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LHC Commissioning Status

LHC Commissioning Status. Gianluigi Arduini CERN – AB Department For…. Outline. Beam Commissioning Preparation: Cryogenics HW Commissioning Machine Check-Out Synchronization tests Beam Commissioning Sector 34 Incident and status. First beams around LHC.

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LHC Commissioning Status

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  1. LHC Commissioning Status Gianluigi Arduini CERN – AB Department For… LHC Commissioning Status - G. Arduini

  2. Outline • Beam Commissioning Preparation: • Cryogenics • HW Commissioning • Machine Check-Out • Synchronization tests • Beam Commissioning • Sector 34 Incident and status LHC Commissioning Status - G. Arduini

  3. First beams around LHC Simultaneous Cryo start/maintain All sectors at nominal temperature Cryogenics Short in connection cryostats and repairs UX85 Ph1 works Open Days Christmas and water maintenance shut-down Cooling sectors + Cryo tuning + Powering activities S. Claudet LHC Commissioning Status - G. Arduini

  4. HW Commissioning • Started in the middle of 2007 • 7 out of 8 Sectors commissioned for 5 TeV operation and 1 sector (Sector 34) commissioned to ~1 TeV before the Beam Commissioning start on 10th September • Almost 2000 circuits tested (each with several test steps) LHC Commissioning Status - G. Arduini

  5. Machine Check-Out • Verification of the remote control functionalities from the Control Room for the various systems as they became available from HW Commissioning • Magnetic circuits • Injection & extraction elements • Beam instrumentation • Synchronous powering of circuits together with other systems (e.g. collimators, RF) • Validation of the beam Interlocks • Vacuum valves • Power converters • Beam Loss Monitors • Experiments COLLIMATORS LHC Commissioning Status - G. Arduini

  6. First Synchronization Test (8-10 Aug.) LHC Commissioning Status - G. Arduini

  7. First Synchronization Test (8-10 Aug.) • What did we do: • Trajectory correction • Optics measurements • Physical aperture measurements • Instrumentation setting-up • What did we find: • Quench limit: ~4×109 p (as expected) • BPM sensitivity (excellent) • Aperture restriction in the inj. line • misaligned vacuum port (corrected) • Optics problem IP3 • Polarity convention error of trim quadrupoles (corrected) S. Redaelli F. Zimmermann R. Jones LHC Commissioning Status - G. Arduini

  8. Second Synchronization Test (22-24 Aug.) LHC Commissioning Status - G. Arduini

  9. Second Synchronization Test (22-24 Aug.) • Achieved (Beam 1, Beam 2) • Trajectory correction • Optics measurements • Physical aperture measurement • Aperture in injection region OK • Optics OK after polarity correction • Discovered • Optics problem at the end of the TI8 line (being investigated) R. Calaga V. Kain, J. Wenninger LHC Commissioning Status - G. Arduini

  10. Third Synchronization Test (5-7 Sep.) • Discovered and corrected: • Polarity convention errors in Pts. 7 and 4 B. Goddard LHC Commissioning Status - G. Arduini

  11. LHC commissioning with beam (10 Sep.) September 10 LHC Commissioning Status - G. Arduini

  12. Beam 1 • Beam 1 threaded around the machine in 1h • Trajectory steering gave 2 or 3 turns Kicker ON Injected beam After 1 turn Kicker OFF LHC Commissioning Status - G. Arduini

  13. Beam 2 • Beam 2 threaded around the machine in 1h30 • Trajectory steering gave 2 or 3 turns R. Bailey, J. Wenninger LHC Commissioning Status - G. Arduini

  14. Beam 2 • Orbit corrections • Q and Q’ trims gave a few hundred turns by the evening LHC Commissioning Status - G. Arduini

  15. Beam 2 • RF capture on 11/9 evening RF ON – wrong frequency RF OFF RF ON – wrong phase RF ON – correct injection phase and frequency: beam captured ! TURNS E. Ciapala TIME WITHIN A TURN [ns] LHC Commissioning Status - G. Arduini

  16. Beam 2 on 12/9 early morning Beam lifetime of few hours ! LHC Commissioning Status - G. Arduini

  17. Beam Instrumentation All beam instrumentation available on DAY 1 LHC Commissioning Status - G. Arduini

  18. Optics analysis tools K. Fuchsberger Very useful for: • Functionality checks of the instrumentation and of the magnetic circuits (e.g. polarities) • Characterization of the quality of the machine optics • Removal of aperture bottle necks F. Zimmermann IR3 IR6 R. Tomas I. Agapov LHC Commissioning Status - G. Arduini

  19. Machine Start-up Summary • Very Fast Start-up has been made possible by: • Meticulous preparation • Dry runs • Synchronization tests • Accurate Magnetic model • Powerful Control System and Analysis Tools • Powerful instrumentation working on Day 1 • Allowed: • early look at several machine parameters (optics, aperture, ….) • Partial but systematic check of orbit system and magnetic circuits • Beam Commissioning stopped on Friday 12 Sep. • Transformer failure (12 MVA) in Pt 8 resulting in a cryogenics stop • Speedy replacement of the transformer with similar one (from CMS) • Hardware commissioning and Accesses in the shadow of the recovery from electrical and cryogenics problems • Ready for beam again on 18 Sep. • Injected and worked with beam 1 up to the dump (pt. 6) until 19 Sep. LHC Commissioning Status - G. Arduini

  20. Incident in LHC sector 34 (19 Sep) • During the HW commissioning (without beam) of the last Main Bend Circuit of the ring at high current for operation at 5 TeV • Resistive zone developed in the electrical dipole bus bar between a dipole (C24) and a quadrupole (Q24): • the power converter tripped and the energy discharge switch opened inserting dump resistors in the circuit as expected • Within 1 s: electrical arc development  He enclosure damaged  He into the insulation vacuum in subsector 23-25 • After 3 (4) s: beam vacuum degrades in aperture 2 (1) respectively and then insulation vacuum deteriorates in the neighbouring subsectors (19-21 and 27-29) • Spring-loaded relief disks on the vacuum enclosure opened as expected for p > 1.1 atm  He release in the tunnel • In spite of that the pressure in the vacuum enclosures of subsector 23-25 increased above 1.5 atm  Large forces on the vacuum barriers leading to the displacement of some of the SSS cryostats and to the displacement of some dipoles from their cold internal supports inside the un-displaced cryostats LHC Commissioning Status - G. Arduini

  21. Investigations and Diagnostics • Initially priority given to restoring powering and services in the tunnel and to ensure mechanical stability of the displaced magnets. • Opening of the cryostat sleeves in the interconnections between magnets is ongoing: • Confirmed the location of the electrical arc • Revealed contamination by soot-like dust over a limited area in the beam pipe • Revealed damage to the multilayer insulation (MLI) blankets in the cryostats • Magnets to be repaired: • Up to 5 quadrupoles • Up to 24 dipoles • More might have to be removed for cleaning or MLI exchange. In-situ cleaning of the beam vacuum chamber is being considered to minimize this number LHC Commissioning Status - G. Arduini

  22. Preliminary recommendations • Aimed at: • preventing any other any other occurrence of the event • mitigating its consequences • Being considered: • Modification of the quench protection system to generate early warnings and interlocks • Increase in number and capacity of the relief devices on the cryostat vacuum vessels • Reinforcement of the external anchoring of the quadrupole cryostats equipped with vacuum barriers LHC Commissioning Status - G. Arduini

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