Re: [asa] LHC, TOE, and the limits of knowledge

From: Kirk Bertsche <Bertsche@aol.com>
Date: Tue Sep 16 2008 - 16:13:48 EDT

interestingly, there IS an exponential "law" in accelerator physics
called the Livingston Curve. But unlike Moore's law, it only plots
the equivalent collision energy on a fixed target, not the physical
size of the devices. And it looks like the Livingston curve may be
starting to plateau with the LHC (http://accelconf.web.cern.ch/
accelconf/e02/PAPERS/MOZGB004.pdf)

In order to accelerate particles to a high energy in a small physical
size, one of two things is needed:
1) a recirculating ("circular") acceleration scheme with extremely
strong bend magnets
2) a linear acceleration with an extremely high accelerating gradient

Bend magnet strength is limited by fundamental physics.
(Superconductors lose their superconductivity if the field is too
high. Normal electromagnets would require prohibitively high power.
Permanent magnets would require a very tiny beam aperture for higher
fields.) I don't see much room to reduce the size of circular
machines; maybe a factor of 2 or so with lots of good ideas and hard
work.

Linear acceleration may be a bit more promising. Some interesting
high-gradient linear acceleration schemes are being investigated,
such as using the electric fields in an intense laser pulse to
accelerate electrons. (http://www.lnf.infn.it/conference/lp01/poster/
slac/ARDB_LP_2001.pdf) But even with all of this, getting to higher
energies than the LHC would require a very long accelerator.

I agree with Don's and Randy's pessimism; I don't see how we can ever
get anything in the neighborhood of the LHC energy on a tabletop.

Kirk Bertsche
(accelerator physicist)

On Sep 16, 2008, at 11:02 AM, Randy Isaac wrote:

> Those of us who have grown up with the electronics industry have
> practically come to believe that the scaling law is a universal
> entitlement; we merely wait for the right invention. In fact, the
> transistor and the magnetic storage cell are two rather unique
> examples with surprisingly few additional examples. Does anyone
> know of another? Will there be unforeseen inventions which will
> trigger new ways of doing things. Absolutely. Can we predict what
> they will be? No. But we can have some guesses. Getting a tabletop
> TEV accelerator is not one where I would recommend putting all your
> life's savings. Maybe not even a dime of it. At least until Burgy
> has his rocket that will take us to Betelgeuse and back in one
> lifetime.
>
> Randy

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Received on Tue Sep 16 16:14:06 2008

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