Chamonix 2006 LHC Project Workshop What is required

Chamonix 2006 – LHC Project Workshop What is required to get the beam safely out of the LHC B. Goddard AB/BT Input from E. Carlier, J. Uythoven, R. Assmann, V. Kain, J. Wenninger + others http: //proj-lbds. web. cern. ch/proj-lbds/ 23 January 2006 Chamonix 2006 - LHC Project 1

Outline of talk • Beam dumping system : – Operational states and sequencing • Beam commissioning – what, when and how: – Overview of beam commissioning needed – Fitting into the overall LHC commissioning – Breakdown of individual LBDS beam tests – TCDQ positioning • Discussion points and conclusion 23 January 2006 Chamonix 2006 - LHC Project 2

Scope I will focus on ‘Stage I’ as detailed earlier by Roger 1 pilot 43 bunches ( 4 1010 p+) 156 bunches ( 9 1010 p+) Requirements for ‘Stage II’ are basically more of the same 23 January 2006 Chamonix 2006 - LHC Project 3

Reminder • Dilution kicker system MKB is staged (2 H, 2 V) – Limits extracted intensity at 7 Te. V to 50% of nominal – For 25 ns spacing, this is a limit on single bunch intensity, NOT on total in LHC – Not an issue for “Stage I” : could safely dump full beam intensity up to about Te. V – (no interlock - rather unlikely to be needed in first few months…) BTVDD trace – full dilution 23 January 2006 BTVDD trace – staged MKB Chamonix 2006 - LHC Project 2 Allowed dumped intensity (staged MKB) 4

Q: “when is the LBDS needed…. ”? See J. Wenninger’s presentation ! System Commissioning before beam possible ? Beam Dumping System 450 Ge. V PARTIAL Beam Dumping System 7 Te. V PARTIAL • First pilot beam 10^12 43 bunches 1. 7 10^12 156 bunches 6 10^12<N<1. 4 10^13 936 bunches 10^13 >5 System tests, HWC and Reliability Run to validate internal dependencies of LBDS subsystems, and connection with MP systems (including BIS) no operational Beam Dump system = no Beam permit • However…. LBDS can be “operational” for pilot intensity, but “not operational” for 43 bunch running need representation of “operational state” (LHC sequencer) A: “day 1” 23 January 2006 Chamonix 2006 - LHC Project 5

“Bootstrapping” the LBDS operational state Need to drive LBDS operational state from “Not ready” to “Ready for beam” Diagnostics IPOC, XPOC Arming procedure Beam dump triggered Not ready. Ready for no beam Ready for pilot Tests with pilot beam Ready for beam LBDS operational states BUT LBDS “Ready for beam” can’t distinguish between 1 or 2808 bunches of 1011 p+ need formal representation of the progress of the LHC commissioning process could envisage MCS + SIS (plus sequencer? ) to manage this 23 January 2006 Chamonix 2006 - LHC Project 6

Safety critical aspects of the LBDS • Signal from beam interlock system (test in HWC/RR) – • Energy tracking – • Insufficient dilution could damage TDE, BTVDD and TDE entrance window Abort gap ‘protection’ – • Dump with bad orbit could damage extraction elements MSD, TCDS or MKB MKD – MKB connection and sweep form – • Undetected ‘dead’ MKD severely reduces reliability Aperture, optics and orbit – • Wrong w. r. t. orbit exposes LHC arc / triplets / collimators. System self-tests and post-mortem – • No retriggering could put whole 7 Te. V beam at ~10 s TCDQ setting – • Potentially catastrophic (whole beam at “any” amplitude) MKD retriggering (test in HWC/RR) – • No trigger = no beam dump Beam in the abort gaps risks quench, or TCT/LHC damage if TCDQ position error Fault tolerance with 14/15 MKD – The system is designed to operate safely with only 14 out of the 15 MKDs Nearly all aspects need beam commissioning (validation or optimisation) 23 January 2006 Chamonix 2006 - LHC Project 7

