Imagine a planar array where each pixel gathers counts like an MCA (multichannel analyzer), mounted in some lead pinhole camera obscura.
This would give an extremely wide range of channels didactically illustrating the presence of calcium in gypsum (dryboard etc), visually show backscatter, etc.
Such pictures of modern and old city scenes would be mesmerizing to watch, partially seeing into buildings, the ground, ...
* https://www.ga.gov.au/bigobj/GA13928.pdf
* https://www.ga.gov.au/bigobj/GA18007.pdf
Visualising full 256 channel multispectral data can be tricky, the approach taken above was to take the raw data and process it to create a false colour RGB image representing the strength and interaction between natural background potassium, thorium, and uranium.
i made a small 3x3 proof of concept using more expensive geiger tubes, and their really long 'z-axis' lengths made 'traces' happen very often, like a persistent cloud chamber
trying to find a reliable semiconductor (read:cheaper) method i can scale to an arbitrary number of pixels, but something seems to happen in between the bench and the wall :(
I have considered
* scanning a linear array of BPW34 photodiodes, in a similar spirit to a scanner to cover a plane, each photodiode going to its own "MCA circuit" (TIA->cheap audio codec like those from Everest Semi). Either direct measurement of generated charge pulses or covering the photodiode with phosphor on aluminum foil or so
* cloud or bubble chamber (cloud chamber is less dense and will generate fewer events, so probably bubble chamber): instead of needing a large 2D or 1D array of parallel circuits, we image and track generated charged particles and use the trajectory starting end (less curved) to determine the source direction!
* consider X-ray crystallography, an incoming straight beam can diffract in many directions on a monocrystal. rotating say a silicon wafer, and measuring the incoming photon energies with one or more photodiode/MCA circuits we can assign a source likelihood distribution by keeping track of the orientation of the monocrystal. akin to sparse sampling but instead of masks its diffraction patterns.
If you have better ideas or variations in mind, let me know!
There's one in the Musée des Arts et Métiers in Paris — blew my mind!
[^1]: https://en.wikipedia.org/wiki/Cloud_chamber
Edit: turns out people make these at home all the time. Sick!
- Dry ice (mine came from something shipped cold)
- Dark piece of metal (I used a 3D printer hot bed) on top of dry ice to get cold
- IPA vapour (I poured some on a shop towel)
- Some transparent container to house it all - I found a glass display cube on the side of the road, fish tanks or Tupperware also work.
- Torch or something to provide side lighting
Very cool to see evidence of the particles zooming around us, can highly recommend.
https://home.cern/news/news/experiments/how-make-your-own-cl...
https://hackaday.com/2019/01/13/see-the-radioactive-world-wi...
You really have to get your eyes adjusted to the dark to see anything with the spinthariscope. It ends up looking mostly like static on a green crt, but if your only reference frame is a cloud chamber, the volume of particles that are emitted from such a weak source is pretty remarkable.
