Using Duplicate Elements in Probe for EPMA

[Probeman]

One of the cool features in Probe for EPMA is that the program can properly handle the presence of "duplicate" elements for fully quantitative analysis.

This feature is often utilized with the "aggregate" mode,  for increasing the "geometric efficiency" of the instrument by combining photons (in software!) from different spectrometers to improve sensitivity. Note however, for this "aggregate" mode, the software will only combine photons from elements that utilize the *same* x-ray emission line! Why?  Because the physics doesn't care about the analyzing crystals used (photons is photons!), but the photon energies are very important for the physics, so they cannot be combined at the photon level.

Of course one might also just want some replicate measurements on multiple spectrometers without combining them using "aggregate" mode. If these are trace elements they will not affect the matrix correction enough to matter so that is fine.  But if the concentrations of the duplicate elements are large enough, the matrix correction will be adversely affected.

Let's look at an example of this, using some GaAs and GaSb synthetic standards. Here is the output from the analysis of GaSb:

St  669 Set   2 GaSb (synthetic)
TakeOff = 40.0  KiloVolt = 20.0  Beam Current = 20.0  Beam Size =   10
(Magnification (analytical) =  40000),        Beam Mode = Analog  Spot
(Magnification (default) =      400, Magnification (imaging) =    800)
Image Shift (X,Y):                                          .00,   .00

(MAC block)
Number of Data Lines:   5             Number of 'Good' Data Lines:   5
First/Last Date-Time: 01/07/2014 05:39:27 PM to 01/07/2014 05:47:40 PM
WARNING- Using Exponential Off-Peak correction for as ka
WARNING- Using Exponential Off-Peak correction for sb la

Average Total Oxygen:         .000     Average Total Weight%:  154.313
Average Calculated Oxygen:    .000     Average Atomic Number:   39.191
Average Excess Oxygen:        .000     Average Atomic Weight:   84.510
Average ZAF Iteration:        5.00     Average Quant Iterate:     2.00
WARNING- Duplicate analyzed elements are present in the sample matrix!!
Use Aggregate Intensity option or Disable Quant feature for accurate matrix correction.

St  669 Set   2 GaSb (synthetic), Results in Elemental Weight Percents
 
ELEM:       Ga      Ga      Ga      As      In      Sb
BGDS:      LIN     LIN     LIN     EXP     LIN     EXP
TIME:    60.00   60.00   60.00   60.00   30.00   30.00
BEAM:    19.94   19.94   19.94   19.94   19.94   19.94

ELEM:       Ga      Ga      Ga      As      In      Sb   SUM 
XRAY:     (la)    (ka)    (la)    (ka)    (la)    (la)
   137  28.309  34.369  28.601   -.038   -.059  63.473 154.656
   138  28.262  34.325  28.414   -.144   -.040  63.320 154.137
   139  28.303  34.444  28.558   -.097   -.070  63.177 154.315
   140  28.363  34.395  28.473   -.038   -.096  63.243 154.339
   141  28.368  34.292  28.484   -.080   -.051  63.107 154.120

AVER:   28.321  34.365  28.506   -.079   -.063  63.264 154.313
SDEV:     .044    .059    .074    .044    .022    .141    .216
SERR:     .020    .026    .033    .020    .010    .063
%RSD:      .16     .17     .26  -55.91  -34.07     .22

PUBL:   36.413  36.413  36.413    n.a.    n.a.  63.587 100.000
%VAR:   -22.22   -5.62  -21.72     ---     ---  (-.51)
DIFF:   -8.092  -2.048  -7.907     ---     ---  (-.32)
STDS:      662     662     662     662    2002     669

STKF:    .4679   .5103   .4679   .4873   .5621   .5907
STCT:   648.92  694.60  232.91   91.23  200.87  236.11

UNKF:    .1403   .3532   .1413  -.0008  -.0006   .5906
UNCT:   194.62  480.73   70.31    -.15    -.21  236.09
UNBG:     2.62   12.42     .73    3.04    1.66    2.79

ZCOR:   2.0181   .9730  2.0181  1.0192  1.0841  1.0711
KRAW:    .2999   .6921   .3019  -.0016  -.0010  1.0000
PKBG:    75.25   39.72   97.62     .95     .88   85.59
INT%:     ----    ----    ----    ----    ----    ----


First note that we are acquiring Ga La on two spectrometers and Ga Ka on one spectrometer, plus As, In and Sb. GaSb is the primary standard for Sb and GaAs is the primary standard for Ga.

