1. LHC Commissioning Phases Phase A.5 450 GeV, Increasing the Beam Intensity presented by Jan Uythoven on behalf of the LHCCWG Particular thanks to Laurette Ponce and the other EICs, Gianluigi Arduini, Ralph Assmann, Andy Butterworth, Roger Bailey, Brennan Goddard, Rhodri Jones, Verena Kain, Mike Lamont, Stefano Redaelli, Rüdiger Schmidt

2. 2LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Outline Phase A.5: Increasing the Beam Intensity at 450 GeV – Overview of the phases – Objectives and comments – Entry conditions – Commissioning procedures – Exit conditions Summary and Discussion

3. 3LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT The Different Stages: Top Level R. Bailey, 2006 Table for 7 TeV collisions Phase A.5: 450 GeV only

4. 4LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Details Stage A Above assumed damage limit of ~1e12 p + at 450 GeV

5. 5LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Bunch Schemes Up to 16 x 9  10 10 = 1.4  10 12 p + /inj.: Injection around damage threshold 43 x 43 156 x 156

6. 6LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT LHC Stage A: Commissioning phases PhaseDescription A.1Injection and first turn: injection commissioning; threading, commissioning beam instrumentation. A.2Circulating pilot: establish circulating beam, closed orbit, tunes, RF capture A.3450 GeV initial commissioning: initial commissioning of beam instrumentation, beam dump A.4450 GeV optics: beta beating, dispersion, coupling, non-linear field quality, aperture A.5450 GeV Increasing intensity: operate the LHC with unsafe beam A.6450 GeV two beam operation A.7450 GeV, collisions A.8Snap-back and ramp: single beam A.9Top energy checks: single beam A.10Top energy checks: two beams A.11Top energy collisions A.12Squeeze: Commissioning the squeeze in all IPs Phases for full commissioning Stage A (pilot physics run) First time that unsafe beam is being used: accent on Machine Protection issues From here on not clear that phases will be done sequentially: can first do a ramp with pilot – at the edge of being unsafe at 7 TeV – before increasing intensity at injection Can also have started two beam operation with pilots Assume separation bumps are switched on all the time, crossing angles not needed for first collisions and not commissioned until 75 ns operation

7. 7LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Machine Protection System Commissioning Subgroup Machine Protection Checks are obligatory and not ‘nice to have done’ Working on detailed procedures in MPS Commissioning Subgroup, reporting to the LHCCWG: http://lhccwg.web.cern.ch/lhccwg/MPS/mps.htmhttp://lhccwg.web.cern.ch/lhccwg/MPS/mps.htm Procedures being defined for all systems important for Machine Protection Follow up in MTF, identical to what is being done for the Hardware Commissioning This work is ongoing and the details of the MPS procedures are not finished yet

8. 8LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Objectives Safe operation at 450 GeV with increased beam intensity: – Previous intensities used: single bunch of intermediate intensity or two pilots for LBDS timing commissioning  I b < 3  10 10 p + – Target of this phase is 43 bunches with 4  10 10 p + per bunch  I b < 1.7  10 12 p + : just above the safe limit at 450 GeV – Limit of this phase 156 bunches up to 9  10 10 p + per bunch  I b < 1.4  10 13 p + : order of magnitude above the safe limit at 450 GeV Repeat all commissioning steps for beam 1 and beam 2, sequentially Intensity steps: slowly increase the injected and circulating intensity – Target Increase number of bunches to 43 of 1  10 10 p + Increase intensity per bunch up to 4  10 10 p + – Limit Increase number of bunches to 156 of 1  10 10 p + Increase intensity per bunch up to 9  10 10 p + This will probably be interleaved with ramp commissioning Parts of the described procedures can probably be done with two beams in parallel

