1. Overview of performance and limitations of current scanners and technical choices for a new wirescanner CERN wire-scanner development review 18.04.2013 J.Emery for the BWS team

2. Presentation focus Operational scanners Architecture, performance & Limitations Calibrations System failures tables Scanner under design Technical choices Failure modes Design guidelines Emittances across the injectors and LHC (A. Guerrero) In ‘BI MD Studies on June 29th 2011‘ (CERN-ATS-Note-2011-069 MD), F. Roncarolo & D. Belohrad, E. Bravin, A. Boccardi, E. Calvo, B. Dehning, M. Favier, J. Emery, A. Guerrero, T. Lefevre, J-J. Gras, A. Jeff, L. Soby, A. Rabiller, M. Sapinski, R. Steinhagen, BE-BI CERN wire-scanner development review 18.04.2013 J.Emery LMC summary on injector emittance measurements (G. Arduini)

3. Operational scanners team A. Guerrero, B. Dehning, D. Gerard, R. Sautier, M. Hamani, C. Vuitton, W. Andreazza, R. Veness, J. Adam, J.J. Gras, L. Jensen, F. Roncarolo, E. Piselli, J. Emery, BE-ABP group, BE- OP group, V. Kain, M. Kuhn, G. Sterbini, and more… => 31 scanners installed across the CERN site BOOSTER (8) PS (5) SPS (10) LHC (8) Position [mm] Intensity ≡ Number of particules [] 2x Sigma CERN wire-scanner development review 18.04.2013 J.Emery

4. Vacuum tube Wire Scanner Working Principle LHC beam transversal profile Particules beam Control and acquisition Electronics (VME) Forks position mouvement Scintillator Optical filters Photomultiplier (PM) amplifier PM current Particles generated by the wire – beam interactions CERN wire-scanner development review 18.04.2013 J.Emery

5. Operational system layout for all scanner types since 2009 (2012 for SPS) SURFACE INSTALLATION UNDERGROUND (radioactive) Up to 270m ! BST master MTG master CCC & databases Motion control board CPURIO3CPURIO3 CPURIO3CPURIO3 HVCTRLHVCTRL HVCTRLHVCTRL DAB+IBMSDAB+IBMS DAB+IBMSDAB+IBMS TIMINGTIMING TIMINGTIMING BOBRBOBR BOBRBOBR Power amplifier behind the VME Step motor control Multiplexer s Power Position CERN wire-scanner development review 18.04.2013 J.Emery

6. Operational Scanners overview MachineScanner type installedSecondary particles detector (Scintillator Filters Photomultiplier) Fast acquisition (bunch profiling) Scanner per tank Maximum speed (m/s) Wire sizeAperture (mm) Accuracy/ *beam size repeatability [µm] 2012 run, Number of cycles per scanner PSBRotating fast 81 for 2 scannersx220 12x7  m (C) 112≈1003k – 11k PSRotating fast 52 per scannerx115-20 12x7  m (C) 112≈1002k – 11k SPSRotating (short and Long) 61 for 2 scannersYes26 30  m (C) 17040*4.5k - 9.5k SPSLinear41 for 2 scannersyes21 30  m (C) 5615*0.2k LHCLinear81 for 4 scannersyes41 30  m (C) 6015*4k PSB scanners LHC scanners beam 1 CERN wire-scanner development review 18.04.2013 J.Emery SPS scanners 416

7. Calibration using movement geometry & Performance validation by beam local bumps LHC Linear scannersSPS rotational Beam 92.5mm 108.8⁰ 208.1⁰ 71.2⁰ Projection plane Home In

8. Calibration using laser beam (PSB, PS) Laser Photodiode Motorised linear stages PS Scanner PS tank Laser & Photodiode are moving with linear stages at every possible measurements position, wire-scans at every mm. A similar calibration bench will be developed for the future scanner to:  To validate the performances of the prototype (accuracy, repeatability)  Calibrate every produced scanners Forks position laser photodiode Calibration table Time when the wire hide the laser laser photodiode CERN wire-scanner development review 18.04.2013 J.Emery

