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V.Kain, H. Burkhardt, B.Goddard, W. Hofle, V.Mertens, S. Redaelli, J.Uythoven, J.Wenninger

V.Kain, H. Burkhardt, B.Goddard, W. Hofle, V.Mertens, S. Redaelli, J.Uythoven, J.Wenninger. Injection and Associated Protection Devices. Scope - Contents. Scope: Stage A: limit 43 x 43, 156 x 156 with 9 x 10 10 p + per bunch Only commissioning steps which require set-up with beam

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V.Kain, H. Burkhardt, B.Goddard, W. Hofle, V.Mertens, S. Redaelli, J.Uythoven, J.Wenninger

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  1. V.Kain, H. Burkhardt, B.Goddard, W. Hofle, V.Mertens, S. Redaelli, J.Uythoven, J.Wenninger Injection and Associated Protection Devices

  2. Scope - Contents • Scope: • Stage A: limit 43 x 43, 156 x 156 with 9 x 1010 p+ per bunch • Only commissioning steps which require set-up with beam • Injection/SPS extraction interlocking not covered • Commissioning steps are described for one beam • other beam requires repetition of same steps • Time estimate per step in general: 1 – 2 shifts maximum • Not very specific yet about exact values of target parameters • Contents: • Injection commissioning during phase A.1 • Injection commissioning during phase A.2-A.3 • Injection commissioning during phase A.4 • Injection commissioning during phase A.5 *target parameters need to be properly defined

  3. Injection Region LEFT OF IP2 (H plane) Kicker MKI TCDD TCDI Septum MSI TDI MKI +90˚ RIGHT OF IP2 (H plane) TCLIM TCLIA TCLIB

  4. PHASE A.1 First turn

  5. Preparation Phase A.1, pilot intensity, OP/BT • Requirements: • Transfer line re-commissioned with beam • With TED in, then TED moved out • Orthogonal steering available for MSI and MKI • Settings generated for TDI (out, coarse, protect) • Shot-by-shot logging configured • Timing tables verified (BI capture events) • Remove extraction permit at SPS • All TCDIs/TCLIs out • TDI masked (completely IN) • TCDD in point 2 IN • MKI ON, kick disabled • Soft-start done • All screens in, downstream of TED and downstream of MSI • Cameras on BTVSS: first screen in the LHC

  6. First Injections – MKI NOT pulsing Phase A.1, pilot intensity, OP/BT • Enable extraction permit • Injection (MKI disabled): • Beam should arrive at TDI, off-center • Steer if required • orthogonal steering at MSI and MKI already implemented in YASP • Check signals at screens and BPMs (BLMs no losses) • BTVSS, BTVSI1, BTVSI2, BPTX, BPMW, BTVST (in front of TDI) • Steer to have correct offset at TDI on screen • ~ + 30 mm • Verify BLM readings on TDI: • Triggered acquisition of BLM readings • Calibrate parasitically (mGy vs. intensity lost) • Thresholds should not trigger Screen in front of TDI

  7. First Injections – MKI pulsing Phase A.1, pilot intensity, OP/BT • Remove extraction permit – enable MKI, pulse • Enable extraction permit • Inject • Adjust delay such that beam is in middle of waveform • Verify vertical position on BTVST in front of TDI • Steer MKI angle • Beware of BETS constraints • Move TDI to PROTECT position • +/- 7 mm • Remove BIC mask on TDI • Start threading around ring… • (Move out injection screens)

  8. PHASE A.2 - PHASE A.3 Circulating beam – 450 GeV initial commissioning (BI, beam dump,…)

  9. Injection re-steeringPhase A.2, pilot intensity, OP; Phase A.3, 3 x 1010, OP • Phase A.2: after establishing closed orbit: • Inject & circulate • Initial optimisation of injection oscillations: re-steer injections • Phase A.3: high precision orbit measurements: • Inject & circulate • Optimisation of injection oscillations: re-steer injections • Minimise to… De < 0.5 s (results in 12 % emittance growth without damping) *target parameters need to be properly defined

  10. PHASE A.4 450 GeV optics measurements

  11. Injection stability - reproducibility Phase A.4, 3 x 1010, OP • Injected beam: check stability of injection point • Transfer line and MKI effects • Inject & dump • 1000 shots • Use BPMs and BTVs in injection region + BPMs and BTVs before MSI in transfer line • Shot-by-shot, restarting after a couple of days (temperatures, MKI soft-start, …) • Circulating beam at injection • Orbit at injection point/TDI • Beam sizes at injection point/TDI • Looking at nominal cycle only… • Parasitically every time we fill

  12. Aperture in injection region (1) Phase A.4, pilot intensity – 3 x 1010, OP/BT • Aperture bottlenecks in the LHC injection regions: • MSI, Q5, MKI, D2 • → Q5 tilted • + 1 mm on IP side • - 2 mm on IP side • Q5 tight under nominal conditions – n1 = 6.2 • MKI and D2 tight for • Non-kicked injected beam • Kicked circulating beam → beam in the injection kicker rise time gap (~ 0.9 ms) J. Uythoven J. Uythoven: InjWG 07-05 Injected non-kicked beam

  13. Aperture in injection region (2) Phase A.4, 3 x 1010, OP/BT Aperture measurement: MSI and Q5 Use injected beam → inject & dump, TDI out BLMs triggered acquisition mode FBCTs in point 4/point 6 Transfer line knobs in sigma to measure aperture Limited by aperture of MSI Calibrate BLMs at MSI (on TCDIM and MSIs) Aperture measurement: MKI and D2 Use circulating beam → circulate & dump, TDI needs to be in PROTECT Kick circulating beam + scan bump at D2 or MKI BLMs triggered acquisition mode (Take out bumps at the end)

  14. Scan MKI waveform Phase A.4, 3 x 1010, BT/OP • Scan MKI waveform: • Inject & dump • Use screen at TDI (90º downstream) • Scan kicker delay Example: LHC extraction commissioning – SPS LSS6 – 2006 kick delay was changed, position measured with screen.