Next we note that the analysis is crazy.  The total is over 150% and we have three times as much Ga as we should... we makes sense because we are measuring Ga on three spectrometers!  So let's begin by turning on the "aggregate" mode in the Analytical | Analysis Options dialog as seen here:



Now we get this output when we click the Analyze button:

St  669 Set   2 GaSb (synthetic)
TakeOff = 40.0  KiloVolt = 20.0  Beam Current = 20.0  Beam Size =   10
(Magnification (analytical) =  40000),        Beam Mode = Analog  Spot
(Magnification (default) =      400, Magnification (imaging) =    800)
Image Shift (X,Y):                                          .00,   .00

(MAC block)
Number of Data Lines:   5             Number of 'Good' Data Lines:   5
First/Last Date-Time: 01/07/2014 05:39:27 PM to 01/07/2014 05:47:40 PM
WARNING- Using Exponential Off-Peak correction for as ka
WARNING- Using Exponential Off-Peak correction for sb la
WARNING- Using Aggregate Intensities for Duplicate Elements
Element ga la on channel 1(LTAP) is duplicated by ga la on channel 3(TAP)
Element ga la on channel 1(LTAP) is duplicated by ga la on channel 3(TAP)

Average Total Oxygen:         .000     Average Total Weight%:  129.446
Average Calculated Oxygen:    .000     Average Atomic Number:   40.787
Average Excess Oxygen:        .000     Average Atomic Weight:   88.152
Average ZAF Iteration:        5.00     Average Quant Iterate:     2.00

St  669 Set   2 GaSb (synthetic), Results in Elemental Weight Percents
 
ELEM:       Ga      Ga      Ga      As      In      Sb
BGDS:      LIN     LIN     LIN     EXP     LIN     EXP
TIME:    60.00   60.00     .00   60.00   30.00   30.00
BEAM:    19.94   19.94     .00   19.94   19.94   19.94
AGGR:        2                                       

ELEM:       Ga      Ga      Ga      As      In      Sb   SUM 
XRAY:     (la)    (ka)    (la)    (ka)    (la)    (la)
   137  31.221  34.985    .000   -.038   -.059  63.615 129.725
   138  31.123  34.941    .000   -.143   -.039  63.462 129.343
   139  31.202  35.062    .000   -.097   -.070  63.319 129.417
   140  31.220  35.011    .000   -.038   -.095  63.387 129.485
   141  31.233  34.907    .000   -.080   -.050  63.249 129.259

AVER:   31.200  34.981    .000   -.079   -.063  63.406 129.446
SDEV:     .044    .060    .000    .044    .021    .141    .177
SERR:     .020    .027    .000    .020    .010    .063
%RSD:      .14     .17     .09  -55.91  -34.07     .22

PUBL:   36.413  36.413    n.a.    n.a.    n.a.  63.587 100.000
%VAR:   -14.32   -3.93     .00     ---     ---  (-.28)
DIFF:   -5.213  -1.432     .00     ---     ---  (-.18)
STDS:      662     662       0     662    2002     669

STKF:    .4637   .5222   .0000   .4908   .5621   .5976
STCT:   881.83  694.60     .00   91.23  200.87  236.11

UNKF:    .1393   .3614   .1413  -.0008  -.0006   .5976
UNCT:   264.92  480.73     .00    -.15    -.21  236.09
UNBG:     3.35   12.42     .00    3.04    1.66    2.79

ZCOR:   2.2399   .9679  2.0181  1.0065  1.0729  1.0610
KRAW:    .3004   .6921   .3019  -.0016  -.0010  1.0000
PKBG:    80.05   39.72     .00     .95     .88   85.59
INT%:     ----    ----    ----    ----    ----    ----


This is a little better because the two Ga La channels have been "aggregated" as we specified, but we still have duplicate Ga La and Ga Ka.  What we need to do here is to "turn off" either the 2 Ga La channels or the single Ga Ka channel using the "Disable Quant" feature. 

