XRF


X Ray Fluorescence

Illuminating radioactive substances with a radioactive source you excite the electrons of their atoms which then decays emit energy x-ray characteristics. For example,, in the image above, concerning analysis of silver gilt, Silver features energies were detected (electronic shell K ) and dell’ Gold (electronic shell L).

With this technique you can distinguish many materials, including silver, and even see through the plating, What is the base material.

With the energy that we provide is most likely to affect the electrons in the first shell (K), the innermost (less energy). The vacuum must be filled necessarily (to the laws of quantum mechanics) from another electron, from an outer shell and then with greater energy. Excess energy is emitted as photons with an energy characteristic that depends on the item and the electronic shell interested. The electronic shell concerned depends on the energy that we provide. Using americium (59 Kev). We can only examine substances with binding energies, in K shell, less than about 50 Kev – for metals with high binding energies we can examine the second shell, named L, and through this we can analyze most elements atomic number, like gold.


Documentation about XRF techniques

This four-page white paper explains everything you need to know about XRF techniques. The document also contains reference tables on the energies of the most important elements for these analyses. Everyone should download it and keep it handy.
XrayFluorescence_ITA
XrayFluorescence_ENG

Those wishing to make fixes and translations into other languages can download this compressed file that contains the originals in ODT format (Open Office): XrayFluorescence_ODT_Files


XRF Searches

Many researchers are active in research and XRF are already available guidelines for building efficient and simple sensors.

The recommendations to minimize the noise PmtAdapter
http://pico.dreamhosters.com/ThereminoPmtAdapter.html

The most interesting links:
http://pico.dreamhosters.com/XrfSpectrums.html
http://pico.dreamhosters.com/XrfSpectrumsPartTwo.html
http://pico.dreamhosters.com/XrfFluteSpectrums.html
http://pico.dreamhosters.com/ThereminoMcaSpectrums.html

In the following PDF file you see a great realization of probe for low energies. The quality of the probe is great, in a very short time of only 120 seconds, provides precise and obvious lines. In addition to the construction of the probe on file shows the lines of many materials including Zinc, Copper, Silver, Gold, White Gold, Nickel, Carbon steel and thin gold Plating. Low energie.pdf probe (file posted by Mario Mueller of death on Gamma Spectrometry in this forum messaggio_12740)


Research on antiques

This file: Test_Sr90_Am241 view part of our research collaborator. This is a comparison between the illuminator and Sr-90 Am-241. The best results were obtained with 4 uCurie of americium placed in 4 buttons all around a ring of lead shielding that prevents gamma radiation of americium to directly hit the Crystal scintillator.

This second file: Tibetan_InkPot_And_Container view tests on some Tibetan objects. NET and precise results. And’ now proved that with americium can do precision analysis in a very short time.

This image shows a filter for herbal infusions purchased in Russia, in a store for foreigners, at the time of Gorbachev. Had been sold as silver gilt – XRF analysis shows that the salesman had told the truth. In this picture the illuminator is the green plastic disk containing Sr-90.

In this document a comparison of two seemingly similar objects, the XRF distinguished sharply.

And in this ChineeseFruits a new interesting research. A test on the possibility of revealing the presence of arsenic in the pigments of ancient ceramic objects.

Finally this XRF_Additional_Notes focuses on the differences in results obtained using as illuminator the Sr-90 or the Am-241.

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  1. Luigi says:

    To excite x-ray fluorescence are normally utilized a variety of isotopes, on the basis of the items that you want to locate.
    L’ Am-241 is one of the most versatile, being able to excite the fluorescence from copper until tulio (K-shell emission) and the tungsten up to uranium (L-shell emission).
    For the lighter elements can’ use of Fe-55, which raises the fluorescence X from sulphur to chrome (shells K) and molybdenum barium enema (Shell L).
    We also use Cd-109, SR-90, Cm-244.
    Curium is used by Rover sent to Mars to determine the mineral composition of the planet's surface.
    A brief explanation of the technique used can be found here:
    http://mars.jpl.nasa.gov/msl/mission/instruments/spectrometers/apxs/

  2. Luigi says:

    Using the XRF is possible not only to determine the components of a metallic alloy, but also quantitative analysis in the same.
    The amount of x-rays emitted by the test substance depends on the concentration of the sample and therefore the width of several peaks is proportional to the quantity of each element present in the alloy.
    In practice, measuring the area subtended by the individual spikes (corrected to take account of the difference in efficiency of the sensor to different energies considered) that is proportional to the amount of the element emits x-rays that energy.
    For the exam only takes a few minutes, After that you can determine which, for example,, a bronze object consists, always as an example, from 60% of copper and from 40% by pond.

