LHC Beam Commissioning meeting - 3rd March 2009

Present:  Etienne Carlier, Kajetan Fuchsberger, Rossano Giachino, Brennan Goddard, Jean-Jacques Gras, Lar Jensen, Verena Kain, Greg Kruk, Mike Lamont (chair), Alick Macpherson, Malika Meddahi, Mirko Pojer, Bruno Puccio, Ghislain Roy, Katarina Sigerud, Matteo Solfaroli, Ralph Steinhagen, Ezio Todesco, Jan Uythoven, Antonio Vergara Fernandez, Walter Venturini, Frank Zimmermann.

Reported by Mike Lamont

Presentations

Matters arising

• Kicker test mode  - proposal to be approved by MPP...
• It seems that it will be possible to install a prototype for the 3rd April. What we are going to install for the 3rd April (Jean-Claude Bau):

• A hardware prototype card which implements the logic discussed but simplified. We are not going to check BPF1 and BPF2 because we know that there is no beam in the LHC.
• For the “Test mode” button, we are going to use one of the existent button in CCC connected to the external conditions.
• The final version will be delivered before the LHC startup with beam.

• 12 TB space requirement - controls follow-up required
• Coordination of RBAC changes
• Definition of polarities of skew circuits etc. Cross-check with powering diagrams.
• Re-generate squeeze
• Ralph's follow-up on intensity limits
• Latest ABT planning (v8) (Jan). Commissioning of LBDS beam 2 wks 17-18-19. This has been moved FORWARD by one week. Cabling UA and quench detection system in wk 20, also moved forward by one week. Followed by commissioning LBDS beam 1 and continuation on beam 2 as of wk 21 onwards. This leaves one week margin for the pumping of the MKBs beam 2 (63 side), and two weeks margin for the MKBs beam 1. So still ok, but the MKBs and the vacuum work on them should not slip any further.

Notes

Orbit Logging

• Log complete measurement to SDDS and additionally "vector" to Logging database
• Ralph Steinhagen - the data is already logged (written to SDDS) every 10 seconds. Jorg suggested that if this (SDDS) will remain the only sink for orbit logging, we should go to a 1 Hz logging rate. In response to that, Ralph added that combining 1 minute worth of data would reduce the overhead w.r.t. intrinsic overheads (BPM/COD mapping, de-compression, ...).
• Log also orbit corrector strengths (from GOFB)
• Should clearly make this mode dependent to avoid logging when no beam.

Kicker Test Mode

See Verena's slide above.

• Allow sending of injection forewarning event in test mode. Dependent on external conditions to CBCM (No LHC beams (in DEST), No SPS extraction, No beam in LHC)
• No worried about mastership in this mode
• BPF (which is untested up to now) is critical (don't want kickers firing if beam in machine). Question arose "Is BPF adequate?". To be discussed in MPP.
• Will also use operational procedures as another level of security (TED in etc.; Make going into the mode a key rather than a button.)
• Jorg notes that similar test mode for MKE in the pipeline.

Controls

See Eugenia's talk above.

• Timing available week 14.
• Space. Space. Space. Need 12 TB (under RAID) - seems reasonable for 2009/2010. Audience credulity strained at suggestion that this might be a problem, given that you can buy 1 TB for 200 CHF at Media Markt. Data will have to be spilt across volumes but this shouldn't be a problem.
• Definitely need smarter filtering to avoid logging junk.
• Watch FESA versions and RBAC

ABT etc

See Jan's ABT planning above

• Rossano to supervise transfer line cold checkout - as last year.
• Some dilution kickers not yet installed, but should be able to commission one system in W14. Aim to start distributing energy by then.
• Test MKQA and AC dipole W17/18.
• Still unresolved scheduling/access issues.

Beam Instrumentation

See Lars' presentation above.

• CMW proxies to be configure and tested.
• Use Bruno's energy generator until BETSsim come on-line.
• Start testing circulating beam stuff now.
• Ramp events for testing - 3 week of March.
• Squeeze settings now generated (Marek) - "I've just finished preparing a squeeze beam process (at IR5), so now there are: precycle, ramp, squeeze, ramp down with their actual settings where necessary, put together into INJ_TEST hypercycle.
• We generate with crossing angle on - check in ramp.
• Stephane noted b2 change in ramp - leading 45 degree change in phase advance between IP1 and IP5 - what about the sensitivity matrix?
• Test post mortem in June in dedicated tests
• Profile monitor - not before May/June.

Bunch configuration

See Delphine's presentation above.

• tau 3, tau 4 in injection schemes are important
• possible addition of distance between batches in SPS to beam configuration parameters
• Injection sequencer should publish expected bunch configuration. Either Injection Quality Check to make sure that what is in the ring corresponds to what is expected (via WCMs). IQC to be triggered by injection event
• Beam Quality Monitor performs similar role in SPS

LHC proton limit

See Ralph Assmann's presentation above

• With only 0.5% of nominal intensity - match Tevatron in term of energy in beam
• RA notes discrepancies in measured quench limits with transient losses (2* off in V, 6* off in H)
• 1.8 mm rms misalignment for dipoles with 1.5 sigma cut.
• All collimators to tight settings for collisions. Settings of W tertaries independent of beta.
• Off momentum beating - not important
• Cleaning efficiency set at 99.97% per metre or 3x 10^-4 per metre leakage rate in the first year. Assume peak lost rate of 0.002 % for the first year - around 0.2 hour minimum lifetime. Noted that assuming this value for lifetime dips is critical.
• First estimate gives a limit of 1 10^13 @ 7 TeV. Ralph to have a closer look at the scaling down to 5 TeV from 7 TeV (since done - 10% of nominal intensity at 5 TeV would be tough but conceivable)
• Note existence of spikes at Hera and elsewhere - "you can quench in a second".
• Total beam current important, less sensitive to bunch intensity unless you have bad lifetimes for individual bunches
• Phase 2 collimation scheme to be review at start of April