World’s Finest Gold Specimen Probed With Los Alamos Neutrons

World’s Finest Gold Specimen Probed With Los Alamos Neutrons

John Rakovan: Silver wires, and gold
wires which are much more rare, even though they’ve been known for hundreds of years,
we know very little about them. We’ve been studying wire silvers, how they
grow, we have some hypotheses that we’ve developed based on our characterization of
the texture and crystallinity, we have no idea in the context of gold. So the first thing we have to do is look to
see, are these the same things as silver wires in terms of their internal structure and their
texture. Raquel Alonso-Perez: This is one of the first
Gold Rush specimens, gold specimens. It was described in a newspaper in 1893, and
there’s a drawing of the wire. Back then someone bought it for $160, so already in 1893 it was considered a unique specimen in many aspects. Rakovan: The specimen that we’re looking
at from Harvard University is hand’s down the very finest example of that ever discovered. Sven Vogel: Here at the Los Alamos Neutron Science Center we use neutrons to characterize materials. Here at LANSCE we have our half-mile-long
accelerator that provides us with a very intense source of pulsed neutrons. We then use those neutrons to characterize
materials, one parameter that we measure is the orientation of the little crystals, or
grains, that make up a large chunk of material. We normally use this method to materials that
are relevant to the Los Alamos mission, such as uranium alloys or nuclear fuels, but we
sometimes get to apply it to , for instance, geological samples like this very famous gold
sample. Alonso-Perez: That’s why we are here at
LANSCE. Thanks to the facilities and the instruments
we can really look through and see what it’s made of, how it crystallized, it’s structure,
there are many type of studies that we can do. Vogel: The gold sample that we characterized
looks like a bundle of wires, and while that is very typical for silver, it is very, very
rare for gold. We characterized a few silver samples also,
to have a comparison, and what we found in the silver sample is that the silver is made
up of many, many small grains, and their little crystals all share one special crystal direction
with the axis of those little wires. Because the big gold sample looks very similar to
the silver samples, we expected something similar for that gold sample. And we were very surprised when we analyzed
our data and we saw that in the gold it looks much more like there are just a few very large
crystals and not these many, many small grains that we found in the silver. Rakovan: This is actually a wire silver. We find them in nature, we can grow them in
the laboratory. There are aspects of the growth mechanism
that we think have technological applications or potential applications. Vogel: They push the envelope for us, these
academic collaborations. And of course it’s a lot of fun too, to
apply these methods and help the universities to gain insight that otherwise they would
have no chance to gain, so it’s a win-win situation for Los Alamos and the universities.

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