop. 2007:

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Proposed tests with beam

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  1. Proposed tests with beam Massimo Giovannozzi Acknowledgements: G. Arduini, B. Goddard, M. Lamont, S. Redaelli, N. Sammut, J. Uythoven, J. Wenninger. M. Giovannozzi - Extended LTC

  2. Evolution of sector test proposals • 2006: • Detailed analysis presented at the Chamonix Workshop. • 2007: • Sector test without triplets and D1 in IP8 (right). Option quickly discarded. • LHC MAC presentation (M. Lamont). • 2008: • Extensive analysis of various phases of LHC commissioning performed by LHCCWG: sector test would allow applying procedures that will be needed later. • Beam 1 is also considered in the general scheme of a sector test. M. Giovannozzi - Extended LTC

  3. Brief summary of the items/systems to consider • Injection and threading • Instrumentation • Optics measurements • Aperture checks • Effect of magnetic cycle • Field quality checks • Quench limits and BLM response • Others M. Giovannozzi - Extended LTC

  4. Boundary conditions - I See presentation by H. Vincke • LSS and arc(s) should not be irradiated • LHCb should also be preserved • This can be achieved by: • Minimising losses • Optimising/minimising the amount of beam used for the tests. • The beam parameters are • Pilot beam is the preferred choice: 5 x 109 p+, below quench limit, about x100 below damage threshold • Some tests with 1-3 x 1010 or up to 1 x 1011 p+ in one bunch • Beam emittance: 1 mm < en < 3.5 mm (lower emittances might be problematic for machine protection…) • Momentum spread: nominal, but smaller might be useful… M. Giovannozzi - Extended LTC

  5. Boundary conditions - II • Optics • Nominal one: (nx, ny) = (0.28, 0.31). • Commissioning one: (nx, ny) = (0.285, 0.385). To be used only in case of problems. • Other conditions • Start with zero separation/crossing angle to maximise aperture • LHCb spectrometer will be off • Beam losses across LHCb should be quantified (BPM intensity signals are an option) • Circuits used: those already foreseen in Phases A.1 and A.2 (one single beam, only). • Circuits should be commissioned at least to 450 GeV+ for limited recycling. M. Giovannozzi - Extended LTC

  6. LHC magnetic cycle • Start beam tests using the ‘nominal’ cycle: • MB current cycled to < 100% (reduced HWC?) • Cycle correctors to 100%, to avoid over-large hysteresis effects • A ‘de-Gauss’ cycle might be used in a second stage to check the geometric field quality of the magnets. Sector 7-8 Nominal - waiting de-Gauss Recent studies revised the expected decay to smaller values (N. Sammut et al. EDMS 842273): see following slides. Nominal M. Giovannozzi - Extended LTC

  7. End of TL/injection commissioning Right of IP8 (H plane) D2 Q5 Q4 TDI (MKI +90˚) MSI MKI Left of IP2 (H plane) M. Giovannozzi - Extended LTC

  8. Arc(s) Courtesy M. Lamont X 23 M. Giovannozzi - Extended LTC

  9. TL re-commissioning, end of TL and injection commissioning • 24 hours foreseen (Of course, it might be much faster if everything works according to specs…) • Key hardware systems • TL elements (including TCDI), MSI, MKI, Q5+Q4+D2 on injection side (Right for IP8, Left for IP2), correctors, TDI, BTV, BPM, BLM, timing • Dedicated or expert application software • Injection steering, injection post-mortem, TDI positioning, injection fixed displays, equipment expert applications • Crucial issues • Tight aperture at MSI, Q5, MKI, and D2 • Synchronised shot-by-shot logging for each injection M. Giovannozzi - Extended LTC

  10. Aperture bottlenecks Aperture situation in IP2 (similar in IP8). See J. Uythoven, InjWG 13/09/2007 Proposal to change longitudinal angle of Q5 (IP2 and IP8). See J.-B. Jeanneret, InjWG 29/06/2007 M. Giovannozzi - Extended LTC