Since the Ga La channels are being "aggregated" it is critically important to use the "Disable Quant" feature on *both* the standards *and* the unknowns.  Since this is a secondary standard for Ga, we would want to apply the "Disable Quant" flags to both the primary GaAs standard and the GaSb secondary standard.

Or we could just set the "Disable Quant" flag for *only* the Ga Ka channel in this standard sample as seen here:



since it is not duplicated as far as the "aggregate" mode is concerned.

Now, when we again click the Analyze button in the Analyze! window we obtain these reults:

St  669 Set   2 GaSb (synthetic)
TakeOff = 40.0  KiloVolt = 20.0  Beam Current = 20.0  Beam Size =   10
(Magnification (analytical) =  40000),        Beam Mode = Analog  Spot
(Magnification (default) =      400, Magnification (imaging) =    800)
Image Shift (X,Y):                                          .00,   .00

(MAC block)
Number of Data Lines:   5             Number of 'Good' Data Lines:   5
First/Last Date-Time: 01/07/2014 05:39:27 PM to 01/07/2014 05:47:40 PM
WARNING- Using Exponential Off-Peak correction for as ka
WARNING- Using Exponential Off-Peak correction for sb la
WARNING- Using Aggregate Intensities for Duplicate Elements
Element ga la on channel 1(LTAP) is duplicated by ga la on channel 3(TAP)
Element ga la on channel 1(LTAP) is duplicated by ga la on channel 3(TAP)
WARNING- Quantitation is Disabled For ga ka, Spectro 3

Average Total Oxygen:         .000     Average Total Weight%:   99.891
Average Calculated Oxygen:    .000     Average Atomic Number:   43.717
Average Excess Oxygen:        .000     Average Atomic Weight:   95.732
Average ZAF Iteration:        7.00     Average Quant Iterate:     2.00

St  669 Set   2 GaSb (synthetic), Results in Elemental Weight Percents
 
ELEM:       Ga      Ga      Ga      As      In      Sb
BGDS:      LIN     LIN     LIN     EXP     LIN     EXP
TIME:    60.00     ---     .00   60.00   30.00   30.00
BEAM:    19.94     ---     .00   19.94   19.94   19.94
AGGR:        2     ---                               

ELEM:       Ga    Ga-D      Ga      As      In      Sb   SUM 
XRAY:     (la)    (ka)    (la)    (ka)    (la)    (la)
   137  36.465     ---    .000   -.038   -.057  63.792 100.162
   138  36.363     ---    .000   -.142   -.039  63.634  99.817
   139  36.467     ---    .000   -.096   -.068  63.491  99.794
   140  36.475     ---    .000   -.037   -.094  63.562  99.905
   141  36.479     ---    .000   -.079   -.049  63.425  99.776

AVER:   36.450     ---    .000   -.078   -.061  63.581  99.891
SDEV:     .049     ---    .000    .044    .021    .141    .159
SERR:     .022     ---    .000    .020    .009    .063
%RSD:      .13     ---     .09  -55.91  -34.07     .22

PUBL:   36.413    n.a.    n.a.    n.a.    n.a.  63.587 100.000
%VAR:      .10     .00     .00     ---     ---  (-.01)
DIFF:     .037     .00     .00     ---     ---  (-.01)
STDS:      662     ---       0     662    2002     669

STKF:    .4557     ---   .0000   .4976   .5621   .6098
STCT:   881.83     ---     .00   91.23  200.87  236.11

UNKF:    .1369     ---   .0000  -.0008  -.0006   .6097
UNCT:   264.92     ---     .00    -.15    -.21  236.09
UNBG:     3.35     ---     .00    3.04    1.66    2.79

ZCOR:   2.6622     ---   .0000   .9833  1.0529  1.0428
KRAW:    .3004     ---   .0000  -.0016  -.0010  1.0000
PKBG:    80.05     ---     .00     .95     .88   85.59
INT%:     ----     ---    ----    ----    ----    ----


See the line above labeled VAR% which is the relative percent variance from the "published" value. Of course a relative accuracy of less than 1% is almost too good to be true, but we'll take it!  :-)

Especially since the matrix correction for Ga La in this standard is over 200%, so perhaps we ought to call it "spurious accuracy".

