2017 will be a shorter operational year because of EYETS but with no ion run, there should be around 150 days of proton physics.
- 150 days of proton physics including intensity ramp-up
- Intensity ramp-up - assume 4 weeks
- Maximum luminosity was previously assumed to be around ~1.7e34 cm-2s-1 from triplet cooling limitations. Recent measurements indicate that this might be pessimistic.
- BCMS confirmed as an option, assume injection restricted to 144 bunch injection
Assumed parameters
| Parameter |
Standard 25 ns |
BCMS 25 ns |
BCMS 25 ns
Pushed
|
Comments |
| Energy [TeV] |
6.5 |
6.5 |
6.5 |
|
| β* (1/2/5/8) [m] |
0.4 / 10 / 0.4 / 3 |
0.4 / 10 / 0.4 / 3 |
0.33/ 10 / 0.33 / 3 |
Either 40 cm as 2016 or further squeeze to 33cm |
| Long-range separation [sigma] - assumed emittance |
10 sigma - 3.5 um |
10 sigma - 2.5 um |
10 sigma - 2.5 um |
|
| Half X-angle (1/2/5/8) [μrad] |
-185 / 120 / 185 / -150 |
-155 / 120 / 155 / -150 |
-170 / 120 / 170 / -150 |
Went to 140 with lower intensities in 2016
|
| Number of colliding bunches (1/5) |
2736 |
2448 |
2448 |
BCMS - 144 bunches/injection from SPS |
| Bunch population |
1.25e11 |
1.25e11 |
1.25e11 |
around 1.3e11 injected for both Standard and BCMS |
| Emittance into Stable Beams [μm] |
3.2 |
2.3 |
2.3 |
Nominal 2.6 for Standard, 1.4 for BCMS at injection |
| Bunch length [ns] - 4 sigma |
1.05 |
1.05 |
1.05 |
As 2016 |
| Peak Luminosity (L0) |
1.4e34 |
1.7e34 |
1.9e34 |
|
Peak mean pile-up
(inel xsection 80 mb) |
37 |
51 |
56 |
Fast decay at start of fill |
| Average mean pile-up |
27 |
33 |
36 |
NB Have to assume average fill length and lumi lifetime. Assume average fill length of 13 hours (June-July 2016 - optimistic)
|
| Average luminosity lifetime (tau) |
21 hours |
15 hours |
14 hours |
Approx. - assuming burn only |
- BCMS is now proven; we should be able to push to the stated number of bunches in 2017 fro both nominal and BCMS; and push bunch intensity a bit (MKI vacuum issue should have been mitigated in EYETS).
- Integrated luminosity estimate: if we take the 2016 figures we get a Hubner factor of ~0.25. Naively appling this to the above numbers and assumng similar availability the 2017 total ranges from 45 to 60 fb-1.
- The LHC delivered ~40 fb-1 in a scheduled 122 days in 2016.
Time in Stable Beams
- Looking at 2016 and taking the time in Stable Beams from the end of April to end July (includes some major stops - weasel etc.), we get a physics efficiency of 47%. let's round up to 50%.
- 150 days with 50% of the time in Stable Beams - 6.5 million seconds
- If the intensity ramp-up is fast and we enjoy similar availability to June-July throughout the year: 150 days with 60% of the time in Stable Beams - 7.8 million seconds
(Jan 2016 estimate for the record: 160 days of proton physics (includes ramp-up). If one is optimistic, one might hope the physics efficiency will improve to 40% which would give ~5.5 million seconds, 45% (would be exceptional) brings 6.2 million seconds.)
Usual caveats very much apply.
Updated November 2016 - Mike Lamont
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