3/31/2026 at 12:31:25 AM
I was hoping this would be an artists project page describing the passive imaging of radiation (i.e. not a simple X-ray scan).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, ...
by DoctorOetker
3/31/2026 at 3:31:44 AM
Takes a while to do an entire continent this way, luckily when you start in the 1970s it's all over by now.* 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.
by defrost
3/31/2026 at 4:50:36 AM
Thank you for this reference! I had been looking for such data for a long time.by DoctorOetker
3/31/2026 at 5:50:26 AM
It's been kicking about in geoscience collections, mining company archives, etc. for a while.Russians, South Africans, USAians, et al all run crews - we (Australia) have done Australia, Mali, other African regions, all of Fiji (many islands), India in May 1998 (the Pokhran-II nuclear test sites as they happened), and elsewhere.
The data is one thing, processing raw spectrometer data is a whole other thing - calibrations, corrections, dead time, etc.
See: Grasty / Minty GUIDE TO THE TECHNICAL SPECIFICATIONS FOR AIRBORNE GAMMA−RAY SURVEYS https://www.ga.gov.au/bigobj/GA7667.pdf
by defrost
3/31/2026 at 6:05:38 AM
Do you know of similar maps for Europe?by DoctorOetker
3/31/2026 at 9:48:49 AM
This is a different kind of radiometric data that is available: The EUropean Radiological Data Exchange Platform (EURDEP) consists of data exchange mechanism and presentation website for radiological monitoring data which is collected and shared by 39 participating countries in almost REAL TIME.
Certainly useful for a mapping European normal background, the details under the hood could be a pain (types and formats of data, etc), it's historic and ongoing chronological data for distributed fixed points.
Their interactive public play map is normalised(?) raw total counts, _not_ a spectrum of gamma events bucketed by energy - ideally they are also recording and sharing full spectrum data at some stations in their network .. and making that publically available.
Of possile interest:
* https://www.abc.net.au/news/2022-08-10/hedley-marston-marali...
by defrost
3/31/2026 at 6:48:09 AM
Know of .. yes.Off hand, I'm not familiar with any public facing portals for downloading raw data.
Bear in mind, these are "snapshot" static, historic, broad area spectrum maps - they're not live, they won't show new leaks, changes, etc.
They are, however, "training data" for forming a kernel of a NASVD - Noise Adjusted Singular Value Decomposition - a bundle of all the major features of typical regular environmental radiation for some locale.
If you fly about or have an instrument taking live readings and subtracting a normalised background kernel .. you get the faint trace "weird arse stuff" lighting up instead of being buried.
Finland's the home of the NASVD author, the country used to run "find a barrel of waste" in a forrest compitions back in the day, they're adjacent to some radiometrically filthy submarine docks and pens just over a border.
The game goes thus - fly at about 70m/sec about 80m above the deck in some kind of frame carrying 30 to 40 litres of doped crystal packs .. and pick out a signature in near real time from one second spectrum windows.
They have data, I don't know about portals.
https://www.helsinkitimes.fi/finland/finland-news/domestic/2...
Can confirm, though, Cresco STOL's make a good platform: https://www.youtube.com/watch?v=1_MO5Wfomks
by defrost
3/31/2026 at 1:30:08 AM
currently trying to make a flip-dot display (think https://theartistbreakfast.com/works/spectral-flashbacks-ser...) but with some kind of radiation detector behind each pixel that will flip the dot when something passes throughi 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 :(
by jareklupinski
3/31/2026 at 4:49:32 AM
How many pixels would you aim for?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!
by DoctorOetker