Particle interactions with matter

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  • Thread starter Mahavir
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Hello,

Currently studying electromagnetic radiation and ionisation and a bit stuck on a concept. From what I think I've understood, an electromagnetic photon enters matter, and if the energy is > 10eV it will displace an electron causing it to ionise (and therefore moving out of the atom). This secondary electron will then collide with other atoms within the matter causing further ionisations and excitements of the matter. This entire process continues until the electron runs out of energy. All this also releases heat. Is this correct?

Secondly, my textbook is also comparing this to 'heavily charged particles' such as alpha particles and protons. I'm trying to understand why this is being discussed in this context. Is it because of the notion of alpha decay that is loosely related?

Many thanks in advance.
 

Answers and Replies

  • #2
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From what I think I've understood, an electromagnetic photon enters matter, and if the energy is > 10eV it will displace an electron causing it to ionise (and therefore moving out of the atom).
That is a possible reaction but usually not the only option, and it can happen at a bit lower energies as well (material-dependent).
This secondary electron will then collide with other atoms within the matter causing further ionisations and excitements of the matter.
Only if it gets sufficient energy to do so.
All this also releases heat.
Sure. Depending on the material you can also get some light, sound (microscopic, nothing to hear) or similar things.

Secondly, my textbook is also comparing this to 'heavily charged particles' such as alpha particles and protons. I'm trying to understand why this is being discussed in this context. Is it because of the notion of alpha decay that is loosely related?
Alpha decay is something completely different, but the emitted alpha particles (=helium nuclei) moving through matter cause ionization as well.
 
  • #3
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Thank you so much for your reply! I just have a few follow-up questions, if I may.

Only if it gets sufficient energy to do so.

Right. So, does this energy come from the interaction with the photon?

Alpha decay is something completely different, but the emitted alpha particles (=helium nuclei) moving through matter cause ionization as well.

So, in your opinion, do you think this is why it could be discussing this? Is it common for light particles (e.g. electrons) and heavily charged particles to be compared?
 
  • #4
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So, does this energy come from the interaction with the photon?
Sure.
So, in your opinion, do you think this is why it could be discussing this? Is it common for light particles (e.g. electrons) and heavily charged particles to be compared?
I don't know your textbook. Maybe.
Comparing ionization for different ionizing particle types looks reasonable.
 
  • #5
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Sure.I don't know your textbook. Maybe.
Comparing ionization for different ionizing particle types looks reasonable.

Thanks a lot for your replies! You've really helped me out.
 

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