Current Events Discussion

The place to discuss the LHC. Commissioning, operation, issues, events ....
tomey36
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Re: Current Events Discussion

Post by tomey36 » Sat May 08, 2010 10:12 pm

collisions again! hopefull they fixed what ever has been holding them back the past couple weeks :)

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jmayes
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Re: Current Events Discussion

Post by jmayes » Sun May 09, 2010 1:27 am

So now we can consider all green on P1 w/red "Setup Beam" as the perfect norm. Kinda weird to have a red item the norm, just good to know. Good find DCWhitworth!

DCWhitworth wrote:Found an interesting fact in a CERN article recently about what the 'safe beam' tag actually does.

When the machine is operating in 'setup beam' mode they can mask various feedbacks from detectors, so if they have a slight issue with the sensitivity of something or it is slightly glitchy they can work around it by masking it so the feedback, which might cause a dump, is ignored. Obviously this is not something they want to do a lot of but is useful for working around small issues that might otherwise slow them up.

When they have unsafe beams so that the 'setup beam' flag goes out then all masks are automatically removed so everything has to be right or the MPS will kick in automatically.

tomey36
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Re: Current Events Discussion

Post by tomey36 » Sun May 09, 2010 7:43 am

so i was watching the colissions and the beam just disiapeard. no dump or anything, yet the display still shows stable beams. so what is going on?

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Bornerdogge
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Re: Current Events Discussion

Post by Bornerdogge » Sun May 09, 2010 8:30 am

just some bug with the displays...

good run last night! nearly 1e8 events stored by cms, with a collision rate of 4khz, and going on!

ferar
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Re: Current Events Discussion

Post by ferar » Mon May 10, 2010 2:48 am

Hi, where can you see the collision's rate and the number of collisions?
Thanks very much.

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Bornerdogge
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Re: Current Events Discussion

Post by Bornerdogge » Tue May 11, 2010 8:24 pm

just right there: http://cmsdoc.cern.ch/cmscc/cmstv/cmstv ... frames=yes

but nothing's expected till tomorrow evening I think...

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mrgumby
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Re: Current Events Discussion

Post by mrgumby » Wed May 12, 2010 8:53 am

There is just sooooooo much stuff on that page. I understand about 20% of it...

oxodoes
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Re: Current Events Discussion

Post by oxodoes » Wed May 12, 2010 9:42 am

This one: http://lhc-webcast.web.cern.ch/lhc-webcast/ is way easier to understand.
It was launched for the 3.5 TeV event and is still active...

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Bornerdogge
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Re: Current Events Discussion

Post by Bornerdogge » Wed May 12, 2010 8:45 pm

Yeah but there's not much on it...

It'd be nice if the guys from cms wrote some kind of explanation page about cms tv... Maybe I could ask at my university (they worked on the tracker...)

Kasuha
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Re: Current Events Discussion

Post by Kasuha » Wed May 12, 2010 9:04 pm

It contains what you asked for - collision rates and graphs. Just click on appropriate experiment...

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Bornerdogge
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Re: Current Events Discussion

Post by Bornerdogge » Fri May 14, 2010 10:40 am

new step today: 4 bunches of 2e10 protons! They're squeezing right now; I'm curious to see the luminosity increase...

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PhilG
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Re: Current Events Discussion

Post by PhilG » Fri May 14, 2010 12:04 pm

The choice of buckets means that there will be no more collisions per turn than the previous 3 bunch configuration. However, the higher intensity per bunch could increase luminoisity by something like 2 to 3 times over previous runs.

6 bunch runs are planned for the next few days along with other tests at higher intensity per bunch. Hopfully this means more rapid progress ahead.

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Bornerdogge
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Re: Current Events Discussion

Post by Bornerdogge » Fri May 14, 2010 1:13 pm

However, I see a 3,5x10^28 luminosity right now in CMS... That's 3 times more than the previous record, isn't it??

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jmayes
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Re: Current Events Discussion

Post by jmayes » Fri May 14, 2010 1:19 pm

Another milestone! (Kilometer-stone).

Great work Cern!
:clap: :dance: :clap: :dance:

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CharmQuark
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Re: Current Events Discussion

Post by CharmQuark » Fri May 14, 2010 7:09 pm

woot :thumbup:
Anyone who doesn't take truth seriously in small matters cannot be trusted with large ones either by Albert Einstein.

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