Interleaved HW and Beam Commissioning? G. Arduini, M. Pojer, R. Schmidt

1. Interleaved HW and Beam Commissioning? G. Arduini, M. Pojer, R. Schmidt Discussions with: L. Bottura, M. Giovannozzi, M. Lamont Your feedback is welcome!!

2. Aim • Delays in the availability of the Sectors (schedule already obsolete...) • Determine the minimum conditions required for: • Sector tests (in particular for Beam 2) • 10/9 type of event: i.e. Injection, circulating beam and RF capture • After this phase? K. Foraz – LMC 3/6/2009 Beam Commissioning Meeting - GA

3. Day 2 Circuits & 60-120 A • Circuits not required for early commissioning (M. Giovannozzi): • RTQX1 • RCO • RO • RQSX • Circuits not required for Early physics (e.g. no crossing angle and b* >1 m) • RSS • Non linear triplet corrector spool pieces (RCSX, RCSSX, RCOX, RCOSX, RCTX) • 60 – 120 A orbit correctors to be fully commissioned before beam injection to identify polarity errors as soon as possible with beam. • Gain to be expected by fractionated commissioning of these circuits is limited (can be powered in large number in parallel during Phase 1) Beam Commissioning Meeting - GA

4. 600 A • Minimum commissioning for 600 A might be an option in particular for Sector 34: • not fully tested in 2008 due to DSLC problem • Could be interesting if tuning of the QPS proves to be long (inductance tables, etc) • Otherwise limited gain for other sectors (several 600 A circuits can be powered in parallel during Phase 1, furthermore reduced test programme for UNAFFECTED circuits) • Limit to 200 A (PCS to identify possible weak circuits ASAP) 4h/circuit 3 h/circuit

5. IPQs • Minimum commissioning for IPQs (Q4 to Q10): • Up to PLI_2 currents (300 to 900 A) > I_injection • Possible in phase 1 but limited to 1 circuit/cryostat 2 shifts/circuit 1 shift/circuit

6. IPDs • Minimum commissioning for IPD: • Up to PLI_2 currents (~1kA) > I_injection (heaters induced quench) • Can be done during Phase 1 (1 circuit/cryostat) 1 shift/circuit 3 h/circuit

7. Main Bends and Main Quads • Minimum commissioning for MBs/MQs: • Up to 2 kA (PLI_2) allowing nQPS system check, as well as energy extraction (new time constants!) • Only possible during Phase 2 powering • Sufficient for injection tests and circulating beam and likely for studying the start of the ramp (pre-cycle to 2 kA should be sufficient for getting reproducible injection settings similar to those obtained for ramps to larger energy) • Once this is done, make splice measurement (QPS and calorimetry) up to nominal current so to characterize splices and to complete commissioning calorimetry calorimetry 2 days/circuit 2 days/circuit 3 days/circuit 3 days/circuit

8. Inner Triplets • Minimum commissioning for ITs: • Up PLI_3 allowing to verify behaviour of the 2 main circuits (RQX and RTQX2) in case of PC failure, slow power abort and quench and to commission the IT circuits above injection levels • Only possible during Phase 2 powering • Once this is done, make splice measurement (calorimetry) up to nominal current so to characterize splices and to complete commissioning • RTQX1 can be postponed calorimetry 1 day/IT 2 days/IT

9. Pros & Cons of interleaved HWC • Cons: • Delay in the complete commissioning of machine protection elements like the beam dump (tracking require availability of the Sectors 45-56-67-78 which are coming late) • Risks related to the cohabitation of overlapping activities during high power tests: • E.g. need to implement tools preventing powering at high current if vacuum valves opened • Delay in getting a snapshot of the SC splices in the machine. • Risk to lose focus and concentration in the HW commissioning in particular in Phase 2 (high power!) • Remanent radioactivity during interventions required for HWC • Pros: • Early verification of the status of the machine (aperture, polarities, optics, etc.) with possibility of intervention in the shadow of the remaining HWC activities • Possibility of profiting of other sources of downtime in other parts of the machine to complete the HWC commissioning

10. Proposal • Minimum commissioning scenario can be envisaged for Injection tests and for machine check with beam at 450 GeV/c (circulating beam and RF capture for both beams) and possibly a mini-ramp to ~1 TeV (?): • Only essential circuits • 600 A commissioning limited to PCS for Sector 34 if difficulty in reaching performance • IPQs commissioning limited to PLI_2 (300-900 A  Phase 1, constraint on parallelism) • IPDs commissioning limited to PLI_2 (1 kA  Phase 1, constraint on parallelism) could be interesting if difficulties in reaching 5 TeV settings (e.g. D3/D4 in LSS4) • Main bends and main quads commissioning to 2 kA allowing verification of the nQPS • Provided few sectors (2 or 3, including high luminosity IPs are fully commissioned to exercise a full-scale powering of a sector through the whole phases of the cycle (pre-cycle, injection, ramp, squeeze, ramp-down)

11. Proposal • This can allow anticipating injection tests and circulating beam by 1-2 weeks likely (exact extent difficult to estimate now, depending on sector availability and maximum achievable parallelism) • Beam commissioning for a predefined time (2 weeks?) • After that: • Commission the machine to nominal and get precise picture of the splices • Final Machine Check-Out • Possibility of leaving behind (for possible unscheduled stops) circuits requiring training (if any) and low priority circuits.