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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

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

k 0 formula overview

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

k 0 formula using fc

Or:

a: analyte

m: neutron fluence rate monitor

k0-formula using Fc

4th International k0-Users Workshop,

September 11th-14nd 2005, Funchal Portugal

k 0 formula and comparator factor
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

k 0 formula epicadmium enaa
k0-formula epicadmium ENAA

FCd,a: cadmium transmission factor for epi-thermal neutrons

4th International k0-Users Workshop,

September 11th-14nd 2005, Funchal Portugal

k 0 formula fc benefits
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

reactor calibration f and

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

reactor calibration f and1
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

detector calibration
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

detector calibration1
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

detector calibration2

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

detector calibration3

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

detector calibration4

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

irradiation aspects
Irradiation aspects

Not (yet) handled in Kayzero, but covered in literature

4th International k0-Users Workshop,

September 11th-14nd 2005, Funchal Portugal

measurement aspects
Measurement Aspects

4th International k0-Users Workshop,

September 11th-14nd 2005, Funchal Portugal

conclusion

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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