9. 9LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT How do we limit the LHC ? Maximum intensity in the SPS can be “set” – Based on BCT reading – Half hardware – half software to set the maximum intensity – Used during TT40 / TT60 / TI 8 commissioning ‘Commissioned Beam Envelope’ in the LHC – The maximum intensity of circulating beam in the LHC should agree with commissioned phases of the machine: ‘Commissioned Beam Envelope’ Depends also on beam energy,  *,  n – The desired circulating beam intensity will be “programmed” via the sequencer and communicated via the timing system to the injector chain – Presently not (clearly) agreed upon check or control on this via any other system – Protection needed against Failure in sequencer or timing system (hardware or software) Human mistake made during the use of the sequencer – Could be injecting more beam than ‘allowed’ under certain conditions and not notice – Could be checked upon by software interlocks Do we agree that this that this is sufficient? If yes: We need to further specify this and agree who is doing this

10. 10LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Entry Conditions Finished phase A1 - A4 successfully Particularly important procedures from the previous phases: – Mechanical aperture of the machine known in numbers of sigma – A.4.5: Commission collimators and Protection devices Assume that this is done in phase A.4: obligatory to have TCP protecting the aperture of the machine before going to 43 bunch mode: TCP at 5.7  This way the TDI and TCDQ can be moved in without becoming a primary collimator Procedures to set the collimators ‘repeated’ under A.5.6; can first be used with some pilots TDI at roughly 10  (A.3.4.1.1), protecting against very big injection errors – Fine timing adjustments of dump system with 2 pilots beam (phase A.3.9.2.3) Other entry conditions: – Complete hardware commissioning of LHC BIS finished successfully – Hardware commissioning tests of other important systems passed successfully Vacuum, QPS, PIC, WIC, Experiments,… – Some interlocks which were masked with the Safe Beam Flag, will now need to be commissioned – Transfer lines TI 2 and TI 8 commissioned with intermediate beam intensities – Injection BIS completely hardware commissioned and commissioned with beam up to TI 8 downstream TED – Injection BIS in injection region commissioned without beam – Transfer line collimators not yet commissioned – Orbit feedback working (very much desired) Beam requirements – Beam 1 and Beam 2 separately, easy change from one to the other – Single pilot or intermediate bunch, 43 bunches and 156 bunches – Nominal and reproducible beam emittance (value agreed for ramping)

11. 11LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Increasing Intensity at 450 GeV – Overview of Steps Involved StepActivity Priority A.5.1Fine tuning of injection (up to 4 bunches, 1e10 p + /bunch)1 A.5.2Commissioning of the beam dumping system (43 bunches)1 A.5.3Check Beam Instrumentation and beam parameters (43 bunches)1 A.5.4Check MPS functionality of BLM (43 bunches)1 A.5.5Setting-up of RF (43 bunches)1 A.5.6Setting-up of the ring betatron and momentum collimation (43 bunches)1 A.5.7Re-check and optimise injection settings (43 bunches, 4e10 p + /bunch)1 A.5.8Check some of the previous phases with (43 bunches, 4e10 p + /bunch )1 A.5.9Check intensity dependence of safe beam flag (just over limit with 43 bunches)1 A.5.10Check beam load on cryogenics and vacuum system1 For going to 156 bunches: A.5.11Fine tuning of injection (156 bunches, 1e10 p + /bunch up to 9e10 p + /bunch)1 A.5.12Commissioning of the beam dumping system (156 bunches)1 A.5.13Check Beam Instrumentation and beam parameters (156 bunches)1 A.5.14Setting-up of RF (156 bunches)1 A.5.15Setting-up of the betatron and momentum collimation (156 bunches)1 A.5.16Setting-up of the transfer line collimators (156 bunches)1

12. 12LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Beam Interlock System The back bone of the Machine Protection System is the LHC Beam Interlock System Its functionality will be fully tested without beam Other Machine Protection System components will need to be tested without and with beam Most important components to be tested also with beam: – Injection System – LHC Beam Dumping System (LBDS) – Beam Loss monitors (BLMs) – Collimation System This is also the time to bring the ‘additional safety systems’ into operation: – Fast Beam Current Change Monitor – Fast Beam Position Change Monitor

