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Status on 62,63 Ni(n, g )

Status on 62,63 Ni(n, g ). Claudia Lederer Goethe University Frankfurt Cristian Massimi INFN Bologna. Introduction. 62 Ni(n, g ) measurement 2009 and 2011 63 Ni(n, g ) measurement 2011 Detector calibration: Weighting functions: Normalization: Background subtraction:

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Status on 62,63 Ni(n, g )

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  1. Status on 62,63Ni(n,g) Claudia Lederer Goethe University Frankfurt Cristian Massimi INFN Bologna

  2. Introduction • 62Ni(n,g) measurement 2009 and 2011 • 63Ni(n,g) measurement 2011 • Detector calibration: • Weighting functions: • Normalization: • Background subtraction: • Resonance analysis:

  3. Introduction • 62Ni(n,g) measurement 2009 and 2011 • 63Ni(n,g) measurement 2011 • Detector calibration: DONE • Weighting functions: DONE • Normalization: DONE • Background subtraction: EMPTY+AMBIENT (filter dips match to empty + filters) • Resonance analysis: This talk

  4. 62Ni(n,g) 2009 vs. 2011 • Agreement at low energy side <5%

  5. 62Ni(n,g) 2009 vs. 2011 • Agreement at low energy side <5% • Agreement individual resonances: to be investigated • This talk: only data of 2011 used

  6. 62Ni(n,g) known resonances

  7. 62Ni(n,g) known resonances

  8. Resonance analysis: • SAMMY • Reich Moore Approximation, RPI phase I, simulated BIF • Systematic uncertainties: 5.5% total (Flux, WFs, Normalization,..) propagated

  9. Resonance analysis: • SAMMY • Reich Moore Approximation, RPI phase I, simulated BIF • Systematic uncertainties: 5.5% total (Flux, WFs, Normalization,..) propagated Problems: • Fit results sometimes worse than initial parameters • Uncertainties given sometimes ridiculously small • Choice of correct fudge factor

  10. 62Ni(n,g) fit of known resonances 8-90 keV Gn= 581±6 meV Gg= 1014±10 meV ER= 9540 eV J=0.5- l=1 Gn= 35±0.3 meV Gg= 1000±10 meV ER= 8439 eV J=0.5- l=1

  11. 62Ni(n,g) fit of known resonances 8-90 keV Gn= 197±2 meV Gg= 1004±10 meV ER= 17793 eV J=0.5- l=1 Gn= 265±3 meV Gg= 1221±12 meV ER= 24625 eV J=0.5- l=1

  12. 62Ni(n,g) fit of known resonances 8-90 keV Gn= 1350±13 meV Gg= 997±10 meV ER= 29508 eV J=0.5- l=1 Gn= 562±6 meV Gg= 1088±11 meV ER= 28430 eV J=0.5- l=1

  13. 62Ni(n,g) fit of known resonances 8-90 keV Gn= 1829±18 meV Gg= 2000±20 meV ER= 38281 eV J=0.5- l=1 Gn= 544±5 meV Gg= 1004±11 meV ER= 34484 eV J=0.5- l=1 ?

  14. 62Ni(n,g) fit of known resonances 8-90 keV Gn= (3.5±0.3)e5 meV Gg= 700±7 meV ER43000 eV J=0.5+ l=0 Gn= 307±3 meV Gg= 945±9 meV ER= 40550 eV J=0.5- l=1 Gn= 308±3 meV Gg= 1016±10 meV ER= 41246 eV J=0.5- l=1

  15. 62Ni(n,g) fit of known resonances 8-90 keV Gn= 318±3 meV Gg= 987±10 meV ER= 53399 eV J=0.5- l=1 Gn= 14699±146 meV Gg= 281 ±3 meV ER= 57011 eV J=0.5- l=1 Gn= 1020±10 meV Gg= 970±10 meV ER= 45139 eV J=0.5- l=1

  16. 62Ni(n,g) fit of known resonances 8-90 keV Gn=2158±21 meV Gg= 1093±11 meV ER= 74433 eV J=0.5- l=1 Gn= 345±4 meV Gg= 1002±10 meV ER= 63449 eV J=0.5- l=1

  17. 62Ni(n,g) fit of known resonances 8-90 keV Gn=449±4 meV Gg= 3057±30 meV ER=77498 eV J=0.5+ l=0 Gn= 345±4 meV Gg= 1002±10 meV ER= 63449 eV J=0.5- l=1

  18. 62Ni(n,g) fit of known resonances 8-90 keV Gn=20825±207 meV Gg=538±53 meV ER=78505 eV J=0.5+ l=0 Gn= 345±4 meV Gg= 1002±10 meV ER= 63449 eV J=0.5- l=1

  19. The unfittable resonance at 4.6 keV Previous data:

  20. The unfittable resonance at 4.6 keV Case 1: keep Gn=1.822 keV constant Litvinskiy et al. Fit from 3-8 keV ER=4.641±0.003 eV Gg=2.895±0.003 eV

  21. The unfittable resonance at 4.6 keV Case 2: start with Gn=2.026 keV and Gg=2.376 eV (=JENDL) and vary everything Fit from 3-8 keV ER=4.617 keV Gg=3.037 eV Gn=2.042 eV

  22. The unfittable resonance at 4.6 keV Case 2: start with Gn=2.026 keV and Gg=2.376 eV (=JENDL) and vary everything Fit from 3-8 keV ER=4.617 keV Gg=3.037 eV Gn=2.042 eV ??????

  23. Problem with multiple scattering corrections? SAMMY input: Multiple, finite slab

  24. Multiple Scattering for 62Ni in 63Ni sample

  25. 62Ni in 63Ni sample Gn fixed to 1.8 keV: Gg~2.4 eV Fitting both: Gn =2.2 keV: Gg=3.2 eV Including first fit of 59Ni and 63Ni resonances (p wave assignment)  better agreement at thermal neutron energies

  26. 62Ni in 63Ni sample Gn fixed to 1.8 keV: Gg~2.4 eV Fitting both: Gn =2.2 keV: Gg=3.2 eV Thermal cross sections: 62Ni: 15 b (prev. 13-15 b) 63Ni: 25 b (prev. 20-26 b) Including first fit of 59Ni and 63Ni resonances (p wave assignment)  better agreement at thermal neutron energies

  27. Conclusions: • good progress on 63Ni data, sample composition known to about 1% accuracy (mass ratios 63/62, 59/62 etc...) • 62Ni sample is too thick to fit the 4.6 keV resonance since multiple scattering corrections are much larger than the 0-scattering capture yield • extraction of 62Ni RP for that resonance is problematic (powder sample, characterization...)  is it worth to remeasure that resonance with a thinner sample?

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