4 ms·

Very cool -- one thing I don't understand though. I know that alpha radiation is stopped by a piece of paper thickness. How does this then detect such radiati

Very cool -- one thing I don't understand though. I know that alpha radiation is stopped by a piece of paper thickness. How does this then detect such radiation through the metal of a box if the detector has to be inside?

sllabres 6y ago
If i understand correctly, the sensor hast to be inside the metal box, as well as the item to be measured. Both shilded from light. Even the glas covering the diode has to be broken away / removed
polishdude20 6y ago
Actually alpha radiation can get through a piece of paper. Check out thought emporiums videos on it on YouTube. I remember he did a video about the different types and had a detector between the sources and some thickness of stuff and they seemed to go through paper just fine. I think it's his video about those healing bracelets that actually emit radiation.
- bunje 6y ago
  I once did an experiment with a rock containing uranium and a Geiger counter. The noise stopped immediately after putting printing paper between them and resumed after taking it off.
- 0zelot 6y ago
  Unfortunately, that video contained some flawed conclusions. I had left a comment back then. Alpha particles from natural sources like an uranium stone penetrate 50 micrometers of solid hard material at most. Let's give it maybe 100 micrometers of soft paper, but that's about it. What was most likely observed in that video is radon, which is a radioactive gas, slowly diffusing out of uranium or thorium stones. Since it's gaseous, it can circumvent the paper and then do its alpha decay just behind it. I wrote a few lines on those aspects in this article https://www.mdpi.com/1424-8220/19/19/4264 https://www.mdpi.com/1424-8220/19/19/4264
  - polishdude20 6y ago
    Oh that's pretty cool! I guess the best way to check would have been to have it in a paper box then?
    - 0zelot 6y ago
      Yes, radon is pretty hilarious and spreads in very unexpected ways. Completely wrapping sources of radon like uranium or thorium minerals (or these bracelets containing some of that), only holds back the diffusion process for some time unless the shielding is really thick and very dense. That's why radon accumulates so well in household cellars, it penetrates concrete walls easily. If you look closely in thought emporiums video (link below), the thick clouds - representing each the full paths of individual alpha particles (from the point of decay until full absorption in the air) - don't originate right at the surface of his shielding materials (paper, chicken skin... whatever). Instead, the alpha particle clouds stand by themselves in free space and can only really stem from radon that decided to decay at those positions somewhere outside of the shielding (transforming to "solid" polonium in that process and sticking itself to the next closest lump of molecules/dust). If the alpha particles would penetrate the shieldings (which they can't because of too much material/density), we would see clouds stemming directly from the shielding surfaces which I don't see happening: https://www.youtube.com/watch?v=C7TwBUxxIC0&feature=youtu.be&t=897 https://www.youtube.com/watch?v=C7TwBUxxIC0&feature=youtu.be... You may find and like my comment there, maybe it helps to fight some misconceptions about natural radioactivity. ;-)
      - polishdude20 6y ago
        Awesome thanks!
semi-extrinsic 6y ago
This device does not detect radiation outside the box. You have to put the object you want to measure radiation from inside the box, close to the sensor.
- supernova87a 6y ago
  Oh, well that is a big, big, caveat. It's fine for what it is. But I think a particle detector that most people imagine is really something you want to be able to hold portably in the air and detect ambient/impinging radiation from unknown sources, rather than have to put samples in a closed container. If there were some modification that made that possible (getting around the light-tight requirement), that would make this incredibly more useful.
  - 0zelot 6y ago
    this is possible! you can use a thin foil made from e.g. mylar, for example taken from a cracked-open old large foil capacitor and superglue one layer on the rim of the diode's metal case. It can then point through a hole into the outside of the tin box if not held into direct sunlight (some additional foam ring can be used to help block more light). Using one of the sturdy aluminum die-cast cases I've listed in the schematic should be favored in a mobile scenario. Much less affected by vibrations/microphonic effect.
    - supernova87a 6y ago
      Interesting, thanks!

sllabres 6y ago

If i understand correctly, the sensor hast to be inside the metal box, as well as the item to be measured. Both shilded from light. Even the glas covering the diode has to be broken away / removed

polishdude20 6y ago

Actually alpha radiation can get through a piece of paper. Check out thought emporiums videos on it on YouTube. I remember he did a video about the different types and had a detector between the sources and some thickness of stuff and they seemed to go through paper just fine. I think it's his video about those healing bracelets that actually emit radiation.

bunje 6y ago
I once did an experiment with a rock containing uranium and a Geiger counter. The noise stopped immediately after putting printing paper between them and resumed after taking it off.
0zelot 6y ago
Unfortunately, that video contained some flawed conclusions. I had left a comment back then. Alpha particles from natural sources like an uranium stone penetrate 50 micrometers of solid hard material at most. Let's give it maybe 100 micrometers of soft paper, but that's about it. What was most likely observed in that video is radon, which is a radioactive gas, slowly diffusing out of uranium or thorium stones. Since it's gaseous, it can circumvent the paper and then do its alpha decay just behind it. I wrote a few lines on those aspects in this article https://www.mdpi.com/1424-8220/19/19/4264 https://www.mdpi.com/1424-8220/19/19/4264
- polishdude20 6y ago
  Oh that's pretty cool! I guess the best way to check would have been to have it in a paper box then?
  - 0zelot 6y ago
    Yes, radon is pretty hilarious and spreads in very unexpected ways. Completely wrapping sources of radon like uranium or thorium minerals (or these bracelets containing some of that), only holds back the diffusion process for some time unless the shielding is really thick and very dense. That's why radon accumulates so well in household cellars, it penetrates concrete walls easily. If you look closely in thought emporiums video (link below), the thick clouds - representing each the full paths of individual alpha particles (from the point of decay until full absorption in the air) - don't originate right at the surface of his shielding materials (paper, chicken skin... whatever). Instead, the alpha particle clouds stand by themselves in free space and can only really stem from radon that decided to decay at those positions somewhere outside of the shielding (transforming to "solid" polonium in that process and sticking itself to the next closest lump of molecules/dust). If the alpha particles would penetrate the shieldings (which they can't because of too much material/density), we would see clouds stemming directly from the shielding surfaces which I don't see happening: https://www.youtube.com/watch?v=C7TwBUxxIC0&feature=youtu.be&t=897 https://www.youtube.com/watch?v=C7TwBUxxIC0&feature=youtu.be... You may find and like my comment there, maybe it helps to fight some misconceptions about natural radioactivity. ;-)
    - polishdude20 6y ago
      Awesome thanks!

semi-extrinsic 6y ago

This device does not detect radiation outside the box. You have to put the object you want to measure radiation from inside the box, close to the sensor.

supernova87a 6y ago
Oh, well that is a big, big, caveat. It's fine for what it is. But I think a particle detector that most people imagine is really something you want to be able to hold portably in the air and detect ambient/impinging radiation from unknown sources, rather than have to put samples in a closed container. If there were some modification that made that possible (getting around the light-tight requirement), that would make this incredibly more useful.
- 0zelot 6y ago
  this is possible! you can use a thin foil made from e.g. mylar, for example taken from a cracked-open old large foil capacitor and superglue one layer on the rim of the diode's metal case. It can then point through a hole into the outside of the tin box if not held into direct sunlight (some additional foam ring can be used to help block more light). Using one of the sturdy aluminum die-cast cases I've listed in the schematic should be favored in a mobile scenario. Much less affected by vibrations/microphonic effect.
  - supernova87a 6y ago
    Interesting, thanks!