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

Determination of experimentalcross-sections by activation method

Pierre-Jean Viellenave

Tutor: Dr. Vladimir Wagner

Nuclear Physics Institute, Academy of Sciences of Czech Republic


Contents
Contents

  • Introduction

  • Spectrum analysiswith DEIMOS32

  • Cross-sections calculation

  • Statisticalanalysis (incertaintycalculation)

  • Results


Introduction
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 analysis with deimos32
Spectrum analysiswith DEIMOS32

  • Gamma linespeakanalysiswith the software DEIMOS 32


Spectrum analysis with deimos321
Spectrum analysiswith DEIMOS32

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


Spectrum analysis with deimos322
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 analysis with deimos323
Spectrum analysiswith DEIMOS32

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


Cross sections calculation

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 calculation1
Cross-sections calculation

  • Detector efficiency (given):

    Nyield approximation:


Cross sections calculation2
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 calculation3
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})


Statistical analysis
Statisticalanalysis

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

Aerr: incertainty of peak area (data from DEIMOS)

So =>


Statistical analysis1
Statisticalanalysis

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

Aerr: incertainty of peak area (data from DEIMOS)

So =>


Statistical analysis2
Statisticalanalysis

  • Finally:

With:


Results
Results

197Au (n, 2n) 196Au


Results1
Results

197Au (n, 4n) 194Au


Results2
Results

197Au (n, 2n) 196m2Au


Results3
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.


Determination of experimental cross sections by activation method

Thankyou for your attention !!!