Search found 153 matches

by jmc2000
Thu Jul 28, 2016 9:17 pm
Forum: The Accelerator
Topic: Which page holds the correct luminosity results?
Replies: 1
Views: 5627

Which page holds the correct luminosity results?

There's a difference between the luminosity results for ATLAS and CMS recorded on the main coordination page: [/url]https://acc-stats.web.cern.ch/acc-stats/#lhc/[url] And on the CMS ATLAS sites: [url]https://twiki.cern.ch/twiki/bin/view/CMSPublic/LumiPublicResults[url] [url]https://twiki.cern.ch/twi...
by jmc2000
Sun Jul 24, 2016 7:47 pm
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

The BCMS scheme now reliably delivers 120% design luminosity. Also a noticeable improvement in initial beam life time from 5 to 7 hours, giving an incredible 100\fb over just 2.5 hours. Fingers crossed they may even take it to 130%, but the current problem with cryogenics might be a sign of this be...
by jmc2000
Sun Jul 24, 2016 7:11 pm
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

https://lpc.web.cern.ch/lumiplots_2016_pp.htm Is this what you mean? There is also the statistics page which is linked on the portal. Something more like this: https://op-webtools.web.cern.ch/vistar/vistars.php?usr=LHC3 But a luminosity plot for a particular fill rather than over the last 24 hours....
by jmc2000
Sun Jul 24, 2016 12:57 am
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

The luminosity lifetime might go down a bit, but for a given time in stable beams the luminosity should always be higher, so no disadvantages (higher pileup in the experiments, but that's what you get if you want more luminosity for a given number of bunch crossings). Just challenging for the preac...
by jmc2000
Thu Jul 21, 2016 12:02 am
Forum: The Accelerator
Topic: 2016 Machine Development
Replies: 1
Views: 5483

2016 Machine Development

Is there any information on the type of machine development that is planned for 2016, how it's hoped to improve operation of the LHC?

JMc
by jmc2000
Mon Jul 18, 2016 1:58 am
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

What's going on when there is a sudden increase in luminosity during stable beams, as shown here with Atlas at t=2:50 https://www.flickr.com/photos/48562472@ ... res/W4K8nQ

JMc
by jmc2000
Sat Jul 09, 2016 3:18 pm
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

https://lpc.web.cern.ch/lpc-minutes/2016-06-27.htm This seems like they are not planning on fixing the SPS beam dump system this year. There's an interesting paper on BCMS mentioned in the link which is now being used for fills as we speak to increase the luminosity further: http://emetral.web.cern...
by jmc2000
Thu Jul 07, 2016 6:27 pm
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

They plan to reduce the emittance a bit, which could increase the luminosity further even without a fix of the SPS issue. What are the disadvantages to reducing the emittance? I remember in 2012 that the beam half life was severely reduced from 20 hours to around 8 hours as the luminosity was incre...
by jmc2000
Thu Jul 07, 2016 4:48 pm
Forum: The Accelerator
Topic: 2016 operation
Replies: 52
Views: 35903

Re: 2016 operation

Both experiments reached 10/fb today. Compared to the plan they pushed from 2 weeks behind end of may to 3 weeks in front the projection.http://lhc-commissioning.web.cern.ch/lhc-commissioning/images/2016/lumi-proj-16-27June.png What can we expect for the year and run 2? Optimistic would be somethin...
by jmc2000
Tue Jun 28, 2016 3:48 pm
Forum: The Accelerator
Topic: What are the current records for LHC fills?
Replies: 45
Views: 35020

Re: What are the current records for LHC fills?

~35 hours luminosity lifetime (approximated from last fill) and 4 hours turnaround time would suggest an ideal fill length of just ~16 hours, for 0.65 times the maximal luminosity as average over the whole cycle. With 7 hours of turnaround time ~20 hours of fill time are optimal (57%), and we need ...
by jmc2000
Mon Jun 27, 2016 4:50 pm
Forum: The Accelerator
Topic: What are the current records for LHC fills?
Replies: 45
Views: 35020

Re: What are the current records for LHC fills?

New lumi record, Atlas 1.08 e34, design target reached. Even the average between ATLAS and CMS was slightly (~1%) above 1E34. They changed the SPS injection a bit, instead of one train with 72 bunches they injected two trains with 48 bunches each, that reduced the heat load on the LHC dipole magnet...
by jmc2000
Wed Jun 15, 2016 11:17 pm
Forum: The Accelerator
Topic: What are the current records for LHC fills?
Replies: 45
Views: 35020

Re: What are the current records for LHC fills?

Reading the article, I just wonder which data will be used for the summer conferences, when will be the deadline? With 3 >400/pb runs in a row, I guess at the end of the week they will far above 5/fb. They will run than 5 other weeks without longer stops. At the actual great pace (I guess some peop...
by jmc2000
Wed Jun 15, 2016 11:00 pm
Forum: The Accelerator
Topic: CMS and ATLAS luminosity: are they jealous?
Replies: 6
Views: 8526

Re: CMS and ATLAS luminosity: are they jealous?

You probably noticed that CMS always seems to get a little less luminosity than ATLAS. In the latest fills, I noticed CMS is always a bit earlier (one or two minutes) with taking data so that during the first few minutes or so, their integrated luminosity is higher than ATLAS. Of course, with ATLAS...
by jmc2000
Sat Jun 11, 2016 11:00 pm
Forum: The Accelerator
Topic: How can the intensity be increased?
Replies: 3
Views: 2947

How can the intensity be increased?

Fill 5013 is another record, yet at constant number of bunches. How are they increasing the intensity, and where can I see the corresponding parameter?

Cheers,

JMc
by jmc2000
Sat Jun 04, 2016 1:17 am
Forum: The Accelerator
Topic: How stringent is the ~100fb for 2016-2018?
Replies: 7
Views: 4308

Re: How stringent is the ~100fb for 2016-2018?

Currently at 2048b, the LHC is accumulating ~1.5fb/week for 30% stable beams which is great news, considering the lost two weeks over bad luck. If they can get to 2800 bunches, that should mean ~2fb/week bringing 25fb/year on target! At the moment they appear to be limited to 72 bunches per injecti...