We’ve been looking at hand held XRF spectrometers.  If you have not been introduced to this, you may be in for a real treat. A variety of companies make them- Bruker, Thermo, and Innov-X to name a few. These things are in the low-end Lexus price category, but are they ever amazing.  It’s straight out of Star Trek.

Clarke’s Third Law states that any sufficiently advanced technology is indistinguishable with magic. I gotta tell ya that these hand held XRF’s are just amazing.  You point at a sample and it gives a tally of the elements present, or most of them at least.  Some even have a built-in GPS you can punch to take a waypoint of the location of the sample you just analyzed out in the field.  It is a great tool for mineral prospecting.  

What is embarrassing is that this is the first I’ve heard of it. Our geologist friends have been using these things for a while now. 

The whole thing depends on a miniature X-ray source.  I’ve been looking into this.  For the curious folks out there, lithium niobate- LiNbO3- is a very interesting material.  Crystals of LiNbO3 have the property of pyroelectric potential. A pyroelectric crystal is one that is able to generate a polarization across the crystal faces in proportion to the temperature.  A pyroelectric xtal placed on a heating/cooling block in a vacuum is able to generate a stream of electrons energetic enough that, when stopped by a copper electrode, will generate x-rays. 

One manufacturer, AmpTek, produces a miniature x-ray unit called the Cool-X that has a photon output equivalent to two milliCuries, with 75 % of the flux less than 10 KeV.  Elsewhere in the product literature, the output is described as 5 milliSieverts per hour.  So, the user has to be a little careful with this thing. But rad safety issues aside, this is quite an amazing source. The product literature doesn’t come out and say what kind of crystals are used, but they may be a tantalate salt.

AmpTek Cool-X

The unit does not operate continuously. It can only generate x-rays durig a thermal cycling period, The xtal starts out cool and as it’s heated, generates the electron flux that is de-accelerated by impacting the copper to produce the x-rays. The lit gives a cycling interval of 2-5 minutes.  It is referred to as a Kharkov X-ray generator.

It’s magic.