Determination of experimental cross sections by activation method
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Determination of experimental cross-sections by activation method. Pierre-Jean Viellenave Tutor : Dr. Vladimir Wagner Nuclear Physics Institute, Academy of Sciences of Czech Republic. Contents. Introduction Spectrum analysis with DEIMOS32 Cross-sections calculation

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Determination of experimental cross-sections by activation method

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Determination of experimentalcross-sections by activation method

Pierre-Jean Viellenave

Tutor: Dr. Vladimir Wagner

Nuclear Physics Institute, Academy of Sciences of Czech Republic


Contents

  • Introduction

  • Spectrum analysiswith DEIMOS32

  • Cross-sections calculation

  • Statisticalanalysis (incertaintycalculation)

  • Results


Introduction

  • Myworkconsists:

    • In analysing gamma spectrumsfromexperimentwith DEIMOS32…

      • Experiment= measurement of radioactive sample (activated by activation method in a cyclotron) withdifferent configurations

    • …To getexperimental cross-sections


Spectrum analysiswith DEIMOS32

  • Gamma linespeakanalysiswith the software DEIMOS 32


Spectrum analysiswith DEIMOS32

  • We’re able to plan possible reactions and isotopes produced


Spectrum analysiswith DEIMOS32

  • Comparisonbetween the result tables from DEIMOS 32 analysis and the internet data base (decay data search) on gamma linesto identify the isotopes


Spectrum analysiswith DEIMOS32

  • 4 isotopes foundfrom (n,2n) to (n,4n) reactions and 1 isotope (198Au) foundfrom (n,gamma) reaction.


Dead time correction

Decay during cooling and measurement

Peak area

Self-absorption correction

Beam correction

γline intensity

Decay during irradiation

Weight normalization

Detector efficiency

Correction for coincidences

Square-emitter correction

Cross-sections calculation

  • Nyieldcalculation:


Cross-sections calculation

  • Detector efficiency (given):

    Nyield approximation:


Cross-sections calculation

  • Nyieldcalculation:

Sp: peak area

Iγ: gammaline intensity (in %)

Treal & Tlive: datas from exp.

λ: decay constant

Tirr: irradiation time

T0: beam end – start of measurement


Cross-sections calculation

  • Cross-section calculation:

Nn: neutrons number (depends on experiment)

mfoil: foil mass

S: foil size (in cm2)

A: mass number (197 for Au)

NA: Avogadro’s number (6,022.1023 {mol-1})


Statisticalanalysis

  • N yield_averagecalculation for each isotope => to increase the precision:

Aerr: incertainty of peak area (data from DEIMOS)

So =>


Statisticalanalysis

  • N yield_averagecalculation for each isotope => to increase the precision:

Aerr: incertainty of peak area (data from DEIMOS)

So =>


Statisticalanalysis

  • Finally:

With:


Results

197Au (n, 2n) 196Au


Results

197Au (n, 4n) 194Au


Results

197Au (n, 2n) 196m2Au


Results

  • Comments:

    • Fluctuations are purelysystematical

    • Nyield-averageisn’tdepending on the configuration

    • But the difference of Nyield-average(calculated for each gamma line and isotope) isbiggerthan the uncertainty of weightedaverage. It comesfrom the systematicuncertainty of efficiencydetermination.


Thankyou for your attention !!!


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