13. 13LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Orbit Feedback In this phase an orbit feedback system will be extremely useful – For setting up the beam dumping system – For setting up the collimation system – To guarantee reproducibility Should be able to easily deliver 0.5  stability If the ‘real’ orbit feedback system does not work at this stage one can run “automatic orbit corrections” – Similar to what we did at LEP in the end – Correct every couple of minutes – The ‘real’ orbit feedback will be required for the energy ramp

14. 14LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Quenches They might (already) start to occur in this phase and problems need to be understood and solved to be able to continue If quenches occur – Reduce beam intensity (a bit) – Have to work on beam stability and collimators settings ‘earlier’ in this commissioning phase before ideal conditions have been reached – Might have to work on injection damper, cryogenics system, …. – Etc. Actions will need to be decided at the heat of the moment However, extreme care should be taken not to damage the machine After possible quenches are under control, can work through the commissioning program presented here

15. 15LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.1: Injection of 43  1  10 10 StepActivity Priority A.5.1Fine tuning of injection (up to 4 bunches, 1e10 p+/bunch).01Check beam presence flag to allow higher intensity injection1.02Check stability of last elements of transfer lines and injected trajectory without MKI1.03Idem with MKI gives MKI waveform 1.04Calibrate BLMs in the injection region establish loss pattern in MSI, TDI to optimise injection verify with BLM interlock levels (equipment protection) 1.05Measure injection efficiency Should be above 95 %, otherwise further optimise injection at this stage 1.06 Move TDI to 7  obligatory for 156 bunches stay in the shade of TCP already at 5.7  watch BLM readings determine loss location in case of injection failure 2 (43) 1 (156).07Set up Injection BIS with beam This includes incorporating the TDI setting, BLM readings etc. 1

16. 16LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.2: Beam Dump I StepActivity Priority A.5.2Commissioning of the beam dumping system (43 bunches).01Setup of TCDQ and TCS – circulating beam 1.02Verification of TCDQ system protection of mechanical aperture – Inject and Dump mode 1.03Circulating beam:.04 Circulating beam: Check response BDI dedicated to LBDS in IR6 1.05 Check hardware interlock on IR6 beam position 1.06 Check software interlock on beam position at TCDQ 1.07 Check orbit feedback and stability at TCDQ (0.5  ) 1.08 Check interlock on beam energy from RF frequency Integrated orbit correction 1.09 Test response of abort gap monitor 2.10 Commission abort gap cleaning 2

17. 17LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.2: Beam Dump II StepActivity Priority A.5.2Commissioning of the beam dumping system (43 bunches) - continued -.11Circulating and dumped beam:.12 Check EMC on BI and controls signals EMC from pulsed LBDS equipment EMC from increased beam intensity* 1.13 Check extraction trajectories and adjust MSD, MKD, MKB when required 1.14 Check TD line beam instrumentation 1.15 Define reference values for correctly executed beam dump 1.16 Check XPOC response 1.17 Check TDE thermal response 2.18 Make beam loss profiles (extracted beam, TD lines and TDE) 1.19 Check losses at TCDQ in abort gap 1 * EMC more general (GA): keep statistics of number of (spurious) alarms as function of beam intensity… (TT40 experience)

18. 18LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.3: BDI and Beam Parameters StepActivity Priority A.5.3Check Beam Instrumentation and beam parameters (43 bunches).01Check multi bunch operation of BPM system1.02Check multi bunch operation of FBCT1.03 Check DCCT agrees with  FBCT Check if any lifetime dependency on beam current 1.04Check measured tune values – dependency on current1.05Check measured chromaticity values – dependency on current (should not be)1.05Measure bunch profile and emittance, check any emittance blow-up and bunch to bunch variation required for collimation 1.06Check orbit feedback with multi bunch operation1.07Check tune feedback with multi bunch operation2

