www'kayzero'com

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Kayzero for Windows A complete NAA Data
evaluation tool based on the orginal k0-method

• R. van Sluijs, k0-ware, Heerlen, the Netherlands
• A. De Wispelaere, UG, Gent, Belgium
• D. Bossus, DSM, Geleen, the Netherlands
• F. De Corte, UG, Gent, Belgium

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k0-formula (overview)
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k0-formula using Fc
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k0-formula and comparator factor
With Comparator Factor Fc
Relation between Fc and neutron fluence rate
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k0-formula epicadmium ENAA
FCd,a cadmium transmission factor for
epi-thermal neutrons
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k0-formula Fc benefits

• Fc is proportional to ?e
• Fc is independent of monitor element, detection
  efficiency (Asp is not)
• Fc allows averaging
• Fc gives information on
• flux gradients (several monitors in a irr. vial)
• flux stability (monitor history)
• Detects any gross irregularities in efficiency,
  data-entry, decay times

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Reactor Calibration f and ?

• Calibration methods
• Zr-Au-method
• Multi-monitors bare
• Multi-monitors Cd-covered
• Multi-monitors Cd-ratio

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Reactor Calibration f and a

• Zr-Au method
• - uses only two monitors
• - can be done easily with every irradiation
• - optimized to reduce measurement uncertainties
• Cd-ratio method
• - most accurate but takes more irradiations and
  measurements
• -gt Re-calibrate if reactor configuration changes
• -gt For most reactors f and a calibration
  frequency is very low (every 1-2 years or less)
• -gtCalculations look difficult but are automated

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Detector Calibration
Full-energy peak detection efficiency ?p,
concept a) Measure reference efficiency() using
point-sources b) Convert ?p,ref to ?p for
counting geometry/position
geo sample geometry/position ref reference
position ?p effective solid angle ? p full
energy peak detection efficiency for photon
energy p () At a position true-coincidence free
position ()See Moens et al.(1981) and Moens and
Hoste (1983)
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Detector Calibration
a) Measure reference efficiency ?p using
point-sources --gt fit to efficiency curve
(several polynomes)
Fits for the 3 energy regions
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Detector Calibration
b) Calculate effective solid angles (?s)
- Numerical Integration Program Solang () -
Input needed dimensions and material
com-positions and densities of sample
(vial) detector (from manufacturer)
source support - Fine-tuning of Vacuum Gap
(VG) and Top Dead Layer (TDL)-Thickness. (
)For Cylindrical and concentric detector
(p-type) and sources smaller than detector
diameter
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Detector Calibration
b) Fine tune to find vacuum gap and dead-layer
thickness
Fine Tuning - select detector - select
geometry per source - enter peak area countrates
- press the button Results in a best
guess Refine manually if needed (instantaneous
results)
Fine-tuning of VG and TDL-Thickness Measure
true-coincidence free isotopes at different
positions and optimize values VG and TDL (See
De Wispelaere et al., Proc. Int. k0 -Users
Workshop, Gent Belgium, 1992)
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Detector Calibration
Calibration Procedure - measure reference
efficiency - fit-reference efficiency - collect
all dimensions and detector material compositions
and densities - fine tune Vacuum Gap and Top Dead
Layer using measurements of true-coincidence free
isotopes - calculate the effective solid angles
for the reference position
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Irradiation aspects
Not (yet) handled in Kayzero, but covered in
literature
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Measurement Aspects
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Conclusion

• The k0-method describes INAA in fysical and
  mathematical understandable definitions and is
  very suitable for computer evaluation.
• With the modern tools k0-NAA can serve as a
  routine analysis technique
• The necessary k0-method calibrations are
  reasonable elaborate but straight forward.
• All data, formulas and other aspects of k0-INAA
  incorporated in Kayzero are traceable to
  open-literature.
• As with every program good knowledge of the
  k0-method and gammaspectrometry remains essential
  for correct and error-free use.