LHC@home

The SixTrack Studies consist of many Cases and one or more Studies are run in a Workspace, and sometimes one Study across several workspaces.
A Case is a Work Unit.

The namimg convention (which I described once before but can't find it!) is a follows.

For example the work unit:
wlxscan0_w0cbb__17__s__64.31_59.32__10.5_11__6__34.5_1_sixvf_boinc23918
11111111 22222 33 4 55555555555 6666666 7 8888 999999999999900000 where "_" is the field separator has the following fields as shown.
1. Workspace - A Linux disk directory containing studies (data and results) 2. Study - A set of Cases for one LHC configuration 3. Seed - 60 configuration variations with different magnet errors 4. Runtype - s for Simul long-term tracking (rather than various short studies) 5. Tunes - The x/y tunes 6. Amplitude Range (in Sigma) The range of initial amplitudes 7. Turns exponent e.g. 6 implying 10**6 or one million turns 8. Angle in Phase Space - initial angle 9. Redundant historical information 0. A sequence number unique to the Study.

We are currently studying plans for the High Luminosity LHC HL-LHC.
We are particularly comcerned about beam-beam effects, assumimg other basic options are resolved such as new magnets, crab cavities, etc etc bean-beam effects become significant after a largish number of turns and require at least one million turns (field exponent 6).
This is not too many turns given that the protons are circulating at almost the speed of light, 27km per turn. However it is not clear that the model will be valid for a larger number of turns given the gradual accumulation of floating-point errors. I have some ideas for investigating this issue where I would run a series of one million turn jobs, each depending on the prvious, but this awaits discussion along with the deadline scheduling problems etc.

At present I, in person, am running various studies as part of an intensity scan where the bunch size i.e. the beam-charge, is varied between studies. The initial amplitudes vary from 0-12, with the lower amplitudes being more stable. (Remember our run time estimates assume all particles survive for the maximum specified turns; this will not always be the case especially at higher amplitudes.)

Hope all this helps you to understand what is going on. Eric.

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