19. 19LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.4: BLMs StepActivity Priority A.5.4Check MPS functionality of the BLM system (43 bunches).01Test BLM interlocking by setting threshold of a BLM to a very small value and generate small beam losses at the BLM 1.02Make a general beam loss map and check on any surprises Check on ‘globally’ correct readings from BLMs 1.03Provoke controlled quench to verify the theoretical quench level and corresponding BLM readings Gives confidence in the protection system before going to higher intensities Gives values for required cleaning efficiency by the collimation system Can be done with single pilot, steer the beam into sc magnet; increase intensity in small steps if one does not quench Number, type and locations of magnets to be tested remains to be determined ! 1.04Adjust BLM thresholds when (really) necessary1

20. 20LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.5: Setting up the RF StepActivity Priority A.5.5Setting up the RF (43 bunches).01Check bucket selector; change reference sent to SPS when required (RF synchro)1.02Check the phase loop and the radial loop (check averaging per turn)1.03Monitor SPS / LHC synchro stability1.04Parasitically observe cavity feedback behaviour (fast RF feedback on cavity)2.05Set up longitudinal injection damping (no longitudinal feedback at this moment)1.06Set up transverse feedback for multiple injections1.07Confirm energy jitter ~ 10 -5 2.08Determine longitudinal beam life time Compare current inside and outside bucket as a function of time Can we do this? 2

21. 21LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.6: Collimators StepActivity Priority A.5.6Setting up of the betatron and momentum collimation (43 bunches).01Determine the required cleaning efficiency = number and settings of collimators from available information: available arc aperture: mechanical, orbit and optics stability of orbit and optics beam losses to be handled and quench limits 1.02Set up betatron cleaning IR7 Beam based alignment of collimators: beam position, local beta, jaw angle 1.03Set up momentum cleaning IR3 Beam based alignment of collimators: beam position, local beta, jaw angle 1.04Measure cleaning efficiency by diffusion of the beam (ideally tails, otherwise by increasing emittance) 1.05Scrape beam with collimator (TCP in/out) to kill halo and check reduced losses afterwards1 Protection settings of the arc by primary collimators was an entry condition. Now set-up the required cleaning by the collimators.

22. 22LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Collimators There are collimators / protection devices with several functionalities – Betatron cleaning (IP7) – Momentum clearing (IP3) – Collimators for arc protection, triplet protection, … – Injection protection: TDI, TCDD and TCLI (injection system) – Dump protection: TCDQ, TCS and TCDS point 6 (beam dumping system) The different functionalities can not be adjusted independently – Can not close TCDQ without the collimators in point 3 at some reasonable setting, giving a similar protection In proposed procedure TCDQ and TDI always in the shade of TCPs: entry condition Stable orbit required for setting up any of the collimators – Should be able to deliver something like 0.5  – Requirement around 0.4  (for two stage cleaning) Stable optics required as well – Drift in beta beat below 8 % – Stability of dispersion better than 10 % in the H-plane Stable beam sizes required – Emittance and local beta to be known – Bunch-to-bunch emittance variations can become an issue

23. 23LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.7: Injection of 43  4  10 10 StepActivity Priority A.5.7Fine tuning of injection (43 bunches, higher intensity).01Optimise injection settings with higher intensity bunches check beam loss readings in injection zone check images on screens: matching (inject and dump mode, ok up to which intensity?) check trajectories check TDI setting 1

24. 24LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.8: Checks with 43  4  10 10 StepActivity Priority A.5.8 Check some of the previous phases with (43 bunches, 4  10 10 ).01Commissioning of the Beam Dumping system (see A.5.2)1.02Commissioning of the Beam Instrumentation (see A.5.3)1.03Commissioning of the RF system (see A.5.4)1.04Commissioning of the Collimation system (see A.5.2)1

