More On The International Linear Collider

paragon_au writes "The UK Independent is reporting that details for a purposed 40km long international Linear Collider have been released by 'An international panel of particle physicists [that] decided the high-energy linear collider - a £3bn machine for smashing matter against antimatter - will use revolutionary superconducting technology to shed light on the origin and nature of the universe. Plans for the International Linear Collider have still to be finalised but scientists hope that construction of the underground machine will begin in six years.'"

Yay No Curves

[Anonymous Coward]

As much as we all love CERN, Curves don't allow electrons thus no clean experiments. electron collisions are clean and pretty!

Straight vs Curved

[DumbSwede]

Wouldn't Linear be a straight line Tunnel?
Your half built SSC is curved.

We could revisit reactivating the SSC project, but that's a different debate.

More news

[daveschroeder]

German lab wins linear collider contest [physicsweb.org]

Particle physicists have chosen to base the proposed International Linear Collider on superconducting technology developed by an international collaboration centred on the DESY lab in Germany. The superconducting approach was chosen by an international panel ahead of a rival technology developed at Stanford in the US and the KEK lab in Japan. The eagerly-awaited decision was announced at the International Conference on High Energy Physics in Beijing today.

The 30-km-long International Linear Collider (ILC) will collide electrons and positrons together at energies of at least 500 billion electron volts. Particle physicists will use the ILC to make detailed studies of the Higgs boson and any other new particles, such as supersymmetric particles, that might be discovered at the Large Hadron Collider (LHC). It is envisaged that the ILC will turn on by around the middle of the next decade, about eight years after the start up of the LHC, which is currently being built at CERN in Geneva.

Is this the answer to God, the universe and all that? [guardian.co.uk]

Physicists plan £3bn experiment in a 20-mile long tunnel

They call it the God particle: a mysterious sub-atomic fragment that permeates the entire universe and explains how everything is the way it is. Nobody has ever seen the God particle; some say it doesn't exist but, in the ultimate leap of faith, physicists across the world are preparing to build one of the most ambitious and expensive science experiments the world has ever seen to try to find it.

ITER Impasse Illustrates Challenge of Site Selection [physicstoday.org]

...indeed, site selection is often a thorny matter, even for scientific projects not as costly or international as ITER or the next-generation linear collider.

Re:Why not revive the SSC?

[Ev0lution]

The SSC was a circular collider, not a linear collider, so it isn't a direct replacement. ILC would study collisions between electrons and positrons. With circular colliders, one problem is that particles lose energy as they go round the ring (due to synchnotron radiation). As the energy increase these losses also increase. This is less of a problem for heavy particles (e.g. proton-antiproton) collisions, but circular colliders don't scale well for electron-positron collisions, hence the need for a linear collider.

The SSC?

[daveschroeder]

The SSC [hep.net] was originally intended [wikipedia.org] to be a 54 mi (87 km) ring. 14 miles of tunnel were complete.

Despite the incredible importance of this research - not to mention basic research in general - it was dismissed as a boondoggle and sandbox for particle physicists [cato.org].

More reading: Science and Patriotism run amok in Texas [washingtonpost.com]

Purposed

[Elladan]

"Proposed"

That is all.

Re:dual-nature of light is really "brownian motion

[Aardpig]

namely the idea that our universe is like a soap bubble among a conglomerate. then the extra dimensions could be the axes to adjacent universes. perfect.

Do a Google for 'brane theory' -- it is similar to what you appear to be thinking of.

but einstein's special theory of relativity was instigated by the simple idea that acceleration and gravity are equivalent.

That would be 'general theory' -- special relativity deals solely with unaccelerated frames of reference.

Hollywood disaster movie directors take note...

[spamster]

Might as well bring up the mention of strange matter before some other paranoid ninny does. http://en.wikipedia.org/wiki/Strangelet . Unlikely it could be made, but I'm sure the same people who worry about neutron emissions and world destroying asteroids will like this also.

Re:Another sub TeV Collider

[Anonymous Coward]

Energy isn't everything; you can do things with electron-positron colliders that you can't with proton colliders like the LHC. For instance [europhysicsnews.com],

Because electrons and positrons produce collisions that are much "cleaner," they are viewed to have certain advantages above the colliding protons in the LHC for investigating energies above those reached by LEP. There is much less background, and the production rates for new particles or events are not that different from the known production rates, says Peter Zerwas, a theorist at DESY, the German particle physics laboratory near Hamburg. "You can project out the new physics elements much easier," he adds. The strength of the LHC will be as an exploratory machine, says John Ellis, a theorist at CERN.

Re:Why not revive the SSC?

[vondo]

Magnet's don't boost the energy, they only bend the particles. The RF cavities boost the energy. So, with better magnets, you can build a smaller, more powerful proton accelerator, but they don't help you with an electron accelerator.

The problem with an electron accelerator is that energy is lost due to the bend radius and unless you have a very large accelerator, you quickly get to the point where energy is coming out just as fast as you can put it in. Solution: an infinite-bend-radius (linear accelerator).

