1. Session 4 Beam Plans For Accelerator Systems - LHC Beam Instrumentation Extended LTC Days 3 rd – 7 th March 2008 Rhodri Jones (CERN Beam Instrumentation Group)

2. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Beam Instrumentation - what’s required & when ● First turn ● Screens, BPMs, fast BCT, BLMs ● Circulating beams at 450 GeV ● DC BCT & lifetime ● Tune Coupling & Chromaticity ● Emittance: wire scanners ● Snapback and Ramp ● Continuous Orbit, Tune, Coupling & Chromaticity (+ feedback) ● Continuous emittance monitoring: synchrotron light, IPM ● First Collisions ● Luminosity ● Schottky

3. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A1 – First Turn ● BTV System ● Same acquisition chain as for transfer lines ● Already commissioned in TI2 & TI8 ● Screen & filters set for pilot intensity ● Matching (Dispersion in LSS3 / Betatron in LSS4) ● Decision that images were required not just profiles  fast cameras (not radiation hard) ● Part of delayed instrumentation - money & manpower issues (only have 1 of 4 cameras) ● Not foreseen for start-up in 2008 Phase A1Entry Conditions.01BTVs: TV display, screens movable, timing, acquisition, applications.02BPMs: auto-triggering, timing, acquisition, application, intensity measurement mode.03Ring BLMs: calibration, timing, links to SLP and BIC, acquisition, applications.04Mobile BLMs prepared, required electronics available and ready to be used.05FBCT: timing, calibration, acquisition, application StepActivityWhoPriority A.1.1Commission injection region: 1 pilot.04Beam commissioning injection BTVsBI1 Procedures I

4. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A1 – Procedures II StepActivityWhoPriority A.1.2Threading around the ring:.02Coarse beam commissioning of BPMs (asynch. acquisition) and BLMsBI1.03Commission trajectory acquisition and correctionOP1.06First BPM and corrector polarity checks and repairsOP1.09Systematic BPM and corrector polarity checks and repairsOP2 Position (  m) See Jorg Wenninger’s Talk in Session 5 for more info on how threading is done

5. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A1 – Procedures II ● BPM System ● Sequencer (before each fill) ● Via WorldFIP retrieve installed electronic card serial numbers ● Load in relevant calibration settings from MTF ● Via WorldFIP set all BPMs to calibration mode ● Save current calibration settings ● Via WorldFIP set calibration OFF & set BPM sensitivity ● HIGH sensitivity for intensity 3x10 10 ● Download and initialise all new settings for the 68 VME front ends ● Asynchronous mode ● Electronics triggers on any signal above threshold ( ~ 1x10 9 ) ● No bunch to bunch or turn to turn tagging ● Tested during HWC with RF ball tests ● Check for polarity errors during threading ● Limited number of personnel for intervention & journeys can be long! ● Diagnosis & repair has to be staged (disable BPM in meantime) ● ½ day required per sector

6. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A1 – Procedures III StepActivityWhoPriority A.1.2Threading around the ring:.07Beam commissioning IP4 fast BCTsBI1.08Commission BPM intensity measurement mode (parasitic)BI1 ● Fast BCT in Point 4 ● Commissioned for first turn reading (used as transfer line BCT) ● BPM Intensity Mode ● Requires at least intermediate intensity bunch ● Pilot bunch will not give relative intensity to much better than 50% ● Intermediate bunch(es) should give relative intensity to better than 20% ● Single bunches are more problematic for the electronics than bunch trains ● Has to be corrected for position reading to be meaningful ● Error up to 100% possible if not corrected for very off-centre beams ● Complicated software mapping ● B1 position becomes B2 intensity or vice-versa ● Would only invest time commissioning if threading becomes a problem ● Propose to move it to priority 2/3 (available if required) ● BPM position autotrigger will already show where a large loss occurs

7. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A1 – Procedures III 50% variation observed on first bunch in the train

8. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A1 – Procedures IV ● BLM System ● Parasitic investigation of loss patterns as threading proceeds ● Mobile BLMs (installed only if required) ● 2 extra ionisation chambers can be added per spare channel ● Number of spare channels per tunnel card: ● 2 at each quad in the arcs (i.e. possibility to add 4 chambers) ● more complicated in the LSS because of more elements ● All the spare channels/card are predefined in databases to allow configuration/use without touching the threshold tables ● Additional channels can be gained by using the 2 spare optical fibres from the tunnel to surface at each quadrupole ● Can add up to 8 additional ionisation chambers per half cell ● Requires additional electronics to be added ● Can cover a half-cell every 3m if all 10 ionisation chambers are added ● Access of ½ to 1 day (depending on number of monitors) will be required to cable, connect and test the extra chambers ● Assuming no more than 1 or 2 half cells have to be covered

9. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A2 – Circulating Pilot and RF capture Phase A2Entry Conditions.01BTV screens should be OUT. One should get an alarm when they are IN..02BPM in intensity mode possible.03BPM synchronous acquisition possible.04Fast BCT available, even if not calibrated (providing relative information) StepActivityWhoPriority A.2.1Instrumentation and corrector checks.02Commission BPM intensity measurement modeBI1 A.2.2Establish closed orbit (One beam at a time).03Closed orbit measurement and correction to get few turnsOP1.04Fast physical aperture scans, free oscillations with BPM intensityOP1 A.2.3Measurements with few turns (One beam at a time)OP1.01Fractional tune measurement from injection oscillationsOP1 Procedures I

10. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A2 – Procedures II ● BPM System ● Synchronous mode ● Not available before RF timing is stable (Stage A3) ● Orbit at injection ● Calculated from asynchronous mode from first 1000 (or less!) values ● Intensity mode commissioned only in case of problems ( see Stage A1 ) ● Are BLMs not better suited for the fast aperture scans? ● BPM intensity with pilot will not give much better than 50% relative accuracy ● Tune Measurement ● Tune determined from injection oscillations & asynchronous BPM data ● 1 value per turn in the FIFO memory for a single pilot bunch ● BBQ data only available once beam is stored for several hundred turns ● Determined by the charging time of the capacitors to mean intensity level ● Fast losses will also render the system “blind” while capacitors discharge

11. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A3 – 450 GeV Initial Commissioning Phase A3Entry Conditions.01BCTDC ready for beam commissioning - acquisition chain - application/fixdisplay.02BCTFR ready for commissioning in circulating beam mode.03BQK ready for beam commissioning - acquisition from the control room - tune meter.04Abort gap monitor (BSRA) ready for beam commissioning - acquisition chain - application/fixdisplay.05Wire scanner ready for beam commissioning - acquisition chain/control – application.06Synchrotron light monitor and undulator ready for beam commissioning - acquisition chain/control - application/fixdisplay.07Priority 2: Rest gas ionisation monitor ready for beam commissioning - acquisition chain/control - application.08All screens out!.09BBQ ready for beam commissioning - acquisition chain/control.10PLL ready for beam commissioning - control - tune measurement application.11Tune, orbit, coupling feedbacks - controls requirements fullfilled, ready for testing – application.12Concentration for BPMs for bunch-by-bunch multiturn data fully available

12. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A3 –Procedures I ● Time-in the BPM & BCTFR systems with respect to RF ● Adjust BST for all crates (68 BPM & 2 BCTFR) to get same turn on all systems ● Put bunch 1 in slot 1 for all channels ● Adjust the 40MHz phase for each channel ● Semi-automatic procedure being investigated for the BPMs ● Estimate ~4hrs - if all goes well! ● Commission the real-time channel for continuous orbit measurement ● Orbit data concentration initially at 1Hz ● First step in setting up orbit feedback ● Scan a few orbit correctors & acquire all monitors ● Allows check on BPM quality and calibrations. ● Measurements require only 4-20 correctors/plane/ring ● Use response data for first rough linear optics check ● Flatten orbit in injection regions and dumping region StepActivity WhoPriority A.3.2 BCTFR and BPM checks with pilot intensity.01 Commission BCTFR in circulating beam mode BI.02 Time in BPM system with respect to RFBI1.03 Commission real time channel for continuous orbit measurementBI/OP1.04 Rough calibration of BPM & corrector systemBI/OP1

13. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 BPM Calibration & Quality Checks MDHD.118 MDV.121 BPMs & correctors calibrated – extent will depend on lattice model J. Wenninger – LHCCWG June 2006 ● SPS Test ● lattice is simple so model tune set far (0.2) from the actual tune to make things harder ● Response for a horizontal and a vertical corrector (1% of the matrix)

14. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 StepActivity WhoPriority A.3.4Commission systems with higher intensity (3 x 10 10 ) ~ 3 x 10 10 3.4.10 Full BCT Commissioning – for single intermediate bunches!.11Commission the BCTDC with beam to give acquisitions updates at 1HzBI1.12Commission the Safe Beam Flag using the BCTDC measurementBI/OP/CO1.13Commission the BCTFR in bunch to bunch modeBI1.14Commission the Beam Presence Flag using BCTFRBI/OP/CO1.15Commission the BCTFR lifetime measurementBI1.16Cross calibrate the BCTDC and BCTFRBI2 Phase A3 – Procedures II ● Commission Safe Beam Flag using 1Hz BCTDC intensity measurement ● Verify the generation & distribution ● Verify the logic at the LHC master BIC concerning the LHC safe beam flag ● Commission the Beam Presence Flag using BCTFR ● Verify the generation & distribution ● Commission the lifetime measurement ● Will use turn by turn data from the BCTFR to calculate the lifetime ● Lifetime initially updated at 1Hz

15. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Measurement Mode Beam Type Accuracy/ Resolution Requested Fast BCT (BCTFR) DC BCT (BCTDC) Injection Pilot bunch±20% / ±20% ±10 9 (OK) N/A Nominal bunch ±3% / ±1% ±3·10 9 / ±10 9 (OK) N/A Circulating Beam (>200 turns) Pilot bunch±10% / ±10% ±0.5·10 9 (OK) 1  A (on 10  A) (resolution ~2-10  A) Nominal bunch ±1% / ±1% ±10 9 (OK) 2  A (on 180  A) (limit for short integ. time) 43 pilot bunches ±1% / ±1% ±10 9 (OK) 2  A (on 390  A) (limit for short integ. time) Lifetime Pilot bunch 10% (10hrs/1min) (OK)N/A Nominal bunch 10% (30hrs/10sec) (OK)N/A Early LHC BCT System Performance

16. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A3 – Procedures III ● Commission the Tune Meter (see R. Steinhagen’s talk in Session 5) ● FFT analysis of BBQ data after applied excitation ● Easiest to commission with chirp excitation via transverse damper (Priority 1) ● Damper as exciter will be available from day 1 (W. Hofle) ● Commission Head-Tail Monitor for chromaticity measurement ● In parallel to Tune Meter with MKQ excitation ● Initial BLM System Commissioning (see L. Ponce’s talk in Session 5) ● At this stage perform threshold adjustment on “accidental quench & learn” basis ● If quenches are very frequent then a more detailed study may be necessary StepActivity WhoPriority A.3.4Commission systems with higher intensity (3 x 10 10 ) 3.4.20 Tune Meter Commissioning.21Commission single kick tune measurement using MKQ & BBQBI/BT1.22Commission chirped tune measurement using BQK & BBQBI1.23Commission chirped tune measurement using transverse damperBI/RF2.24Commission head-tail chromaticity measurementBI1 3.4.30 Initial BLM system commissioning.31Adjust thresholds on "quench & learn basis"BI/ST1.32Lose / quench on purposeBI/ST2

17. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A3 – Procedures IV ● Systematic calibration of the BPMs & Correctors ● Required before thorough orbit correction can be attempted ● Scan all orbit correctors and acquire all monitors ● ~30 s per COD (530 CODs per beam)  ~1 shift per beam ● Check response data for BPM & COD polarities and calibrations ● Use response data for a more detailed linear optics check ● PLL (see R. Steinhagen’s talk in Session 5) ● Requires transverse damper or BQK tune tickler in excitation mode ● Wire Scanners ● PMT gain and attenuation have to be established for different beam conditions ● May need to slow them down to get desired resolution on a single bunch ● 2m per second  180  m per point ● Will be the reference for all other beam size measurements StepActivity WhoPriority A.3.6Further commission beam instrumentation with lifetime > 1hr 3.6.10 Systematic BPM & Corrector Calibration.11Scan all orbit correctors and acquire all monitors - polarity and calibrationBI1 3.6.20 Commission PLL Tune & Coupling Measurement BI1 3.6.30 Commission Wire Scanners BI1

18. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Wire Scanners – What are the Limitations ● Wire breakage due to heating ● Simulations corroborated by SPS measurements show that a 30  m carbon wire scanned at 1ms -1 will survive ( T < 4000K ) with: ● 25% of nominal LHC beam at injection energy ● 7% of nominal LHC beam at top energy (a function of beam size not energy) ● OK for 156 on 156 nominal bunches at 7TeV ● Quench of downstream magnets ● Number of events with large energy deposition is higher in Q5 than D4 ● The wire scanner can work to between 1 to 6 x 10 12 protons at 7 TeV ● Main uncertainty due to simulation of small number of interactions in small volume ● This will limit wire scanner use at 7TeV ● May be OK for 45 on 45 nominal bunches at 7TeV ● Speeding up the scan to 2ms -1 can gain a factor 2 Mariusz Sapinski

19. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A3 – Procedures V ● Undulator ● Both Abort Gap and Synchrotron Light monitor use the same light source ● Undulator below 2TeV & D3 above 2TeV ● Use first light from undulator to check for difference in alignment between the test target and the undulator ● Request to switch on undulator as soon as possible ● If there is a big difference an access will be required to re-align ● Abort Gap (BSRA) ● Commission the optics ● may require tunnel intervention for fine adjustment ● Define and check timing and injection bucket ● Calibrate photon production versus proton number using a single bunch ● Use intermediate intensity bunch ● Gate system on single bunch ● Use bunch intensity from BCTFR to calculate photon yield per proton ● Estimate 4 hours per ring (parasitic) with “stable” pilot++ bunch StepActivity WhoPriority A.3.6Further commission beam instrumentation with lifetime > 1hr 3.6.40 Commission Synchrotron Light monitors BI1.41Commission the undulatorsST1.42Commission the abort gap monitorBI1

20. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A3 – Procedures VI ● Synchrotron Light Monitor (BSRT) ● Commission the optics ● may require tunnel intervention for fine adjustment ● Verify video transmission to CCC and 1Hz update of H and V beam profiles using standard CCD camera ● Cross calibrate the system at 450GeV with the wire scanners ● Estimate of 2 days per ring (parasitic) with “stable” pilot++ bunch ● Fast Camera ● One per beam installed from Day 1 ● Currently no intensifier available so cannot perform bunch by bunch acquisition ● Minimum integration time is 5  s ● Single bunches at pilot or pilot++ intensities cannot give turn by turn image (not enough light) ● Considered as “delayed beam instrumentation” ● Secondary to standard CCD acquisition (without intensifier the result is the same!) ● Lack of manpower (SW) to complete for initial commissioning StepActivity WhoPriority A.3.6Further commission beam instrumentation with lifetime > 1hr 3.6.40 Commission Synchrotron Light monitors (cont) BI1.43Commission the synchrotron light beam size monitorBI2

21. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A3 – Procedures VII ● Rest Gas Ionisation Monitor (BGI) ● BGI not expected to have enough gain to operate without a gas injection for single pilot or pilot++ bunches ● The LHC camera does have higher gain than those of the SPS so something may still be visible without a local pressure bump ● Gas injection ● Original design of gas injection system agreed with AT/VAC is now considered risky ● Gas transfer to the cold D3 may lead to vacuum instability due to the build up of gas on the cold bore or beam screen of D3 ● AT/VAC are now investigating other gas injection schemes for the future ● The current agreement is that gas injection will only be used for a limited time during dedicated MDs and not for standard operation ● Set-up and Calibration ● Need to establish gain sets for MCP & camera for different gas pressures ● Cross calibration with wire scanners required for small beams due to resolution limitation StepActivity WhoPriority A.3.6Further commission beam instrumentation with lifetime > 1hr 3.6.50 Commission Rest Gas Ionisation Monitor BI2.51Commission the gas injection systemBI/VAC2

22. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A3 – Procedures VIII ● Commission Dump line Beam Instrumentation ● BLMs, BPMs, BTVs & FBCTs ● Commission Beam Dependent Interlocks ● Verify beam position interlock in IR6 (set to dump at > 3.2mm) ● Verify count rates on BLM monitors at TCDQ (hardware link to dump) ● Commission Feedback Systems ● see R. Steinhagen & Jorg Wenninger’s talks in Session 5 StepActivity WhoPriority A.3.9 Further commissioning of beam dumping system (3 x 10 10 ).01 Measurements with circulating beamBT/OP1.02 Measurements with extracted beamBT/BI/OP1 A.3.10 Commission feedback systems (3 x 10 10 ).01 RF radial loopRF1.02 Commission transverse feedback equipmentRF1.03 Commission RF radial modulationRF1.04 Commission continuous chromaticity measurementBI1.05 Test/commission orbit feedbackOP/BI1.06 Test/commission tune & coupling feedbacksOP/BI2

23. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A4 – 450 GeV Optics Phase A4Entry Conditions.01Orbit feedback operational.02BPM system All monitors polarity checked and calibrated Sum signal available [imposes constraints for the operation with two beams!] Synchronised acquisitions with other devices (kickers, wires,...) Turn-by-turn acquisition available 1000-turn acquisition, both for position and sum signals.03BCT system: BCTDC cannot be used at pilot or pilot+ intensities Measurements must rely on the BCTFR measurements - Turn-by-turn acquisitions synchronized to kicker/BPM/wires/BLM.04Emittance measurements (only as beam size measurements). Full commissioning of - Wire scanners [priority 1] - Synchrotron radiation monitor [priority 2] - Ionization profile monitors (IPM's) [priority 3].05Beam loss monitors (for identification of loss locations) Signal acquisition available for all the available monitors with appropriate display Movable monitors ready to use.06Screens: Emittance measurements in the TL for pulse-to-pulse monitoring.07Appropriate software for acquisition/display of the required BI Has limited resolution At 450GeV

24. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A4 – 450 GeV Optics StepActivity WhoPriority A.4.2Measurement and correction of the linear optics.02TuneABP/BI/OP1.03Coupling (possibly needs another iteration with 2 beams)ABP/BI/OP1 A.4.11 Detailed Beam Loss Studies.01Estimates of cleaning inefficiency of the collimation sub-systemBI/Collim2.02 Preliminary beam loss map studiesBI/Collim2

25. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A8 – Snap-back & Ramp ● Synchrotron Light Monitor ● Required fully commissioned by Phase A9 (top energy checks) ● As beam energy increases ● the light source changes (undulator to D3) ● the light intensity increases ● the beam size shrinks ● The simple 450GeV calibration cannot cover all of these conditions ● Time will be required at different energies to check the optimum settings and to cross calibrate with the wire scanners ● Estimated to take ~1 hour/ring at several different energy levels ● Same is true for the abort gap monitor Phase A8Entry Conditions.01BCT commissioned..02Closed orbit acquisition..03PLL commissioned..04BCT & lifetime commissioned..05Synchrotron light monitors commissioned (not critical).

26. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A8 – Snap-back & Ramp ● Feedbacks ● Allowing time for commissioning feedbacks early on (Phase A3) will significantly reduce the time required to complete this phase ● RHIC experience showed that first ramp with tune & coupling feedback operational reached top energy with over 90% transmission ● Took several days for other ring even with 6 years of experience StepActivityGroupPriority A.8.1Prepare ramp, single beam 1.08BLM thresholds up the ramp - check.BI/OP1.10Check BLM threshold table (energy dependent).BI/OP1 A.8.2Ramp single beam.05FeedbacksOP/BI - Orbit feedback 1 - PLL 1 - Tune and Coupling 2.08Chromaticity (RF modulation synchronized with orbit/dispersion)OP/BI1 A.8.7Commission feedback using PLL BI 1

27. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A10 – Top Energy Collisions StepActivityWhoPriority A.10.4 Optimize Luminosity: separation scans (simple orthogonal separation for commissioning) OP/ABP2.02Measure the luminosity with the BRAN detectors (Fig. 1). Phase A8Entry Conditions.01BRAN detectors commissioned and available.02BPM (high resolution, non-directional button pickups) commissioned and good calibration.03Tune shift measurement available for beam-beam transfer function lumi optimisation - BBQ with tiny excitations or (better) Schottky.04BLMs commissioned and calibrated.05BCT commissioned and calibrated.06Wire scanners commissioned Procedures

28. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A10 – Top Energy Collisions ● Collision Rate Monitors (BRANA & BRANB) ● Ionisation Chambers in IR1 & IR5 (BRANA) ● CdTe detectors in IR2 & IR8 (BRANB) ● Low luminosity means longer integration time ● L=10 34 event rate ~10 6 events/second (7TeV unsqueezed) ● L=10 29  there are ~10 events/second (43 on 43 initial) ● Background expected to be factor ~10 to100 lower ● At 450GeV event rate is approximately a factor 100 lower (difficult to see anything quickly) ● Start commissioning the BRANs as soon as there is circulating beam ● Look at beam losses & beam gas events (any intensity/energy) ● Allows timing to be adjusted if only a few bunches are present ● Time required to understand what is going on may be rather long ● There is not much experience with these devices and few installed ● Much can already be learned before beams are put into collision ● Procedure: ● Observe signals on scope (remotely for BRANB - this is a real complication) ● Adjust shaper trims (for BRANA) - delicate & time consuming process ● Adjust timing - 40MHz and turn clock delays ● Perform threshold scans to measure signal amplitudes (BRANB – 10 detectors per monitor) ● Adjust delay for coincidence – most useful if lumi to background ratio is lower than expected ● Study incoming v. outgoing signals (incoming is background for sure) ● Commissioning with Collisions ● Study signals v. separation ● Perform scans and study results

29. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A10 – Top Energy Collisions ● Schottky Monitors ● Should be able to see single nominal bunch ● Signals will be observed as soon as there is circulating beam ● All of the set-up can be performed parasitically ● Gating required to improve S/N ratio for few bunches ● Timing-in of gate with respect to beam using scope ● Control & application software earmarked as Phase II ● Will be implemented as soon as time & manpower permits ● Special BPMs & BPM measurements around the IRs ● Proposal to have non-directional BPM in front of Q1 looking at both beams ● Same BPM & electronics chain used for both beams ● For zero crossing angle can “perfectly” overlap beams ● Only possible in IR1 & IR5 ● Excluded for IR2 & IR8 due to space constraints ● Only works for bunch spacing > 100ns ● Not available for start-up but if they are to be installed should be foreseen for first shut-down due to radiation ● BPM time-of-flight measurements for accurate IR positioning using Q1 BPMSW ● Replace intensity card with special laser transmitter card ● Initially observe signals on surface using scope ● Equalise time difference between the two beams on either side ● Should be able to obtain resolution of a few 100ps (3cm)

30. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Phase A11 – Squeeze ● By this stage all instrumentation should have been tested and have undergone at least a first pass commissioning for up to 156 bunches at low/intermediate intensity Phase A11Entry Conditions.01Orbit feedback operational (at least in cleaning and dump insertions).02Tune / chromaticity feedbacks operational if possible.03Synchrotron radiation monitor commissioned

31. Rhodri Jones – CERN Beam Instrumentation GroupLHC Beam Instrumentation – LTC Days 2008 Conclusions ● Commissioning phases worked out through the LHCCWG with input from equipment and operations experts ● No major inconsistencies are apparent ● Some minor procedural orders still to be tweaked ● Some BI commissioning will need to be carried out every time beam conditions change (intensity, energy, fill pattern etc) ● Fully commissioned = OK for current beam conditions ● It is clear that what is presented here is a best case scenario ● HWC completed with no major problems ● Instruments respond in the manner that was expected ● Many have been prototyped in the SPS & this should limit any surprises ● Beam conditions are conducive to good measurements! ● A “chicken & egg” problem ● Good measurements are needed to obtain good/stable beam conditions ● Good measurements often require good/stable beam conditions ● Have tried to make the BI systems as robust as possible ● Feedbacks can help to limit the beam parameter space ● e.g. stabilise the orbit & feed-down from orbit changes in sextupoles (tune & coupling) no longer have to be corrected for or interfere with measurements ● All instruments & procedures are in place to achieve first LHC collisions ● Now all we need is the beam