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LHC Status & Progress

LHC Status & Progress. P. Collier 33 rd Session of the Joint CERN-Russia Committee, Saturday, 13 th November 2010. Recap – Status in May. February 27 th 2010 First beams injected and circulating after the winter technical stop March 30 th 2010

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LHC Status & Progress

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  1. LHC Status & Progress P. Collier 33rd Session of the Joint CERN-Russia Committee,Saturday, 13th November 2010

  2. Recap – Status in May • February 27th 2010 • First beams injected and circulating after the winter technical stop • March 30th 2010 • First Physics run at 3.5TeV/beam, 2 bunches of 2x10+10 • Luminosity ~1x10+27 cm-2 s-1 • April 2010 • Successfully injected nominal bunch intensity, 1.15x10+11 ppb • Established Collisions with Squeezed b*, reduced to 2m. • May 2010 • Physics with up to 13 bunches per beam • Bunch intensity increased Slightly to 2.4x10+10 ppb • End May, time taken out of Physics operation to establish nominal bunch intensity in physics. LHC - highest energy collider

  3. Progress at the end of May 2010

  4. 2010 Goal (Chamonix) to Deliver 1fb-1 by the end of 2011 • Required reaching L ~10+32 by the end of 2010(= 35MJ Stored beam energy) • And running at, or above this level for most of 2011 • Plan Drawn up for the progressive increase in bunch intensity and number of bunches based on machine protection considerations. • The plan was modified with experience gained: • Go straight to nominal bunch intensity (>1x10+11 ppb) • Fairly rapidly move to bunch trains using a larger spacing of 150ns (new beam from the injectors) • Push the number of bunches slowly up towards ~400

  5. The Result – LHC Proton Run 2010 5 decades of improvement in just 7 months! At each change in the operating conditions of the machine a concentrated period of Machine development was used to set-up the new scheme, establish the collimation and machine protection and qualify it.

  6. 2 Weeks in August • Remarkable machine availability: impressive performance of cryogenics, QPS, converters, RF, instrumentation, collimators, injectors… • Very effective use of available time 25b 48b 50b 6

  7. Increasing Stored Energy in the Beam Already handling beams around 30 MJ However, No Beam induced quenches during 2010 Operation!

  8. Stored Energy in the LHC 8

  9. 2010 Proton Run End May End May Excellent Performance of the LHC and its Injectors. Stepping up of the number of bunches went smoothly and safely – good control over the machine parameters Reproducibility of the machine was good – eg <100mm in collimator positioning wrt. orbit over several weeks.

  10. Good Surprises … • Can Routinely inject accelerate and collide beams with a normalized emittance much smaller than nominal. • (LHC Design en = 3.75mm ~2.2 routinely achieved at the start of physics. • Single beam lifetime very high >>100h – excellent vacuum • Lifetime in collisions still very good, at around 25hours • in spite of the large beam-beam tune shift (approaching 0.02) • Luminosity lifetime around 10-15 hours coming mainly from emittance growth. • Measurements of the aperture in the inner triplets show that we have more space than we thought • Better alignment of of components, well controlled beta-beating (<20%), excellent orbit control and stability • More margin – either to squeeze further, or increase the crossing angle. … all opens new possibilities for the future …

  11. Less Good Surprises … but not completely unexpected • Passing to 50ns bunch spacing at the end of the proton run strong electron cloud phenomena were observed. • Vacuum pressure rises in warm regions where there is no NEG coating • Evidence for additional heat load on the beam screens – e-cloud in the arcs • Instabilities on trailing bunches of a 50ns train. 9x12 1x12+4x24 Valves Close Vacuum pressure

  12. Impact on the beam • 12 bunches + 4 trains of 24 bunches spaced by 1.85 ms • Build-up of the electron cloud over more than one train leading to instabilities and emittance blow-up along the trains • Consistent with preliminary results of simulations for a Secondary electron yield (SEY) ~2.5 (c.f. 1.7 expected)

  13. Electron Cloud Studies • Systematic measurements of pressure rise in the straight sections and heat load in the arcs for different filling patterns to provide input for simulations and guide predictions: • Dependence on bunch intensity • Dependence on bunch train length • Dependence on bunch train spacing • Comparison between pressure rise before and after scrubbing run with 12+36 bunches at 450 GeV (-> reduction by ~1 decade in ~3 days) 12+36 12+24 12+12 1.1x1011 p/bunch 0.8x1011 p/bunch 0.6x1011 p/bunch Important input for discussions concerning the strategy for 2011.

  14. Changeover to Ions Thursday 4th November – Switched from Proton to 208Pb82+ Circulating beam quickly established: identical magnetic machine. First ever Synchrotron light from Nuclei First 24 hours Beam1 : injection and capture Beam2: injection and capture First ramp, collimation at high energy and squeeze Optics Checks, Beam Instrumentation & Collimation

  15. Collimation As expected the system acts as a single stage collimation system. Therefore losses leak out into the cold parts of the machine at the few percent level. Spikes in the arcs are coming from specific ion species – under study. System behaves reasonably well and the settings from proton operation were still valid! Only the collimators around the experiments needed re-optimization.

  16. Heavy Ion Run Monday 9th November: First Stable Beams 2x2 bunches ions. Tuesday 10th November: Physics with 17x17 bunches of ions. Thursday 12th November: Physics with 69x69 bunches Luminosity performance ~2x10+23 cm-2 s-1 per bunch crossing

  17. Heavy Ion Run 2010 Presently still in the period of increasing the performance. 4 physics fills so far: 2x2 bunches 5x5 bunches (4 crossings) 17x17 bunches (16 crossings) 69x69 bunches (66 crossings)

  18. Heavy Ion Run 2010 • Just over 3 weeks running time left for ions. • Will move to 121x121 scheme very soon then just produce collisions. • Should be able to accumulate around 300-400mb-1 per day. • 8mb-1 in total (target >3mb-1 ) • Machine issues dominated by IBS and significant emittance growth during stable physics (especially beam 2) • Beam quality from the injectors is excellent. Routinely injecting 50% more than the design intensity per bunch. Emittance is small – but grows through the LHC cycle. …an Excellent start to a new way of operating LHC

  19. Conclusions • It has been an exciting year for everyone associated with the LHC! • The speed with which the machine has been commissioned to a respectable performance is quite remarkable. • Huge effort from all the teams, both at CERN and our from collaborators. • Performance to date exceeded our goals for 2010 and our expectations in many areas: • We can reach the 1fb-1 goal next year with the performance we have already achieved. • We can handle higher than nominal bunch intensities with lower than nominal emittances • Good news for the future! • The strategy for operation in 2011 will be decided once all the data collected on the electron cloud have been digested. • The first 206Pb82+ has started well • Rapid switch from p+ to Pb82+ • Already exceeding the nominal bunch intensity (by 1.5x) • Rapid increase in the number of bunches per beam is in progress • Looks good for meeting out 2010 target.

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