Beam Instrumentation Overview Status for initial commissioning & recent results with BBQ & PLL LHC Machine Advisory Committee 7 th December 2006 Rhodri Jones (CERN – AB/BI)

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Overview What’s required & when Status of BI Systems  Orbit & trajectory measurement  Beam loss measurement  Synchrotron light monitor  Other Systems Recent Results with the BBQ & PLL system  US-LARP Collaboration with BNL & FNAL  Tune, chromaticity & coupling measurements RHIC and SPS results

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Instrumentation – the essentials First turn  Screens, BPMs, fast BCT, BLMs Circulating beams at 450 GeV  BPMs, DC BCT & lifetime, BLMs  Tune & chromaticity  Emittance: wire scanners. Snapback and Ramp  Continuous Tune, Coupling & Chromaticity  Orbit (+ feedback)  BLMs to beam interlock controller etc.  Continuous emittance monitoring: synchrotron light

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) 100 Warm, Button Electrode BPMs Buttons Recuperated from LEP LHC BPM System - General Layout 24 Directional Couplers 52 Enlarged Button & 8 Trigger BPMs Interaction Regions 912 Button Electrode BPMs (24mm) for the Main Arcs & Dispersion Suppressors Total of 1186 BPMs for the LHC and its Transfer Lines 36 Warm BPMs - 34mm Button Electrodes 54 Special BPMs for Tune & Chromaticity, Transverse Damper & RF, Beam Dump

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Delivery Status of BPM Hardware BPM components all delivered  3750 standard and 500 enlarged buttons  3724 pre-formed arc cables and 592 special configurations  430 coupler feedthroughs  1000 cryostat feedthroughs Warm BPM & stripline electrode production  Manufactured by BINP initial delivery non conform delivery schedule was a worry in 2005 MAC presentation  Extensive follow-up during 2006 by both AB/BI & AT/VAC Delivery of all components now complete (few non-conformities pending) Special BPMs for Tune Measurement & Dump  Design only completed early 2006  Production by TS/MME and CECOM (Italy)  Delivery was “just in time” for LSS4 installation  Awaiting final delivery of dump line BPMs

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Installed BPMs Total of ~660 cold BPMs installed (~330 SSS) Warm BPMs in LSS 8, LSS 1L and LSS 4 all installed Enlarged button BPMs installed in Point 4 Warm directional coupler installed in Point 8

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Status of BPM Acquisition System Series Production of all components underway  Wide Band Time Normaliser (40MHz position measurement) 480 of 2400 front-end cards received 200 of 2400 digitiser cards received all delivery to be completed by March 2007  Digital Acquisition Board (DAB64x - TRIUMF) Standard for BPM, BLM, Fast BCT, Wire Scanners, Luminosity & Q measurement 220 of 1200 BPM type modules received 185 of 500 BLM type modules received all delivery to be completed by March 2007 Reception Testing  2 automated test benches constructed and manned by external personnel  Used for adjustment and calibration of all Wide Band Time Normaliser Cards  Beam simulator allows position & intensity linearity measurement for all cards  All data stored in MTF & linked to serial number chip located on each card

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Status of BPM Acquisition System Installation  Tunnel installation and hardware commissioning has started in 8L 23 of 34 positions in place (92 channels) Infrastructure  Nearly all fibre-optic, coaxial cable and WorldFIP control links in place LSS7 and LSS3 will be equipped with radiation hard fibres Produced by Fujikura (Japan) – first batch in production Tests by Fraunhofer Institute and mixed field test in the SPS has shown them to be an order of magnitude less susceptible than the standard CERN mono-mode fibre BPM/BLM limit of 6dB

