1. 1 Chamonix 09 Highlights J. Wenninger BE-OP 23.02.2009Chamonix 09 Highlights

2. Chamonix 2009 program – 9 sessions 23.02.2009Chamonix 09 Highlights2 What did we learn without beam in 2008 – R. Saban Safety – R. Trant Repair of 34 – R. Schmidt Strategy for consolidation to avoid incident and limit collateral damage – A. Siemko Shutdown Modifications 2008/9 and Future shutdowns – S. Baird What else can go wrong – J. Wenninger What did we learn with beam in 2008? – M. Lamont What we will do for beam preparation in 2009 – G. Arduini What will we do with beam in 2009/10 – R. Bailey

3. Warning ! 23.02.2009Chamonix 09 Highlights3 This is not the official summary of Chamonix 2009. >> Official summary is Tuesday 24 th February. This presentation is a summary of highlights that may be of interest to ‘users’ like you.

4. Contents 23.02.2009Chamonix 09 Highlights4 Sector 34 incident Vacuum repair Pressure relief improvements Magnet repair Magnet training to 7 TeV Cryogenics Machine protection Scheduling & physics runs

5. Sector 34 Incident 23.02.2009Chamonix 09 Highlights5 Presentations by P. Lebrun, A. Verweij

6. For your eyes only ! THE Electrical arc between C24 and Q24 23.02.2009Chamonix 09 Highlights6 M3 line V lines M3 line = dipole busbar

7. Displacements 23.02.2009Chamonix 09 Highlights7 QBBI.B31R3 Extension by 73 mm QBQI.27R3 Bellows torn open

8. Secondary arcs due to extensions 23.02.2009Chamonix 09 Highlights8 QQBI.27R3 M3 line QBBI.B31R3 M3 line

9. Resistive joint model 23.02.2009Chamonix 09 Highlights9 No electrical contact between wedge and U- profile with the bus on at least 1 side of the joint No bonding at joint with the U-profile and the wedge ⇒ Loss of clamping pressure on the joint, and between joint and Cu stabilizer. ⇒ Degradation of transverse contact between superconducting cable and Cu stabilizer. ⇒ Interruption of longitudinal electrical continuity in Cu stabilizer.

10. Simulation of incident with 220 n  23.02.2009Chamonix 09 Highlights10

11. Bus-bar voltage: simulation vs measurements 23.02.2009Chamonix 09 Highlights11 Quench trigger threshold : 1 V

12. Energy balance 23.02.200912 EnergyMJ% Stored in the magnets595.0100 Dissipated in UJ3371.012 Dissipated in UA43104.818 Dissipated in cold mass144.424 Dissipated in electrical arcs274.846

13. Future incident prevention 23.02.2009Chamonix 09 Highlights13  New quench detection system for all dipole joints. The threshold must be set 0.3 mV to cover entire range down to joint resistances of 25 n  (so far 1 V for entire busbar). Possible with ‘heavy’ filtering… >> Electronics & cables in production..  The new system would have prevented 19 th Sept, and will be able to prevent incidents if there are ‘pre-cursors’ like on 19 th Sept, but it will never protect against a bus-bar that ruptures suddenly.  Clamping joints : ideal, but no good solution so far (space constraints).  Pressure relief systems (see later) can only reduce the ‘collateral’ damage!

14. Status of other sectors – suspicious resistances 14 (1) suspected cases from calorimetric measurements 1 confirmed cases by electrical measurement. Old SM18 test data analysis : no clear if it will yield useful data ! SectorsArc dipoleArc QuadrupolesIPQ Tests Calorimetric El. Magnet El. Bus-bar (on request) Calorimetric El. Magnet El. Bus-bar (on request) Calorimetric El. Magnet El. Bus-bar (on request) 1-2(2)1 2-3 3-4 4-5 5-6(0)0 0 6-7(1)1 0 7-8(1)00 0 8-1(1)00(0)0

