Particle interactions with matter

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Discussion Overview

The discussion revolves around the interactions of electromagnetic radiation and charged particles with matter, specifically focusing on ionization processes and comparisons between different types of particles, such as photons and alpha particles. Participants explore the mechanisms of ionization, energy requirements, and the implications of these interactions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that an electromagnetic photon can ionize an atom if its energy exceeds 10 eV, leading to the displacement of an electron.
  • Another participant notes that ionization can occur at lower energies depending on the material and emphasizes that the secondary electron can cause further ionizations and excitations.
  • It is mentioned that the process of ionization can also release heat, and potentially light or sound, depending on the material.
  • Participants discuss the relevance of comparing electromagnetic photons to heavily charged particles like alpha particles, with one stating that alpha decay is a different process but that emitted alpha particles also cause ionization.
  • Questions arise regarding the source of energy for ionization, with a consensus that it comes from the interaction with the photon.
  • There is a suggestion that comparing ionization effects of light and heavily charged particles is reasonable, although one participant expresses uncertainty about the textbook's approach.

Areas of Agreement / Disagreement

Participants express some agreement on the mechanisms of ionization and the role of energy in these processes, but there is uncertainty regarding the specific comparisons made in the textbook and the implications of those comparisons. No consensus is reached on the appropriateness of the textbook's discussion.

Contextual Notes

Participants acknowledge that the energy thresholds for ionization can vary based on material properties, and there are unresolved questions about the nuances of comparing different types of ionizing particles.

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.
 
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Mahavir said:
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).
Mahavir said:
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.
Mahavir said:
All this also releases heat.
Sure. Depending on the material you can also get some light, sound (microscopic, nothing to hear) or similar things.

Mahavir said:
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.
 
Thank you so much for your reply! I just have a few follow-up questions, if I may.

mfb said:
Only if it gets sufficient energy to do so.

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

mfb said:
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?
 
Mahavir said:
So, does this energy come from the interaction with the photon?
Sure.
Mahavir said:
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.
 
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mfb said:
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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