[Probeman]

Here's an important tip on using the aggregate mode with duplicate elements:

The duplicate elements on your spectrometer/crystals that are aggregated for your unknowns, must match the duplicate elements on your spectrometer/crystals that are aggregated for your standards.

Why?  Because the intensities from each duplicate elements are summed for both the standards and the unknowns.  If they don't have the same geometry efficiency (intensity/area) then when the k-ratio is formed, it will not be accurate.

It would be like standardizing on one crystal/spectrometer combination and using a different spectrometer/crystal combination for the unknowns.  I thought about adding code to check that the user does this properly, throughout a run that could be any combination of duplicate elements/spectometers/crystals, but my brain exploded...  so I decided to leave responsibility for this to you, kind users.
john

[John Donovan]

I recently had a colleague of ours contact me because they were analyzing a trace element on several spectrometers to improve their sensitivity. That is, by improving the "geometric efficiency" of the instrument by tuning up the trace element on several spectrometers. Here is an example (posted above) of analyzing some duplicate major elements, which shows the issue more clearly:

https://probesoftware.com/smf/index.php?topic=155.msg646#msg646

However in examining their trace element data, they found that they needed to "disable quant" on one of the spectrometers for an electronic/mechanical reason, but when they disabled the quantification for that element/spectrometer, the k-ratio was no longer correct.

I wanted to recall this topic to remind everyone that because Probe for EPMA aggregates the intensities for *both* the unknowns *and* the standard samples (both are necessary to construct the k-ratio!), both the unknowns and the standards need to be treated the same. So if one disables an element in the unknown sample, one should also disable the quantification for the same element in the standard sample.

Now maybe a really smart developer would find a way to warn the user that the element /spectrometer for a particular unknown is disabled, but that the same element/spectrometer for the corresponding standard is not disabled, but it gets complicated let me assure you!  But we are thinking about how such a warning in the code could be implemented!

So in the meantime, if you decide you want to disable quantification for a particular duplicate element in an unknown sample, be sure to also disable the quantification for that same duplicate element in the standard samples.

The easiest way to do that is to simply click the "All Samples" option in the Analyze! window, then click the Select All button, then click the Elements/Cations button, then disable the quantification for the duplicate element as usual.

[John Donovan]

I'm popping this topic forward because Ben Wade noticed that when he disabled some duplicate elements in a sample he found an anomaly in the aggregate averages of the aggregated channel. So, make sure you are "buckled in" because this gets "down into the weeds" as they say!

It's really my fault because I could not figure out how to handle this issue automatically, but it's simply the case, that when you are analyzing duplicate elements on multiple spectrometers (usually to improve your sensitivity for trace elements), one must acquire their standard intensities in the same manner as their unknown intensities.  You know, the k-ratio is the unknown intensity divided by the standard intensity, Iu/Is.  So this is also true when acquiring duplicate elements on multiple spectrometers.

So here, Ben (used with permission), analyzed chlorine using all 5 spectrometers:

ELEM:       Cl      Cl      Cl      Cl      Cl   SUM
XRAY:     (ka)    (ka)    (ka)    (ka)    (ka)
   229  .03827  .03803  .03709  .03733  .03756 100.367
   230  .03833  .03919  .03795  .03770  .03694 100.369
   231  .03773  .03516  .03829  .03928  .03818 100.368
   232  .03869  .03898  .03822  .03723  .03735 100.369
   233  .03840  .03895  .03783  .03689  .03848 100.369
   234  .03791  .03882  .03796  .03869  .03805 100.370
   235  .03952  .03721  .03832  .03809  .03766 100.369
   236  .03761  .03892  .03753  .03841  .03867 100.370
   237  .03797  .03810  .03787  .03667  .03878 100.368
   238  .03903  .03849  .03795  .03692  .03833 100.369

