1. 2015 Cameca Users Meeting Background characterization – must account for background shape Curvature Spectrometer efficiency Natural Bremsstrahlung shape Interferences From elements in the excitation volume From elements fluoresced from a distance – can be 10s to 100s of microns Absorption edges S K edge S K  S K  Bi Mα

2. Background characterization – must account for background shape ‘Holes’ Compositional variation within phase of interest 2012 Workshop: Dating Tectonic Events using Monazite/Xenotime

3. 2015 Cameca Users Meeting Background characterization – must account for background shape ‘Holes’ Compositional variation within phase of interest

4. 2015 Cameca Users Meeting Curvature and interferences…

5. 2015 Cameca Users Meeting

14. Ti Kα1 (2)

15. Th Mα Th Mβ High net intensity (pk-bkg) and large pk/bkg Major element analysis is primarily characterization of peaks… 2015 Cameca Users Meeting

16. Measured net Int. 20% error, ~350ppm error Correct net Int. Trace element analysis is primarily characterization of background… 2015 Cameca Users Meeting

17. Curvature and interferences… 2015 Cameca Users Meeting

19. How do we know the analysis is correct ? Analysis of elemental concentration Test against secondary standard of “known” composition Secondary must be appropriate for monazite, etc. REE phosphate Th U Very difficult to find or make homogeneous trace element secondary standard 2015 Cameca Users Meeting

20. If you can’t check against a known value, then try for a zero result in something appropriate that doesn’t have any of the trace element of interest (blank). Clearly, “If you can’t analyze something, then see if you can analyze nothing…” “Because, if you can’t do nothing right, then you can’t do anything.” A start for assessing accuracy…Blank analysis 2015 Cameca Users Meeting

21. Test for Pb in synthetic GdPO4 (no Pb flux!) Savitsky – Golay low pass filter 2015 Cameca Users Meeting

22. Savitsky – Golay low pass filter 2015 Cameca Users Meeting

23. Blank test for Pb 2015 Cameca Users Meeting

24. Blank test for Pb 2015 Cameca Users Meeting

25. Determination of background intensity by the multipoint method Fit via exponential or polynomial regression 2015 Cameca Users Meeting

26. Determination of background intensity by the multipoint method Blank testing… GdPO4PrPO4 Avg allStd dev.Avg allStd dev. 0.00410.0048-0.00590.0033 0.01170.00240.01230.0018 0.00040.00270.00060.0016 0.00330.0096-0.00860.0028 0.01330.00150.01290.0019 0.00120.0042-0.00220.0016 -0.00190.0096-0.01300.0026 0.00930.00150.01020.0019 -0.00890.0044-0.01260.0017 Multipt bkg U Th Pb 2-pts bkg, EXP. U Th Pb 2-pts bkg, LIN. U Th Pb 2015 Cameca Users Meeting

28. Interferences and absorption edges… It’s not just background, but background on interference correction measurements also

29. 2015 Cameca Users Meeting Interferences and absorption edges…

30. 2015 Cameca Users Meeting Interferences and absorption edges… How do we measure the interference correction?

31. 2015 Cameca Users Meeting Interferences and absorption edges… How do we measure the interference correction?

32. 2015 Cameca Users Meeting Interferences and absorption edges… How do we measure the interference correction?

33. 2015 Cameca Users Meeting Interferences and absorption edges… How do we measure the interference correction?

34. 2015 Cameca Users Meeting Interferences and absorption edges…

35. 2015 Cameca Users Meeting Interferences and absorption edges…

36. 2015 Cameca Users Meeting Interferences and absorption edges…

37. 2015 Cameca Users Meeting Interferences and absorption edges…

38. 2015 Cameca Users Meeting Interferences and absorption edges…

39. 2015 Cameca Users Meeting