1 / 19

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

onella
Download Presentation

LHC Status & Progress

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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.

More Related