AVER:   .03834  .03819  .03790  .03772  .03800 100.369
SDEV:   .00060  .00122  .00037  .00087  .00060  .00103
SERR:   .00019  .00039  .00012  .00028  .00019
%RSD:  1.56001 3.19181  .97764 2.30551 1.59035
STDS:      545     545     545     545     545

All channels show roughly 380 PPM of Cl. Now here he aggregates all these duplicate elements:

ELEM:       Cl      Cl      Cl      Cl      Cl   SUM
XRAY:     (ka)    (ka)    (ka)    (ka)    (ka)

   229  .03760  .00000  .00000  .00000  .00000 100.217
   230  .03781  .00000  .00000  .00000  .00000 100.217
   231  .03806  .00000  .00000  .00000  .00000 100.217
   232  .03799  .00000  .00000  .00000  .00000 100.217
   233  .03809  .00000  .00000  .00000  .00000 100.217
   234  .03816  .00000  .00000  .00000  .00000 100.217
   235  .03828  .00000  .00000  .00000  .00000 100.217
   236  .03811  .00000  .00000  .00000  .00000 100.217
   237  .03799  .00000  .00000  .00000  .00000 100.217
   238  .03818  .00000  .00000  .00000  .00000 100.217

AVER:   .03803  .00000  .00000  .00000  .00000 100.217
SDEV:   .00020  .00000  .00000  .00000  .00000  .00015
SERR:   .00006  .00000  .00000  .00000  .00000
%RSD:   .51712   .0000   .0000   .0000   .0000
STDS:      545       0       0       0       0

Everything looks as expected. Now he disables the 5th Cl channel:

ELEM:       Cl      Cl      Cl      Cl    Cl-D   SUM
XRAY:     (ka)    (ka)    (ka)    (ka)    (ka)

   229  .02709  .00000  .00000  .00000     --- 100.208
   230  .02748  .00000  .00000  .00000     --- 100.209
   231  .02738  .00000  .00000  .00000     --- 100.209
   232  .02755  .00000  .00000  .00000     --- 100.209
   233  .02732  .00000  .00000  .00000     --- 100.209
   234  .02751  .00000  .00000  .00000     --- 100.209
   235  .02775  .00000  .00000  .00000     --- 100.209
   236  .02729  .00000  .00000  .00000     --- 100.209
   237  .02714  .00000  .00000  .00000     --- 100.208
   238  .02745  .00000  .00000  .00000     --- 100.209

AVER:   .02740  .00000  .00000  .00000     --- 100.209
SDEV:   .00020  .00000  .00000  .00000     ---  .00015
SERR:   .00006  .00000  .00000  .00000     ---
%RSD:   .71560   .0000   .0000   .0000     ---
STDS:      545       0       0       0     ---

And now the average Cl is significantly lower. How is this possible?  The answer is that because one of the unknown elements was disabled for quant, but the same element channel in the standard was *not* disabled for quant, the k-ratio was improperly constructed.

The solution is to also disable the 5th element channel in the standard sample. Once we've done that, we get the following correct results:

ELEM:       Cl      Cl      Cl      Cl    Cl-D   SUM
XRAY:     (ka)    (ka)    (ka)    (ka)    (ka)
   229  .03761  .00000  .00000  .00000     --- 100.217
   230  .03815  .00000  .00000  .00000     --- 100.217
   231  .03801  .00000  .00000  .00000     --- 100.217
   232  .03824  .00000  .00000  .00000     --- 100.217
   233  .03793  .00000  .00000  .00000     --- 100.217
   234  .03820  .00000  .00000  .00000     --- 100.217
   235  .03852  .00000  .00000  .00000     --- 100.217
   236  .03789  .00000  .00000  .00000     --- 100.217
   237  .03768  .00000  .00000  .00000     --- 100.217
   238  .03811  .00000  .00000  .00000     --- 100.217