25. 25LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.9: Safe Beam Flag StepActivity Priority A.5.9Check intensity dependence of the Safe beam flag.01Check change of state of safe beam flag1

26. 26LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Detailed Steps A.5.10: Cryo and Vacuum StepActivity Priority A.5.10Check beam load on cryogenics and vacuum system.01Do we see the increased beam intensity as an additional load of the cryogenics system? Can this be extrapolated? 2.01Do we see an effect of the beam on the vacuum system? Can this be extrapolated? Will we need any vacuum conditioning (scrubbing)? 2

27. 27LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Repeat for 156 bunches of 1 - 4 - 9  10 10 The details of the phases below are identical* to those already described for 43 bunches and will need to be repeated when going to 156 bunches: first with bunch intensities of 1  10 10 followed by bunch intensities up to 4  10 10 protons and then 9  10 10 protons StepActivity Priority For going to 156 bunches: A.5.11Fine tuning of injection (156 bunches, 1e10 p+/bunch up to 9e10 p+/bunch)1 A.5.12Commissioning of the beam dumping system (156 bunches)1 A.5.13Check Beam Instrumentation and beam parameters (156 bunches)1 A.5.14Setting-up of RF (156 bunches)1 A.5.15Setting-up of the ring betatron and momentum collimation (156 bunches)1 A.5.16Setting-up of the transfer line collimators (156 bunches)1 * Additional step A.5.15: Setting up the transfer line collimators reach dangerous beam levels at injection

28. 28LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Exit Conditions Safe Operation with up to 1.4  10 13 p + at 450 GeV. Operation above the damage threshold Multi-bunch injection, up to 16 x 9  10 10 p + commissioned and well tuned – Including cleaning and protection Beam dumping system commissioned up to 1.4  10 13 p + at injection Collimators set-up for operation up to 1.4  10 13 p + at injection – Settings entered in data base (centre, opening) – BLM loss pattern established – TCDI collimators in transfer lines just behind TED will need to be commissioned for operation with higher intensity 156 bunch operation BI operational with up to 156 bunches and total intensity of up to 1.4  10 13 p + RF adjusted for injection and circulating multi bunch operation Higher intensity beam under control and safe: we should not be quenching all the time….

29. 29LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Summary and Discussion Phase A.5 : – Increase beam intensity at 450 GeV above safe beam limit For circulating beam maximum beam 1.4  10 13 p + Also for injected beam: 16 x 9  10 10 p + = 1.4  10 12 p + Main focus is on: – Machine Protection System Many checks to take place during the Hardware Commissioning period, without beam: not presented here Additional checks and set-up required with beam: presented here ‘Control systems’ should be in an advanced phase and working according to their specifications Sequencer, Management of Critical Settings, Software Interlock System, XPOC, Post Mortem etc. System required to manage the ‘Commissioned Beam Envelope’ via measured operational parameters Increasing the beam intensity will be a gradual, iterative process: – Same tests will need to be repeated every time the intensity is significantly increased above the already commissioned values – Also to be repeated when the bunch structure or optics is changed from the already commissioned values – Slowly gain experience of feedback systems, beam instrumentation, cryogenics etc. Path of commissioning is not unique any more: – Could already have taken a pilot beam up the ramp – Could already have started two beam operation with pilots – Could already have collided pilot++ before finishing this stage

30. 30LHC Comm. Phase A.5, LTC 25/4/07Jan Uythoven, AB/BT Spare slides

31. Peak energy deposition E dep in Cu vs beam sigma, for 450 GeV and 7 TeV protons estimate E dep  E 1.7 (includes effect of emittance reduction) If assumed pilot safe at 7 TeV: Safe Beam intensity at 450 GeV : 5e11 p+ PILOT INTENSITY = SAFE BEAM INTENSITY @ 7 TeV Pilot Safe beam intensity vs energy, assuming 1e12 p+ is safe intensity at 450 GeV