[throwbadubadu]

In some other thread I believe someone said with his known equipment, even if not occluded, a scan would take some seconds... so with that wouldn't have been to be that easy? So now not sure if normal.or amazing that they can do this with a 70km/h drive by?!

( Edit: https://news.ycombinator.com/item?id=34623782 sounds like not too amazing :) )

[defrost]

It's not too amazing.

Perth has a few companies that do this work for a living - as a grind job, flying contracts for an actuall million line kilometres of 256 channel radiometric mapping at anything from $7 to $15 AU per line kilometre for mineral exploration.

This has been ongoing for 50 years (see: Radiometric Map of Australia) and I'm slighlty baffled why a plane wasn't flown along the road on day one.

Realistic guesses are that all airframes were fully booked AND the national agencies wanted to shine and test their new gadget.

It's slightly complex gear to set up - but no more so than properly running the lines for a concert from pickups to to desk to foldback and main speakers, etc. If you can do one you can do the other.

Complicated is when you go and map some area in India near the Pakistan border and suddenly a surprise nuclear test happens beneath you .. which happened to one local crew .. but that's a whole other story.

[fghorow]

Your guess about the airframes being booked has a ring of truth to it. I hadn't thought of that, and was wondering why radiometrics wasn't being used from the beginning.

[wnkrshm]

I want to know this other story, I haven't found it by cursory search - what should I be searching for?

[defrost]

Pokhran-II was a series of five nuclear bomb test explosions conducted by India in May 1998, Pakistan responded with six underground nuclear tests at the Chagai and Kharan test site conducted fifteen days after India's last test.

It was all abit unexpected at the time and the US was interested to know how it came to be that Australians were present.

[albert_e]

I am sorry I am not following the connection between Pokhran-II nuclear tests and Australia. Would you mind sharing some more information or a link maybe?

[defrost]

An Australian radiometric survey team were there at the time over the area during the first detonation .. and for the rest of the series.

Things got ... interesting.

[albert_e]

Oh. and why were they there in the first place? On some scientific research field study / invited by the Indian government?

[MockObject]

It sounds like a fascinating story indeed, but I can't find anything about it after a search.

[defrost]

True story, and these days you'd probably have to go to paper copies to find quotes from senior US defence | politicians expressing surprise at tests that seemingly came out of nowhere.

I dare say somebody might write it up well after retirement for release after death.

[gtirloni]

> the national agencies wanted to shine and test their new gadget

Exactly. After reading the press release and how they promote their device, I'm not so sure this wasn't deliberate.

[xrayarx]

My thought exactly

[xrayarx]

What I don't understand is, what kind of technology is it? It is obviously great. The technical explanation is not there

[defrost]

The simplest spectrometer is dark sealed tubes of doped sodium iodide crytals with a counter at the ends.

When an energetic gama burst hits a bit of crystal it flashes in a manner that gives up the energy .. over the course of a second and a few thousand events (normal background radiation) you have a spectrum [1].

You no have an indication of all the radiation all arounf the tube.

All around. With no indication of direction. Literally they could have come from anywhere, up, down, left, right, behind you, etc.

What we have here appears to be a vertical tube (or tubes) with mobile masking templates that rotate about and provide some axis of ingress information coupled with any energetic flahes that appear at the same instant.

There is some topographical statistics that needs to be performed and overall there are reduced signal levels (as some incoming gammas are masked and never make a flash) but you can end up with a positional image of where various radiation sources are in the space about the tube.

The other wrinkle they gloss over ('compressed', 'needs fewer counts') suggests (it's either obfuscated or I haven't read deeply enough) they have an eigen library of responses (ie. mean Australian background, Pure Potassium, Pure Uranium, Pure Thorium, Cs-137) baked in to facilitate faster recognition of spectrum patterns.

It's a pattern matching in N^256 type problem in a space that reduces to about N^11 or so when an SVD is applied .. and there are ways to "cheat" and do this faster on the fly.

[1] https://en.wikipedia.org/wiki/Gamma_spectroscopy

[idiocrat]

Last month I have ordered this pocket scintillator/spectroscope "Radiacode-101" from a Cyprus sales company.

https://radiascan.com/products/detector-of-ionising-radiatio...

The waiting time is few months, so I hope the toy arrives eventually.