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) The LHC Beam Loss System Role of the BLM system: 1.Protect the LHC from damage 2.Dump the beam to avoid magnet quenches 3.Diagnostic tool to improve the performance of the LHC Name Type NumberArea of useMaskable Time resolution BLMQI Ionisation Chamber~3100 Arcsyes1 turn BLMCI BLMCS Ionisation Chamber SEM ~150 Collimation regions no1 turn BLMEI BLMES Ionisation Chamber SEM ~400 ~150 Critical aperture limits or positions no1 turn BLM__ ACEM (phase II)~10 Primary collimators yes bunch-by- bunch

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Beam Loss Detectors Design criteria: Signal speed and reliability Dynamic range (> 10 9 ) limited by leakage current through insulator ceramics (lower) and saturation due to space charge (upper) Secondary Emission Monitor (SEM):  Length 10 cm  P < 10-7 bar  ~ times smaller gain Ionization chamber:  N 2 gas filling at 100 mbar over-pressure  Length 50 cm  Sensitive volume 1.5 l  Ion collection time 85  s Both monitors:  Parallel electrodes (Al, SEM: Ti) separated by 0.5 cm  Low pass filter at the HV input  Voltage 1.5 kV

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) BLM production at IHEP After readjustment of the production schedule in March a constant rate has now been achieved SEM production to start after ionisation chamber production is complete Sector 7 – 8 fully equipped with ionisation chambers

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) BLM integration and installations Integration of monitors in layout of ARC, IR 1 and IR 8 finished Integration will continue for the remaining points following installation schedule IHEP installation team (1 team leader and 4 technician):  test of monitors with radiation source, shrinking of insulation tube, mounting of monitors, cable tray/cable fixation and electrical test of system  in case of accelerated interconnection closure an increase in the team is possible ARC quadrupole with 3 monitors on either site Beam I Beam II Triplet quadrupole magnets IR 8

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) First use of LHC chamber design at CERN 270cm Fluka simulation; P. Sala et al 3.20 m CNGS Secondary beam width measurements Interleaved CERN produced and IHEP produced LHC type Ionisation Chambers  Give very similar response

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) BLM Acquisition Electronics Threshold Comparator: Losses integrated and compared to threshold table (12 time intervals and 32 energy ranges). Implemented on BDI DAB64x

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) BLM test measurements at the SPS dump Remaining beam dumped at end of slow extraction FULL beam intensity on dump Remnant decay after full intensity dump Injection & acceleration losses Validation of complete BLM readout electronics chain  200MHz fixed target beam  Use of SPS ionisation chamber located near the internal SPS dump

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Measuring Beam Size Beam Profile Measurements in the LHC  Workhorses Synchrotron light monitor Wire scanners for cross calibration  For injection & matching OTR screens  For ions Rest Gas Ionisation Monitor (BGI) –Also used as back-up for SR monitor

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Synchrotron Light Monitors (BSRx) BSRT light source: 5T Superconducting undulators Latest news: both SC undulators in place, see next CERN bulletin!  Congratulations to the AT/MAS team

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Synchrotron Light Monitors 36 Tons of shielding and support structure in place Dielectric coated silicon extraction mirror  first of its type - replaces traditional beryllium mirror  over 98% reflectivity in visible/IR achieved by a small Scottish company (Helia) using similar techniques to coating silicon diodes

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) LHC BSRT fast camera tested in the SPS, Nov 2006  Image is single turn beam intensity seen by OTR screen  Scale in pixels  optical magnification gives 20x20mm frame. Able to capture and store raw images at the SPS revolution frequency  Will have to optimise the trade off between transfer rate, data treatment & dead time between measurements Synchrotron Light Monitor (BSRT)

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Abort Gap Monitor (BSRA) System based on gated photomultiplier Tested in the SPS with synchrotron light source on fixed target beam  Observation of injection kicker gap while beam is debunched before extraction. Worked extremely well Gain of photomultiplier is not as high as advertised  Requires 15x more light For LHC a longer integration time is possible (every ms for SPS) BUT BSRA will require more light than anticipated at expense of BSRT

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Wire scanner tanks and mechanisms in place DCCT and FBCT awaiting final installation Rest gas ionisation chambers and compensation magnets in place Dump line BTV tanks awaiting final installation Other Systems Nearly all specialised BI equipment located in LSS4  After LSS8 this was the second full LSS to be installed  A big effort made by BI technicians and engineers during 2006 together with TS/MME and AT/VAC to get everything ready in time We just about made it !!

