Alvarez proposed muon tomography in 1965 to search the Egyptian pyramids for unknown chambers. Using naturally occurring cosmic rays, his plan was to place spark chambers, standard equipment in the high-energy particle physics of this time, beneath the Pyramid of Khafre in a known chamber. By measuring the counting rate of the cosmic rays in different directions the detector would reveal the existence of any void in the overlaying rock structure.[48]
[1] https://spectrum.ieee.org/muon-imaging-finds-hidden-chamber-...
One day hopefully we can find out if the remaining giant looking open area exists too!
Building A DIY Muon Tomography Device For About $100
https://hackaday.com/2025/02/26/building-a-diy-muon-tomograp...
https://news.ycombinator.com/item?id=43195525 ("A $100 DIY muon tomographer (ieee.org)", 20 days ago, 45 comments)
Muons are much nicer as you don't have to carry a neutron source around with you.
> However, if anyone is now thinking of standing under the bridge to get their body scanned, they shouldn't bother. First, they'd have to stand still for an hour, and second, the security patrol would be there within minutes.
Security patrol will come and bother you if you hand around the bridge for a few minutes?
There’s a land war in Europe. Hundreds of thousands have lost their lives during the past few years. There have been cases of sabotage against the Baltic states as well as the Nordic states. Things are pretty grim there and lurking around basic infrastructure pretty much guarantees a talk with the police.
Paranoia surrounding critical infrastructure is skyrocketing at the moment, and I'd say for a bunch of very good reasons.
[1] https://en.wikipedia.org/wiki/Moore_County_substation_attack
Most of the frames will just show noise from the sensor and electronics (the low temperature minimises that), but occasionally you'll see a bright streak as a muon hits it.
And if [0] is correct about the approximate muon flux - being that "about one per second passes through a volume the size of a person’s head.", the volume of a the CCD sensor that it would have to interact with is so much smaller (being some 10 microns thick) that I doubt it'll be "Take a few 30s exposures" sort of chance, so much as "Winning the lottery" level chance to actually have a muon pass through the sensor, and interact.
[0] https://home.cern/science/physics/cosmic-rays-particles-oute...
Video on the subject: https://www.youtube.com/watch?v=49870qW9pQ8
The second void is more exciting, in my option. It is much larger - it is thought to be of similar size of the Grand Gallery, and sits some distance above it.
https://www.nationalgeographic.com/science/article/giza-pyra...
https://thedebrief.org/darpas-secretive-new-neutrino-detecto...
I’m already using the €235,999 Harbor Freight version for my bridge tests
