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Cross-sections of Neutron Threshold Reactions studied by activation method

Nuclear Physics Institute, Academy of Sciences of Czech Republic é cole des Mines de Nantes (France). Cross-sections of Neutron Threshold Reactions studied by activation method. Anne Larédo Supervisor: Dr. Vladimír Wagner. Plan. Introduction Uppsala experiment Spectrum analysis

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Cross-sections of Neutron Threshold Reactions studied by activation method

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  1. Nuclear Physics Institute, Academy of Sciences of Czech Republic école des Mines de Nantes (France) Cross-sections of Neutron Threshold Reactions studied by activation method Anne Larédo Supervisor: Dr. Vladimír Wagner

  2. Plan Introduction Uppsala experiment Spectrum analysis Cross section measurements Incertaintycalculation Correction calculation

  3. Introduction Threshold reactions on Au, Al, Bi, In, Ta, Ni, Zn, Y, I Up to nowalmost no experimental cross-section data for highenergyneutron reaction (E>20MeV) The Uppsala experimentenablenew cross-section measurements for highenergy neutrons (62 to 93 MeV). Myworkconsists in analysing the gamma spectrumresultingfrom the experiment to obtainexperimental cross-sections.

  4. Uppsala experiment (1/2) • Took place in February 2010 in Uppsala, Sweden • Neutron source : • quasi-monoenergetic • based on reaction 7Li(p,n)7Be • energy range  11-175 MeV • Proton beamenergies : 62, 70, 80, and 93 MeV

  5. Ta Al Au Bi Co In Uppsala experiment (2/2) Threshold reactions on Au, Al, Bi, In, Ta, Ni, Zn, Y, I Experimental disposition

  6. Spectrum analysis(1/5) • Gamma spectrumpeakanalysisusing DEIMOS32 software

  7. Spectrum analysis(2/5) Gamma spectrum for different neutron energy and different time

  8. Spectrum analysis(3/5) • Possible reactions and isotopes producted by thesereactionenable to know whatwe are looking for.

  9. Spectrum analysis(4/5) • Determination of present isotopes using the result tables from DEIMOS32 compare to data base (decay data search) on gamma radiations. • ..\ANALYSIS\Bi analysis - 4.xlsx

  10. Spectrum analysis(5/5) • 10 isotopes foundfrom (n,2n) to (n,9n) reactions

  11. 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-section measurement (1/4) • Determination of Nyield

  12. Cross-section measurement (2/4) First approximation of Nyield • Detector efficiencydetermination

  13. Cross-section measurement (3/4) • Peak area Sp : given by DEIMOS for eachpeak • γline intensity Iγ : fromdecay data search • treal : data fromexperiment • tlive : data fromexperiment • Decay constant λ : • T1/2 : data fromlibreries as decay data search • t0 = Beam end – start of measurement • tirr : time of irradiation

  14. Cross-section measurement (4/4) • Nyield : previouslycalculate • Nn : number of neutrons in peak (per cm²) • For experiment condition and energies • Foil mass mfoil (given data fromexperiment) • Foil size S : (2,5)² cm² = 6,25 cm² • Relative mass A : 208,98 [g.mol-1] • Avogadro’snumber NA = 6,022.1023

  15. Incertaintydetermination (1/4) First approximation : Nyield_average : mean of Nyield for a same neutron energy Ni : Nyieldfor a neutron energy Preciseanalysis :

  16. Incertaintydetermination (2/4) With : aerrdeimos : incertainty on the peak area from the software Deimos32 Then :

  17. Incertaintydetermination (3/4) Nextstep : If: Else : ..\ANALYSIS\Bi analysis - 4.xlsx

  18. Incertaintydetermination (4/4) Last step : combinaison of the relative uncertainty (from the Deimos data) with the uncertainty from intensity, neutron spectra, detector uncertainty : • ΔNyield_average : Deimosuncertainty • 10% : Beamintensityuncertainty • 10% : neutron spectrauncertainty • 3 % : detector efficiencyuncertainty Finally: ..\Results - Cross-section graphs\XS Bi vysledne srovnani.xls

  19. Results (1/7) Bi207: The results for this isotope are for now out range. Currentwork : usingspectrumfromafter and before irradiation to soustract the gammas which are not from the irradiation we are interrested in but fromprevious one.

  20. Results (2/7) Bi206: verysmallincertainty

  21. Results (3/7) Bi205:

  22. Results (4/7) Bi204:

  23. Results (5/7) Bi203:

  24. Results (6/7) Bi202:

  25. Results (7/7) Bi201:

  26. Correction calculation COI : correction for coincidencesbetweenseverals gamma rays of an isotope. ..\COI\COI calculation.xlsx Ba : Beam correction ..\beamcorr-Upps2010.xls Background correction ..\ANALYSIS\Bi analysis - 4.xlsx CS-A : Self absorption correction ..\Self-absorption\Self-absorption correction.xlsx

  27. Conclusion Now the first result for the cross section are calculated. Wecomparedexperimental datas to theorical model. Most importants correction have been added

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