AVER:   .03803  .00000  .00000  .00000     --- 100.217
SDEV:   .00027  .00000  .00000  .00000     ---  .00021
SERR:   .00009  .00000  .00000  .00000     ---
%RSD:   .71557   .0000   .0000   .0000     ---
STDS:      545       0       0       0     ---

My bad was that I did not have a warning about this possible situation, where once is acquiring duplicate elements, using "aggregate" mode to combine the intensities, but then disabling one of the duplicate elements channels.  This now fixed in the latest version of PFE as seen here:



Again, my apologies, and thank-you to Ben Wade for noticing this oversight and reporting it to me.  Update, as usual, from the PFE Help menu and you will now have this warning when it is appropriate.

[John Donovan]

This might be slightly esoteric, but still worth a post...

As you all know, this topic describes how one can acquire duplicate elements in Probe for EPMA and have the software "aggregate" the intensities when constructing the k-ratio for quantitative analysis.  Of course, this requires that one acquires these duplicate elements on both ones unknowns and ones standards. This is because the k-ratio requires appropriately scaled intensities...

Here is an example that Andrew Locock sent me a few days ago where he acquire duplicate Al and Mg for an amphibole composition:



Note that because Al and Mg are major elements, the totals are too high and of course this affects the overall matrix correction adversely for all the elements. Note that if these duplicate elements were only present at trace levels, these adverse matrix effects would be minimal.

So, we now turn on the "aggregate" feature from the Analytical | Analytical Options menu as described earlier in this topic and now we get much more reasonable totals:


 
Note that the duplicate elements are now zero. This is because the intensities of these duplicate elements (from the unknowns *and* standards) has now been summed into the first instance of these elements. 

Note also that I've highlighted the Locock amphibole export menu in the Analyze! window.  This is where Andrew found a problem because the amphibole export code was looking for each element and loading the results into the export format. But since the duplicate elements are after the first instance of the elements, these zero values from the duplicate elements were loaded into the exported file.
 
After a quick tweak of the code we now obtain the export output that we should expect:



This code modification fixes this export format for both the Locock amphibole export and the garnet export format.  Update as usual  from the Probe for EPMA Help menu to get this latest version.

[Rom]

Great option, thank you.
Does it mean the "aggregate option" we can use only by 2 ways:
1. the system can aggregate data of 1 line from several channels (for instance, Ka from channels 1,2,3...)
2. the system can aggregate data of 2 lines only from 2 channels (for instance, La from channel 1 (TAP-crystal) and Ka from channel 3 (LIF-crystal))

The system cannot aggregate data of 2 lines from 3 channels and more (for instance, La from channels 1 and 2 (TAP-crystals) and Ka from channel 3 (LIF-crystal))

[John Donovan]

Great option, thank you.
Does it mean the "aggregate option" we can use only by 2 ways:
1. the system can aggregate data of 1 line from several channels (for instance, Ka from channels 1,2,3...)
2. the system can aggregate data of 2 lines only from 2 channels (for instance, La from channel 1 (TAP-crystal) and Ka from channel 3 (LIF-crystal))

The system cannot aggregate data of 2 lines from 3 channels and more (for instance, La from channels 1 and 2 (TAP-crystals) and Ka from channel 3 (LIF-crystal))

Probe for EPMA can aggregate duplicate element intensities that are the same element and same emission line at the same beam energy and on different spectrometers (not different channels).  Basically PFE aggregates intensities for both standards and unknown samples (to construct the k-ratio for quantification) regardless of the number of data points in each sample.

[Rom]

Of course different spectrometers (not different channels), sorry for using wrong terminology. Here

https://probesoftware.com/smf/index.php?topic=449.msg2479#msg2479

we can see Pt aggregated from 2 spectrometers: for Ma and La lines. Or Ma line was just disabled for calculation?

[John Donovan]

Of course different spectrometers (not different channels), sorry for using wrong terminology. Here

https://probesoftware.com/smf/index.php?topic=449.msg2479#msg2479

we can see Pt aggregated from 2 spectrometers: for Ma and La lines. Or Ma line was just disabled for calculation?

Yes, disabled.  The "-D" indicates the element channel has been disabled.

