Lhc 2012
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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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Lhc 2012

LHC- 2012

Mike Lamont

Acknowledgements: Steve Myers, Freddy Bordry, Roderik Bruce


2012 schedule v1 0 q1

2012 schedule V1.0 Q1

with reservations

  • 2 days machine checkout without beam

  • 3 weeks re-commissioning with beam

LHC - 2012


2012 schedule v1 0 q2

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


2012 schedule v1 0 q3

2012 schedule V1.0 Q3

ICHEP

  • Production running one imagines

LHC - 2012


2012 schedule v1 0 q4

2012 schedule V1.0 Q4

  • Atlas ZDC installation (5 days minimum) during last technical stop

LHC - 2012


Injector schedule q3

Injector schedule Q3

LHC - 2012


2012 breakdown

2012 - breakdown

~150 days

LHC - 2012


Lhc 2012

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


Lhc 2012

LHC - 2012


Bunch spacing

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


Bunch spacing1

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


Tight collimator settings

Tight collimator settings

Roderik Bruce

LHC - 2012


Lhc 2012

N.B.

Roderik Bruce

Not totally given yet.

LHC - 2012


Pile up

Pile-up

Luminosity per crossing

Inelastic cross section (~72 mbat 3.5 TeV)

average number of visible interactions per bunch crossing

LHC future running


50 ns intermediate settings

50 ns: intermediate settings

Essentially as is

LHC - 2012


50 ns tight settings

50 ns: tight settings

LHC - 2012


25 ns tight settings

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


Lhc 2012

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


For discussion

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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