large hadron collider update

F

Fred

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Well if you are into physics or happen to work in the field, this is *the* big experiment of the 2000s, yes perhaps even more important than WMAP. It will define the direction that physics goes for the next 30 years.

Currently in construction at CERN, it obviously has every single one of us all jittery and giddy.

Anyway theres been an update.
http://mgt-lhc-machine-advisory-com...achine-advisory-committee/lhcmac19/Agenda.htm

The cliffs are

1) slighly lower than expected initial luminosity while people calibrate and test fallbacks.
2) Some delays on the first runs

A nice overview here
http://cosmicvariance.com/2006/06/20/the-lhc-dashboard/
 
I presume the first thing they're going to test for is the Higgs boson once in full operation?
 
that second link article is terrible in some ways:


Hopefully it aborts as planned, otherwise….much energy is dumped somewhere it should not be! At full throttle (7 TeV beams), the energy stored in the LHC beam is 700 MegaJoules, or 10 TeraWatts. How big is that? Well, 10 TeraWatts is about half of the world’s total energy output. No wonder the accelerator folks are a bit jittery! They don’t want to dump 10 TeraWatts of beam just anywhere…
Click to expand...

writing article about a big ring where bunch'a HalfLife-like shit happens is nice, but understanding the difference between power and energy would be even more nice.
 
Umm I think Joanne knows the difference =) She works at SLAC and is using particle physicist lingo. And they are correct the 10 terrawatts comes from a beam burst of 100 femtoseconds or something like that.

About the higgs..

Once in full operation its anyone's guess as to which bandwidth they will focus on first if any. Most people believe they will look for a higgs scalar somewhere around 95-120 GeV to see if it matches Fermilabs controversial event and then decide (privately) whether its worth to continue running that particular experiment or to move onto different regimes.

Hadron colliders are pretty 'dirty', you look at hadron cascade showers and things like that, so basically you have to run a ton of calibration scans and background checks and things of that nature.

Anyway, the most promising channel to see a higgs decay at low to moderate energy is H --> ZZ -->l+ l- l+ l- (l is some lepton) with the LHC high lumonisity run mode. There are some intermediate zones where other events start to dominate, but they tend to have high backgrounds.

Its a phenomonological nightmare to sort through the data and to decide what to look at, b/c the theory space is absolutely huge and maps many to one to the possible signal space.
 
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Yea the SSC would have been huge. Which is why everyone is clamoring about the ILC. We need lepton events to get a 'clean' read, even though the center of mass lumonisity tends to be smaller than these hadron colliders.

The nightmare scenario is the LHC gives us a ton of data, but we won't have sufficient constraints to be able to sort out which model statistically is favored. Hence the ILC and another 20 years of waiting.
 
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