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Message 15433 - Posted: 12 Nov 2006, 14:56:11 UTC

Hi,

I know that I could read this somewhere on these pages, but I'd prefer that the explanations I need come out of discussions.

I hope that you won't mind me putting this that way ... :)

So, what exactly are we doing by crunching these data we are sent ?

Please, English not being my mother tongue, I would be very grateful if you used plain English, thank you ! :)

Anne

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Message 15435 - Posted: 12 Nov 2006, 16:21:12 UTC - in response to Message 15433.  

Hi,

I know that I could read this somewhere on these pages, but I'd prefer that the explanations I need come out of discussions.

I hope that you won't mind me putting this that way ... :)

So, what exactly are we doing by crunching these data we are sent ?

Please, English not being my mother tongue, I would be very grateful if you used plain English, thank you ! :)


Hi again Anne,

The program is a simultation of a charged particle going round the LHC accelerator. It is quite a detailed simulation, with every magnet modelled separately. The engineers can also alter the simulated fiedl round a magnet if after they make measurements they discover it is not made ecactly as planned.

The program takes the particle round 100,000 or 1000,000 round the loop, to see if the beam stays stable or if the particle hits the wall.

Each aet of work coming out now is designed to test a slightly different problem, or a slighlty different way of working. The hope is that by the time the real thing is built, the engineers will know as much as they can about how to tune the accelerator up for real use.

In the past, when a new accelerator is built, there has been a delay after the building is finished and before the particle physicists can start work. During this delay the beam physicists are testing the machine, and finding out exactly how much current each magnet needs to keep the beam stable at that particle energy, or this particle energy, etc.

The work we are doing now will help to make that delay as short as possible.

Earlier in the project the work we were doing (using the same program) was about the basic settings of each magnet - now we are helping with the finer tuning. Without us, the LHC builders would have done the basic settings on their own grid of copmuters (at CERN, in the UK, and in ohter EU countries). This would have taken a lot longer, and it is unlikely there would have been time or funding for the fine tuning.

The reason there is so little work is that almost all the questions the engineers and beam physicists had have been answered - it is only when someone thinks of a new question (or when a magnet is found to have a field that is not as expected) that we get some new work to answer that new question.

Having ~6000 computers on standby to take on new work on a few hours notice is a very valuable resource for this stage of the build. We are not needed often, but when we are needed then we are *really* useful.

River~~
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Message 15436 - Posted: 12 Nov 2006, 16:45:45 UTC

In future, we will be doing at least two things.

1. Occasionally there will still be a need for runs like we have at present. Perhaps a magnet has been replaced, or perhaps the particle physicists ask the beam physicists, please can you make the LHC do something we did not plan for.

The most famous event like that in the history pf particle physics happened when people though 3GeV was a powerful accelerator, back in the late 70's. There were four or five accelerators around which went up to 3GeV because it sounds like a very nice round number. The universe was unkind. There is some really interesting physics that you need 3.06GeV to see (creation of the J/psi particle). So there were a lot of interesting discussion at the time between beam physicists and particle physicists to see if they vould get that extra 2% out of the machine.

2. In response to requests from participants, many of whom do not like being attached to a project that has no work for several months on end, we will in due course also be running other work, called Garfield, which is used to model how charged particles move inside a detector.

After the super energetic particles have reacted in the LHC, they create other particles and to find out what happened the particle physicists need to know what particles were created, where they came out, and how much enrgy did they have. One way these questions can be answered is to let the created particle go through a gas, releasing electrons from the atoms in the gas on the way. These electrons drift in an electric filed towards a signal wire, where they are detected, thus giving an indirect measurement of postion, charge, and speed of the created particle.

To know what the signal means, you need to know how these electrons "drift" in the gas under the exact field inside the detector. (These drifts are quite fast by human standards, but slow by particle physics standards, maybe 1/100 or 1/1000 the speed of light.) And that is what Garfield will be doing -- helping the experimentalists design better detectors, and helping them understand better the ones they already have.

But still, the most important work this project does will be the one or two times a year that our current program is run again due to some new problem. The detector is useless without a beam to make the collision happen.

R~~
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Message 15511 - Posted: 18 Nov 2006, 12:25:07 UTC

Hi,
interesting question - good awnser.
Could you place this on a more obviouse place at the homepage? I guess many users have the same question. And two sentences well hidden under "technical callenges" are not enough information to cure curiuos spirits.

I wondered myself several times about why nothing seems to happen at the project and didn't even find really helpful information here in the discussion board (By the way - the FAQ-link doesn't work).
The newsboard is outdated and one can easily get the impression the last thing that happened in that project was a computer crash.
Contrary to other users who wrote in the forum I don't mind having a project on standby, waiting for work most of the time - it's not the only boinc project. But I need to know if the project still works and why I am on standby.

Think about this: A computer grid consisting of 6000 computer needs technical maintenance. But this grid also consists of 6000 computer owners who are willing to donate their CPU time to you (which is and at the end of the day real money if you take into account that energy consumption of newer CPU depends on the workload). They also need some "maintenance" if you don't want your grid to break into pieces sooner or later.
Just tell us whenever new work was sent out in the news board and maybe if new work is on the way. Just to let us know we are still needed.

Sören Ebser
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Message 15513 - Posted: 18 Nov 2006, 13:08:55 UTC - in response to Message 15511.  
Last modified: 18 Nov 2006, 13:15:57 UTC

Hi,
interesting question - good awnser.
Could you place this on a more obviouse place at the homepage? I guess many users have the same question. And two sentences well hidden under "technical callenges" are not enough information to cure curiuos spirits.

I wondered myself several times about why nothing seems to happen at the project and didn't even find really helpful information here in the discussion board (By the way - the FAQ-link doesn't work).
The newsboard is outdated and one can easily get the impression the last thing that happened in that project was a computer crash.
Contrary to other users who wrote in the forum I don't mind having a project on standby, waiting for work most of the time - it's not the only boinc project. But I need to know if the project still works and why I am on standby.

Think about this: A computer grid consisting of 6000 computer needs technical maintenance. But this grid also consists of 6000 computer owners who are willing to donate their CPU time to you (which is and at the end of the day real money if you take into account that energy consumption of newer CPU depends on the workload). They also need some "maintenance" if you don't want your grid to break into pieces sooner or later.
Just tell us whenever new work was sent out in the news board and maybe if new work is on the way. Just to let us know we are still needed.

Sören Ebser

Some news or updates from the admin. on how is going this project would be a good idea.


Do you want to get banned for 31 years, your account and credits deleted at a Boinc project ? Predictor@home is your best choice.
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Message 15541 - Posted: 18 Nov 2006, 19:54:27 UTC
Last modified: 18 Nov 2006, 19:57:21 UTC

I should have made it clear for newcomers, when I said "we" in my previous post, I meant we participants...

I am not a project admin, not a project programmer, not a webmaster, not even a forum moderator. If I were any of those things it would say so under my name on the left of every post. So while I agree with the suggestions that are being made, I am no more able to do anything about them that you are. I'd be really pleased & proud if someone from the project did link my words from the homepage :)

At present, this project has caretaker admins who work for CERN, but who do not have time to do much more than firefighting. More info about that here. As I say over there, nothing wrong with making suggestions, but we can't expect them all to be implemeted quickly once the staff are properly in post. It will all take time.

R~~
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Message 15542 - Posted: 18 Nov 2006, 19:55:43 UTC

hey @nne, cool change of spelling of your name :)
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Message boards : LHC@home Science : What exactly are we doing ?


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