Visible light bremsstrahlung?

In summary, it is possible to 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, allowing for the emission of visible photons with a high energy electron beam. However, it may be difficult to observe a continuous spectrum in the visible region due to low efficiency. It is also worth noting that Cerenkov radiation can also occur in the visible spectrum and has been observed in various experiments.
  • #1
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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
nightvidcole said:
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
Yes, you can see it, but I won't recommend looking at it
 
  • #4
Henryk said:
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
nightvidcole said:
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
sophiecentaur said:
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
Henryk said:
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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