  11. Threading to arc(s) - I • Proposed strategy • Inject pilot and measure • Correct over small range (manual BPM rejection) • Iterate • Pay attention to the separation/recombination dipoles (transfer functions…) • Method checked by coupling MADX to YASP steering program, with aperture filter, noise etc. (LHC Beam 1) BPMs : ± 3 mm errors, flat distribution Dipoles : b3 = -20 units (systematic), other components : error table Multipole correctors : OFF Courtesy J. Wenninger M. Giovannozzi - Extended LTC

  12. Threading to arc(s) - II • 24 hours foreseen (see comment on slide 8…) • Key hardware systems • LHC machine… • BPMs, correctors, LHCb radiation monitoring, BLMs, BTVs (in case LBDS is used, also those in LSS7 – right – and in the dump line will be available) • Dedicated/expert application software • YASP, MADX on-line model, BPM intensity acquisition (see next slide...) and signal display. • Models • TL + LHC ring (sequence and aperture model) available • Where to stop: • Beam 1: IR3 • Beam 2: up to TDE M. Giovannozzi - Extended LTC

  13. Threading to arc(s) - III • Monitoring beam intensity during the sector test phases will be crucial for many reasons, e.g.: • Controlling beam losses and correlate them with activation • Aperture measurements (see next slides) • Quench behaviour tests (see Ralph’s presentation) • How to get the intensity information: • BPM in intensity mode: this prevents the signal from the other beam (not a problem for the sector test...). Is this mode operational? • Temporary BCTs (not necessary if dump line is used)? • The selected beam intensity should be high enough to allow for losses (in early stages of the tests) without losing BPM triggering. M. Giovannozzi - Extended LTC

  14. Linear optics tests - I • Trajectory response using correctors and BPMs • BPM + corrector polarity and calibration errors • Phase, coupling, Twiss • Dispersion measurement with dp and BPMs • Betatron matching measurement with BTVs Courtesy B. Goddard M. Giovannozzi - Extended LTC TED TI 8 LHC TED IR7

  15. Linear optics tests - II • 12 hours foreseen • 1-2 x 1010 p+ for improved BPM and BTV response • Semi-automated tests. Efficient tool for quick off-line data analysis • Key hardware systems • BPMs, correctors, BTVs • Dedicated/expert application software • On-line re-matching and analysis tools might not be needed • In general tools were developed (TI8/2 tests in 2004/7) and are under development (e.g., MADX on-line model). M. Giovannozzi - Extended LTC

  16. BLM system tests - I • Get the system up and running, recording losses • Prior calibration with source: expect reasonable numbers quickly • Acquisition and display of beam losses for some monitors • Some crosstalk studies possible (in principle ‘other beam’ monitors available…) Courtesy B.Dehning BLMs will be important for the quench tests! M. Giovannozzi - Extended LTC

  17. BLM system tests - II • Parasitic measurment • Will be plenty of other opportunity for parasitic commissioning • Probably to be organised together with the aperture measurements • Key hardware systems • BLM system • Dedicated/expert application software • BLM displays, MCS, BLM expert applications • Remaining issues/areas for study • Finalise data exchange with control system (logging, Post Mortem, thresholds) • BLM display (prototype for final LHC version?) • Triggering for single-shot logging? • Post Mortem to be tested? M. Giovannozzi - Extended LTC

  18. Aperture measurement • Verify physical aperture as expected (bottlenecks, arc, IP) • First iteration : oscillation from 2 correctors at 90º to probe ‘all’ phases • Second iteration if needed/time available: p bumps (local anomalies, specific regions) Horizontal plane 8 s oscillation Vertical plane 8 s bump Courtesy B. Goddard Expected aperture Need corrector strengths of about 50 mrad M. Giovannozzi - Extended LTC

  19. Momentum measurement • Transmission vs momentum offset by changing SPS RF frequency • Probably limited by TL arc (present measured acceptance ±0.003), hence not too relevant. Courtesy B. Goddard dp/p = 0.004 (1mm en) M. Giovannozzi - Extended LTC