LBDS beam commissioning in phase I • Pilot beam: – – • Before first extraction…. Before first ramp… During ramp… At 7 Te. V… Before moving to potentially unsafe beam: – Interlock commissioning – TCDQ positioning • 43 bunches – Before first extraction… – Before first ramp… • 156 bunches – Before first ramp… 23 January 2006 Chamonix 2006 - LHC Project 8

Before first extraction… Circulating beam, 1 pilot at 450 Ge. V • Optics and other measurements in IR 6 – Beta, dispersion, orbit correction, stability • Commission dedicated LBDS BDI for circulating beam – Synch BPM, BLMs (MKD, MSD, TCDS, TCDQ), check direct LBDS interlock BLM • Aperture measurement with circulating beam – MSD, TCDS, MKD, TCDQM Opening for circulating beam (H plane) at TCDS and MSD 15. 3 mm (n 1=6. 5) 20. 8 mm (n 1=7. 0) 23 January 2006 Chamonix 2006 - LHC Project 9

Before first pilot ramp…i Extracted beam: 1 pilot @ 450 Ge. V (inject & dump) • First extraction – Into “Inject & Dump” mode • “Rough” extraction timing – Adjust RF synch MKD kick delay, S signal from IR 6 BPM (UA access for each delay trim!) • Commission extraction line BDI – BTV (SE, D, DD), BPM (SE, D), BLMs, BCTs Any major problems will be apparent at this stage! 23 January 2006 Chamonix 2006 - LHC Project 10

Before first pilot ramp…ii Extracted beam: 1 pilot @ 450 Ge. V (inject & dump) • Verification of extraction trajectory and aperture – Vary orbit in IR 6 and measure aperture at TCDS/MSD/TD line – Optimise extraction trajectory (orbit, MKD, MSD); define ‘reference’ (UA access for MKD trim!) – Define limits for interlock BPM reference • Explicit check that aperture is adequate for 14/15 MKD case – Unplugging 1 MKD is not desirable (interlocks to be strapped, undo HWC/RR validation, etc. ) – Prefer to check by varying orbit in IR 6 (1/15 of 270 mrad…) Opening for extracted beam (H plane) at TCDS and MSD MKD sweep Extracted beam aperture vs IR 6 orbit { 23 January 2006 Chamonix 2006 - LHC Project 11

Before first pilot ramp…iii Extracted beam: 1 pilot @ 450 Ge. V (inject & dump) • Logging and fixed displays – Checks that the beam related data is being correctly acquired and displayed • XPOC basic functionality (trajectory, BLMs, BCT, kickers, BTVDD, …) – Check that XPOC validation is working correctly for pilot setup • Issue: safe change of configuration when changing beam. With MCS/SIS/sequencer? • BDI Post-Mortem data – Check that all beam-dependant transient signals from the LBDS systems are being PM’d 23 January 2006 Chamonix 2006 - LHC Project 12

Before first pilot ramp…iv Extracted beam: 1 pilot @ 450 Ge. V (inject & dump) MKD kick waveform measurements MKB sweep measurements • Important for aperture at TCDS/MSD • Important for MKB and TD line aperture • BPMD, BTVDD and BLMs. inject & dump, vary injected bunch bucket (5 meas. points) • BPMD and BTVDD. inject & dump, vary injected bunch bucket (≈10 meas. points) MKD kicker waveforms (current signal) BTVDD ‘screenshot’ 89 ms bunch 1300 23 January 2006 Chamonix 2006 - LHC Project 13

During ramp with pilot… Extracted beam: 1 pilot @ 450 -7000 Ge. V (dump in ramp) • MKD, MKB kicker and MSD septum energy tracking – – Extract single pilot at pre-defined energies in the ramp (calibrated points) Adjustment of kicker lookup tables means UA access Time-consuming if done as dedicated measurement…. need to organise in a quasi-parasitic way Extraction with 2 pilots during the ramp is also needed to verify the abort gap timing… combine? MKD lookup table calibration data 23 January 2006 Chamonix 2006 - LHC Project 14

