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Rose

irradiated dimes

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I truly hate to post this. I feel very stupid. I apparently care less about being perceived as dull witted, however, and more about my level of curiosity.

I often see irradiated dimes from the fair offered for sale on ebay. What was the purpose of exposing dimes to radiation? How were the dimes exposed to the radiation? Would the dimes, to this day, retain any level of radiation?

Thank you for putting up with these questions.

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I can't answer the first two questions, but no, there is no residual radiation in the dimes. And there was none when they came out of the "irradiator" either.

You can't even be sure the dime ever got irradiated, as I have several empty blue disks, in which one could put any old 64/65 dime. (But I wouldn't!)

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There is no long temr impatc to ayn of yuor abitilies.

I can attets to htis persollany.

As logn as it was hadned to yuo by a guy dresded like htis, yuo are A-Oyake.

radiation_guy_holding_atom_md_clr.gif

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Rose,

I think the idea was probably dreamed up by the Atomic Energy exhibitor in order to let you hold atomic energy in your hand and see how safe it is. I'll see if I can find the info on what exactly the energy was that supposedly irradiated the dimes.

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Found this very concise explanation at <a href="http://www.vanderbilt.edu/radsafe/0212/msg00420.html" target="_blank">http://www.vanderbilt.edu/radsafe/0212/msg00420.html</a>

I attended the Fair and I have an irradiated dime (you can also find them

occasionally on eBay). The irradiator was probably the same one used by the

Museum of Atomic Energy. Here's an unabashed quote from "Living With

Radiation: The First Hundred Years":

"From the early 1950s to about 1975, the Museum of Atomic Energy at Oak

Ridge, Tennessee irradiated dimes for its visitors. The visitor's dime went

into a "miniature atomic pile" where it rolled in front of a water shielded

antimony-beryllium neutron source for a few seconds. Silver-109 in the dime

was activated to Silver-110 with a 24-second half-life. The dime dropped

onto a screen above a Geiger-Mueller counter that registered the short-lived

silver isotope. A museum employee placed the dime in a cardboard ring,

capped it with a clear plastic cover and crimped the assembly in a flat

aluminum case. Irradiated dimes on souvenir postcards could also be

purchased at the museum. In addition to Silver-110, trace amounts of

Silver-108 with a 130-year half-life were produced by activation of

Silver-107 in dimes but the levels were too low to be detectable with a

Geiger counter. As the silver content of dimes started to decline in the

mid-1960s, a hotter plutonium-beryllium neutron source had to be

substituted. By that time, it was estimated over a quarter-million dimes had

been irradiated. For a brief period the museum also operated a traveling

atomic energy exhibit that featured a dime irradiator."

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Thanks, Rose, for bringing out the question that I'm sure many of us have had in the back of our minds for years!

And Bradd... you couldn't have come up with a better answer... excepting Randy's, of course.

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It's very strange, but the 5 or 6 irradiated dimes I have are all very badly tarnished compared with other non-irradioated dimes of similar age. I don't own a Geiger counter, nor do I know anyone who does, but something happened to those dimes to make them tarnish that much!

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It's the effect of the low-grade radiation eminating from the iris in your eyeballs after you've lovingly pulled them out to look at them every day for 43 years. Normal dimes don't get that much examination.

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Hmmm, that guy states that they are radioactive. I remain skeptical.

And he says to beware of open casings, as they cannot be proved authentic... right before saying they are very different from other coins and will make a geiger counter chatter.

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The great majority of the isotope produced had a half life of 24 seconds. This means the original geiger counter reading would be half as strong in 24 seconds, 1/4 as strong as original in 48 seconds, 1/8 in 72 seconds, and so on. By the end of 24 hours, this division by 2 would have occurred 3600 times. This is roughly equivalent to dividing by the number of atoms in the known universe, let alone in a dime - so we can safely say there would be no radiation left after less than a day.

(There were much smaller amounts of a longer-lived isotope produced, but it was too small to detect to start with, and only gets less with time.)

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