LHC Ramp Commissioning Mike Lamont Reyes Alemany-Fernandez Thanks to: Stefano, Verena, Walter

LHC ramp commissioning2 9/5/2007 LHC ramp commissioning Ramp generalities Overall strategy Beam entry conditions and tolerances Entry conditions Procedures Exit conditions What’s in place Upcoming tests

LHC ramp commissioning3 9/5/2007 Magnets The basic design of the LHC ramp (parabolic, exponential, linear, parabolic (PELP)) is designed to:  P: Push up the time in which the snapback is resolved.  E: Constant Bdot – ramp induced coupling current  L: Max dI/dt of MB power converters  P: smooth round off at top energy Start [s]End [s]Start p [GeV]End p [GeV] Snapback070450~500 Parabolic ~900 Exponential405820~920~2400 Linear ~2400~6800 Parabolic ~ LHC main dipole proposed baseline current ramping - Bottura, Burla and Wolf

LHC ramp commissioning4 9/5/2007 Ramp Construction Construct idealized MB current function (PELP) using standard prescription (defined in terms of current variation during snapback etc.) From this generate momentum(t) using averaged calibration curve Use this a scale parameter for settings generation Optics defined as a function of time  Design optics  (Note change of IR2 optics) Circuit currents via FiDeL generated calibration curves

LHC ramp commissioning5 9/5/2007 Nominal cycle I ~ t 2 I ~ e t I ~ t

LHC ramp commissioning6 9/5/2007 Possible variations Skip exponential  Ramp induced inter-strand coupling currents small  Simplifies ramp structure – easier to stop anywhere  Cost – one minute per ramp Slower snapback  Measurements planned to check dependency Programmed stop in ramp  Parabolic – (Linear) - Parabolic Pre-cycle (as entry condition)  Snapback minimization – particularly during commissioning

LHC ramp commissioning7 9/5/2007 Stopping with beam in the ramp Must be programmed before starting the ramp  with appropriate round-off behaviour of the functions  Might need to handle (much reduced) decay after the stop Restart with beam is possible in theory.  requires a new set of functions to be loaded  including corrections for handling the associated snapback  during commissioning will be dumping the beam Used for commissioning of beam dump, beam loss monitors, beam measurements, optics checks, physics...

LHC ramp commissioning8 9/5/2007 Settings/Trim Run to run feed forward Feed forward from feedback system Incorporation of TRIMs into settings before ramping  Ensure and test compatibility with feedbacks and make sure that machine safety cannot be compromised  constant strength, smoothed out etc. as appropriate.  This will be configurable depending on the parameters involved. The appropriate strategy will be decided based on common sense and experience with beam. Real time knobs on key beam parameters (tune, chromaticity) are planned. To be tested during commissioning. LSA

LHC ramp commissioning9 9/5/2007 Magnets Transfer functions DC components  Geometric, DC magnetization, Saturation, Residual MB MQ (Decay &) Snapback predictions  b1, b2, b3, b5, a2, a3… Cycling prescriptions – all magnets Corrector Hysteresis Handled on-line by LSA’s implementation of FiDeL  Snapback “on the fly” invocation and incorporation Import of FiDEL coefficients into LSA database in progress

LHC ramp commissioning10 9/5/2007 Power converters Load I(t) to all 1700 power converters  Ramp won’t load if I(0) not within 0.01 of actual reference value  100 µs granularity  up to 5000 points, maximum duration s.  Linear interpolation of supplied points  FGC runs full table – no stop/re-start  Abort running ramp possible - don’t expect to keep the beam  There can be no trims after loading the ramp  Changes can still be put through the real time channel, however, the real time TRIMs are not ramped  Ramp start on receipt of timing event

LHC ramp commissioning11 9/5/2007 RF Use multiplexed FGCs for function generation  The FGC2_RF will generate sixteen 16-bit integer functions at 1 kHz and will use the RFC-500 card to distribute the function values to the relevant nodes on the bus Will ramp:  2*8*Cavity voltages & phase  Coupler positions  RF frequency (offset from 400 MHz). Both rings nominally locked to the same frequency to avoid re-phasing before physics  gain of the phase loop  gain and time constant of the synchro loop  Plus transverse damper etc.

