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PhilG wrote: They managed a turnround of only 2.5 hours between runs, much better than last year.

Last 2 turnarounds from dump to physics were less than 3 hours. Theoritical limit is around 2 hours. Good Job!!

sciing wrote:

PhilG wrote: They managed a turnround of only 2.5 hours between runs, much better than last year.

Last 2 turnarounds from dump to physics were less than 3 hours. Theoritical limit is around 2 hours. Good Job!!

They're smooth operators

If the turn around time is 2.5 hour look more like 3 hours Physic to Physic. It would appear to a untrained eye that they may be reseting a little early.

RocketManKSC, nice analysis although your extrapolation of the luminosity decay seems pessimistic. It should decay exponentially (perhaps faster at the start) The luminosity half life is about 15 hours.

Theoretically the optimum runtime would be roughly 2 x sqrt(L*T) where L is the lifetime and T is the turnround time. If they could average about 3 hours they should run for about 12 hours at least, so yes they are stopping too soon.

However, they are not yet aiming to run at optimum efficiency. The present objective is to meet the qualifying conditions as quickly as possible to allow them to move to the next increase in bunch numbers. I don't know what the conditions are but they may be required to do three runs with a total of 12 hours in stable beams or something like that.

The condition for the next step in the number of bunches is 3 complete cycles (going into Physics) and around 20 hours of Stable Beams - hence fills of around 7 hours. Fills will be kept longer once they get into running with a stable number of bunches.

pcatom, thanks. I understand that they will increase bunch numbers as 32,64,104,152,200.
Will they go all the way with 8 bunch injections or switch to 24 bunch injection at some point?

If the current smooth running continues they should easily make it to 200 before the next technical stop on 28th March.

The next step will be 136 bunches - hopefully this evening. This will use 24 bunch injection (plus a couple of 8 bunch injections).
After that would be around 200 bunches. However, the plan is now to get the 1.38 TeV run out of the way before the technical stop. Expect a change to running like this around Wednesday.

Thanks for all your comment and input. This forum is a great place for sharing information.
Hope they can keep up the same production rates in the future. If so will make for a great
year of data collection.

Thanks for all your comment and input. This forum is a great place for sharing information.
Hope they can keep up the same production rates in the future. If so will make for a great
year of data collection.

We are hoping for a much higher production rate ... a factor 15 higher luminosity than at present (64 bunches).
What is impressive is the overall efficiency.

They are starting on the 136 bunch fill now. This is an amazing rate of progress.

This is a good summary of what has been going on so far at the LHC and the current plan for the weeks ahead. It also give a nod to LHC protal and Pcatom!

http://blog.vixra.org/2011/03/20/lhc-de ... tes-plans/

New luminosity record of over 2.5x10^32 - peak in 2010 was 2.0x10^32.

Well done guys

Wow, a whole heap of new LHC records have been set this week -

http://lhc-commissioning.web.cern.ch/lh ... 03-11.pptx

Does anybody know the purpose of the current 1.38TeV run?

Bornerdogge wrote:Does anybody know the purpose of the current 1.38TeV run?

It's calibration for the lead ion runs. Basically they learn a lot by comparing how lead ion collisions differ from proton collisions. BUT no one has ever done proton collisions at the same centre of mass energies they they have been doing lead collisions at so their comparisons are based on modelled extrapolations of proton collisions at lower and higher energies. While the models are pretty good they're not going to be 100% right. So these runs are to produce collision data at exactly the right energies for comparison with the lead ion energies. They don't need much data so these runs won't last very long.

Next up 296 proton bunches at 3.5 TeV