Visible light bremsstrahlung?

  • #1
nightvidcole
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Summary: Can one observe visible light bremsstrahlung when an electron beam stops in a transparent medium?

The theoretical form of a bremsstrahlung spectrum is flat at low photon energies. This means that even a high energy electron beam incident on matter should cause the emission of visible photons, albeit with extremely low efficiency. So why is it so hard to observe a continuous spectrum ( and not just line emission) in the visible region from cathode rays in a low pressure gas or a vacuum tube with residual gas?
 

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  • #2
sophiecentaur
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Summary: Can one observe visible light bremsstrahlung when an electron beam stops in a transparent medium?

flat at low photon energies.
I think that 'low photon energies' means low for X Rays. I was trying to think of how electrons of, say 3eV energy, could be passed through a dense transparent medium and produce visible photons (of that sort of energy). I thought that, to produce bremsstrahlung, you needed an electron beam to penetrate the substance.
 
  • #3
Henryk
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Yes, you can see it, but I won't recommend looking at it
 
  • #4
sophiecentaur
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Yes, you can see it, but I won't recommend looking at it
That would all depend on the energy of the beam. A few eV is enough KE if you can actually get it to penetrate a suitable substance to produce optical frequencies.
 
  • #5
ZapperZ
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Summary: Can one observe visible light bremsstrahlung when an electron beam stops in a transparent medium?

The theoretical form of a bremsstrahlung spectrum is flat at low photon energies. This means that even a high energy electron beam incident on matter should cause the emission of visible photons, albeit with extremely low efficiency. So why is it so hard to observe a continuous spectrum ( and not just line emission) in the visible region from cathode rays in a low pressure gas or a vacuum tube with residual gas?

The blue'ish glow that one sees in a water pool of a nuclear reactor is such Cerenkov radiation.

I've also done measurement on the Cerenkov radiation given off when 40 MeV electron bunches slam into a piece of Aerogel to measure the longitudinal bunch length of those electron bunches. Again, that's in the visible range.

There's nothing in the physics that indicates that a Cerenkov radiation can't be in the visible spectrum.

Zz,
 
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  • #6
Henryk
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That would all depend on the energy of the beam
No, I've seen it, I accidently looked into the x-ray source when it wasn't blocked. It does glow.
 
  • #7
sophiecentaur
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No, I've seen it, I accidently looked into the x-ray source when it wasn't blocked. It does glow.
I was questioning the idea that it would have to be risky (as in your case). I was suggesting that bremsstrahlung could be generated (safely) with a low energy beam in the 'appropriate' transparent medium.
 

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