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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.

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

- 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 =>

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.

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