www.kayzero.com

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NAA using Kayzerofrom peak areas to element
concentration

• R. van Sluijs, k0-ware, Heerlen, the Netherlands
• D. Bossus, DSM Geleen, the Netherlands
• F. De Corte, RUG, Ghent, Belgium

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Problem? No problem!?
Simple? Perhaps not, but very well
documented! nowadays there
are many programs to help!
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No problem,but ..... (1)

• How to get the correct peak area?
• Use a perfect gamma spectrometry system and keep
  it in the best possible condition!
• Use the perfect gamma spectrum deconvolution
  program!
• However who has this perfect set-up?

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No problem, but......... (2)

• How to select the analytical line
• K0-library has data for 68 elements, 144 nuclides
  and more than 700 gamma-lines
• For a panoramic analysis you use preferably 2
  irradiations (short and long) each followed by
  2-3 measurements
• A single element will give data for several
  nuclides and probably tens of gamma lines.
• All we want one single list
• Containing the all elements with their
  concentrations and/or limits of detection.

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DSMs/Kayzeros method
User Input
Automatic

• Optimise the peak table!
• Peak Table Areas and Energies from gamma
  spectrum deconvolution program
• Calculation
• Concentrations for all lines in the k0- library
• Evaluation
• Identify the nuclides in the sample
• Correct for gamma interferences
• Calculate averages per nuclide and per element
• Average over all measurements
• Refine the results

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Optimise the peak table!

• Peak Areas
• Broadened peaks (due to count rate effects, bad
  pile-up correction, etc..) can be split by the
  gammaspectrum deconvolution program into two
  separate peaks.
• Sum the false/artificial peaks for a correct
  result
• Peak locations
• Linear energy calibration, non-linear is often
  better
• Re-do the energy calibration
• Hypermet shifts data 1 channel to the left
• Shift back

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Measurement Input screen
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Peak summation screen

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Re-do energy calibration

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k0-calculations

• Calculate concentrations for all library lines
• Including Corrections for
• background,
• dead-time,
• gamma-absorption,
• burn-up,
• neutron self absorption,
• True-coincidence correction
• No matching peak the LD concentration is
  calculated using the spectrum base line.
• No result if calculated concentration gt100

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Evaluation of the results Check the presence of
a nuclide
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Evaluation of the resultsCheck the presence of
an element
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Evaluation of the resultsCorrect for gamma
interferences

• Nnumber of interfering
• nuclides on line E

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Evaluation of all results Calculate averages and
standard deviations

• over the lines of a nuclide
• weighing factor wi 1/s2i
• sobserved should be approx. equal to sexpected

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Refine the resultsselect the analytical lines

• Select by hand
• gammas to be used
• correct for threshold, fission, second-order
  reaction interferences,
• blank correction,
• Alarm for high epi-thermal self shielding

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Ba-131 large observed SD
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Deselect Ba-131 line
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Fission Correction for La-140
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Fission Correction
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Blank subtraction
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The goal of all our worka (digital) list of
concentrations
51 elements reported 30 with concentration, 21
only detection limit
Final result
51 elements reported - 30 concentrations - 21
only detection limit
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Conclusion

• k0-method (DeCorte/Simonits) is a very complete
  method, all aspects of INAA are taken into
  account, elaborate calculations are needed but
  this is no problem nowadays
• The method presented to handle k0-data is based
  on almost 20 years of experience, analysing all
  kinds of samples
• Evaluation of the data of a panoramic elemental
  analysis of an unknown sample takes less than
  half an hour
• Although very much automated the analyst is in
  control
• The competition in our lab is though, NAA is the
  most expensive technique so quality and
  reliability is a prerequisite