LHC ramp commissioning12 9/5/2007 Radial Loop Fixed radial position, variable frequency Adjusts RF frequency to centre beam at pickup in IR4  measure frequency offset and feed correction forward into functions [LSA] Choices  Single pickup as planned  Global orbit average – correct via RT system (robust)  Two pick-ups at Pi  Feed forward – check mean orbit – implies RT global orbit acquisition – correct either radial loop reference or frequency

LHC ramp commissioning13 9/5/2007 Beam Dump Loaded with the reference energy ramp On-line secure energy monitoring MSD/Q4 – FGC – I(t) locked in MKD, MKB kicker and MSD septum energy tracking  Extract single pilot at pre-defined energies in the ramp (calibrated points)  Check MKD kicker “fine” timing adjustment Brennan Goddard Cham 2006 Orbit/aperture Extraction trajectory Instrumentation Kicker timings, retriggering Post mortem and XPOC

LHC ramp commissioning14 9/5/2007 LBDS beam commissioning – pilot beam LBDS beam commissioning activityLHC modeBeam typeEnergy GeV Things to do before first pilot extraction IR6 optics measurementsInjectionCirculating 1 pilot450 Commission dedicated LBDS BDI in IR6InjectionCirculating 1 pilot450 Extraction element aperture measurementsInjectionCirculating 1 pilot450 … before first pilot ramp First extractions: rough timing adjustmentInject & dumpExtract 1 pilot450 TD line BDI commissioningInject & dumpExtract 1 pilot450 Extraction trajectory and aperture measurementsInject & dumpExtract 1 pilot450 Data diagnostics: IPOC, logging, FDs, PM, XPOCInject & dumpExtract 1 pilot450 MKD waveform overshoot measurementsInject & dumpExtract 1 pilot450 MKB sweep measurementsInject & dumpExtract 1 pilot450 … with the pilot ramp Energy tracking measurementsRampExtract 1 pilot …before moving to operation with potentially “unsafe” beams Fine timing adjustmentInject & dumpExtract 2 pilots450 Commission SW interlock on beam position at TCDQInjectionCirculating, safe beam450 Commission IR6 orbit BPM interlockInjectionCirculating, safe beam450 Commission abort gap watchdogInjectionCirculating, safe beam450 TCDQ “injection setting” positioningInjectionCirculating, safe beam450 Fine timing in rampRampExtract 2 pilots TCDQ positioning at 7 TeVAdjust/squeezeCirculating, 1 pilot7000 = time consuming

LHC ramp commissioning15 9/5/2007 Collimators Motor positions(t) down loaded to controllers Functions triggered with timing event Settings maintained on LSA with full parameter space defined (position, angle, emittance, Twiss etc.) High Intensity ramp behaviour defined  C. Bracco: Collimator settings during the energy ramping Low Intensity ramp commissioning  Cleaning not an issue, protection.  Set TCDQ/TCS at ±10  at 450 GeV, primary at 7-8   Good enough for intermediate energies  Provides protection at 7 TeV, but still might want to bring them in Stefano and Delphine

LHC ramp commissioning16 9/5/2007 Timing System Timing table(s) pre-configured and loaded to the CBCM  Start PC ramp  Start RF ramp  Start collimator ramp  BPM – closed orbit/capture  BLM – burst  Fly Wire Scanner  Etc. etc. Executed on request by timing system

LHC ramp commissioning17 9/5/2007 Measurements on ramp Periodic  BCT/Lifetime  Synchrotron light monitors  Beam Loss Monitors  Schottky  WCM Continuous  Tune PLL – clear priority  Chromaticity RF modulation (Synch with orbit -> dispersion) Ramp – different f rf  “Slow” orbit acquisition ~ 1 Hz  RT orbit acquisition ~10 Hz

