Muons used to test the condition of a road bridge in Estonia

[csours]

https://en.wikipedia.org/wiki/Luis_Walter_Alvarez

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]

[kulahan]

They were indeed able to do this after all [1], and found some unknown voids.

[1] https://spectrum.ieee.org/muon-imaging-finds-hidden-chamber-...

[megadata]

Muons were also recently on hackaday. DIY ground penetrating radar ...

Building A DIY Muon Tomography Device For About $100

https://hackaday.com/2025/02/26/building-a-diy-muon-tomograp...

[perihelions]

Also on HN,

https://news.ycombinator.com/item?id=43195525 ("A $100 DIY muon tomographer (ieee.org)", 20 days ago, 45 comments)

[tagami]

Here is an example used in the mining industry. I heard them present at a NASA/USGS conference last month regarding in situ resource ultilization: https://ideon.ai/

[rdtsc]

Neutrons can be used for these things as well. The advantage, say from x-rays, is attenuation is not by material density, where all metals will just look dark, but by thermal neutron absorption cross section. So boron might be dark, but metals won't be.

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?

[thinkingQueen]

> 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.

[schoen]

I did not know this was a thing!

https://en.wikipedia.org/wiki/Muon_tomography

[teamonkey]

Muons can be picked up by a standard DSLR. Put the cap on (remove the lens if possible), set it to continually take long exposures of 30s or more, put it in a sealed plastic box with some silica gel packets and put the whole thing in the fridge for a while.

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.

[agnishom]

How do you know it's related to a muon?

[IndrekR]

Bit more info about the startup behind it: https://www.gscan.eu/

[aigen000]

If I recall correctly, a similar method was used to discover a hidden passageway in the Egyptian pyramids.

[dpedu]

Two voids were discovered - and the one you mentioned has since been breached and a camera inserted. I'm avoiding the word passageway because the general interpretation is that it seems to be an inspection space or stress relief chamber, as it sits directly above the "actual" entrance to the pyramid.

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.

[throw-qqqqq]

You do recall correctly!

https://www.nationalgeographic.com/science/article/giza-pyra...

[superjan]

This story? https://www.jst.go.jp/EN/achievements/research/pdf/mitsuhiro...

[dzhiurgis]

Wonder if one could use muography to detect passing submarines

[webdoodle]

Yes. Nato is has been testing the Watchment muon detection system that was designed to track nuclear material, specifically looking for nuclear submarines.

https://thedebrief.org/darpas-secretive-new-neutrino-detecto...

[RickyS]

It's a bit challenging as the submarine would need to stand still for a while and not be very deep but some people has thought about that.

[cameldrv]

Another one along these lines is antineutrinos. They're created by fission reactions, so a nuclear reactor puts out a lot of them. From what's available in the open literature, this seems like it might be getting close to being practical.

[tomcam]

> This week, a new technology was tested in Jõgisoo, Harju County, as part of a nearly €1.3 million research project.

I’m already using the €235,999 Harbor Freight version for my bridge tests

[aitchnyu]

Is there a diagram of this? I'm imagining a plate that "see" at a 180 degree field of vision when cosmic rays hit it from every angle from the sky there are opaque things between the sky and sensor.

[dinkblam]

on that topic, rust costs us 3.4 trillion per year [1] and the (public) construction industry has not even started to address the issue

[1] http://impact.nace.org/economic-impact.aspx

[hugh-avherald]

Can we have one topic on hackernews that doesn't mention rust?

[krzysiek]

They still do, but they used to too.