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Activation of a Sterling Silver Spoon

Posted: Wed Oct 21, 2020 4:36 am
by Mark Rowley
Ran across a set of sterling silverware in the family storage vault the other day and decided to try a small spoon for activation. I’m not too sure on the actual silver content but some internet sources put this particular late 1920’s vintage at 85% or better. I exposed it to a roughly estimated neutron TIER of 1.3E+6 The spoon was 17cm from the fusor grid.

After four minutes exposure, I wasted about 5-7 seconds getting it out of the moderator and under a TBM-3 pancake meter. It still registered nicely at about 2kcpm and quickly decayed after a couple minutes.

Here’s a video I made of the activation:
https://youtu.be/WYreMUalsjE

Mark Rowley

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Re: Activation of a Sterling Silver Spoon

Posted: Wed Oct 21, 2020 10:14 am
by Richard Hull
Nice work with the activation!

Registered, hallmarked Sterling silver is by law, 92.5 % silver. No variation allowed. That is the sole requirement to bear the hallmarked word "Sterling" stamped into the item. Typically, the remainder is copper for strength..... Mexico, in its heyday of silver coinage along with only a few other nations tended to have their coinage .800 pure, Virtually all other nations tended to use .900 coinage in both silver and in gold. My jewelry making background comes to the fore. Again, the term Sterling must be stamped into the metal not raised via some casting or stamping process, If the common registered practice is followed.

For the sake of discussion and illumination, let us assume your silver is not sterling but plate, every bit as pretty, but less expensive. For neutron activation the plate should work no different than true sterling. Any activation in plate would take place in the typical very heavy silver plating which would be not sterling but, instead, pure, "fine" silver .999 pure. Regardless, be the silverware true sterling or plate or fine 999 the activation and resulting radiation (beta) would be stopped from coming out of the surface at the level of a few hundred microns, due to the stopping power of the High Z silver. This is why no more thickness than a thin foil is always desired for any activation work where beta rays are being measured with a GM counter. Added thickness would do nothing to enhance the results. Yes, you might uniformly activate a 1" thick ingot of pure silver, but you'll only detect those activation betas from just microns below or at the surface of the ingot. Gamma is another matter, if the isotope also emits gamma, providing you use a gamma ray spectrometer.

Richard Hull