LHC ramp commissioning18 9/5/2007 Measurements at intermediate energies Tunes, Chromaticity, Orbit, Coupling Tracking between sectors Transfer functions Beta beating

LHC ramp commissioning19 9/5/2007 Feedback using the PLL tune system Tune feedback requirements  Stable PLL tune measurement system  Knowledge of correction quad transfer functions already known from initial tune corrections  Implementation of feedback controller Coupling feedback requirements  Stable PLL tune measurement system  Knowledge of skew quad transfer functions  Implementation of feedback controller Chromaticity feedback requirements  Stable PLL tune measurement system  RF frequency modulation All of these will require dedicated beam time for testing the control loop response and the final closing of the loop. Rhodri Jones

LHC ramp commissioning20 9/5/2007 Machine Protection Single beam through snapback Switch to nominal cycle Ramp – single beam Single beam to physics energy Two beams to physics energy Star t End Low intensity, single bunch, low energy... same as at 450 GeV  BLMs: acquisition – no dump, check losses against thresholds  collimators & TDCQ coarse settings Critical machine protection systems must be in place  minimum subset of BLMs connected to beam interlock system  collimators interlocked in place  local orbit stabilisation around beam cleaning insertions and dump region  further commissioning of beam dump & BLMs  BEM & SBF

Overall strategy

LHC ramp commissioning22 9/5/2007 Initial Ramp Commissioning Baseline 450 GeV commissioning Snapback light pre-cycle Pilot beam Wait it out at injection Snapback using FiDeL predictions Ramp to reduced energy Recycle full machine Thus in seven steps with seven ramps to seven TeV Repeat for beam 2

Procedures

LHC ramp commissioning24 9/5/2007 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.8Snap-back and ramp: single beam A.9Top energy checks: single beam A.6450 GeV Two beam operation A8.bRamp two beams A.10Top energy checks: two beams A.5450 GeV Increasing intensity: prepare the LHC for unsafe beam A.11Top energy: collisions A.12Squeeze: commissioning the betatron squeeze in all IP's Commission snap-back corrections Commission the RF up to top energy Commission beam dump and machine protection (MPS) at different intermediate energies Commission BI acquisition in the ramp Snap-back & Ramp with single pilot beam – Basic Objectives

LHC ramp commissioning25 9/5/2007 Overview of Steps Involved StepActivityPriority A.8.1 Prepare ramp: Prepare ramp: Correction of snap-back and TRIM incorporation; beam 1 1 A.8.2 Ramp  E=1TeV RF system Ramp beam 1 up to pre-defined energy steps (  E=1TeV); commission the RF system 1 A.8.3 Checkinstrumentationbeam parameters Check the key instrumentation and control key beam parameters: orbit, tune, coupling, chromaticity 1 A.8.4 Stopcommission beam dumpmachine protection systems Stop in the ramp and commission beam dump and machine protection systems at intermediate energies. Perform beam based checks at intermediate energies 1 A.8.5 Ramp to 7 TeV Ramp to 7 TeV, beam 11 A.8.6Repeat A.8.1 to A.8.5 for beam 21

LHC ramp commissioning26 9/5/2007 Beam Entry Conditions Beam Entry conditions: One bunch, I b = 5x10 9 p to 3x10 10 p Separate commissioning for beam 1 and beam 2 Nominal beam emittance (value agreed for ramping) Beam tolerances: 450 GeV tolerances should also apply for the ramp as the available beam aperture stays constant Need to allocate budgets for static and dynamic tolerances Relaxed tolerances on key beam parameters