What I haven't seen mentioned here yet is that we use both types of accelerators (proton and electron) for different reasons. Protons colliding give the highest energies and the collisions produce a wide variety of particles and interactions at a variety of interaction energies. Electron collisions are much cleaner, but tend to be at lower energies and rates. (This is because electrons are fundamental particles but protons are made of 3 quarks each and it's really the quarks colliding.) But, if you know the energy (mass) of the particle you want to study, you can produce them reliably and in a very clean environment so you can study them more precisely.

how this works

[Anonymous Coward]

FROM A PHYSICIST:

First Why. Natural Science is a lot like mining. Physicists discover things about nature. They attempt to put together an idea of how the fundamental works, both large and small, and create methods to predict phenomena based on these ideas. Applied Physicists and Engineers then take this knowledge and ask themselves the question "How might I use this for mankinds advantage". A simple example is the transister. The transistor could be the most powerful invention of the last century. But, without the knowledge of quantum mechanics discovered by natural physicists the transistor would never be. Natural physicists mine for the knowledge that will be later used for application. Their are countless examples of this from maxwell and wireless applicatons, certainly quantum mechanics and solid state technology, and even general relativity and GPS satellites.

Second Linear Collider vs SSC, etc: The linear collider is not a discovery machine per se. It is a precision measurement machine meant to refine knowledge about discoveries that will be made by the Large Hadron Collider which is being built in Europe. Natural physics isn't about finding a particle alone. This does nothing for us. It's about building and understanding a model of nature that can later be used to predict phenomena as accurately as possible. Neither of these machines is focused on a single particle (HIGGS, SUSY, etc.) Saying so is the equivalent of saying we're building a workbench to put together only rocking chairs. Our 'workbench' is an experiment meant to study interactions spanning the entire current model of nature. It is an expensive tool, but keep in mind once it is built it will last 20-30 years (fermilab as an example). I don't believe it's very expensice considering this keeps the flow of technology rolling.

Superconducting: The magnets proposed are revolutionary because they will be at 2 kelvin. Fermilab operates at 70+.

Re:The SSC?

[Anonymous Coward]

Despite the incredible importance of this research - not to mention basic research in general - it was dismissed as a boondoggle and sandbox for particle physicists.

It was dismissed because its head administrators had no idea of how to budget an R&D project. They treated all the cost estimates as if they were standard contracts for a mature technology. When their fixed-price fixed-schedule plan did not survive contact with reality, they cooked up a new fixed-price fixed-schedule plan and presented it to Congress. When the new plan ... etc. They were so out of touch that the took budget estimates from scientists as gospel without even considering monetary inflation over the multi-year course of the work. Congress is willing to overlook a lot, but the administrators did everything in their power to surprise and confuse them. So Congress pulled the plug.

Re:Circular Colliders

[jpflip]

Yes and no. The Linear Collider doesn't depend on the discovery of the Higgs per se, but it does become more compelling if the LHC (or Fermilab) discovers _something_. The most likely scenario is that the LHC (which comes online in 2007 or so) at CERN will discover some new things - supersymmetric particles, the Higgs, the physics that gives us neutrino masses, etc. The Linear Collider would then be used to study what's been discovered. If the LHC doesn't see anything interesting (which most physicists think is unlikely, because of various arguments, but it's possible), then the Linear Collider will be a lot less useful. But there are a LOT of different ideas for what the LHC could discover - it doesn't all hinge on testing one particular model.

From the physicists' point of view, though, you don't want to wait that long. Say the LHC starts in 2007 (though such projects are often delayed) and discovers something by 2009. Then you start a proposal for the Linear Collider, which you finalize by 2012. Then you build it, and it's working in 2020. That's a LONG wait! These projects take so long that physicists want to get the ball rolling and construction started ASAP.

Re:Another sub TeV Collider

[vondo]

Not quite. The Higgs and SSM particles are expected to be less than 1 TeV in mass. With a proton collider, you need a lot of extra energy because you produce many, many, other particles. But, because they are easier to build and have higher collision rates, they are ideal discovery machines.

With an electron-positron collider, you can make these new particles singly or in pairs and use up all the energy, so they are great for doing detailed studies of the particle in question.

Re:What they'll probably do first...

[jpflip]

That's probably not the first thing they'll do, but not because it's not interesting. In most theories, the energies needed to directly explore quantum gravity (string theory, M-theory, etc.) in this way are more than 15 orders of magnitude higher than this accelerator can achieve. The first order of business is to look for physics at the TeV energy scale, such as the Higgs boson and supersymmetry.

There will, of course, also be people sifting through the data looking for the things you describe - low-energy effects of quantum gravity, evidence for extra dimensions, and so forth. People are already looking for such things in Tevatron data.

Re:dual-nature of light is really "brownian motion

[RWerp]

einstein's special theory of relativity was instigated by the simple idea that acceleration and gravity are equivalent.

Errr, no. It was General Relativity.

