status on 62,63 ni(n, ) claudia lederer goethe university frankfurt cristian massimi infn bologna
TRANSCRIPT
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?