There’s been great progress made recently at the LHC, with successful commissioning of “trains” of bunches, allowing significantly higher collision rates. Last night’s fill produced an integrated luminosity of .684 inverse picobarns (or 684 inverse nanobarns), which can be compared to the total integrated luminosity up until this week of about 3.5 inverse picobarn. The highest instantaneous luminosity reached is now at about 1/5 the goal set for this year, with a further increase in number of bunches planned for this weekend. For more details, there’s a message from the CERN DG here.
Update: The latest fill, with 104 bunches, recently started, with an initial luminosity now at 1/3 of the goal for this year.
Update: For more information about latest events at the LHC and upcoming plans, see here. Latest luminosity plots are here, now including highest instantaneous luminosity.
Thanks for this informative post. Could you please clarify how this ‘.684 picobarn’ of integrated luminosity has been estimated? I’m asking because the luminosity decreases since a collision run started. If you could make a rough estimation to get this number, I’d be thankful. Or if you take this number from the official page, I’d be glad to see the links.
Hasti
hasti, instantaneous and integrated luminosity during runs can be monitored on this page: http://op-webtools.web.cern.ch/op-webtools/vistar/vistars.php?usr=LHCLUMINOSITY
You are forgetting the observation of long-range correlations in rapidity observed in p-p collisions
http://arxiv.org/abs/1009.4122
They are bound to challenge quite a few people’s ideas, as these kind of correlations are associated with “collective” phenomena.
Of course, its also an experimental verification of string theory 🙂
hi lun,
I`ve read somewhere that the fragmentation of some ” Unknown Elongated Object” could have led to the correlations seen (an UEO)
🙂 …
But You should not une such s-words here :-)…
Oops, there was an “inverse” missing in original posting, fixed.
lun,
For commentary on the CMS result, see comments of previous posting. The exciting thing about the latest progress at the LHC is the promise they’ll be able to say something new about something other than QCD…
Thanks, I missed those comments.
I have something to add: One important thing a lot of commenters are missing is that these structures were already seen at RHIC, in A-A collisions. They are generically understood as being due to two things:
a) “hotspots” in nuclei creating “strings” (see, string theory 🙂 ) which stretch longitudinally across the event. These create correlations in rapidity
b) Collective flow (the fluid flows “outwards”) which focuses these correlations in angle.
p-p, however, throws a somewhat big wrench in this consensus:
Are hotspots have to be smaller than the proton size (ie, Lambda_{QCD})? Is there flow in proton-proton collisions? (If so, why is it missing in particle spectra?)
Or are we misunderstanding the origin of these structures in heavy ions too?
Honestly, I think this is physics at its best: Pesky experimental data throwing an established theoretical consensus in disarray.
Its a shame in areas of particle physics “other than QCD”, such events are rare to non-existant.
The latest fill mentioned in your update has produced 1.06/pb of data, with initial luminosity of 3.5E31. I think it is worth noting that given these numbers, the LHC is the main factory of top quarks and Higgs bosons by now (as shown here: http://www.science20.com/quantum_diaries_survivor/lhc_surpasses_tevatron_top_and_higgs_factory).
Cheers,
T.
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