XRF Scan Question For Clad Or Plated Coins - Page 2

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Author	Replies: 20 / Views: 6,682	Page: of 2

SPP-Ottawa Moderator Canada 10458 Posts	Posted 05/28/2018 4:03 pm I do test coins for collectors, at no cost. Usually one or two coins, if all other avenues to determine composition (for example off-metal coins) have not ruled the coin as a garage job. You have to pay for the postage - the caveat is that if it is something interesting, I get to publish the results (either here at CCF or in research articles). "Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search." -- J. Robert Oppenheimer Content of this post is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. See: http://creativecommons.org/licenses...0/deed.en_US My eBay store Report this Post to the Staff
SPP-Ottawa Moderator Canada 10458 Posts	Posted 05/28/2018 4:05 pm Quote: Another question: what is the expected penetration depth for Cupro Nickel (75% Cu and 25% Ni)? If the beam source is constant - it is a function of density... I showed two metals of differing densities in my previous post. A quick peek at the Periodic Table should be a good clue for you... try and figure it out! "Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search." -- J. Robert Oppenheimer Content of this post is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. See: http://creativecommons.org/licenses...0/deed.en_US My eBay store Report this Post to the Staff
Pete2226 Pillar of the Community United States 3330 Posts	Posted 05/29/2018 10:18 am Quote: If the beam source is constant - it is a function of density... I showed two metals of differing densities in my previous post. A quick peek at the Periodic Table should be a good clue for you... try and figure it out! I am not sure how to do the math, but just trying to approximate, I offer penetration depths: 75%Cu 25%Ni = approx. 140 microns @ 20 keV 75%Cu 25%Ni = approx. 950 microns @ 35 keV Quarter clad layer of the composite strip out of which blanks are punched = 228.6 microns +/- 25.4 microns I would conclude that if a scan is at the higher levels of keV, the clad layer of a quarter should be able to be penetrated with room to spare. What am I missing? Report this Post to the Staff
SPP-Ottawa Moderator Canada 10458 Posts	Posted 05/30/2018 10:19 am My XRF has a 50 keV iridium beam source... maybe I should grab a clad US quarter and test your math... but I am skeptical... Don't forget that is penetration depth only, there still has to be enough energy for the "escape depth", meaning that the energy penetrates but also has to escape back to the detector. Also, energy is attenuated all the way down to maximum penetration depth, "Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search." -- J. Robert Oppenheimer Content of this post is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. See: http://creativecommons.org/licenses...0/deed.en_US My eBay store Report this Post to the Staff
Pete2226 Pillar of the Community United States 3330 Posts	Posted 05/30/2018 2:31 pm Quote: My XRF has a 50 keV iridium beam source... maybe I should grab a clad US quarter and test your math... but I am skeptical... I don't know about my math either, but those are approximate values from comparing densities of the elements. I was surprised to see that Ni and Cu are only 0.06 different in density! I would be most interest in the results of such a scan. I am aware of the need for the ray to escape, but I have seen very little about calculating the depths for that! (Except that it will probably be from a more shallow depth). Edited by Pete2226 05/30/2018 2:35 pm Report this Post to the Staff
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