Before moving to unsafe beams…i Extracted beam: 2 pilots @ 450 Ge. V (inject & dump) MKD kicker “fine” timing adjustment • Inject 2 pilots into positions 1 and 2808 (3. 0 ms spacing) • Fine adjustment of MKD timing (IR 6 synch BPMs and RF frequency) • Acquire last turn of bunch 2808 in LHC to verify MKD kick ( 0. 5 s or 3 mrad) bunch 1 turn n 270 mrad kick MKD kick waveform 3. 0 ms bunch 2808 turn n-1 3 mrad kick Note: this also needs to be checked through the ramp… 23 January 2006 Chamonix 2006 - LHC Project 15

Before moving to unsafe beams…ii Circulating beam: safe beam @ 450 Ge. V • Abort gap “watchdog” – Commission the link between the LBDS and the injections – Fine timing between IR 6 and injections needs to be adjusted with beam • Interlock BPMs for IR 6 maximum orbit – Interlocked to around ± 3. 6 mm. Threshold setting and tests 23 January 2006 Chamonix 2006 - LHC Project 16

Before moving to unsafe beams…iii TCDQ Circulating beam: 1 pilot @ 450 Ge. V • Adjustment of TCDQ/TCS jaws to 450 Ge. V position (≈10 s) – – – • Beam axis wrt jaw, adjustment of jaw tilt, movement cross-calibration TCS – 2 jaws - more accurate movement - tighter setting (by ≈1 s) Needs BLMs and collimator controls Orbit at TCDQ – Measurement of beam axis Circulating beam: safe beam @ 450 -7000 Ge. V • Establish TCDQ movement function during ramp – Interdependence with collimation system Circulating beam: safe beam @ 7 Te. V • Establish TCDQ movement function during squeeze • Accurate adjustment of TCDQ and TCS jaws in final position – – Establish reference settings for target b* during next phase of commissioning Interdependence with collimation system Interdependency on collimation settings, and on orbit feedback Iterations (changes of orbit, b-beat, b*) to finalise TCDQ reference function This looks like a major workup! 23 January 2006 Chamonix 2006 - LHC Project 17

Alternative for TCDQ setting during phase I… TCDQ protects arc at 450 Ge. V and TCTs/triplets at 7 Te. V squeezed • 450 Ge. V - set TCDQ/TCS system up at ± 10 s – Rely on ± 4 mm interlock to protect arc (maximum excursion at TCDQ is ≈2 s ) – Asynch dump with 156 b, max. 2 bunches in interval 7 -12 s Safe for 450 Ge. V • 7 Te. V - pilot near to damage level - set TCDQ/TCS at ± 10 s – Rely on 2 -jawed TCS to protect the TCTs – don’t worry about the orbit – Keep TCTs at ≈20 s protected for any orbit in IR 6 (limits b* to 2 m) • Can then (if needed) delay final orbit feedback + TCDQ beam position + SW interlock full commissioning to b* <2 m • Should improve operational efficiency during stage I • Need to check through all detailed implications – Protection level with TCS - decide safe combinations of intensity/filling pattern – Optics control/knowledge at TCDQ, TCTs and triplets (plus orbit at TCTs/triplets) 23 January 2006 Chamonix 2006 - LHC Project 18

Before first 43 b ramp… Extracted beam: 43 b @ 450 Ge. V (inject, fill & dump? ) – Start with 43 pilots, to keep below the damage threshold – When this is OK, move to 43 bunches of 4 1010 for validation • Losses in extraction channel and along the dump line – Reduced sweep with staged MKB means generous TD aperture • Check BDI response • Logging, PM and XPOC validations – Establish new reference data for XPOC… BPMD 23 January 2006 BTVDD Chamonix 2006 - LHC Project 19

Before first 156 b ramp… Extracted beam: 156 b @ 450 Ge. V (inject, fill & dump? ) • As per 43 b activities… • Plus…. . TDE thermal behaviour? – ≈10 k. W for nominal beam at 7 Te. V every 10 hours – Could load with ≈4 k. W with repeated inject, fill & dump of 156 bunches… 23 January 2006 Chamonix 2006 - LHC Project 20

