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

Chamonix 2009 program – 9 sessions Chamonix 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

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

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

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

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

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

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

Resistive joint model Chamonix 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.

Simulation of incident with 220 n  Chamonix 09 Highlights10

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

Energy balance EnergyMJ% Stored in the magnets Dissipated in UJ Dissipated in UA Dissipated in cold mass Dissipated in electrical arcs

Future incident prevention Chamonix 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!

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) (0) (1) (1) (1)00(0)0

Vacuum Repair Chamonix 09 Highlights15 Presentations by V. Baglin

Vacuum Chamonix 09 Highlights16 V1V2V1V2Total Ok %18 %22 % MLI %61 %59 % Soot %21 %19 % To be done 000 % Total % All beam lines in the tunnel have been inspected. (MLI : Multi Layer Insulation)

Beam vacuum contamination Chamonix 09 Highlights17

Soot cleaning in tunnel Chamonix 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.

MLI removal Chamonix 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.

Vacuum summary Chamonix 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…

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

Simplified sub-sector schema Chamonix 09 Highlights22

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

MCI Chamonix 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.

Cold sectors, temporary relief system Chamonix 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

DN200 relief valves on dipoles Chamonix 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).

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

Safety Chamonix 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 !  …

Magnet Repair Chamonix 09 Highlights29 Presentations by L. Rossi

Status of dipoles on 19 th September Chamonix 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.

Magnets in D-zone Chamonix 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.

Magnet repair schedule Chamonix 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  30 magnets will be rescued and rebuild, timescale ~ Mid-2010.

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

Dipole circuit quenches Chamonix 09 Highlights34 Sector 1 st training quench [A] I_max [A] # training quenches Starting in: # ALS# ANS# NOE (bus) Nominal current ~11800 A 9310 A corresponds to 5.5 TeV (5 TeV + 10% margin)

Magnet distribution / sector Chamonix 09 Highlights35

Dipole training during HWC Chamonix 09 Highlights36

Quenches to 7 TeV Chamonix 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.

Cryogenics Chamonix 09 Highlights38 Presentations by S. Claudet

First cool-down of LHC sectors Chamonix 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

LHC cryogenics towards beam Chamonix 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 !

LHC cryogenics : after beam Chamonix 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 !!

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

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

Energy Scales GeV 5 TeV ‘156 b’ physics kJ Chamonix 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 p 72 kJ Nominal beam 23.3 MJ Stored Energy (J) 2 MJ !

MPS Issues Chamonix 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…

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

Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct 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 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

Today’s cheapest EDF Prices Today’s operation

Power consumption Chamonix 09 Highlights49 EfficiencyPower Injectors LHC PC, RF Injectors LHC PC Cryo CV Machine CERN Hardware commissioning, set-up, start-up, % -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

Schedule options… Chamonix 09 Highlights50

Schedule & Run Chamonix 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 – until ~ November >> 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 …

Running scenarios / I Chamonix 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 = p/ bunch

Running scenarios / II Chamonix 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