  3. Giacomo says:

    I can't figure out how to link a linear CCD to system theremino there is some documentation about?

    • Livio says:

      Theremino the system communicates with the hardware, using the PIN, lying on Master and Slave modules. And then through the slots, who are the boxes of communication with software.

      The PIN can be programmed with about twenty-five types of InOut “precooked”, all of which are analog, or at the very least that can be represented with a single numeric value.

      To control and read a CCD, You must exchange digital data, write and read books and follow particular protocols, differ from one model to another. And you cannot pull signals of this type through the pins and slots.

      This doesn't mean that you couldn't use a CCD, and let it interact with our applications. But that it should be done through other avenues, for example the USB, exactly as you do with the webcam.

      We have not developed anything on the subject but the network are many examples to easily read the CCD of mice (and the like).

    • Livio says:

      If you add some details about what you want to achieve and the initials of the CCD, We can give you some better advice or suggest alternatives.

      – – – – – – –

      Apparently this type of sensors it reads better in serial and USB. You may start from one of our application, using the serial port and modify it for the particular protocol to sensor.

      Some suitable application (with the functions for serial) are these:
      http://www.theremino.com/downloads/automation#balancereader
      http://www.theremino.com/downloads/radioactivity#bridge

      A good example that explains how to read a CCD sensor:
      http://www.bidouille.org/hack/mousecam

      Another example:
      http://spritesmods.com/?art=mouseeye

      In many of these projects use an Arduino but really serves no purpose, You can directly use the PC serial (RS232). Or, If your PC doesn't have the serial, There are convenient USB-to-serial adapters, they are cheaper, small and comfortable to an Arduino. And that work for, While the Arduino you should write special firmware.

      • Giacomo says:

        Thanks Livo, I looked in the meantime I wanted to start with a linear CCD TCD1304AP to get UV-VIS-NIR spectrometer, and learn to control CCD. Because I saw a post on a theremino spectrometer but in fact does not use the theremino but a simple webcam.

        My goal was to, Once you learn the basics, also moving on to other more complicated array sensors: I wanted to get myself a camera.

        I've already implemented a form of FLIR Lepton http://www.flir.com/cores/content/?id=66257 and an Arduino but this in my opinion is not ideal because I can't communicate fairly quickly with the computer, I'm then using a Raspberry Pi to capture images from the camera but the ideal thing would be to connect the printer directly to the computer and that's why I wanted to use a theremino. The problem is that I think theremino doesn't support well the I2C Protocol and then maybe I'll have to stick with the Raspberry.

        • Livio says:

          To use the i2c you should reprogram the firmware of Theremino Master. So I suggest you continue with Raspberry.

          You will need the same program the I2c communication, but you haven't done so already and then know how to do it. Instead to program the Master you should familiarize yourself with the firmware of the PIC and with difficult and little intuitive techniques.

          But the best solution is as follows:

          Use any Tablet with Windows 10 (starting from 50 Euro) or embedded PC as Meegopad T2 with Windows 10 (great and cost only 87 Euro). These PCs costing just over a Raspberry but are worth much more. Consume more or less the same current, but they are 100 times more powerful, are quadcore, have Ram and HardDisk at will, have WiFi, the Bluetooth, the sound card, battery control, etc..

          Then, to connect I2C devices, you could use any USB to I2C. There are various models on eBay, starting from few euros.

          And finally you could program comfortably in VbNet, CSharp, CPP or any other preferred language at a high level and communicate with the rest of the system Theremino through the slots.

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