How to find a tiny radioactive source while doing 70 kph

This is more of an ANSTO PR piece to promote a new piece of kit [1] based on a recent paper [2].<p>I&#x27;m guessing they loved the opportunity to field test this in a sea of global public interest.<p>What they&#x27;re not actually saying is that the source in question could have just as easily been found using 1990s technology in a low flying aircraft at 70m&#x2F;sec ( ~250 km&#x2F;hr ) - once you get the target peaks (which were bright against the background) in a 70m square it&#x27;s a simple matter to wave handheld detectors about to zero in on the capsule by the road.<p>Also of note &quot;How to find ..&quot; is somewhat misleading is there is great deal of gloss here but relatively little substance.<p>[1] <a href="https:&#x2F;&#x2F;www.ansto.gov.au&#x2F;products&#x2F;detection-and-imaging-coris360" rel="nofollow">https:&#x2F;&#x2F;www.ansto.gov.au&#x2F;products&#x2F;detection-and-imaging-cori...</a><p>[2] <a href="https:&#x2F;&#x2F;iopscience.iop.org&#x2F;article&#x2F;10.1088&#x2F;1748-0221&#x2F;15&#x2F;04&#x2F;P04014" rel="nofollow">https:&#x2F;&#x2F;iopscience.iop.org&#x2F;article&#x2F;10.1088&#x2F;1748-0221&#x2F;15&#x2F;04&#x2F;P...</a><p>[2a] <a href="https:&#x2F;&#x2F;sci-hub.ru&#x2F;10.1088&#x2F;1748-0221&#x2F;15&#x2F;04&#x2F;P04014" rel="nofollow">https:&#x2F;&#x2F;sci-hub.ru&#x2F;10.1088&#x2F;1748-0221&#x2F;15&#x2F;04&#x2F;P04014</a>

Good job, but a lot of the reports really exaggerate the size of the search area.<p>&gt; in the formidable conditions of the outback...<p>&gt; It’s fair to say finding a piece of equipment the size of a button in a vast desert was no easy task<p>Let&#x27;s not go too far here. It was two metres from the road and they knew exactly which 1400km of roads to check.

Cool use of gamma-ray imaging technology! The underlying technology is a coded aperture to give a random response on the detector that can be used to reconstruct the direction of the gamma-ray source. I think they are using a moving mask with a single detector in the middle. They probably didn&#x27;t know if the source had broken apart and caused more contamination when they found the general area. So the imaging allows you to know from a distance if the source has been distributed without going into a potentially loose contamination area.<p>Shameless plug: our company makes gamma-ray imaging systems and combines them with LiDAR mapping to make real-time 3D radiation maps: <a href="https:&#x2F;&#x2F;www.gammareality.com&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.gammareality.com&#x2F;</a> Basically we can make &quot;nuclear street view&quot; in real-time while driving around, or walking it around on Spot.

Here&#x27;s a more technical&#x2F;curiosity-satisfying answer to the question the title poses,<p><a href="https:&#x2F;&#x2F;inis.iaea.org&#x2F;collection&#x2F;NCLCollectionStore&#x2F;_Public&#x2F;22&#x2F;072&#x2F;22072114.pdf" rel="nofollow">https:&#x2F;&#x2F;inis.iaea.org&#x2F;collection&#x2F;NCLCollectionStore&#x2F;_Public&#x2F;...</a> (<i>&quot;Airborne Gamma Ray Spectrometer Surveying&quot;</i>, 1991; 116p)<p>There&#x27;s some <i>really</i> interesting case studies in chapter 9 (<i>&quot;Searching for Radioactive Objects</i>&quot;). The first one was more or less identical to the highway incident in Australia: <i>&quot;On 21 June 1968, a 325 mCi 60Co source was lost in transit somewhere between Salt Lake City, Utah, and Kansas City, Missouri, a distance of 1800 km.&quot;</i> The other two were an American test ICBM that crashed in remote desert in Mexico, and a Soviet orbital nuclear reactor that crashed in Canada.

Back story: Rio Tinto apologises for losing radioactive capsule in Australia <a href="https:&#x2F;&#x2F;www.bbc.com&#x2F;news&#x2F;business-64448879" rel="nofollow">https:&#x2F;&#x2F;www.bbc.com&#x2F;news&#x2F;business-64448879</a>

Wasn&#x27;t this the opening scene to the Simpsons?

Do gamma rays bounce back on a rock or do you need line of sight to capture the source? If it is the latter they were very lucky, effectively one small stone away from never being able to find it.

I was hoping it was going to be by using antineutrinos, something the U.S. and the U.K. have been developing behind the scenes: <a href="https:&#x2F;&#x2F;www.sheffield.ac.uk&#x2F;physics&#x2F;research&#x2F;particle&#x2F;neutrino&#x2F;watchman" rel="nofollow">https:&#x2F;&#x2F;www.sheffield.ac.uk&#x2F;physics&#x2F;research&#x2F;particle&#x2F;neutri...</a>

In the US, the NNSA has helicopters with very sensitive radioactivity detectors. I live in DC and they‘ve flown straight rows over the city, back and forth, to create a background map of natural radiation. It’s not too surprising AU was able to find their missing capsule.

This is not the title of the article, and it should be changed.<p>Besides, what&#x27;s kph?

The paranoid part of me has me thinking that all this sounds tailor made to showcase a product and a capability in a relatively safe setting. And you&#x27;re really so hot on nuclear tech: don&#x27;t lose your sources. That way you don&#x27;t have to show off later on how good you are at finding them, aka the &#x27;hero model&#x27; applied to nuclear physics.