Re:Yay No Curves

[Gil-galad55]

Actually, curves do allow electrons. It's just that an accelerating particle radiates energy (synchrotron radiation), and that radiation increases exponentially as mass decreases. The LHC uses protons because their much larger mass (~1000 greater) siginificantly decreases synchrotron radiation. The previous accelerator at CERN, the LEP, occuped the same tunnel and used electrons and positrons. However, while the LEP could only reach energies of ~200 GeV, the LHC aims for 27 TeV. A linear accelerator nips the problem of synchrotron radiation in the bud.

Re:FEL anyone?

[stevelinton]

There was a proposal, called TESLA for a 500GeV linear collider, combined with an X-Ray FEL at DESY. They built a far ultra-violet FEL as a technology demonstrator for this.

The recent announcement is that the accelerator technology that had also been developed for TESLA, using superconducting resonant cavities to support very high intensity microwave standing waves that actually accelerate the electrons has been chosen from among four candidates as the acclerator technology for the ILC project. That may or may not be buolt at DESY, and will not, as far as I know, incorporate an X-ray FEL.

Re:Yay No Curves

[Anonymous Coward]

Hey, It happens to be that when something moves it wants to conserve momentum, thus go in a straight line. When something goes around a curve, it must have a force acting on it, thus it undergo acceleration. This applies with electrons as well as baseballs and other fun-lovin' objects.

Re:Yay No Curves

[div_B]

Hey, It happens to be that when something moves it wants to conserve momentum, thus go in a straight line. When something goes around a curve, it must have a force acting on it, thus it undergo acceleration.

Yes, and when you accelerate a charged particle, it sheds energy in the form of EM radiation. This is what the parent said.

This is why the pre-quantum model of the atom was absurd:
Orbiting electron bleeds energy due to centripetal acceleration, the orbit decays, and the electron crashes into the nucleus in ~ 10^-16 s.

Re:Why not revive the SSC?

[edgar_is_good]

To be even more picky, the proton is actually made up of an infinite number of virtual particles, and for many processes of interest, it's dominantly collisions of virtual gluons which contribue.

Re:Circular Colliders

[funkbrain]

While I understand that electron/positron collisions require the linear accelerator, doesn't a lot of this hinge upon the discovery of the Higgs boson?

Yes! Well, sort of.

I am a particle physicist (at the Tevatron). It has been my understanding (and it seems to be conventional wisdom in the field) that the (US) decision to actually go ahead and -build- the NLC will be made -after- the first new discovery at either the Tevatron or the LHC. (Right now the NLC is just in the R&D phase, and is far enough along in the R&D phase that a decision on the choice of accelerator technology has been made).

Now the new discovery could be observation of the Higgs, or observation of new physics (supersymmetry is a perennial favorite, as are large extra spacetime dimensions; there are -many- theories to choose from), or both. If you assume the Standard Model (SM), and plug into the theory parameters already well-measured at the Tevatron, LEP and SLAC, (e.g. the top-quark mass, the W and Z boson masses) you can predict a likely range for the mass of the Higgs boson. The LHC should certainly be able to observe the Higgs in this mass range. So... even if the LHC doesn't discover the Higgs, it is a discovery of sorts: it means there is something wrong with the SM (which physicists have suspected for a long, long time).

Now the real reason for the delay is that we want to make sure that the NLC has a high enough center-of-mass energy (HEP jargon is sqrt(s)) to study interesting things (like the Higgs boson). It'd be a real shame if we start building the NLC now with sqrt(s) = 500 GeV and it turns out that we need a much higher energy to produce the Higgs (or other interesting stuff). But note, that the German (and the US/Japanese) proposal included plans for future upgrades to higher energies.

Actually the whole "superconducting accelerator" thing is rather new. The Tevatron employs superconducting magnets to curve the path of charged-particles, and non-superconducting RF cavities to accelerate those particles. (I think) The LHC does the same. The German NLC proposal is to use superconducting RF cavities to accelerate charged particles. So, using superconductors at accelerators isn't new, using superconductors to accelerate charged particles is.

BTW, the accelerator complex at Fermilab has eight, not five stages: pre-accelerator, linac, booster, main injector, recycler, debuncher, accumulator, tevatron.

Re:how this works

[Dr. Kinbote]

This is not about magnets at all. The "cold technology" developed by DESY and favored by
the committee is about superconducting RF
resonators (which are used for particle
acceleration).

Re:Yay No Curves

[Gil-galad55]

It has to do with the total energy you can get. At relativistic velocities, E = gmc^2, where 'g' is the famous relativistic 'gamma', 1 / sqrt(1 - v^2/c^2). Here, relativistic effects are accounted for solely by gamma, so m is the particle rest mass, and the rest mass of an electron is about 1/2000th (I goofed on my previous post saying the factor as ~1000) that of a proton. So, for equivalent energies, you have a gamma approximately 2000 times higher for an electron than for a proton.

Now, synchrotron radiation, at relativistic velocities, is dominated by the gamma term -- in fact, it goes as g^4. Thus, this factor of 2000 becomes a factor of 1.6 x 10^13! That's why you can't use electrons at high energies! At least, not unless you have a WHOLE lot of power... For more information, see this page:
http://hyperphysics.phy-astr.gsu.edu/hbase/particl es/synchrotron.html