15. Vacuum Repair 23.02.2009Chamonix 09 Highlights15 Presentations by V. Baglin

16. Vacuum 23.02.2009Chamonix 09 Highlights16 V1V2V1V2Total Ok543926 %18 %22 % MLI12412958 %61 %59 % Soot354516 %21 %19 % To be done 000 % Total213 100 % All beam lines in the tunnel have been inspected. (MLI : Multi Layer Insulation)

17. Beam vacuum contamination 23.02.2009Chamonix 09 Highlights17

18. Soot cleaning in tunnel 23.02.2009Chamonix 09 Highlights18  Two separate cleaning heads for horizontal and for vertical parts of the beam screen.  Up to 50 passages in each direction with wet foam (alcohol).  Up to 15 passages with dry foam.

19. MLI removal 23.02.2009Chamonix 09 Highlights19  First step: pumping/venting of one half-cell (52 m)  Each cycle : 20 s pumping, 18 s plateau, 2 second vent.  Applied for 30 min (40 pumping/venting cycles), repeated 5-10 times  Second step: a nozzle blows filtered air, the MLI residues left behind the beam screen and the RF fingers are directed towards the beam aperture where they are pumped.  Takes ~ 30 minutes per half-cell, repeated 5-10 times.

20. Vacuum summary 23.02.2009Chamonix 09 Highlights20  In-situ cleaning works well and everything will be cleaned.  There are however residues of sooth and MLI behind the beam screen and in the bellows (PIMS). Probably OK…

21. Pressure release systems 23.02.2009Chamonix 09 Highlights21 Presentations by V. Parma (and others)

22. Simplified sub-sector schema 23.02.2009Chamonix 09 Highlights22

23. Present relief valves (on quadrupoles) 23.02.2009Chamonix 09 Highlights23  Designed for He flow of 2 kg/s  Estimate for incident is ~ 20 kg/s

24. MCI 23.02.2009Chamonix 09 Highlights24  The (new) “Maximum Conceivable Incident” (MCI) was identified as rupture of all enclosures connected to the magnets. >> He flow of 40 kg/s  To mitigate against the collateral damage to the interconnects and the super-insulation under the MCI conditions (max pressure of 1.5 bar), additional relief valves (200mm diameter, ‘DN200’) must be installed on all dipole magnets. Please don’t forget the vacuum !! Add SSS valves. Add SSS valves +DN200.

25. Cold sectors, temporary relief system 23.02.2009Chamonix 09 Highlights25  Keep existing 2 DN90 relief devices  Mount relief springs on 5 DN100 vac. flanges  Mount relief springs on 8 DN100 BPM flanges  Mount relief springs on 4 DN63 cryo.instr. flanges  Cross section increase: x 10 SV Existing New

26. DN200 relief valves on dipoles 23.02.2009Chamonix 09 Highlights26  Warm sectors will be equipped in-situ with DN200 relief valves on each dipole.  It seems technical issues are solved (risk of ignition due to hot ‘schips’ etc).

27. Oxygen content at ceiling 23.02.2009Chamonix 09 Highlights27 No significant deficiency In UJ4x

28. Safety 23.02.2009Chamonix 09 Highlights28  Following the incident the safety issues related to He are reanalyzed.  Issues:  Safety during powering tests. So far limit for presence of people (=experts) was limited to 1 kA (max is 13 kA for dipoles/quads). New ‘reasonable’ approach being defined…  Large release close to experimental caverns. Can it come from both sides?  Issue of the warm He ‘transfer line’, used to transfer He from one point to another: can be in service even if the sector is warm !  …

29. Magnet Repair 23.02.2009Chamonix 09 Highlights29 Presentations by L. Rossi

30. Status of dipoles on 19 th September 23.02.2009Chamonix 09 Highlights30 DIPOLES : 46 ordered in addition to the 1232 for tunnel However 6 were (are) not available: –1 lost during production (MB1005, bad cable) –1 under repair (MB-2001) because pole or inter-layer splice not conform. This s the first action as MAR (started in Ansaldo, since winding is not yet ready) –3 out-of-service following the string-2 incident: need work to investigate and put in conformity. –1 suspected short circuit (in the tunnel, after late review of test in SM18), MB1055. Of the 40 MBs actually available –one needed more examination:MB2252 incident ROCLA; re-tested and used of OSQAR but waiting Performance Assent –3 were waiting Performance Assent.

