A path to the total integrated luminosity quoted at Chamonix 2009 while keeping the total intensity to a reasonable level. Necessarily approximate. Preliminary.
Step | Comment | Turn |
Max number bunches |
Protons/Bunch |
% nom. intensity |
Min beta* |
Peak Luminosity |
Integrated Luminosity |
events/X |
1 |
Beam commissioning | First collisions |
|||||||
2 |
Pilot physics, partial squeeze, gentle increase in bunch intensity, avaialbility low | Long |
43 |
3 x 1010 |
4 m |
8.6 x 1029 |
100 - 200 nb-1 |
||
3 |
5 |
43 |
5 x 1010 |
4 m |
2.4 x 1030 |
~ 1 pb-1 |
|||
4 |
5 |
156 |
5 x 1010 |
2.5 |
2 m |
1.7 x 1031 |
~9 pb-1 |
||
5a |
No crossing angle - could at this stage push intensity see 5b | 5 |
156 |
7 x 1010 |
3.4 |
2 m |
3.4 x 1031 |
~18 pb-1 |
0.8 |
7 |
|
5 |
156 |
7 x 1010 |
3.4 |
2 m |
4.9 x 1031 |
~26 pb-1 |
|
8 |
50 ns - nominal crossing angle - aperture restricts squeezing further - note limited complement of bunches. | 5 |
144 |
7 x 1010 |
3.1 |
2 m |
4.4 x 1031 |
~23 pb-1 |
|
9 |
50 ns | 5 |
288 |
7 x 1010 |
6.2 |
2 m |
8.8 x 1031 |
~46 pb-1 |
|
10 |
50 ns* | 5 |
432 |
7 x 1010 |
9.4 |
2 m |
1.3 x 1032 |
~69 pb-1 |
|
(11) |
50 ns* | 5 |
432 |
9 x 1010 |
11.5* |
2 m |
2.1 x 1032 |
~110 pb-1 |
|
Assuming:
* Working with these intensities implies impeccable performance of the machine protection system, and a fully commissioned collimation system capable of highly efficient beam cleaning,. This is going to take time and must not be rushed.
Massi Ferro-Luzzi has made some similar estimates (see for example http://indico.cern.ch/conferenceDisplay.py?confId=57607 and here) in which he is slightly more optimistic regarding beta* and bunch intensity in the 156 bunch phase. Here we err on the cautious side (1 metre will not necessarily be straightforward, there might be machine protection, injection and ramping issues with higher bunch currents, and there is the issue of pile-up in the experiments (1e11 at 1 metre at 5 TeV buys approx. 7 inelastic per crossing)).
For beam losses, it would be reasonable to take around 10% of the first year figures quoted in "Estimates of Annual Protons Doses in the LHC" where 25 ns running and a peak luminosity of 1033 cm-2s-1 is assumed.
Mike Lamont August 2009