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Tune, Chromaticity & Coupling Clear three step approach: 1) Day 1 with kicked beams and classical motion analysis Q kicker for both planes & both beams located in Pt 4 Chirp excitation using the transverse damper 2) Day N with PLL tune tracking (US-LARP) Recent experience gives us the hope that N is small! 3) Day N+ with PLL measurement & Feedback (US-LARP) Tune, chromaticity & coupling Requirements for stable PLL operational:  lowering the excitation level to an insignificant level  coping with coupling  coping with chromaticity  achieving compatibility with resistive transverse damping Collaboration with BNL & FNAL via US-LARP

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Measuring with Little or No Excitation – The Base Band Q Measurement (BBQ) System Direct Diode Detection (3D)

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Continuous FFT and PLL Implemented in FPGA Uses Standard DAB64x Module CORDIC: polar  rectangular avoids large LUTs uses simple operations saves FPGA space !

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Setting-up the 25ns Beam in the SPS Low intensity beam Residual oscillation without additional excitation clearly visible

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) PLL tracking in the SPS Nominal Beam - PLL OFF  tune hardly visible Nominal Beam – PLL ON  tracking achieved throughout cycle Resonantly Extracted 25ns Beam in the SPS Real-time Tune Display

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) PLL Measurement on SPS Fixed Target Cycle Tracks tune change of ~0.1 units per second

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) PLL Measurement during Collimator MD Resolution of achieved with 1s integration

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Beam Transfer Functions in the SPS When things go wrong – thought to be due to a coupled bunch instability!  Stable phase shifts – PLL can no longer lock  Multiple peaks appear in Beam Transfer Function Standard Beam Transfer Function

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Measurement of Coupling using a PLL Tune Tracker Frequency Amplitude FFT of Horizontal Acquisition Plane Start with decoupled machine Fully coupled machine:  = |C - | Only horizontal tune shows up in horizontal FFT Gradually increase couplingVertical mode shows up & frequencies shift Hor Ver  Set Tunes H V By looking at contribution of vertical PLL in horizontal plane & vice-versa the degree of coupling can be calculated

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Tune & Coupling Feedback at RHIC (2006)

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Continuous Chromaticity Measurements The focus of the development for 2007  RHIC to attempt chromaticity feedback  SPS used to qualify new techniques for the LHC RF modulation with PLL Tune Tracking  Standard technique used at RHIC & Tevatron  may not be compatible with nominal collimator settings in LHC Other techniques under test  Fast RF phase modulation – tests at FNAL & SPS (RF power an issue for LHC)  Additional side exciters within PLL to measure tune width (phase slope)  Continuous head-tail measurement with PLL excitation Constant phase shift proportional to chromaticity Requires sensitive measurement of head & tail oscillations  diode detection!!

LHC Machine Advisory Committee December Rhodri Jones (CERN - AB/BI) Summary Both large distributed systems (BPM/BLM) currently on schedule  Production of ionisation chambers at Protvino is progressing smoothly One of the major worries last year Support for AB/BI from TS  Significant support for Design and from the main CERN workshops  Regular meetings have allowed problems to be solved quickly and priorities to be juggled to fit with installation requirements Most Vacuum Hardware now in place in Point 4  Attention can turn to completing and testing the final electronics Tune, Coupling and Chromaticity Measurement  Combination of BBQ and PLL is proving very powerful  RHIC demonstration of combined tune and coupling feedback is very encouraging  All efforts in 2007 will be focused on adding chromaticity feedback to the list Outlook for LHC commissioning  All necessary instrumentation for the start-up foreseen to be in place  Functionality will evolve through the commissioning phases