In later versions of Probe for EPMA, one can temporarily disable either the acquisition and/or the quantification.
john

[entoptics]

Thought I'd add another example of how you can get in trouble if using "Aggregate", and not treating the standards the same as the samples.

I set up a Rube Goldberg method on some samples as an experiment for TDI effects. It consisted of 3 passes, later to be combined using the "Combine the Selected Samples into a New Sample" feature in Analyze! I had several elements on multiple spectrometers, and was using MAN backgrounds.

Where things got tricky, was that the multiple spectrometer elements were on different passes. For example...

Pass 1 Na  -  Mn - Sr - S   - K
Pass 2 Mg -   Sr  - S  - Ba - Ca
Pass 3 Al  -   P   - Ba - Mn - Ti

PFE has no trouble using the aggregate intensity feature when all of the duplicate elements are in the same pass, because the first instance of the duplicated element is in the same standard/unknown sample.

When the duplicate elements are in different passes, and you just combine the unknowns into a new sample, PFE will aggregate the intensities in the new combined unknown, but PFE will use the first instance of that element in the standards, as it has no way of knowing there are further standards with that same element.

As indicated above, the cure for this is to combine your calibration standard passes into a new sample, and disable the individual passes. Now PFE has a standard that has the duplicated elements in one sample, and it can aggregate those standard intensities as intended.

Combined the calibration standards for S, Ba, and Sr and problem solved right?

But...

I was using MAN backgrounds! That means there isn't just one standard for Ba/Sr/S...there's a bunch that go into producing the MAN fit!

Because PFE was calculating MAN fit based on the single passes for all the MAN standards, and not able to aggregate the intensities for all passes, I was getting artificially low background calculations, and therefore artificially high concentrations.

So...

Combine all the MAN standards and disable the single passes...Boom. Done.

Moral of the story? You must treat all standards and samples the same when using the "Aggregate" feature.

[Scott B.]

I'm wondering how PFE deals with TDI for aggregate intensities. Does it calculate a TDI corrected intensity for each channel first, then aggregate that value? Or does it add the individual TDI recordings for each channel, then calculate a fit on the resulting TDI series for the corrected intensity?
 
I can see some statistical advantages to the 2nd option (more counts = less scatter), but I’m guessing logistically it would be tough, as the time intervals might not line up, and it seems like it would be a lot of wrangling, particularly if the aggregate channels aren’t happening at the same time.
 
Anyway, just curious about the sausage recipe…

[John Donovan]

I'm wondering how PFE deals with TDI for aggregate intensities. Does it calculate a TDI corrected intensity for each channel first, then aggregate that value? Or does it add the individual TDI recordings for each channel, then calculate a fit on the resulting TDI series for the corrected intensity?
 
I can see some statistical advantages to the 2nd option (more counts = less scatter), but I’m guessing logistically it would be tough, as the time intervals might not line up, and it seems like it would be a lot of wrangling, particularly if the aggregate channels aren’t happening at the same time.
 
Anyway, just curious about the sausage recipe…

Great question.

It's the latter, as we aggregate the interval intensities and then perform the TDI fit. Not easy to find, but see here for more details:

https://probesoftware.com/smf/index.php?topic=71.msg5140#msg5140

The same aggregate method is applied in our "TDI scanning" for performing TDI corrections for quantitative x-ray maps:

https://probesoftware.com/smf/index.php?topic=912.msg9110#msg9110

Though I don't have a TDI aggregate example on the forum to show.  But here is an aggregate quantitative mapping example without TDI:

https://probesoftware.com/smf/index.php?topic=41.msg2180#msg2180

Anyone have an example of a TDI aggregate mapping they can share here?

[Julien]

Here is an example of TDI mapping in K-rich hydrosulfate that I presented at M&M in 2019.

Cheers,

Julien

Edit by John: To see attachments, please login to the user forum.

[John Donovan]

Here is an example of TDI mapping in K-rich hydrosulfate that I presented at M&M in 2019.

Cheers,

Julien

Thanks Julien!

Do you also have an example of a TDI map with duplicate elements being aggregated?