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Probe for EPMA / Re: Basic EPMA
« Last post by John Donovan on Today at 11:52:12 am »
And just to make it all more "symmetrical" we added an Imaging button to the "Basic EPMA" window:



Ready to update now.
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Cameca / Re: SXFive Fe standby and script creation
« Last post by theo_nt on Today at 07:01:02 am »
Hi,

The C2 will go to 2000 if you set Xhi to 999. The main reason for doing it is just to avoid as much as possible the contamination of the two Faraday plates responsible for beam deflection in the Faraday cup. Contaminated plates will result in what we call the "banana effect", which affects the quality of the X-ray mappings (linear elements will became curved). Using Xhi 999 most of the current will not go through the tube, which will reduce the contamination of the Faraday plates. We do not deflect the beam to the Faraday cup at all when the beam is in standby mode.

Theo
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Probe for EPMA / Re: Basic EPMA
« Last post by John Donovan on December 11, 2019, 05:00:40 pm »
Hello,

I am also teaching my class right now and this feature was received very, very well. So, thank you for implementing this and thanks to Julie for suggesting this!!

And I know I had my chance to say something and missed it but based on my own workflow, I would actually say that "Standard assignments" and "Analytical conditions" should be yellow too, "Adjust count times" should be the fifth instead of the third button of the first block and I would also add "Output Images" as an option at the end.

But otherwise, it is perfection  :D

The latest version of Probe for EPMA now has an improved Basic EPMA window as suggested by Anette von der Handt:

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The latest version of Probe for EPMA has a small tweak that some might find useful.

When plotting your wavescans from the Plot! window, one can model their background fits using the Model backgrounds button. This button displays the Model backgrounds dialog which can be utilized to graphically select various background fits, in addition to specifying the multi-point background positions.

In addition one can assign these selections to the current sample (by default), or to a number of selected samples as seen here:



In this latest version of PFE, not only are the background fits and multi-point background positions saved to the selected samples, but now also the normal hi and lo off-peak background positions.  Previously the hi and lo off-peak background positions were only modified in the current sample.

Of course the software will not modify hi/lo or multi-point background positions for samples which already contain data.
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Probe for EPMA / Re: Basic EPMA
« Last post by John Donovan on December 10, 2019, 06:56:21 pm »
And I know I had my chance to say something and missed it but based on my own workflow, I would actually say that "Standard assignments" and "Analytical conditions" should be yellow too, "Adjust count times" should be the fifth instead of the third button of the first block and I would also add "Output Images" as an option at the end.

We can do that!   ;D
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Probe for EPMA / Re: Basic EPMA
« Last post by Anette von der Handt on December 10, 2019, 06:32:21 pm »
Hello,

I am also teaching my class right now and this feature was received very, very well. So, thank you for implementing this and thanks to Julie for suggesting this!!

And I know I had my chance to say something and missed it but based on my own workflow, I would actually say that "Standard assignments" and "Analytical conditions" should be yellow too, "Adjust count times" should be the fifth instead of the third button of the first block and I would also add "Output Images" as an option at the end.

But otherwise, it is perfection  :D
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Discussion of General EPMA Issues / Re: Community consensus k-ratio database?
« Last post by Probeman on December 10, 2019, 11:58:29 am »
Here's a start: let's purchase/synthesize/beg/borrow/steal some simple, synthetic materials that would be a suitable test of of our instruments' ability to make a k-ratio measurement.  Let's start simple, for example just one possibility off the top of my head, let's measure a pure synthetic Al2O3 single crystal, and a pure synthetic spinel (MgAl2O4) single crystal, both available in kilogram quantities and both beam stable.  Let's measure Al Ka in both materials (which is significantly absorbed by Mg in the spinel), and let's see if each of our spectrometers produce the same k-ratios. 

We can bring LiF and PET crystal into play by utilizing other elements, but consider this: for the purposes of a k-ratio comparison between spectrometers or between different instruments, it really doesn't matter what the exact compositions of our two materials are, so long as we are measuring the exact same two compositions. If the two materials are exactly the same compositionally, the k-ratios from all spectrometers, on all instruments (assuming a nominal 40 degrees takeoff), should be the same within precision (let's ignore the differences in effective electron landing energy from different carbon coating thickness, etc. for now, by utilizing significant overvoltages on our measurements!).

On the other hand, obviously, if we picked two materials for which we know exactly their compositions (via considerations of crystallinity, purity, homogeneity, thermodynamics or whatever), we would have a good first candidate for our k-ratio composition database.

This is just a first cut, but I suggest we start thinking about some high purity, beam stable, synthetic single crystal materials which are available already in kilogram quantities, from say laser optics crystal manufacturers for example (just their "cutoff" material as we obtained for our RbTiOPO4 material), and see which ones are good candidates for testing our k-ratio machines.

OK, it seems we have a lack of excitement for this project so I'm going to start locating some pure synthetic materials, Al2O3, MgO, MgAl2O4, etc. and start making up some mounts (with Julie Chouinard's help!).  They can all be carbon coated at the same time for reproducibility so that should not matter too much as long as our overvoltages are significant.

Question to the community: should we circulate a single mount, or should there be a number of replicate mounts that are circulated? 
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Probe Image / Re: PI data transmission and/or logging timelag?
« Last post by John Donovan on December 09, 2019, 02:05:53 pm »
OK, cool. I agree that Julien and Mike are two of the best to learn from.

On bi-directional scanning, yeah, we've thought about implementing that off and on, but the trouble is many stages aren't reproducible enough for this. Of course for low resolution scanning such as you are doing on whole thin sections, it would make some sense.
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Probe Image / Re: PI data transmission and/or logging timelag?
« Last post by orlandin on December 09, 2019, 01:52:22 pm »
Well, the thought of quantifying them did cross my mind since it would be so easy and you can clearly see concentration differences in the Ca, maybe in the P too. Even that travesty of counting statistics would still be more useful than a purely qualitative map!

Yes, exactly like the UMass monazite maps! I learned about this from Julien Allaz while we were trying to find monazites to date in deformed frictional melt veins from lower-crustal earthquakes. What I found here at UT was that folks were spending 8-12 hours collecting full thin section EDS maps, and then just overlaying the P, Zr, and Ti maps. The rest of the gigabytes of data seemed to be entirely beside the point to them, so I proposed this as a much more efficient method for locating their in-situ accessories minerals which could be differentiated with just five elements. Also, the FEI XL30 hosting the OI EDS system died and left them without much choice. So enthusiasm for these UMass-style rapid scans has been growing here too!

Also, you were 100% right about the logging - disabling that has resulted in maps almost as fast as they are supposed to be. Now if only I could double my speed yet again by using the JEOL bidirectional scanning in PI... ;)

Edit: total run time as recorded in .prbimg files went from 3:25 hrs (11.7 ms/pixel) to 1:43 hrs (5.9 ms/pixel) for a map predicted to take 1:02 hrs (3.5 ms/pixel [but entered as 3]) in PI - difference in time on the 'fast' version from predicted because 'carriage returns' at max stage speed take up 41 minutes in a 1024 row map ~1 cm tall?
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Probe Image / Re: PI data transmission and/or logging timelag?
« Last post by John Donovan on December 09, 2019, 01:27:12 pm »
Hi Phil,
I see. So you're not trying to quantify these maps, just using them for sample navigation?  That makes sense.

This is very similar to what Mike Jercinovic does to locate monazite grains in his rocks.  They need to find *every* monazite grain due to the complex fine scale textures in their metamorphic rocks. So they use one of their EPMA instruments just to run stage scans on thin sections all day and night.
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