2011 Events Discussion

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PhilG
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Re: 2011 Events Discussion

Post by PhilG » Mon May 16, 2011 11:17 am

Physics runs are back after the technical stop.

They are now running with 228 bunches and will step up through 480 and 768 bunches to get back to previous luminosities. After two more good fills with 768 bunches they can move up to 912 bunches, but that will require a new injection setup for 108 bunches at a time. There will be three more steps to get to maximum luminosity at 1056, 1200 and finally 1380 bunches, each of which will require 144 bunch injection.

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Re: 2011 Events Discussion

Post by jmc2000 » Tue May 17, 2011 3:22 pm

PhilG wrote:Physics runs are back after the technical stop.

They are now running with 228 bunches and will step up through 480 and 768 bunches to get back to previous luminosities. After two more good fills with 768 bunches they can move up to 912 bunches, but that will require a new injection setup for 108 bunches at a time. There will be three more steps to get to maximum luminosity at 1056, 1200 and finally 1380 bunches, each of which will require 144 bunch injection.
Do you know if they plan to keep beta at 1.5 meters once they get to the highest luminosity?

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Re: 2011 Events Discussion

Post by sciing » Tue May 17, 2011 8:48 pm

PhilG wrote: but that will require a new injection setup for 108 bunches at a time.
Seems to work, just in this moment 108 bunches in one injection were done.

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Re: 2011 Events Discussion

Post by tomey36 » Sat May 21, 2011 2:11 am

Stable beams with 109b per injection if they can keep this fill for a while they should be ready for 900+ bunches!!

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DCWhitworth
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Re: 2011 Events Discussion

Post by DCWhitworth » Sat May 21, 2011 6:48 pm

tomey36 wrote:Stable beams with 109b per injection if they can keep this fill for a while they should be ready for 900+ bunches!!
Indeed, 912 bunches in now.
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tomey36
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Re: 2011 Events Discussion

Post by tomey36 » Sun May 22, 2011 10:08 pm

The luminosity seems kind of low for 912 bunches, any one know why?

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PhilG
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Re: 2011 Events Discussion

Post by PhilG » Tue May 24, 2011 4:36 am

tomey36 wrote:The luminosity seems kind of low for 912 bunches, any one know why?
Possibly some losses at injection and maybe some emittance blow-up. They are going to adjust one of the injection collimators TCLIB so that might fix it.

Still they have had record peak luminosity of 1100/ub/s and now record total for 24 hours at 38/pb and rising, good going!

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Bornerdogge
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Re: 2011 Events Discussion

Post by Bornerdogge » Tue May 24, 2011 9:54 am

Does anybody know when they're moving for the next step?

There's nothing on the plan and if my memory's right they've already passed the (3 good fills && 20 hours) of stable beams with 912b.

Or do they want to run for a time with 912b to see how things are doing, like they did with 768b...

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DCWhitworth
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Re: 2011 Events Discussion

Post by DCWhitworth » Tue May 24, 2011 9:58 am

Bornerdogge wrote:Does anybody know when they're moving for the next step?

There's nothing on the plan and if my memory's right they've already passed the (3 good fills && 20 hours) of stable beams with 912b.

Or do they want to run for a time with 912b to see how things are doing, like they did with 768b...
Latest CERN Bulletin says they will be moving up to 1380 bunches in the next few weeks.
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Bornerdogge
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Re: 2011 Events Discussion

Post by Bornerdogge » Fri May 27, 2011 9:11 pm

At last stable beams!

Hey, the scale of the luminosity axis on the LHC dashboard reaches from 0 to 1664 s/µb...
I think that's made by purpose (cf. french beer brand) XD

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DCWhitworth
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Re: 2011 Events Discussion

Post by DCWhitworth » Fri May 27, 2011 9:35 pm

Bornerdogge wrote:At last stable beams!

Hey, the scale of the luminosity axis on the LHC dashboard reaches from 0 to 1664 s/µb...
I think that's made by purpose (cf. french beer brand) XD
There's clearly a fan there somewhere. Fill 1664 was also highlighted in one of the reports.
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PhilG
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Re: 2011 Events Discussion

Post by PhilG » Sat May 28, 2011 6:41 pm

New record fill of 31.5/pb and in just 10 hours. They could have done more but cut short to go to the next step.

In an uncharacteristic change of plan they are skipping the 1056 bunch scheme and aiming for 1092 bunches. It is not clear if they will still do the 1200 bunch step or jump straight to a maximum bunch number of around 1380 after that.

Edit: looks like they are doing another run at 912b. Perhaps too late in the day for 1092.

Total luminosity delivered is somewhere around 500/pb already.

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Re: 2011 Events Discussion

Post by pcatom » Sat May 28, 2011 8:28 pm

The 1092 filling scheme uses 108b per injection. It is pretty much the maximum that can be fitted in with 108b injection. The next step after that will be the same number of bunches with 144 bunch injection .... then onward and upward.

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Re: 2011 Events Discussion

Post by PhilG » Sat May 28, 2011 9:08 pm

Thanks @pcatom, that makes sense.

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Re: 2011 Events Discussion

Post by zaim » Sun May 29, 2011 5:19 pm

Just now the LHC surpassed 0.5 fb^-1 integrated luminosity delivered to CMS.
Current fill of 32 pb^-1 plus the 468 ps^-1 stated here https://twiki.cern.ch/twiki/bin/view/CM ... licResults

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