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Kayzero for Windows: A complete NAA Data evaluation tool based on the orginal k 0 -method

Kayzero for Windows: A complete NAA Data evaluation tool based on the orginal k 0 -method. R. van Sluijs , k 0 -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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Kayzero for Windows: A complete NAA Data evaluation tool based on the orginal k 0 -method

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  1. 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 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  2. k0-Nuclear Data and Decay correction scheme’s • (all published in open literature) - Reactor parameters: f and α (Høgdahl-convention, well described) • Detection efficiency accounting for absortion in the sample • (according to Moens) • Irradiation and Measurement aspect: neutron self absortion in the • sample dead-time, counting time, coincidence correction etc. k0-formula (overview) 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  3. Or: a: analyte m: neutron fluence rate monitor k0-formula using Fc 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  4. k0-formula and comparator factor With Comparator Factor Fc: Relation between Fc and neutron fluence rate 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  5. k0-formula epicadmium ENAA FCd,a: cadmium transmission factor for epi-thermal neutrons 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  6. 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 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  7. Procedure: - Irradiate monitors (see k0-literature, vade mecum) - Enter Irradiation and Measurement Data - Press Calculate More accurate Solve: Result: - f &  - plot - uncertainty Reactor Calibration f and  Calibration methods: • Zr-Au-method • Multi-monitors: bare • Multi-monitors: Cd-covered • Multi-monitors: Cd-ratio 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  8. Reactor Calibration: f and α • 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 -> Re-calibrate if reactor configuration changes -> For most reactors f and αcalibration frequency is very low (every 1-2 years or less) ->Calculations look difficult but are automated 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  9. 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 Ωp = 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) 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  10. Detector Calibration a) Measure reference efficiency p using point-sources --> fit to efficiency curve (several polynomes) Fits for the 3 energy regions 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  11. Source Support Platform Position 3 Air Layer Position 2 Position Distance Source Support Position 1 VacuumGap Contact Layer Top Dead Layer Detector Can Active Crystal Inert Core Sample Vial 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 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  12. Position 3 Position 2 Position 1 VacuumGap Top Dead Layer Active Crystal 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) 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  13. Use p for the sample on hand: - select detector - select predifined vial - select position - give sample matrix composition (*) - give sample weight (*) - give filling height (**) Calculated using SOLCOI for solid-angles and coincidence correction factors. (*) Slower PC’s : Pre-calculate and use Matrix Interpolation (fixed filling height) (**) Fast PC’s : Direct Solid Angle Calculation Sample Source Support Vial Platform Position 3 Position 3 Air Layer Position 2 Position 2 Position Distance Source Support Position 1 Position 1 VacuumGap Contact Layer Top Dead Layer Detector Detector Can Active Crystal Inert Core 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 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  14. Irradiation aspects Not (yet) handled in Kayzero, but covered in literature 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  15. Measurement Aspects 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

  16. As for every k0-NAA-program: good knowledge of the • k0-method and gammaspectrometry remains essential for correct analysis results. 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. 4th International k0-Users Workshop, September 11th-14nd 2005, Funchal Portugal

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