31. Magnets in D-zone 23.02.2009Chamonix 09 Highlights31 15 SSS (MQ) –1 not removed (Q19) –14 removed 8 cold mass revamped (old CM, partial de-cryostating for cleaning and careful inspection of supports and other components). 6 new CMs In this breakdown there is consideration about timing (SSS cryostating tales long time; variants problems). 42 Dipoles (MBs) –3 not removed (A209,B20,C20) –39 removed 9 Re-used (old CM, no de- cryostating – except one?). 30 new CMs. New cold masses are much faster to prepare than rescuing doubtful dipoles.

32. Magnet repair schedule 23.02.2009Chamonix 09 Highlights32  Magnets of sector 34 back in tunnel Mid-April. ‘Success oriented’ schedule.  Magnet rescue, repair and construction facility in former West Hall (B180), expected to be ready ~ summer 2009.  30 magnets will be rescued and rebuild, timescale ~ Mid-2010.

33. Magnet Training to 7 TeV 23.02.2009Chamonix 09 Highlights33 Presentations by A. Verweij

34. Dipole circuit quenches 23.02.2009Chamonix 09 Highlights34 Sector 1 st training quench [A] I_max [A] # training quenches Starting in: # ALS# ANS# NOE 1-2-93100000 2-3-93100000 3-4- 8715 (bus) 0000 4-59789102743003 5-61000411173270126 6-7-93100000 7-8896593101010 8-1-93100000 Nominal current ~11800 A 9310 A corresponds to 5.5 TeV (5 TeV + 10% margin)

35. Magnet distribution / sector 23.02.2009Chamonix 09 Highlights35

36. Dipole training during HWC 23.02.2009Chamonix 09 Highlights36

37. Quenches to 7 TeV 23.02.2009Chamonix 09 Highlights37  The expected number of RB circuit quenches needed to reach 6, 6.5, and 7 TeV is about 10, 80, and 900 respectively. 900 is a rough estimate since it is based on a large extrapolation of the S56 training curve.  Assuming training in all 8 sectors in parallel, with 3 quenches per day would then require about 60 days to reach 7 TeV, and about the same number of heater firings as the entire SM-18 test campaign. The issue: every quench also presents a very small but non-zero risk for the magnet… Some debate among experts. There will be no training before 2011.

38. Cryogenics 23.02.2009Chamonix 09 Highlights38 Presentations by S. Claudet

39. First cool-down of LHC sectors 23.02.2009Chamonix 09 Highlights39 Christmas and water maintenance shut-down Short in connection cryostats and repairs Open Days UX85 Ph1 work All sectors at nominal temperature First beams around LHC Cool-down time ~ 4-6 weeks/sector

40. LHC cryogenics towards beam 23.02.2009Chamonix 09 Highlights40 Target for global (8 sectors) “Cryo OK for Powering” UX85 Ph1 works Electrical Transformers Beams !!! 19 Sept’08 ‘Cryo Maintain’ is a cryo status signal required to power the magnets. Indicates Cryo is ready !

41. LHC cryogenics : after beam 23.02.2009Chamonix 09 Highlights41 Target for 4 sectors tested with calorimetry A bit frustrating !!! 19 Sept’08 Switch EL network So far it is a tricky to have the cryogenics up at 100% for more than a week >> 2009 challenge !!

