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Experimental Determination of Neutron Cross Sections of Yttrium by Activation Method

Experimental Determination of Neutron Cross Sections of Yttrium by Activation Method. by Barbara Geier Supervisors: Assoc . Prof Dr. Wolfgang Sprengel RNDr . Vladimír Wagner Csc . Ing. Ondřej Svoboda. Internship at the Nuclear Spectroscopy Department of Nuclear Physics.

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Experimental Determination of Neutron Cross Sections of Yttrium by Activation Method

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  1. Experimental Determination of Neutron Cross Sectionsof Yttrium byActivationMethod by Barbara Geier Supervisors: Assoc. Prof Dr. Wolfgang Sprengel RNDr. Vladimír Wagner Csc. Ing. Ondřej Svoboda

  2. InternshipattheNuclearSpectroscopy Department ofNuclearPhysics

  3. Internship • Organizedby IAESTE Graz • 6 weeks • Departement ofNuclearSpectroscopy in Řež

  4. Summary • Irradiation of the yttrium foil by neutrons to produce radioactive isotopes • Analysing of the gamma emission of the daughternuclei by a germanium semiconductor detector • Determination of the area of a gamma peakwith the program DEIMOS32 • Determination of the number of producednucleiNyieldout of the peak area • Determination of the cross section for the single isotopes out of Nyield

  5. Introduction • Cross section: probabilityofnuclearreaction • Depends on theneutronenergy – excitationfunction Example:

  6. ActivationMethod • Reactionof a neutron beam withnucleitoproduceradioactive isotopes • Daughternucleistarttodecaybygammaemission • Semiconductor detector (foranalysinggammaemission) • Compton scattering • Photoeffect • Productionofelectron-positronpairs

  7. Experiment: Productionofthe Neutron Beam • EProtons: 35 MeV • Reaction: 7Li(p,n)7Be • ENeutrons: ~32 MeV • Yttrium sample was irradiatedfor 22 h Quasi- monoenergeticneutronspectrumfor a 7Li(p,n)7Be reaction, withprotonsat an energyof 35 MeV

  8. Experiment • Gamma emissionofyttrium sample was measured in a germaniumsemiconductordetectorfor different distances: 15, 23, 53, 70, 93, 173 mm

  9. Evaluation ofmeasuredgammaspectrumwith Deimos32 Determination ofareaanduncertaintyofareaforgammapeaks

  10. Corrections Nyield: Numberofproducednuclei in a givenfoil

  11. Corrections Weightedaverage: Uncertaintyofweightedaverage: 2 –test:

  12. PossibleReactions

  13. Radioactivepotassium isotope 40K • Gamma peakat an energyof 1460 keV • Analysedforreferencetoseeifthemeasurementwentsmoothly The ratiobetweentheareaofthegammapeakandthelife time ofthedetectorshouldbeconstant

  14. NumberofproducednucleiNyieldforthe isotope 88Y Gamma lines • Reaction: 89Y(n,2n)88Y • Half liveT1/2 = 106.95 d 898.0 keV 1836 keV Comparisonbetweenthe different measurementsofthe 23 mm distancebetween sample anddetectorforthegammalineat an energyof 898.0 keV

  15. NumberofproducednucleiNyieldforthe isotope 88Y The sample was turnedtotheotherside after eachmeasurement. Thereis a slightinfluence on theresultsbetweenside (a) (left) andside (b) (right) ofthe sample.

  16. Nyieldforthe isotope 88Y Comparisonbetweenthe different measurementsat different distancesforthe 898.0 keVgammaline:

  17. Nyieldforthe isotope 87Y Gamma lines • Reaction: 89Y(n,3n)87Y • Half liveT1/2 = 79.8 h 388.5 keV 484.8 keV Comparisonbetweenthe different measurementsof 23 mm distancebetween sample anddetectorforthegammalineat an energyof 388.5 keV

  18. Nyieldforthe isotope 87Y Nearly 100% decaysfromtheisomericstate87mY to87Y The equationforthechangeofradioactivenuclei after irradiationfor87Y is:

  19. Cross section

  20. Cross sectionfor88Y Cross sectionforthe89Y(n,2n)88Y reaction: (0.41±0.05) barn 1 barn = 10-28 m2

  21. Cross sectionfor87mY Cross sectionforthe89Y(n,3n)87mY reaction: (0.56±0.07) barn

  22. Cross sectionfor87Y +87mY Cross sectionforthe89Y(n,3n)87Y + 89Y(n,3n)87mY reaction: (0.77±0.08) barn

  23. Cross sectionfor87Y Cross sectionforthe89Y(n,3n)87Y reaction: (0.21±0.03) barn

  24. Thankyouforyourattention! • Questions?

  25. Calculationofthepeakefficiencycorrectionfactorforthedistanceof 173 mm

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