Author Topic: Using StartWin to adjust the default peaking start sizes in the SCALERS.DAT file  (Read 3237 times)


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    • John Donovan
I've been chatting with Keith Collins recently about his efforts to measure boron and one problem he's run into is low P/B values on his boron standards. So when he attempts to do a ROM (continuous) peaking scan to find the centroid, the software often reports that the P/B is too low. 

At Oregon I have a pure metal boron standard that I use for peaking boron and that seems to work well. Of course since we're usually not measuring pure boron one must eventually apply Area Peak Factors (APFs):

Or perhaps use the integrated scan methods for quantitative analysis so that we obtain the integrated intensity as opposed to merely the peak intensity:

A good summary of analyzing boron is here:

But it also occurred to me that one problem Keith might be running into (in additional to the several dozen other issues well known for analyzing boron!) is that the default start ROM peaking size might not be large enough, especially for spectrometers with smaller Rowland Circle sizes. Of course one can edit the start ROM peaking step size from the Peaking/Scan Options dialog in Probe for EPMA, but how do we determine a proper default size for this starting ROM peaking size?  This would be the value defined on line 19 of the SCALERS.DAT file found in the ProgramData\Probe Software\Probe for EPMA folder and a portion of one such file is shown here:

"1"      "2"      "3"      "4"      "5"    "scaler labels"
 ""       ""       ""       ""       ""     "fixed scaler elements"
 ""       ""       ""       ""       ""     "fixed scaler x-rays"
 3        3        3        3        3      "crystal flipping flag"
 85.      85.      85.      85.      85.    "crystal flipping position"
 2        2        4        2        2      "number of crystals"
 "PET"    "LIFH"   "PET"    "PET"    "LIF"  "crystal types1"
 "TAP"    "PETH"   "TAP"    "TAP"    "PET"  "crystal types2"
 ""       ""       "WSI60"  ""       ""     "crystal types3"
 ""       ""       "NiCrBN" ""       ""     "crystal types4"
 ""       ""       ""       ""       ""     "crystal types5"
 ""       ""       ""       ""       ""     "crystal types6"
 1.0      1.0      1.0      1.0      1.0  "deadtime in microseconds"
 60.      60.      40.      60.      60.  "off-peak size, (hilimit - lolimit)/off-peak size"
 40.      40.      30.      40.      40.  "wavescan size, (hilimit - lolimit)/wavescan size"
 80.      80.      50.      80.      80.  "peakscan size, (hilimit - lolimit)/peakscan size"
 100      100      100      100      100  "wavescan steps"
 40       40       40       40       40   "peakscan steps"
0.08     0.08     0.08     0.08     0.08  "LiF peaking start size"
 0.004    0.004    0.004    0.004    0.004 "LiF peaking stop size"
 30       30       30       30       30    "maximum peaking cycles"
 5.       5.       5.       5.       5.    "minimum peak to background"
 10.      10.      10.      10.      10.   "minimum peak intensity"

Now because the StartWin app doesn't store these values, it reads these "LiF peaking start size" values every time it runs, so I'm wondering if one could edit this value, re-start StartWin and attempt another peaking attempt until enough of the peak is found to calculate the centroid and obtain a decent P/B. My experience is that these values may be too small for some of the really low energy peaks such as boron. The program does calculate the actual peaking start size based on the crystal 2d, so that's a help of course.  See the PFE reference manual for details.

Note that the default P/B can also be edited on line 22 of this SCALERS.DAT file also.

Anyway, just my thought for the day.
The only stupid question is the one not asked!

Dan R

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Hi John, is there a discussion anywhere on setting proper default values? I think my default step sizes are too large and I end up having to play with the peaking parameter, i just tweak it until it looks right but it may be good to have some rules of thumb.

John Donovan

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The calculation of how these "peaking start sizes" are calculated for each crystal and sin theta are in the PFE User's Reference manual. It can be accessed by hitting the F1 key while in Probe for EPMA. It would be in the Installation | Configuration Files | "SCALERS.DAT" section.
John J. Donovan, Pres. 
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