  15. Injection Matching (1) Phase A.4, 3 x 1010 • Mismatch possibilities – leads to emittance growth and tail repopulation • Emittance growth: • Betatron, dispersion mismatch – measurement of twiss parameters at injection point • Energy, steering mismatch – verify with BPMs around the ring → see Jorg’s talk • Geometry • Tail repopulation: verify with scraped beam from SPS and scrapers in the LHC → stage B Results from simulations: Dominant effect: betatron and dispersion mismatch Emittance growth predicition about 3% Tail repopulation after scraping in SPS

  16. Injection Matching (2)Phase A.4, 3 x 1010, OP/ABP • Oscillation of image on matching screen indicates mismatch • Matching screen in point 3 (will not be there for 2008) • LHC optics needs to be measured • To measure twiss parameters at injection point (dispersion, betas and alfas) • Matching screen turn-by-turn • Screens in injection region • Eventually (= stage B) need to control better than: • Betatron mismatch: l < 1.15 • Dispersion: maximum mismatch of 10 cm, 0.001 rad • Screen matching application: • used for TI 2: • 2 D fit for beam sizes • optics calculated at any point in the • line • same application can be used for • LHC *target parameters need to be properly defined

  17. PHASE A.5 Increasing intensity 4 bunches max injected for 43 x 43 16 bunches max injected for 156 x 156

  18. Operational States? • In this phase injection protection starts to play a role • The systems will be commissioned for a certain envelope • Optics • Emittance • Crossing-/separation angle, experimental magnet polarity • Maximum injected intensity • … • What/who makes sure that the systems are not used outside these “operational states” without re-commissioning or adjusting?

  19. Multi-bunch injectionPhase A.5, 4 x 3 x 1010 or 16 x 3 x 1010, OP/BT • Multi-bunch injection: • Adjust delay for MKI kick • For 16 x 3 x 1010: • Only after setting up the TDI • For 4 x 3 x 1010: TDI roughly set up • Optics knowledge from phase A.4 • Centered Example: LSS4/LSS6 extraction

  20. Setting-up of TDIPhase A.5, 3 x 1010 – 4 x 3 x 1010, BT/collimation team/OP The required setting of the moveable passive protection devices depends on the LHC aperture. Assume 7.5 s. • TDI: • ~ 4m long, ~ 10 m upstream of D1, additional mask in front of D1 (TCDD) • Protects machine against MKI failures • Required setting: 6.8 s • TDI – setting-up • At this stage independent of cleaning collimators • Setting-up like cleaning collimators: covered by Ralph’s talk • Centering, alignment, beam size measurement • Test of synchronized (automated) setting-up with the beam cleaning collimators • Verify fill-to-fill reproducibility, orbit feedback • Verify aperture for second beam • Verify protection against MKI failure (3 x 1010): • Trim the MKI angle (beware of BETS limits and critical settings) • Maximum escaping amplitudes must be < 7.5 s and primary loss should only occur at the TDI • TCLIs → Stage B • Unless phase advance between TDI and MKI compromised

  21. Setting-up of Transferline Collimators (TCDI)Phase A.5, 3 x 1010, BT/collimation team/OP • Requirement: • Transferline optics measured • Setting-up: each TCDI individually (the others need to be out) • Inject & dump • Centering, alignment, beam size cross-check, set to 4.5 s • Use BLMs (local, non-local), BCTs TL/point 4/point 6 • Calibrate BLMs on TCDIs and masks parasitically • Thresholds set to: maximum allowed loss: 1 x 1011 • Verify response on nearby superconducting magnets • Check phase space coverage: maximum amplitudes escaping system: < 6 s • Inject & dump, move out TDI • Use aperture scan knobs from transfer lines • Oscillations down the line, generated by combinations of corrector magnets 4.5 s setting with maximum tolerance *target parameters needs to be properly defined

  22. Setting-up transverse damperPhase A.5, 3 x 1010 – 4 x 3 x 1010, RF/OP • Details in Wolfgang’s talk • Commission transverse damper to damp injection oscillations: • Inject & circulate • Could be done in phase A.4: single bunch: mis-steer injection • Measure emittance in line and in ring after injection (with and without damping) • Multi-bunch: injection kicker waveform effect • Verify with emittance measurement • Commission transverse damper to clean MKI rise time gap → stage B / depending on re-population mechanism and aperture in D2 • Might need to clean abort gap at the same time

  23. Injection protection needs to be revisited for… • New LHC optics version • Emittance changes • Injection re-steering • Aperture verifications in the injection region • Transfer line collimator centering needs to be verified • Injection protection needs to be set up again • Poor reproducibility after re-cycling • Re-set up injection protection system • Rematching of transfer lines • Transfer line collimators need to be set up again • Crossing-, separation angle changes, polarity changes of experimental magnets • Injection re-steering

  24. Conclusions • A commissioning plan has been developed to prepare the LHC injections for up to 156 x 156 with 9 x 1010 particles per bunch • Injection quality and injection protection has been taken into consideration • Details of target parameters still need definition • A “procedure/formalism/check list…” must be put in place to guarantee that the systems are not operated outside the parameters they have been commissioned for.

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