Linear Collider Technology Choice

[Severian]

I thought you might like to know that today a panel of 'wise men' have decided on the technology to be used in the planned high energy e+e- linear collider. They have chosen superconducting technology.

 

From the BBC:

 

http://news.bbc.co.uk/1/hi/sci/tech/3583658.stm

 

And the International Linear Collider site (the press release is on the left):

 

http://www.interactions.org/linearcollider/

[Martin]

Isn't anyone interested in this?

 

come on Severian, it is VERY interesting

just knowing about the International collider project is

itself worthwhile, and now we have the fact that it is DESY technology

and liquid helium temperature

 

I read about this first at Peter Woit's blog called Not Even Wrong

I forget how long ago it was---'bout the same time you posted your item.

And it had quite a bunch other detail about it.

Maybe I should fetch the link, in case some people reading this want to

look at Peter Woit's comment too.

 

http://www.math.columbia.edu/~woit/blog/

 

it was the 20August entry:

http://www.math.columbia.edu/~woit/blog/archives/000071.html

 

thanks for posting the news! I see therv been over 16 readers so far.

 

Your comments on this decision might be the most informed, of us here.

What do you think about it?

 

BTW doesnt LHC get turned on in 2007 so that is much sooner than this

International collider. Do you have any ideas about what might be tested at LHC or what possible results might be? susy yes, susy no

[Severian]

I posted it the morning it came out. The announcement was made on the Monday morning at an ICHEP (International Conference on High Energy Physics) conference in Beijing.

 

Yes, the LHC switches on in 2007, but it probably won't have any physics runs 'til 2008-2009 (it takes a while to calibrate the machine). Its primary goal is to find the Higgs boson. If the Higgs boson is not found by the LHC then it almost certainly isn't there and the theory is wrong. The good thing about the LHC is that it is guaranteed to see something. Without the Higgs the model breaks down because it predicts scattering of W bosons with a probability >1 (which is clearly nonsense). So even if the Higgs isn't there, something else must be in oder to tame the W-scattering cross-sections.

 

Its secondary role is to discover or rule out low energy susy. This is more contentious, but if it isn't seen at the LHC most physicists will stop believing in it (although it could still be at very high energies).

 

The trouble with the LHC is that it is a 'discovery' machine. It has a very high energy reach (about a TeV) so it should be able to see (almost) anything which is there, but it is not very accurate. Since it is colliding protons together and protons are not fundamental particles but 'bags of quarks' the collisions are very messy and it is difficult to get accurate measurements. Actually, at these energies the protons are mainly made up of gluons, so it is a 'gluon collider'. Because they are inside the proton we don't really know what energy the gluons have, which makes things difficult.

 

The proposed LC is a precision machine - although it won't have such a high energy reach, what it does see it should see clearly. It is colliding point particles (electrons and positrons) so the collisions are very clean, and you know exactly the energy which goes into the collision. The hope is that the LC can measure things so precisely that it can extrapolate the physics to much higher energies.

 

It would be good to have them running concurrently because the specialise in different things, and there is a synergy between them. If the linear collider sees something that the LHC has missed (due to not looking in the right place) then the LHC can go look for it. This is especially important for the LHC because it has a very strong trigger - there are so many proton-proton collisions the electronics can't read out data to disk quickly enough, so there is an initial check to see if the collision is interesting (the trigger) and if it is not it is thrown away.