Comments on: LHC: Cooler Than Outer Space

By: Ellipsis

Ellipsis — Sat, 14 Apr 2007 08:32:09 +0000

Lab Lemming — that is exactly why LHC will be accelerating protons, rather than electrons, to 7 TeV *. Bremsstrahlung power is proportional to m^(-6) (where m is the mass of the accelerated particle) — see for example chapter 14-15 of Jackson, _Classical Electrodynamics_. P = (mu_0*q^2*a^2*E^6)/(6pi*m^6*c^7). Thus protons emit 10^18 times less total bremsstrahlung power than electrons.

* as well as the fact that, for the identical reason, the power bill for a 14 TeV circular e-p collider would bankrupt the world — hence the pursuit of linear, rather than circular, colliders when higher (> 100 GeV) energies for electron and positron beams, rather than protons, are considered

By: Edo

Edo — Fri, 13 Apr 2007 18:36:17 +0000

No, that one exploded over a pressure test. And it is not the same magnets: those ones have not been designed by the Fermilab ;P

By: Aaron F.

Aaron F. — Fri, 13 Apr 2007 15:24:24 +0000

Errrr… you mean they’re cooling 200 big superconducting magnets just like the one that exploded during a quench test earlier this month? *eyebrows*

By: Edo

Edo — Wed, 11 Apr 2007 22:57:02 +0000

@LabLemming: the beam tubes are equipped with shields to protect the cold bore. Yes, there’s a risk for heating and thus quenching the supraconductor magnets, but the amount of heat deposited has been calculated and will be absorbed by the liquid helium. Moreover, superfluid helium is an excellent heat conductor.

By: Tom Renbarger

Tom Renbarger — Wed, 11 Apr 2007 20:06:34 +0000

That’s very impressive. I have a hard enough time getting the little HDL-8 dewar we have here in the lab down to 2 K, I can barely imagine what it takes getting such a large apparatus cold.

In somewhat related matter, big news (?) from MiniBoone:

http://www.interactions.org/cms/?pid=1025099

By: Adi

Adi — Wed, 11 Apr 2007 17:25:44 +0000

Martin,
there is a web page at CERN explaining whats fact and whats fiction :
http://public.web.cern.ch/public/Content/Chapters/Spotlight/SpotlightAandD-en.html

By: Zooglea

Zooglea — Wed, 11 Apr 2007 15:49:49 +0000

frÃo, frÃo…

… asÃ como 271Âº C bajo cero. Se ha conseguido en las instalaciones del Gran Colisionador de Hadrones (mÃ¡s conocido por sus siglas en inglÃ©s: LHC). Se trata de un acelerador de partÃculas situado en torno a las coordenadas 46Âº14′00″N y 6Âº…

By: Martin Arrowsmith

Martin Arrowsmith — Wed, 11 Apr 2007 15:18:36 +0000

My words bit me. I forgot to ask my question. It was simply, how much of that is true or realistic?

By: Martin Arrowsmith

Martin Arrowsmith — Wed, 11 Apr 2007 15:15:18 +0000

I’m sorry, one last question. For those who haven’t read the book, but would like to answer this question, please read on. It is sort of a spoiler, so please read if you don’t intend on reading the book.

Brown states that his fictional scientists can contain antimatter by “building a reverse polarity vacuum to pull the antimatter positrons out of the accelerator before they could decay, and to separatethe particles between matter and antimatter, you could apply a magnetic field where matter arced one direction and antimatter arced opposites. To contain the matter in a canister, a magnetic field would be applied to suspend the antimatter from touching any matter.”

Forgive my rapid comment posting, but this is the last one.

By: Martin Arrowsmith

Martin Arrowsmith — Wed, 11 Apr 2007 15:07:04 +0000

I also have another question about the LHC. In the book it says to keep the particles going around in cirlces, the magnetic fields have to be turned and off in rapid succession. Do these fields have to be turned on/off just as the particles reach the proximity? If so, how did we get that accuracy?