Am Wed, 02 Apr 2008 12:50:58 +0100 schrieb Stephen:

> But why do you say "synchrotron storage ring although with these
> electrons lose energy simply by getting accelerated *radially*"? Why
> lose energy not gain energy? They are being accelerated is it considered
> a negative acceleration?

I said "radially" not "tangentially". They must be accelerated towards 
the center, otherwise  they'd fly straight-line (it's done by bending 
magnets, so it's not a circle but a N-gon with rounded corners). In spite 
of having the radial force perpendicular to the flight path, yielding 
zero for the scalar product Work=Force \times distance and therefore 
can't change the energy of the electrons, the will lose energy in form of 
electromagnetic radiation (depends on the facility, but most will produce 
X-Rays for all kinds of useful experiments). That comes from 
electrodynamics: accelerated charges emit radiation.

That caused great confusion about how atoms could be stable and resulted 
in the advent of quantum mechanics. How could electrons circle around the 
atom's core, without radiation emission and finally plunging into the 
core? Bohr's model of standing particle waves as electrons was the first 
explanation of atoms, that didn't involve accelerated charges (and as we 
know today, was not quite correct).

Yes, I admit it, I'm a physicist. Now you know it...

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