LBDS beam commissioning – pilot beam LBDS beam commissioning activity LHC mode Beam type Energy Ge. V Things to do before first pilot extraction IR 6 optics measurements Injection Circulating 1 pilot 450 Commission dedicated LBDS BDI in IR 6 Injection Circulating 1 pilot 450 Extraction element aperture measurements Injection Circulating 1 pilot 450 … before first pilot ramp First extractions: rough timing adjustment TD line BDI commissioning Extraction trajectory and aperture measurements Data diagnostics: IPOC, logging, FDs, PM, XPOC MKD waveform overshoot measurements MKB sweep measurements Inject & dump Inject & dump Extract 1 pilot Extract 1 pilot 450 450 450 … with the pilot ramp Energy tracking measurements Ramp Extract 1 pilot 450 -7000 …before moving to operation with potentially “unsafe” beams Fine timing adjustment Commission SW interlock on beam position at TCDQ Commission IR 6 orbit BPM interlock Commission abort gap watchdog TCDQ “injection setting” positioning Fine timing in ramp TCDQ positioning at 7 Te. V Inject & dump Injection Ramp Adjust/squeeze Extract 2 pilots Circulating, safe beam Extract 2 pilots Circulating, 1 pilot 450 450 450 -7000 = time consuming 23 January 2006 Chamonix 2006 - LHC Project 21

LBDS beam commissioning – 43 b LBDS beam commissioning activity LHC mode Beam type Energy Ge. V Things to do before first 43 b extraction Orbit feedback / stability checks at TCDQ Injection Circulating, 43 b 450 … before first 43 b ramp Extraction trajectory checks Inject & dump Extract 43 pilots 450 TD line BDI checks Data diagnostics: XPOC Inject & dump Extract 43 b 450 … with the 43 b ramp Energy tracking and abort gap timing checks Ramp Extract 43 b 450 -7000 … with 43 b at 7 Te. V TCDQ positioning at 7 Te. V Adjust/squeeze Circulating, 43 b 7000 23 January 2006 Chamonix 2006 - LHC Project 22

LBDS beam commissioning – 156 b LBDS beam commissioning activity LHC mode Beam type Energy Ge. V Things to do before first 156 b extraction Orbit feedback / stability checks at TCDQ Injection Circulating, 156 b 450 … before first 156 b ramp Extraction trajectory and BDI checks Data diagnostics: XPOC TDE thermal behaviour Inject & dump Extract, 156 pilots Extract, 156 b 450 450 … with the 156 b ramp Energy tracking and abort gap timing checks Inject & dump Extract, 156 b 450 -7000 …with 156 b at 7 Te. V TCDQ positioning at 7 Te. V Adjust/squeeze Circulating, 156 b 7000 This is essentially the same list of activities as from pilot to 43 b. It will be essentially the same list for all major changes in LHC beam (filling pattern, significant intensity steps, optics, emittance, …) 23 January 2006 Chamonix 2006 - LHC Project 23

Unfinished business… • Inject and dump mode – Needed from first extractions, for efficient commissioning – Details to finalise (timing, PM/logging, , multiple injections, turn delays, HW, SW) • Diagnostics – Split between IPOC, XPOC, logging and PM; XPOC configurations • Abort gap monitoring and cleaning in phase I – Assumed not needed for protection - could be important for efficiency – Topic for another day… • Ensuring that only ‘authorised’ beam can be used – Operational states and allowed LHC beam conditions – MCS, SIS and sequencer • Halo at TCDQ – Effect of “minimum collimation” strategy – risk of frequent Q 4 quenches – FLUKA energy deposition simulations give cause for concern – work ongoing – Beam 2 will be worse…. not checked yet 23 January 2006 Chamonix 2006 - LHC Project 24

Conclusion LBDS beam commissioning for phase I operation: • will depend heavily on HWC/RR; – Validation of subsystem interconnectivity and reliability assumptions – Many key elements will be fully commissioned without beam • requires careful commissioning with pilot beam; – At 450 Ge. V before extraction, to check the optics and aperture – At 450 Ge. V in “Inject & Dump” mode, to check the LBDS functioning – During the ramp, to check the energy tracking • requires specific checks when LHC beam changes; – • To verify instrument response, diagnostics and losses can be somewhat relaxed for difficult TCDQ/TCS positioning; – By taking advantage of limited b* squeeze and number of bunches 23 January 2006 Chamonix 2006 - LHC Project 25