  20. Aperture measurements • 24 hours foreseen • Keep clear of LHCb • 1 mm en for best resolution • Key hardware systems • Correctors, BPMs (some with intensity information), BCTs, BLMs. • Dedicated/expert application software • Need (semi-)automatic applications: • Free oscillations (~5 amplitudes, ~12 phases, 2 planes, ~2 starting locations) • For sliding bumps (~45 correctors, 2 planes, ~5 amplitudes) • NB: the real need of detailed aperture measurements should be evaluated taking into account the general constraint of not irradiating too much the arc(s). M. Giovannozzi - Extended LTC

  21. Quench limits and BLM response • Magnet exposure to beam and BLM response • Golden opportunity to steer beam into magnets…. • 36 hours foreseen • Intensity 11011 p+ (5% of damage level at nominal en) • Higher intensity would require multi-bunch injection to be commissioned (probably not worth it). • See R. Assmann talk for full details M. Giovannozzi - Extended LTC

  22. Effects of magnetic cycle - I • Decay effects: • It depends on IFT/IINJ • It depends on ramp rate. • The decay of b3, usually estimated to 2 units, is indeed only 0.9 units for 10 A/s ramp rate (nominal). • Finally, the actual decay will be very small for IFT < INOM M. Giovannozzi - Extended LTC Courtesy N. Sammut

  23. Effects of magnetic cycle - II • 24 hours foreseen • Variations during decay • Reproducibility • Energy variation on flat bottom • In case, go to a ‘de-Gauss’ cycle • Repeat subset of injection, trajectory and linear optics checks R. Wolf – FQWG meeting September 11th 2007 M. Giovannozzi - Extended LTC

  24. Detailed field errors study– high statistics Kick-response and trajectory analysis • LOCO - average a2, b2 and b3 field errors of MBs, b2 of MQs • Need BPM noise & injection errors <200 mm (or ~0.2 s) • Extending method to check multipole corrector polarities (by strong excitation) might be envisaged • 12 hours foreseen • Should plan part of this fairly early, to test method In sector 7-8, actual b3 will be 2-3 times smaller: a stronger kick will be needed! MB b3 field error effect (mean -9.6 units, rms 1.4 units). H trajectory change for 40 mrad H kick (top) and 40 mrad V kick (bottom) M. Giovannozzi - Extended LTC Courtesy J. Wenninger

  25. Other studies • Transfer line collimation studies • Injection protection studies • Impact of MKI wave form on injection performance • Separation and crossing angle bumps (these are not needed for Phase A) • Injecting onto vertical separation bump • Bump closure, induced dispersion, aperture M. Giovannozzi - Extended LTC

  26. Example: separation and crossing bumps • 6 hours • LHCb spectrometer + compensation off • Injecting onto separation bump • Bump closure, induced dispersion, aperture • Injecting onto opposite polarity bump Vertical aperture with 100% bump H&V bumps M. Giovannozzi - Extended LTC

  27. Beam tests summary - I Courtesy M. Lamont M. Giovannozzi - Extended LTC

  28. Beam tests summary - II Courtesy M. Lamont M. Giovannozzi - Extended LTC

  29. Procedure for a sector test? • Since 2006 the LHC Commissioning Working Group studied and prepared detailed procedures for the various phases of the LHC commissioning. • The sector test will allow gaining experience with the procedures for the later stages. Phases for full commissioning Stage A (pilot physics run) M. Giovannozzi - Extended LTC

  30. Entry conditions for commissioning end of TL, injection, threading - I Some collimators will be fully closed to stop the beam (see talk by S. Redaelli) M. Giovannozzi - Extended LTC

  31. Entry conditions for commissioning end of TL, injection, threading - II Partial hardware commissioning and unavailability of some sectors (LBDS not usable) will relax some constraints with respect to Phase A.1 M. Giovannozzi - Extended LTC

  32. Entry conditions for commissioning end of TL, injection, threading - III LBDS might not be needed unless sector 6-7 (Beam 2 tests) will be available (and also in this case there might be alternatives… M. Giovannozzi - Extended LTC

  33. Breakdown of activities - I M. Giovannozzi - Extended LTC

  34. Breakdown of activities - II In case the LBDS could be used… M. Giovannozzi - Extended LTC

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