LHC ramp commissioning27 9/5/2007 Entry conditions EntryDescription E.A.8.1First optimization of the machine at 450 GeV done.01 Tune, chromaticity, orbit, coupling measured and corrected beta beating at least measured. Aperture reasonably well established.02All circuits up to b3 commissioned – polarities check with beam, etc.03Collimators providing basic protection.04 PC OFF: Skew sextupoles; octupoles spool pieces; decapoles spool pieces; crossing angle; spectrometer magnets; experiments solenoids and separation bumps E.A.8.2Settings generation.01 LSA parameter space fully defined. Settings generation available and debugged. Ramps to pre-defined intermediate energies..02 Decay/snapback effects will be handled by LSA’s implementation of FiDEL. Pre-cycles defined..03RF functions (frequency & voltage etc.) available.04 Collimator ramp settings (not used initially but there with all functionality tested)

LHC ramp commissioning28 9/5/2007 Entry conditions EntryDescription E.A.8.3Power Converters.01All operational functionality tested. E.A.8.4BI.01BCT commissioned.02Closed orbit acquisition.03PLL commissioned.04BCT & lifetime commissioned.05Synchrotron light monitors commissioned (not critical) E.A.8.5Feedbacks.01Orbit (1) and tune (2) feedbacks are the priority.

LHC ramp commissioning29 9/5/2007 Entry conditions EntryDescription E.A.8.6Machine protection.01Critical BLMs commissioned and connected to the BIS.02Collimators interlocked in place.03 Local orbit stabilization around beam cleaning insertions and dump region.04Further commissioning of beam dump(*) and BLMs.05Intensity versus energy logic in SBF tested E.A.8.7Controls.01Timing system fully commissioned/input to equipment.02Ramp timing table populated 03Logging & data acquisition criteria established

LHC ramp commissioning30 9/5/2007 Stage A.8.1 – Prepare ramp StepActivityGroupPriority A.8.1Prepare ramp, single beam, ring 1.01 Snap –back prediction, incorporation into functions, decay at stop point to be anticipated MA/OP GeV trim incorporationOP1.03Prepare RF:RF/OP1 Load RF functions Radial loop on – to be done after last injection and before start ramp

LHC ramp commissioning31 9/5/2007 Stage A.8.1 – Prepare ramp StepActivityGroupPriority A.8.1Prepare ramp, single beam, ring 1 (cont.)1.04Transverse feedback not needed in the first instance.05Load Power Converters (Table)OP.06 Collimators (not ramped during first attempts to lower energy) OP.07Timing table configured and loadedOP.08BLM thresholds up the ramp - checkBI.09TDI, TCT, TCLI out. Kickers off. 0.10Check BLMs threshold table (energy dependence)

LHC ramp commissioning32 9/5/2007 Stage A.8.2 – Ramp single beam StepActivityGroupPriority A.8.2Ramp single beam; ring 1.01Send timing event: Start Ramp.02 Monitor: Lifetime, tunes, orbit, energy, beam losses, beam sizes (synchrotron light) OP.03Measure: Capture losses (flash loss of out-of-bucket beam at start of ramp) Continuous measurements of frequency response of loops during ramp RF Parasitic Bunch length (emittance growth), RF noiseRF Parasitic.04 Feed-forward of measured frequency offset for eventual switch to synchro-loop operation RF 2 Parasitic

LHC ramp commissioning33 9/5/2007 Stage A.8.2 – Ramp single beam StepActivityGroupPriority A.8.2Ramp single beam; ring 1 (Cont.).06Feedbacks: Orbit feedback:  Synchronized acquisition and feed-forward  Global orbit feedback a.s.a.p. OP1 PLL:  Continuous tune, coupling  High priority: feed forward OP/BI1 Tune and coupling:  First ramps can be attempted w/o these feedbacks, however, in our interest to commission them a.s.a.p. Critical will be measurements to monitor variations during snap-back and in the ramp OP/BI3.07 Tracking: the real time orbit acquisition allows us to check the relative tracking during the ramp with similar or better accuracy in delta (use difference w.r.t. injection) as compared to injection OP

