1. LHC Commissioning Status Gianluigi Arduini CERN – AB Department For… 23/10/20081LHC Commissioning Status - G. Arduini

2. Beam Commissioning Preparation: – Cryogenics – HW Commissioning – Machine Check-Out – Synchronization tests Beam Commissioning Sector 34 Incident and status Outline 23/10/20082LHC Commissioning Status - G. Arduini

3. Christmas and water maintenance shut-down Short in connection cryostats and repairs Open Days Cooling sectors + Cryo tuning + Powering activities UX85 Ph1 works All sectors at nominal temperature Simultaneous Cryo start/maintain First beams around LHC Cryogenics S. Claudet 23/10/20083LHC Commissioning Status - G. Arduini

4. 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 10 th September Almost 2000 circuits tested (each with several test steps) HW Commissioning 23/10/20084LHC Commissioning Status - G. Arduini

5. 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 Machine Check-Out 23/10/20085LHC Commissioning Status - G. Arduini COLLIMATORS

6. First Synchronization Test (8-10 Aug.) 23/10/20086LHC 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: ~4×10 9 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) F. Zimmermann S. Redaelli R. Jones 23/10/20087LHC Commissioning Status - G. Arduini

8. Second Synchronization Test (22-24 Aug.) 23/10/20088LHC 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 23/10/20089LHC Commissioning Status - G. Arduini

10. Discovered and corrected: – Polarity convention errors in Pts. 7 and 4 Third Synchronization Test (5-7 Sep.) 23/10/200810LHC Commissioning Status - G. Arduini B. Goddard

11. September 10 LHC commissioning with beam (10 Sep.) 23/10/200811LHC Commissioning Status - G. Arduini

12. Beam 1 threaded around the machine in 1h Trajectory steering gave 2 or 3 turns Beam 1 Kicker ON Injected beam After 1 turn Kicker OFF 23/10/200812LHC Commissioning Status - G. Arduini

13. Beam 2 threaded around the machine in 1h30 Trajectory steering gave 2 or 3 turns Beam 2 23/10/200813LHC Commissioning Status - G. Arduini R. Bailey, J. Wenninger

14. Orbit corrections Q and Q’ trims gave a few hundred turns by the evening Beam 2 23/10/200814LHC Commissioning Status - G. Arduini

15. RF capture on 11/9 evening Beam 2 TIME WITHIN A TURN [ns] TURNS RF OFFRF ON – wrong phaseRF ON – wrong frequencyRF ON – correct injection phase and frequency: beam captured ! E. Ciapala 23/10/200815LHC Commissioning Status - G. Arduini

16. Beam 2 on 12/9 early morning Beam lifetime of few hours ! 23/10/200816LHC Commissioning Status - G. Arduini

17. Beam Instrumentation 23/10/200817LHC Commissioning Status - G. Arduini All beam instrumentation available on DAY 1

18. Optics analysis tools IR6 IR3 F. Zimmermann K. Fuchsberger R. Tomas I. Agapov 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 23/10/200818LHC Commissioning Status - G. Arduini

19. 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. Machine Start-up Summary 23/10/200819LHC Commissioning Status - G. Arduini

20. 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 Incident in LHC sector 34 (19 Sep) 23/10/200820LHC Commissioning Status - G. Arduini

21. 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 Investigations and Diagnostics 23/10/200821LHC Commissioning Status - G. Arduini

22. 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 Preliminary recommendations 23/10/200822LHC Commissioning Status - G. Arduini