Urgent public health warning issued over lost radioactive capsule

Not for something that small (as a source) given the atmosphere thickness etc.

If you're interested:

Guidelines for radioelement mapping using gamma ray spectrometry data International Atomic Energy Agency (2003)

https://www-pub.iaea.org/mtcd/publications/pdf/te_1363_web.p...

( Although, frankly, IMHO, AGSO (Australian Geological Survey Org) have a similar better document, but lets not quibble )

179 pages of breezing overview with simplified details, note that airborne radimetric surveys with ~ 50 litre sodium iodine crystal packs (that flash on an energy spectrum when a gamma ray interects with them) are flown at 80 metres ground clearance and NOT at 20 km+ ground clearance because of EXPONENTIAL signal strength decay . . .

Nice, so, just speculating with what is in the public domain here;

* what kind of counts would you expect from a 19-becquerel caesium 137 ceramic source in a 50 litre NaI spectrometer ~ 40 metres away in a 1 second window ?

I mean the spectrum is going to look like [1], of course, but I'm imagining a crop duster [2] draping at 70 metres / second for along the centre line of the 1,400km stretch of road, maintaining a 40 m clearance and coming preloaded with the 256 NASVD Hovgaard kernel of the West Australian Outback looking for a Cs137 peak and compton.

Would you be expecting any radon interference here?

Of course the fun starts if our nugget of interest isn't on the road but was picked up in a 4x4 | truck tire and carried along for a few hundred km.

Would you expect a contact trace to show up along the road here, good enough that if it dies off one can investigate whether it fell out, or got carried elsewhere by the vehicle turning away?

[1] https://www.gammaspectacular.com/blue/gamma_spectra/cs137-sp...

[2] https://www.youtube.com/watch?v=1_MO5Wfomks

The penetration of a pachinko ball through a volume of various gases, densities, pressures and at tempretures hasn't changed either.

The signature of a Cs137 bolt head sized source on the ground [1] peaks at 662 kev and has the entire atmosphere above, water vapor and all.

That's a lot to push through for a small number of low energy gamm's in order to reach a satellite that would then have to pick out that signature from ALL the ground area below (with no obvious means to determine direction).

This is very different, obviously, to a thunderstorm driven electrical field generating MeV events high above the cloud levels from (presumed) relativistic Bremsstrahlung.

Err, I mean, you do read and understand these links you're providing, I guess?

If not, maybe start there with a picture of what's actually going on here.

[1] https://www.gammaspectacular.com/blue/gamma_spectra/cs137-sp...

Probably work on reading up on detection methods.

( See upstream attached overview on basics )

There's a source object here, the size of a bolt, it emits a certain amount of detectable energy (why? worth checking) in All directions - at any distance the energy that reaches that far is spread across the surface of a sphere .. the surface area of that increases R-squared and so the energy per unit area decreases with the square of the distance.

Worse still, the energy is in packet form - when it hits or interacts it changes or gets knocked out of the game - what energy survives gets smushed out and down to lower energy levels.

By the time energy from our source reaches a satellite it's been spread out to less than nine tenths of sweet fuck all and stretched out and down shifted to have little discernible form ..

AND .. (here's the big one)

it's also coming out to the satellite alongside the competing signals from several hundred square kilometres of adjacent ground, replete with similar (but initially different) spectra from Potassium, Uranium, Thorium, et al .. that have now all weakened, lost their distinct shape, and been smooshed together in a blender.

The high altitude high energy stuff stands out and proud, the rest is an amorphous blob of bachground radiation .. if you could identify a few counts from a Cs137 source, how would you even know where it came from (other than "probably below")?