Secondary radiation from alpha particles?

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Discussion Overview

The discussion revolves around the secondary radiation generated by alpha particles, particularly focusing on whether alpha particles can induce high-energy emissions such as x-rays or gamma rays when interacting with various materials. Participants explore the mechanisms of radiation generation, including electron relaxation and ionization processes, and consider practical implications in contexts like smoke detectors and silicon processors.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that alpha particles can generate secondary radiation through processes like electron relaxation in materials such as Zinc Sulfide, and questions whether they can also induce high-energy emissions in other materials like air, aluminum, and silicon.
  • Another participant explains that alpha particles primarily scatter or ionize atoms, leading to the release of photons characteristic of the energy levels in those atoms, which can include low energy x-rays.
  • A participant expresses skepticism about the claim that silicon processors experience bombardment from their packaging, suggesting that alpha emitters are typically heavy elements.
  • There is mention of historical issues with radiation from packaging materials in early silicon technology, specifically ceramic packages, which some participants recall as a source of random errors.
  • One participant humorously speculates about the materials used in packaging, referencing trace amounts of uranium and thorium found in common materials, and discusses the challenges of achieving radiopurity in experiments.
  • A participant raises a question about the lack of mention of x-ray generation in alpha particle shielding references, wondering if the energy conversion is too low to be significant.

Areas of Agreement / Disagreement

Participants express differing views on the interaction of alpha particles with materials, particularly regarding the potential for secondary radiation generation and the historical context of radiation issues in silicon technology. The discussion remains unresolved with multiple competing perspectives presented.

Contextual Notes

Some claims depend on specific definitions of radiation types and the conditions under which alpha particles interact with various materials. The discussion includes assumptions about the energy levels involved and the context of historical technological challenges.

Who May Find This Useful

This discussion may be of interest to those studying radiation physics, materials science, or semiconductor technology, as well as individuals involved in radiation safety and shielding practices.

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This is probably a naive question, but I've been trying for awhile to figure it out myself and just don't have the background to do so. I know that beta particles can generate x-rays through bremsstrahlung processes, and that some materials excited by alpha particles can generate light through subsequent electron relaxation, such as Zinc Sulfide. I also know that alpha particles can eject neutrons from lightweight materials, like beryllium. However, I was curious about whether alpha particles of ordinary velocity (e.g. 5.5MeV) can induce high energy emanations (such as x-rays or gamma rays) through some process I'm not aware of from different types of materials (e.g. ordinary air vs. aluminum vs. steel vs. silicon) that they bombard. I'm not very familiar with the energy that is emitted when ions recombine or when electrons jump between shells (except for visible light), but I'm guessing those processes would be the sources of most "secondary radiation" from alpha particles. The thing that got me thinking about these possibilities was pondering the construction of smoke detectors that have alpha particles hitting air and whatever metal they use for shielding, and even silicon computer processors that experience periodic alpha particle bombardment from their packaging. I know all that energy from the alpha particles has to go somewhere, and wonder if any of it ends up as high-energy rays. Thanks!
 
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The interaction of alpha particles with Be nucleus is a special case. For other nuclei, the alphas scatter or ionize atoms. Those atoms remove atomic electrons as they slowdown. As electrons recombine with atoms, they release photons which are characteristic of the energy levels in those atoms which are in the range of IR, visible, UV and low energy X-ray.

I'm not aware that silicon computer processors experience bombardment from their packaging. Alpha emitters are heavy elements Po on up.
 
Astronuc said:
...I'm not aware that silicon computer processors experience bombardment from their packaging...

"In the early days" radiation was a problem (random, non-recurring errors). It turned out to be from the packaging. As I recall, it was only the ceramic packages.

Sorry, no references.

Neil
 
I know that some Si was 'doped' by neutron irradiation, but I believe that was Si logs loaded in a neutron source, e.g. a small nuclear reactor. Perhaps the Si became contaminated(?) by ballistic mixing with neutron activated capsule material (?).

Light elements (Bi and below) undergo beta decay (with some gamma emission), positron emission, or electron capture.
 
captn said:
"In the early days" radiation was a problem (random, non-recurring errors). It turned out to be from the packaging. As I recall, it was only the ceramic packages.

Maybe the packaging was made from Fiesta Ware. :biggrin:
 
jtbell said:
Maybe the packaging was made from Fiesta Ware. :biggrin:

That's not too far from the truth. There are trace amounts of uranium and especially thorium pretty much everywhere, unless you take steps to prevent it. Likewise with lead-210, if its been near anywhere with radon.

People who do experiments requiring radiopurity have to work quite hard to keep these isotopes away.
 
Very interesting! In the references I read on alpha particle shielding they didn't mention the possibility of any shielding materials generating x-rays as a by-product of alpha particle "absorption." Do you think that's just because the amount of alpha particle energy converted to x-rays is too low-level to pose any danger?
 

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