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LHC Commissioning with Beam
Following consoldidation, cool-down and testing of the whole machine at cold, the latest schedule sees the re-start of beam commissioning in November 2009. This will be followed by a physics run through the winter until autumn 2010 starting at an initial beam energy of 3.5 TeV.
3.5 TeV will not be possible before Christmas. Given around 3 weeks of commissioning with beam before the end of the year, we hope to provide collisions at 450 GeV and perform initial commissioning of the ramp to 1.1 TeV.
Stages
- Stage A: Initial commissioning with a single bunch moving towards 43 bunches on 43 bunches (moving
to 156 on 156) with moderate intensities. First collisions un-squeezed;
followed by partial squeeze.
- Stage B: Move to 50 ns. bunch spacing with
the aim of moving to intensities around 3 - 4 1010 particles
per bunch
- Stage C : Move to 25 ns. with
the aim of moving to intensities around 3 - 4 1010 particles
per bunch. Would need to be followed by long shutdown for installation
of phase 2 collimation and additional beam dump dilutors.
- Stage D: Nominal 25 ns running
pushing towards design intensity and full squeeze.
Stage A - phases & progress from 2008 - to be continued in 2009
|
Phase |
Schedule/Progress
Notes |
Ring
factor |
Total Time [days]
both rings |
Comments |
A1 |
|
|
2 |
4 |
Time includes injection tests |
A2 |
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2 |
2 |
Beam one still to do |
A3 |
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2 |
4 |
In progress for beam 2 |
A4 |
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2 |
4 |
Priority 1 measurements only |
A6 |
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|
1 |
1 |
Low intensity |
A7 |
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1 |
1 |
Performance Bring CMS (and other experiments') solenoids on before - measure and correct coupling |
A8 |
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2 |
4 |
Single and then two beams. Testing, systems preparation will be required before first serious ramps (~ 2 days) |
A9 |
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2 |
1 |
Single beam initially, performed following successful ramp |
A12 |
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A10 |
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|
1 |
1 |
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Physics un-squeezed |
|
1 |
- |
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TOTAL to first collisions |
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22 |
|
A11 |
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|
2 |
6 |
|
A5 |
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|
2 |
6 |
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Set-up physics - partially squeezed. |
|
1 |
2 |
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Potential performance in 2009 |
Evolution of stages
| Stage |
Estimated time |
Comment |
| Stage A: establish first collisions |
2 months |
1 month beam time, 50% machine availability |
| Stage A: pilot physics |
1 month |
crossing angle off, max 156 bunches,
might expect 1031 cm-2s-1 and around 3 pb-1
156x156 at 1e32 will be a very important achievement, but just a milestone on the road toward 1e33 luminosity. No many-month long physics run with 156x156 will be planned, unless unexpected limitations are found during commissioning. |
| Stage B: 75 ns - commissioning |
2 weeks |
Interleaved with physics |
| Stage B: 75 ns - physics |
1 month |
Gradual increase in intensity, squeeze
5 x 10^32 cm-2s-1 |
| Stage C: 25 ns physics |
|
Intensity limited, 10^33 cm-2s-1 would be good |
The 450 GeV Calibration
Run planned for November 2007 which aimed to establish first
beam collisions at a centre of mass energy of 0.9 TeV has been put on ice. However, collisions at 450 GeV are planned as we go for 5 TeV in 2009 and the requisite commissioning described above is still valid.
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