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LHC - 2012

LHC - 2012. Mike Lamont Acknowledgements: Steve Myers, Freddy Bordry , Roderik Bruce. 2012 schedule V1.0 Q1. w ith reservations. 2 days machine checkout without beam 3 weeks re-commissioning with beam. 2012 schedule V1.0 Q2. Virtual constraint .

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LHC - 2012

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  1. LHC- 2012 Mike Lamont Acknowledgements: Steve Myers, Freddy Bordry, Roderik Bruce

  2. 2012 schedule V1.0 Q1 with reservations • 2 days machine checkout without beam • 3 weeks re-commissioning with beam LHC - 2012

  3. 2012 schedule V1.0 Q2 Virtual constraint • Timing of first MD block open to discussion • Timing and length of scrubbing run open to discussion LHC - 2012

  4. 2012 schedule V1.0 Q3 ICHEP • Production running one imagines LHC - 2012

  5. 2012 schedule V1.0 Q4 • Atlas ZDC installation (5 days minimum) during last technical stop LHC - 2012

  6. Injector schedule Q3 LHC - 2012

  7. 2012 - breakdown ~150 days LHC - 2012

  8. Energy - Conclusion Courtesy Freddy Bordry Last Chamonix 2011 :“edge” regarding the decision about 4TeV with 50s energy extraction time constant. Main arguments against 4TeV were: 1) Number of spurious quenches observed over 2010, in particular 2 events involving the large number of dipoles. 2) Very small margin for nQPS (symmetric quench detectors) at 4TeV with 50 s time constant. In case of simultaneous quench of 15 dipoles the nQPS symmetric quench detectors are saturated and blind. No reason to not operate at 4 TeV in 2012 (to be confirmed at next Chamonix workshop) In 2011 the number of spurious quenches was radically reduced. This was achieved mainly thanks to the improvements introduced to QPS after each event encountered last year and snubber capacitors installation. In 2011: • - Better operational procedures with > 100 MJ • - Better knowledge of the RRR (250 ±50) - No quenches during hardware commissioning and only 1 single-magnet spurious quench with beam (firing of Quench heaterprobably due to SEU, but no prove). 8

  9. LHC - 2012

  10. Bunch spacing Performance from injectors Best in 2011: ~1.45 x 1011 ppb, Less than 2 microns from SPS ~2.3 microns into collision LHC - 2012

  11. Bunch spacing • 50 ns • Proven (injector) performance • Less long range encounters, cansqueeze further • Some limited room for increasing bunch intensity (and perhaps reducing emittance blow-up) • Pile-up • 25 ns • Lower bunch current/higher emittances from injectors • Considerably more total current for same performance • UFOs, SEEs, RF, vacuum • ~twice number of long range encounters • Can’t squeeze as far (LRBB/bigger emittances/increased crossing angle) • Extended scrubbing required • Much lower pile-up LHC - 2012

  12. Tight collimator settings Roderik Bruce LHC - 2012

  13. N.B. Roderik Bruce Not totally given yet. LHC - 2012

  14. Pile-up Luminosity per crossing Inelastic cross section (~72 mbat 3.5 TeV) average number of visible interactions per bunch crossing LHC future running

  15. 50 ns: intermediate settings Essentially as is LHC - 2012

  16. 50 ns: tight settings LHC - 2012

  17. 25ns: tight settings Increasing to 12σ BB separation: we lose about 10cm in β* (R. Bruce) Weigh increase in emittance against decrease in bunch intensity LHC - 2012

  18. Assumptions E = 4 TeV: beta* = 0.7 m: 148 days of physics: no intensity limit for 25 ns 50 ns 25 ns Steve Myers LHC - 2012

  19. For discussion • 70 versus 60 cm with tight settings • Beta* in IP8 • Inclined crossing in IP8 • Beta* in IP2 • Sat-main collisions, enhanced satellites or or un-enhanced plus squeeze in IR2 (if so what value) LHC - 2012

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