1. Determination of experimental cross-sections by activation method
Pierre-Jean Viellenave
Tutor: Dr. Vladimir Wagner
Nuclear Physics Institute, Academy of Sciences of Czech Republic

2. Contents Introduction Spectrum analysis with DEIMOS32
Cross-sections calculation
Statistical analysis (incertainty calculation)
Results

3. 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

4. Spectrum analysis with DEIMOS32
Gamma lines peak analysis with the software DEIMOS 32

5. Spectrum analysis with DEIMOS32
We’re able to plan possible reactions and isotopes produced

6. 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

7. Spectrum analysis with DEIMOS32
4 isotopes found from (n,2n) to (n,4n) reactions and 1 isotope (198Au) found from (n,gamma) reaction.

8. 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

9. Cross-sections calculation
Detector efficiency (given):
Nyield approximation:

10. 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

11. 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})

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

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

14. Statistical analysis
Finally:
With:

15. Results
197Au (n, 2n) 196Au

16. Results
197Au (n, 4n) 194Au

17. Results
197Au (n, 2n) 196m2Au

18. 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.

19. Thank you for your attention !!!