I recall reading about using neutron beams to alter the chemistry of phonograph needles. I think the idea was to make them into a radioactive isotope that continually ionized the needle, so that it repelled dust.

But maybe I'm remembering wrong. The closest article I can find is from Theodore Gray [0]. It talks about old phonograph needles made from osmium, which is very toxic in dust form.

[0] https://theodoregray.com/periodictable/Elements/076/index.s1...

You're probably thinking of polonium record cleaning brushes sold by staticmaster.

Its an interesting case study in planned obsolescence, the radioactive half life being only a hundred days the anti-static effectiveness of the brush would completely disappear a couple years after manufacture, requiring the purchase of yet another brush.

Electronic / ham radio people would sometimes use staticmaster brushes in the winter when soldering RF preamp FET transistors to try and eliminate transistor-destroying static charge; I was never personally a believer in that technique at least at the amateur level.

Thank you! That was driving me crazy. And now I see why I got confused: it's another phonograph-related dangerous-element fact that I learned from reading Theodore Gray's book, The Elements [0] [1].

Now if I could only remember why I thought neutron beams were involved...

[0] https://theodoregray.com/PeriodicTable/Elements/084/index.s7...

[1] https://www.amazon.com/dp/B011IZNWZU

Right.

The article says "a powerful nondestructive testing method"

Which I don't think "nondestructive" is 100.0.0% accurate, if neutron capture will be involved in producing the dark spots.

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

it's basically nuclear transmutation.

Neutron scatter is the main thing producing the dark spots, though there will certainly be some neutron capture too. In some materials, e.g. boron, neutron capture can be significant.

Still, it's always important to compare the induced radioactivity with the background radioactivity as a comment above did. It's easy to forget that we live in a field of natural low-dose ionizing radiation from cosmic rays and from the bowels of the Earth.

Marie Curie, call your office.