9. Operational system failures for all scanner types since 2009 Mechanical parts ComponentmachineOccurrencesFailure sourceMitigationSystem under design WireSPS4 (2012)Beam induced RF heatingModification of the tank, use of ferrites to limit RF mode (already successfully used in the past) Beam pipe inside the tank, thin gap for the wire to pass WireSPS2 (2012)Wire fixation non- conformity More intensive functional verification before vacuum closure Avoid need of performing wire exchange in the tunnel by exchange of complete scanner WireLHC2 (2012)Electronics/Software failures left the wires in ‘IN’ position Investigation during LS1 Trigger function moved from the software to the Hardware/Firmware WireSPS2 (2011) VME bus transaction errors Caused position control failure leading to a mechanical stress. Hardware adapter to new CPU. Decoupling of the actuator control and the VME bus. Wire (damage) LHC, SPS? 1 confirmedInteraction with too intense beams Study of the aging process, review of scanning beam intensity limits. Increase of the nominal speed with better accuracy than the linear scanner BellowsPS2Vacuum leak after 5k cyclesDesign change in 2011 to 100k cycles Avoid bellows by use magnetic force through vacuum barel at the motor gap BellowsLHC1Vacuum leak after 10k cycles Design change forseen in 2013 to 50k CERN wire-scanner development review 18.04.2013 J.Emery

10. Operational system failures for all scanner types since 2009 Multiplexers Step motor control Power amplifier behind the VME Cabling / Electronic VME cards / crate Affected Component machineOccurrencesFailure sourceMitigationSystem under design Linear Power Amplifier All & lab16 (2 in 2012)Electrical glitch to unprotected outputs, Use of componant (PA50) on the limit of its specification Replacement of supplies Use of switch mode power supplies and filters MultiplexersLHC, PS3Mechanical relay failure in the tunnelReplacement of relays Use dedicated cables and control electronics Step motor controler PSB, LHC2Electronic board agingEnd of life electronics to be upgraded Avoid filter wheel by the use of high dynamic detector Motion control PS1VME bus access switch off VMEReplacement of the card Motion control in the power supply disconected from the VME CPU RIO 3SPS1Unexpected rebootReplacement of the card PA50A => For the future scanner, ongoing study to use switch mode power conversion. See last talk. BWS Power amplifier Transformer DC power storage units (Capacitors) ±32V DC power storage units (Capacitors) ±32V motor AOP 150m CERN wire-scanner development review 18.04.2013 J.Emery

11. Operational system failures for all scanner types since 2009 Secondary particules detector Component failure machineFailuresRemarquesSystem under design Filter wheelPS, SPS2Mecanical switch failure / Wheel blockedAvoid filter wheel by the use of high dynamic range detector PhotomultiplierPSB1Procedure of functional test changedFunctional test with radioactive source? PhotomultiplierAllMultiple unusable measures None Linearity due to parasitic signal to the photomultiplier and ‘saturation’ effect Detailed study of charge displacement from the detector to the readout. The detector is directly in the secondary shower. Scintillator Optical filters Photomultiplier amplifier 231 CERN wire-scanner development review 18.04.2013 J.Emery

12. Parasitic signal to the photomultiplier Contribution of this effect to the final signal is > 1% of the light produced by the scintillator. CPS In 2010 PMT shielded with few cm of lead fixed this issue. SPS 2012: Under investigation, we got some result by having shielded the PMT for high intensity beams. LHC 2012: Identified to be between 1-3% Scintillator Optical filters Photomultiplier amplifier Particles generated by the wire – beam interactions CERN wire-scanner development review 18.04.2013 J.Emery

13. ‘Saturation’ of the photomultiplier We ask too much signal in a short time PMT local charges are completely used Output signal of PMT must be lowered by reducing incoming light Sensitivity of the acquisition system must be adapted CERN wire-scanner development review 18.04.2013 J.Emery

14. Operational system failures for all scanner types since 2009 Settings / RT Software / Databases IssuesmachineFailuresRemarques Acquisition settingsAllmultipleUnavailability of the measures, remote manual action needed Scanner settingsAll1Wrong wire speed led to emergency stop and potential damages RT SoftwareLHC2Due to system structure, influence on the safety of the instrument. Complexe to track. Databases relatedLHC, PSB31) Long data array was not saved and no errors were generated. 2) Large number of empty entry 3) No data logged for the PSB CERN wire-scanner development review 18.04.2013 J.Emery

15. Wire scanner under design Contributors to this R&D project: N. Chritin, J. De Freitas, B. Dehning, J. Emery, J. Herranz, J. Koopman, M. Koujili, D. Ramos, S. Samuelsson, M. Sapinski, J. Sirvent, C. Pereira, R. Veness and more to come! Fork Vacuum barrel Shaft Motor Break Resolver Res stator Break stator Optical disk Vacuum Focuser Optical feedthrough Electrical feedthrough Wire Bearings Optical feedthrough Motor stator Vacuum Focuser Bearings Beam pipe Optic Fiber Vacuum chamber Motor Stator Wire Fork Beam Vacuum pipe Optic Disc in vacuum Resolver Bearings Shaft Rotor in vacuum CERN wire-scanner development review 18.04.2013 J.Emery