23 January 2006 Chamonix 2006 - LHC Project 26

LBDS functional dependencies - overview 23 January 2006 Chamonix 2006 - LHC Project 27

External “subsystems” requiring beam LHC control system Ethernet BPM IR 6 TCDQ position DCCTs Access Fast timing (RF synch) BLM 6 Abort gap monitor Direct triggers (to TSU) LBDS Slow timing Emergency stop status IR 6 orbit feedback IR 6 PM trigger Mains & UPS status External outputs External inputs Software interlock SLP Injection BIC interface Machine Protection interfaces LHC beam permit loop 23 January 2006 Chamonix 2006 - LHC Project 28

Primary LBDS failure catalogue

Lookup tables in the LBDS • Lookup tables within Beam Energy Tracking sub-system to convert physical measurements to energy – – – Conversion of main bending currents to energy Conversion of energy to kicker voltage references Conversion of extraction septa currents to energy Conversion of ring quadrupole Q 4 currents to energy Conversion of kicker voltages to energy Modification (e. g. adjust MKD strength) reprogram local FPGAs E. Carlier 23 January 2006 Chamonix 2006 - LHC Project 30

Look-Up Tables - Which Type and Where Interlock Reference Acquisition Main Bends Kicker HV Generators Q 4 & Septa Magnets Imeas. A Imeas B Umeas. Ki Normalisation to Beam Energy Imeas. Mi Settings Ebeam. A Ebeam. B Ebeam. Ki Ebeam. Mi Operational Settings Tracking Interlock Logic Kicker HV Generators Dump Trigger Request |Ebeam. B – Ebeam. Ki. Mi| > 0. 5% * Ebeam. B Acquisition First Order Interpolation 23 January 2006 Uref. Ki Chamonix 2006 - LHC Project Tracking Memory Map 31

Energy tracking performance Power converter DCCT precision ± 0. 1 % Kicker HV divider precision ± 0. 2 % BEA sampling frequency 65 k. Hz BEA resolution 16 bit BEA–BEM / BEI transmission rate ~100 kbit/s Error during ramp (10 A/s) 0. 01% Bending magnet look-up table precision ± 0. 1 % Kicker magnet look-up table precision ± 0. 2 % Beam energy reference error (with interlock on RF & Sextupole) ± 0. 4 % BEI tracking frequency 1 k. Hz BEI tracking reaction time 1 ms Bending magnet tolerance window ± 0. 3 % Kicker magnet tolerance window ± 0. 5 % 23 January 2006 Chamonix 2006 - LHC Project 32

“Bootstrapping” the LBDS operational state BUT LBDS “Ready for beam” can’t distinguish between 1 or 2808 bunches of 1011 p+ need formal representation of the progress of the LHC commissioning process could envisage MCS + SIS (plus sequencer? ) to manage this Ready for pilot commission pilot prepare for 43 bunches Ready for 43 bunches commission 43 bunches prepare for 156 bunches Ready for 156 bunches commission 156 bunches prepare for 936 bunches Ready for 936 bunches commission 936 bunches prepare for 2808 bunches Ready for 2808 bunches commission 2808 bunches LBDS “Ready for pilot” LBDS always “Ready for beam” LHC state Inside each activity are commissioning steps for LBDS, which must be completed and “signed-off” before overall LHC is declared “Ready” for next stage. 23 January 2006 Chamonix 2006 - LHC Project 33

Areas for concern – halo at TCDQ • Halo at TCDQ – – Effect of “minimum collimation” strategy High load on TCDQ risks frequent Q 4 quenches Load from beam tracking: input for FLUKA energy deposition simulations Beam 2 will be worse – not checked yet Thermal load in Q 4 coil due to halo no beam cleaning 15 m. W/cm 3 nominal cleaning 0. 03 m. W/cm 3 A. Presland 23 January 2006 Chamonix 2006 - LHC Project 34