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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

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**Contents Introduction Spectrum analysis with DEIMOS32**

Cross-sections calculation Statistical analysis (incertainty calculation) Results

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**Introduction My work consists:**

In analysing gamma spectrums from experiment with DEIMOS32… Experiment = measurement of radioactive sample (activated by activation method in a cyclotron) with different configurations …To get experimental cross-sections Different configurations = We measured the sample on one side then of the other one several times to make a statistical analysis and obtain a better precision of the results

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**Spectrum analysis with DEIMOS32**

Gamma lines peak analysis with the software DEIMOS 32

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**Spectrum analysis with DEIMOS32**

We’re able to plan possible reactions and isotopes produced

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**Spectrum analysis with DEIMOS32**

Comparison between the result tables from DEIMOS 32 analysis and the internet data base (decay data search) on gamma lines to identify the isotopes

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**Spectrum analysis with DEIMOS32**

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

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**Cross-sections calculation**

Nyield calculation: Peak area Self-absorption correction Beam correction Dead time correction Decay during cooling and measurement γline intensity Detector efficiency Correction for coincidences Square-emitter correction Weight normalization Decay during irradiation

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**Cross-sections calculation**

Detector efficiency (given): Nyield approximation:

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**Cross-sections calculation**

Nyield calculation: Sp: peak area Iγ: gamma line intensity (in %) Treal & Tlive: datas from exp. λ: decay constant Tirr: irradiation time T0: beam end – start of measurement

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**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, {mol-1})

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Statistical analysis N yield_average calculation for each isotope => to increase the precision: Aerr: incertainty of peak area (data from DEIMOS) So =>

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Statistical analysis N yield_average calculation for each isotope => to increase the precision: Aerr: incertainty of peak area (data from DEIMOS) So =>

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Statistical analysis Finally: With:

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Results 197Au (n, 2n) 196Au

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Results 197Au (n, 4n) 194Au

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Results 197Au (n, 2n) 196m2Au

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**Results Comments: Fluctuations are purely systematical**

Nyield-average isn’t depending on the configuration But the difference of Nyield-average (calculated for each gamma line and isotope) is bigger than the uncertainty of weighted average. It comes from the systematic uncertainty of efficiency determination.

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**Thank you for your attention !!!**

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