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Author Topic: Will the LHC cause my knife and fork to fly off the table?  (Read 2762 times)

paul.fr

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When they turn all those magnets on, will thecutlery in the staff canteen start flying around?


 

Offline DoctorBeaver

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Will the LHC cause my knife and fork to fly off the table?
« Reply #1 on: 18/09/2008 07:45:01 »
No.

Next question.
 

Offline syhprum

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Will the LHC cause my knife and fork to fly off the table?
« Reply #2 on: 18/09/2008 10:26:06 »
Although the external field from the bending and quadriploe magnets will be sheilded  by their superconductive nature there must be a magnetic field generated by the Protons zipping round although due to the low current μAs ? I would think it quite low.
Of more concern would be the Xrays or Gamma rays generated any ideas as to the intensity of same and how much RF power is required to replace beam losses.
« Last Edit: 18/09/2008 10:31:57 by syhprum »
 

Offline techmind

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Will the LHC cause my knife and fork to fly off the table?
« Reply #3 on: 19/09/2008 23:31:07 »
Of more concern would be the Xrays or Gamma rays generated any ideas as to the intensity of same and how much RF power is required to replace beam losses.

This will be much like synchrotron radiation, so will be emitted tangentially to the beam-path where it gets bent round the corners by the magnets. I imagine there will be substantial lead bricks to absorb this, but even if there wasn't then it will just head into the ground horizontally (however many metres underground) and won't pose any hazard to anyone on the surface.

How much rf power is required? Don't know, but the Daresbury synchrotron with which I am vaguely familiar and sends electrons-rather than protons- around a much smaller ring uses a 250kW RF Klystron. Some vaguely relevant info in this paper: http://www.astec.ac.uk/rf/PDFs/fpah008.pdf

The rather larger synchroton at the ESRF (Grenoble, France) used as much power as a "medium-sized town", and when I did some work there they had a special deal with the electricity company that they got cheap electricity on the basis they let the grid cut them off if the power was suddenly needed elsewhere to meet a surge in demand!


Ahh, a Google search indicates the LHC uses 16x 300kW Klystrons, providing 4800kW of RF power. Wow!
http://accelconf.web.cern.ch/accelconf/e08/papers/mopp124.pdf

A hazard for anyone working on the ring is if the beam-steering goes slightly awry and the beam accidentally crashes into the side of the tube - you will then get the broad-spectrum X-ray etc Bremstrulung radiation emitted from the crash-point rather than the magnets (which have the sheilding).
(Edit to add: unlike an electron-only synchrotron, I guess the much greater mass of protons and hence stored kinetic energy means that you'll also get vastly more heat dumped somewhere if the beam crashes.)

At Daresbury when they were injecting the electron-beam things weren't as finely balenced/steered as during normal running operation, and there was a measureably elevated level of counts on the Geiger counters around the place...
« Last Edit: 21/09/2008 11:31:01 by techmind »
 

Offline syhprum

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Will the LHC cause my knife and fork to fly off the table?
« Reply #4 on: 20/09/2008 11:07:42 »
As a technician I find such articles much more interesting than esoteric arguments about multiverses and singularities
 

Offline techmind

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Will the LHC cause my knife and fork to fly off the table?
« Reply #5 on: 20/09/2008 13:57:09 »
Before any wavelength filtering (monochromating) I believe the intensity of X-rays off some of the Daresbury beamlines was of the order of kW over a square inch. Enough to completely char a piece of paper in a fraction of a second!
The silicon crystal double-bounce monochromator on the beamline I used was water-cooled.

Presumably the protons which "miss" in a collision go around again, and hit next time a few nanoseconds later?


Yes syphrum, although the "beamline science" was interesting I took more interest than many in the "machine" engineering too.
 

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Will the LHC cause my knife and fork to fly off the table?
« Reply #5 on: 20/09/2008 13:57:09 »

 

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