LHC ramp commissioning34 9/5/2007 Stage A.8.2 – Ramp single beam StepActivityGroupPriority A.8.2Ramp single beam; ring 1 (Cont.).08Transfer functions (may be difficult).MA.09ChromaticityOP/BI1 RF modulation synchronized with orbit/dispersion1.10 Beta beating measurement at intermediate energies – local orbit checks OPABP

LHC ramp commissioning35 9/5/2007 Stage A.8.3 – Post Ramp analysis StepActivityGroupPriority A.8.3Post Ramp analysis.01 Feed-forward of measured frequency offset for eventual switch to synchro-loop operation RF/OP.02Feed-forward of tune measurementsABP/OP1.03 Analysis of orbit and feed-forwarded of orbit corrections (if GOFB not operational) ABP/OP1.04 Analysis of GOFB correction and feed-forward if operational ABP/OP2.05Beta beatingABP/OP

LHC ramp commissioning36 9/5/2007 Stage A.8.4 – Beam at Intermediate Energy StepActivityGroupPriority A.8.4Beam at Intermediate Energy.01Follow decay of tune, chromaticity and orbitOP/ABP1.02 Measure tune, coupling, orbit – only correct if really required OP/ABP1.03Check opticsOP/ABP1.04Monitor beta beatingOP/ABP.05Beam dump commissioningAB/BT1 Check energy tracking calibration (MKD, MSD, MKB) Orbit/aperture Extraction trajectory Instrumentation Kicker timings, retriggering Post mortem and XPOC

LHC ramp commissioning37 9/5/2007 Stages A.8.5 – A.8.7 A.8.5 Iterate: Dump at progressively higher energies: proposal: 7 steps from 450 GeV to 7 TeV Repeat previous stages at each benchmark energy The full procedure will have to be repeated for beam 2 A.8.6 Commission Collimators in the ramp (Group Coll) Procedure should have essentially been commissioned without beam Watch closed orbit at collimators and related beam losses No cleaning issue for pilot.. Primary needs to be defined 10 sigma TCDQ at 450 GeV, primary closer – could leave for first attempts based on findings during 450 GeV optimization A.8.7 Commission Feedback using PLL (Group BI) If at first you don’t succeed

LHC ramp commissioning38 9/5/2007 Exit Conditions Reasonable transmission of pilot through snap-back (first minute of the ramp) Single pilot at 7 TeV – ramp transmission good enough to get pilot intensity up Beam dumps commissioned up to 7 TeV Machine Protection good for these intensities to 7 TeV At the end of this phase: - we can proceed with top energy checks with single beam

What have we got?

LHC ramp commissioning40 9/5/2007 Settings Generation Optics & Twiss import Ramp & squeeze – all circuits Fully integration of LHC power converters Ramp and squeeze tests performed.  Driven by proto-sequencer Collimators  Inc. parameter space – Twiss parameters as functions RF  Incoming BLMs  Just started wrestling with the threshold tables

LHC ramp commissioning41 9/5/2007 Collimators Stefano Redaelli

LHC ramp commissioning42 9/5/2007 Ramping – IR8

LHC ramp commissioning43 9/5/2007 FiDeL Marek

LHC ramp commissioning44 9/5/2007 Timing Delphine Jacquet

LHC ramp commissioning45 9/5/2007 Sequencer Requirements specification  Mike, Reyes & Fermilab First prototype in place  Tasks, sub-sequences, sequences, external conditions defined on database Demo Vito Baggiolini Roman Gorbonosov Reyes Alemany Greg Kruk Mike Lamont

LHC ramp commissioning46 9/5/2007 Upcoming tests Ramp and squeeze tests during HWC  Ongoing Ramp tests in SM18  Hit instrumented MBs, MQ  Effects of different pre-cycles etc. etc.  Stephane Sanfilippo et al. Dry magnet sector test Other systems  Hardware tests during HWC

LHC ramp commissioning47 9/5/2007 Conclusions Principles and mechanics understood Procedures for initial commissioning pretty well established Implementation of tools in progress Tests planned