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Status on 62,63Ni(n,)
Claudia LedererGoethe University Frankfurt
Cristian MassimiINFN Bologna
Introduction• 62Ni(n,) measurement 2009 and 2011• 63Ni(n,) measurement 2011• Detector calibration: • Weighting functions:• Normalization:• Background subtraction:• Resonance analysis:
Introduction• 62Ni(n,) measurement 2009 and 2011• 63Ni(n,) measurement 2011• Detector calibration: DONE• Weighting functions: DONE• Normalization: DONE• Background subtraction: EMPTY+AMBIENT (filter
dips match to empty + filters)• Resonance analysis: This talk
62Ni(n,) 2009 vs. 2011
• Agreement at low energy side <5%
62Ni(n,) 2009 vs. 2011
• Agreement at low energy side <5%• Agreement individual resonances: to be
investigated• This talk: only data of 2011 used
62Ni(n,) known resonances
62Ni(n,) known resonances
Resonance analysis:• SAMMY• Reich Moore Approximation, RPI phase I,
simulated BIF• Systematic uncertainties: 5.5% total (Flux,
WFs, Normalization,..) propagated
Resonance analysis:• SAMMY• Reich Moore Approximation, RPI phase I, simulated
BIF• Systematic uncertainties: 5.5% total (Flux, WFs,
Normalization,..) propagatedProblems:• Fit results sometimes worse than initial parameters• Uncertainties given sometimes ridiculously small• Choice of correct fudge factor
62Ni(n,) fit of known resonances 8-90 keV
n= 35±0.3 meV
= 1000±10 meV
ER= 8439 eV
J=0.5- l=1
n= 581±6 meV
= 1014±10 meV
ER= 9540 eV
J=0.5- l=1
62Ni(n,) fit of known resonances 8-90 keV
n= 197±2 meV
= 1004±10 meV
ER= 17793 eV
J=0.5- l=1
n= 265±3 meV
= 1221±12 meV
ER= 24625 eV
J=0.5- l=1
62Ni(n,) fit of known resonances 8-90 keV
n= 562±6 meV
= 1088±11 meV
ER= 28430 eV
J=0.5- l=1
n= 1350±13 meV
= 997±10 meV
ER= 29508 eV
J=0.5- l=1
62Ni(n,) fit of known resonances 8-90 keV
n= 544±5 meV
= 1004±11 meV
ER= 34484 eV
J=0.5- l=1
n= 1829±18 meV
= 2000±20 meV
ER= 38281 eV
J=0.5- l=1
?
62Ni(n,) fit of known resonances 8-90 keV
n= 307±3 meV
= 945±9 meV
ER= 40550 eV
J=0.5- l=1
n= 308±3 meV
= 1016±10 meV
ER= 41246 eV
J=0.5- l=1
n= (3.5±0.3)e5 meV
= 700±7 meV
ER43000 eV
J=0.5+ l=0
62Ni(n,) fit of known resonances 8-90 keV
n= 1020±10 meV
= 970±10 meV
ER= 45139 eV
J=0.5- l=1
n= 318±3 meV
= 987±10 meV
ER= 53399 eV
J=0.5- l=1
n= 14699±146 meV
= 281 ±3 meV
ER= 57011 eV
J=0.5- l=1
62Ni(n,) fit of known resonances 8-90 keV
n= 345±4 meV
= 1002±10 meV
ER= 63449 eV
J=0.5- l=1
n=2158±21 meV
= 1093±11 meV
ER= 74433 eV
J=0.5- l=1
62Ni(n,) fit of known resonances 8-90 keV
n= 345±4 meV
= 1002±10 meV
ER= 63449 eV
J=0.5- l=1
n=449±4 meV
= 3057±30 meV
ER=77498 eV
J=0.5+ l=0
62Ni(n,) fit of known resonances 8-90 keV
n= 345±4 meV
= 1002±10 meV
ER= 63449 eV
J=0.5- l=1
n=20825±207 meV
=538±53 meV
ER=78505 eV
J=0.5+ l=0
The unfittable resonance at 4.6 keV
Previous data:
The unfittable resonance at 4.6 keV
Case 1: keep n=1.822 keV constant Litvinskiy et al.
Fit from 3-8 keV
ER=4.641±0.003 eV
=2.895±0.003 eV
The unfittable resonance at 4.6 keV
Case 2: start with n=2.026 keV and =2.376 eV (=JENDL) and vary everything
Fit from 3-8 keV
ER=4.617 keV
=3.037 eV
n=2.042 eV
The unfittable resonance at 4.6 keV
Case 2: start with n=2.026 keV and =2.376 eV (=JENDL) and vary everything
Fit from 3-8 keV
ER=4.617 keV
=3.037 eV
n=2.042 eV
??????
Problem with multiple scattering corrections?
SAMMY input:
Multiple, finite slab
Multiple Scattering for 62Ni in 63Ni sample
62Ni in 63Ni samplen fixed to 1.8 keV: ~2.4 eV
Fitting both: n =2.2 keV: =3.2 eV
Including first fit of 59Ni and 63Ni resonances (p wave assignment) better agreement at thermal neutron energies
62Ni in 63Ni samplen fixed to 1.8 keV: ~2.4 eV
Fitting both: n =2.2 keV: =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
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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