16. Design goals 1)Performance - Scanning speed with better position accuracy - Secondary shower acquisition improvement 2)Maintainability & Availability - Decrease needed preventive maintenance (bellows) - One piece, self contained scanner easily exchangeable - Easy to use and high accuracy calibration bench - Simpler control layout 3)Usability - Easier setting point for the acquisition system (high dynamic range) - Limitation of parameters CERN wire-scanner development review 18.04.2013 J.Emery

17. Design guidelines 1)Minimisation of complexity - As less as possible electrical connections - Avoid multiplexing channel - Settings and parameters (control and acquisition) 2)Separate critical and non-critical functions - Instrument safety in the low level hardware - High level software configure, analyse and record the measurements 3)Early failure detection - Constant hardware Condition Monitoring (CM) - Programmed maintenance CERN wire-scanner development review 18.04.2013 J.Emery

18. Use of Condition Monitoring (CM) From the machine industryto be applied in the BWS 1.Mechanical vibrations - Tank vibration (proposal) - Shaft using eccentricity detection with the 2 optical encoder (See Jose’s talk) - Fork vibration using constrain gauge (See Juan’s talk) - Wire vibration using resistance variation 2.Temperature - External tank temperature (LHC BGI failure due to over temperature bake out) - Internal temperature using wire resistance variation (under study) 3.Electrical connections - Constant detection of Motor, resolver, optical encoder, wire 4.Power consumption - Motor (today, done ones per year) - Of the electronics by part 5.Long term recording of information for analysis (missing today due to none selective data reduction) National Instrument (NI) talk on machine Condition Monitoring (CM) CERN wire-scanner development review 18.04.2013 J.Emery

19. Failures scenarios Beam – wire and movement Failurescenariosconsequences today Possible causeExisting Safety procedure Today implementation future scannersFuture implementation (proposal) Wire melting And High beam losses Beam Intensity too high compared to nominal speed Exchange scanner and/or Exchange scanner New beam injection after the trigger of the scan. Before scan: Inhibit movement RT softwareX Nominal speed handle highest intensity Firmware through hardware link. Scanner speed setting too low compared to beam intensity Exchange scanner and/or Exchange scanner Tests, new beam injection after the trigger of the scan. xxBefore scan: Inhibit movement During scan? Firmware through hardware link. Return home? Fork movement don’t follow the expected profile Speed too lowWire melting And/or High beam losses Position Feedback stability lost. High mechanical friction, motor fatigue, power supply issue During scan: ‘Return home’. Risk of breaking wire + Forks Analog electronics Different cases implantable: -Finish movement if safe. -Stop and return home Firmware monitoring of feedback and safety action. Speed too highScanner can’t stop and hit the tank. Wire + fork Position Feedback stability lost. High mechanical friction, motor fatigue, power supply issue During scan: ‘Return home’. Risk of breaking wire + Forks Analog electronics If scanner can’t slow down: Only wire broken Firmware monitoring of feedback and safety action. Vibrations of tank/Shaft/fork /wire Values above limitsNo detectionAging, position feedback/motor issue xxChange of position profile / emergency stop Firmware CERN wire-scanner development review 18.04.2013 J.Emery

20. Failures scenarios Actuator and VME crate Failuremodesconsequences today system Existing Safety procedure Safety procedure during scan Today implementation future scannersFuture implementation (proposal) Angular position measurement unavailable Between movement Cabling/control failure Scanner unavailable maintenance needed Detection of potentiometer unavailable Inhibit scan -Firmware and Software Scanner maintenance needed Firmware During movement Cabling/control failure Movement don’t stop Wire + fork breakage x--Switch to optical sensor to finish movement. then maintenance needed Firmware Motor unpowered Between movement Cabling/electronics failure Undetected (DC motor will not move in case of a movement requested) x--Detection (3-phase brushless) Electronics Firmware During movement Cabling/electronics failure Scanner slow down due to frictions. Probably Wire + fork breakage High beam loss x--If only one phase failure, movement could finish (under investigation) Electronics Firmware Remote action on VME crate, RT software Between movement Crate turned off RT Software failure Scanner unavailable Remote action Xxx Firmware could stop any future actions. During movement Crate turned off RT Software failure Powering of motor failure If position ‘IN’, scanner don’t come back. Wire and/or Fork breakages xXDuring LS1 Implementation of RT software supervision The actuator complete the movement to a safe position Firmware competition of measure cycle and idle. CERN wire-scanner development review 18.04.2013 J.Emery

21. Summary 30 operational scanners in the PSB, PS, SPS, LHC Current performance & Limitations Today’s calibrations procedures Reported failures and mitigation Design goals and guidelines for new scanner Failure scenarios driving the design Questions? CERN wire-scanner development review 18.04.2013 J.Emery