42. He inventory 23.02.2009Chamonix 09 Highlights42 LHC runs with ~ 120 tons of He. Losses of 20-30 tons are considered ‘normal’ (by cryo group)

43. Machine Protection Issues 23.02.2009Chamonix 09 Highlights43 Presentations by V. Kain, B. Goddard, B. Holzer

44. Energy Scales 44 450 GeV 5 TeV ‘156 b’ physics 450-900 kJ 23.02.2009Chamonix 09 Highlights 1001k10k100k1M10M100M1T Pilot b 4 kJ Nominal b 92 kJ Safe Beam Limit - 1.7x10 10 p 13.6 kJ Nominal beam 258 MJ Stored Energy (J) ‘156 b’ physics 5-10 MJ 1001k10k100k1M10M100M1T Pilot b 360 J Nominal b 8.3 kJ Safe Beam Limit - 10 12 p 72 kJ Nominal beam 23.3 MJ Stored Energy (J) 2 MJ !

45. MPS Issues 23.02.2009Chamonix 09 Highlights45  Already with 156 bunch operation we will exceed Tevatron, HERA & SPS in terms of stored beam energy: such a beam can slice open a magnet and trigger another sector-34 like incident.  Many persons are worried about the complexity of the LHC MPS/interlock system (‘will never work’-like comments from Tevatron and HERA…): but we MUST make it work – or we will never be safe. We learned a lot from Tevatron, HERA and SPS ‘mistakes’ (i.e. cracks in the MPS) and avoided them from the start…  In Chamonix we finally got green light to perform the MPS tests with beam (low intensity) that are essential to asses the MPS performance (reaction times). Non-negligible time – not counted in the schedules…

46. Scheduling 23.02.2009Chamonix 09 Highlights46 Presentations by K. Foraz, M. Batz, discussion session.

47. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. 12 23 34 45 56 67 78 81 Jan. Nov.  Intermediate cool-down & QRL warm- up (Stand Alone)  Activities  Arc  LSS  Flushing & ELQA at warm  Cool-down  Powering tests  Cold check-out LHC Performance – 04th Feb. 2009 EN/MEF/LPC – J.Coupard & K.Foraz Sectors 12, 34, 56, 67 warmed up OP group is trying to schedule injection tests for August – similar to 2008

48. Today’s cheapest EDF Prices Today’s operation

49. Power consumption 23.02.2009Chamonix 09 Highlights49 EfficiencyPower Injectors LHC PC, RF Injectors LHC PC Cryo CV Machine CERN Hardware commissioning, set-up, start-up,... - 40% -100%50%100%180 MW 5 TeV LHC operation with fixed targets 85% 100%50%100% 220 MW 5 TeV LHC operation without fixed targets 25%85%50% 100% 180 MW Accelerator shutdown--0% 50% 80 MW Additional cost for running in winter ~ 12 MCHF

50. Schedule options… 23.02.2009Chamonix 09 Highlights50

51. Schedule & Run 23.02.2009Chamonix 09 Highlights51 After some back and forth about the best strategy, ‘it’ was decided to:  Limit the DN200/relief valve consolidation to 4 sectors in 2009 (12,34,56 and 67).  Stick to the shutdown schedule as defined before Chamonix.  Run over the winter of 2009-2010 – until ~ November 2010. >> Aim to deliver some 100’s of pb-1 Issues : Cryo maintenance ~ 4 weeks / point Cooling tower maintenance ~ 3 weeks / point AUG tests 400 kV maintenance …

52. Running scenarios / I 23.02.2009Chamonix 09 Highlights52 Start with no crossing angle 43 or 156 bunches. Can reach  * below 1 m at E>= 4 TeV. N = 4x10 10 p/ bunch N = 10 11 p/ bunch

53. Running scenarios / II 23.02.2009Chamonix 09 Highlights53 Most flexible multi-bunch scheme for learning phase is 50 ns spacing. Variable number of batches (groups of 278 bunches). Batch placing allows to change # collisions/Lumi for LHCb/ALICE. Much less long-range beam-beam effects. No. bunches The amount of energy stored in those beams is already TERRIFIC !! Very ambitious for year 1 !! 75 ns 50 ns 25 ns