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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.
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