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<p>[QUOTE=&quot;calcol, post: 4673769, member: 77639&quot;]Doug,</p><p><br /></p><p>If you read the PCGS article on the sniffer, it describes energy-dispersive X-ray spectrometry (EDX) as one of the techniques it uses.&nbsp; EDX is a more generalized term than XRF (x-ray fluorescence).&nbsp;&nbsp; In EDX,&nbsp; atoms of the test material can be excited by any means to emit x-rays, which are analyzed to determine the elements they came from.&nbsp; The two general means of excitation are EMR (electromagnetic radiation), i.e. gamma rays or x-rays ... and x-rays are the usual choice ... OR ... particle bombardment&nbsp; ... electrons in a scanning electron microscope (SEM) are the usual choice.&nbsp; XRF is EDX where the means of exciting the atoms in the test sample is x-rays.&nbsp; Compact XRF units resemble a gun, but some are the size of a car.&nbsp; The larger units can probe more deeply into the sample, focus on smaller areas, and may have automated sample handling as well.</p><p><br /></p><p>The sniffer almost certainly uses an XRF form of EDX.&nbsp; Using a particle accelerator, like a SEM, would be unnecessarily bulky, expensive and technically demanding.&nbsp; Without seeing the innards of the sniffer, it&#039;s hard to say how compact its XRF unit is.&nbsp; It may, in fact, be a gun.&nbsp; Many of these have a computer interface.</p><p><br /></p><p>Any stand-alone XRF guns PCGS has are probably used when graders suspect, but aren&#039;t certain, that a coin is a counterfeit.&nbsp;&nbsp; If you send a coin to PCGS for elemental analysis, they send it out to a private lab that uses SEM.&nbsp; SEM provides a more accurate elemental analysis.&nbsp; Beyond that, SEM can analyze multiple, very small areas on the coin.&nbsp; An XRF gun is like a shotgun; SEM is like an expensive rifle with a scope.</p><p><br /></p><p>I suggest Wikipedia for further reading:</p><p><br /></p><p><a href="https://en.wikipedia.org/wiki/Energy-dispersive_X-ray_spectroscopy" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://en.wikipedia.org/wiki/Energy-dispersive_X-ray_spectroscopy" rel="nofollow">https://en.wikipedia.org/wiki/Energy-dispersive_X-ray_spectroscopy</a></p><p><br /></p><p><a href="https://en.wikipedia.org/wiki/X-ray_fluorescence" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://en.wikipedia.org/wiki/X-ray_fluorescence" rel="nofollow">https://en.wikipedia.org/wiki/X-ray_fluorescence</a></p><p><br /></p><p>Cal[/QUOTE]</p><p><br /></p>

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