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Neutron inelastic scattering Neutron inelastic scattering measurements at the GELINA measurements at the GELINA
facility of EC-JRC-IRMMfacility of EC-JRC-IRMM
A. NegretA. Negret11, C. Borcea, C. Borcea11, A. Plompen, A. Plompen22
1 NIPNE-HH, Romania 2 EC-JRC-IRMM, Belgium
A. Negret - Neutron inelastic scattering measurements at GELINA
Summary
• Introduction
• Experimental setup
• Experimental results: 56Fe(n,n’)
• Data analysis
• Conclusions
A. Negret - Neutron inelastic scattering measurements at GELINA
Summary
• Introduction
• Experimental setup
• Experimental results: 56Fe(n,n’)
• Data analysis
• Conclusions
A. Negret - Neutron inelastic scattering measurements at GELINA Introduction
HH-NIPNE, Romania & EC-JRC-IRMM, Belgium
A. Negret - Neutron inelastic scattering measurements at GELINA Introduction
What do we measure
vn
(N,Z)
n
(N,Z)n
(N,Z)
(N+1,Z-1)
p
(N2,Z2)
(N1,Z1) n
n
Elastic scattering
Inelastic scattering
Nuclear reactions
Fission
Cross section ()
A. Negret - Neutron inelastic scattering measurements at GELINA Introduction
Neutron inelastic scattering
Gamma production cross section
Level cross section
Total cross section
A. Negret - Neutron inelastic scattering measurements at GELINA Introduction
Why do we measure inelastic cross sections
A. Negret - Neutron inelastic scattering measurements at GELINA Introduction
Sensitivity studies
How do we measure
A. Negret - Neutron inelastic scattering measurements at GELINA Introduction
A(n, n’)A(n, 2n)
Primary experimental result:Gamma production cross section
Databases:Level scheme
Level cross sectionTotal inelastic cross section
Uncertainty ~5% for the strongest transitions
Summary
• Introduction
• Experimental setup
• Experimental results: 56Fe(n,n’)
• Data analysis
• Conclusions
A. Negret - Neutron inelastic scattering measurements at GELINA
A. Negret - Neutron inelastic scattering measurements at GELINA Experimental setup
•Electron linac (150 MeV) + 238U target
•Pulse width ~1 ns
•Repetition rate: 800 Hz
•Energy range: 0 – 25 MeV
•Gamma flash from
bremsstrahlung
•Flight path: 200m
(~20 neutrons/burst)
Neutron source: GEel LINear Accelerator (GELINA)
A. Negret - Neutron inelastic scattering measurements at GELINA Experimental setup
8 HPGe detectors @ 110° & 150° (Accurate integration of angular distribution up to the sixth order of Legendre polynomials)
• TOF technique:Amplitude gamma energyTime neutron energy
• Digitizer-based acquisition (Acqiris DC440, 420 MS/s, 12 bits)
• Beam monitoring: 235U Fission chamber
Gamma Array for Inelastic Neutron Scattering (GAINS)
Acquisition Electronics
A. Negret - Neutron inelastic scattering measurements at GELINA Experimental setup
DC440 Acqiris digitizers:• 420 MS/s (2.38 ns/sample)
• 12 bits (4096 amplitude channels)
Summary
• Introduction
• Experimental setup
• Experimental results: 56Fe(n,n’)
• Data analysis
• Conclusions
A. Negret - Neutron inelastic scattering measurements at GELINA
A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)
56Fe(n,n’)
Sample: • natFe (56Fe / natFe = 91.75%) • Thickness: 3mm, 1mm, 4mm• Purity 99.5%
Beam time:• 3 mm sample: 6 weeks• 4 mm sample: 3 weeks• 1 mm sample: 2 weeks• additional checks: 5 weeks
A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)
56Fe(n,n’): gamma spectrum
A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)
846.8 keV gamma production cross section
A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)
1238.3 keV gamma production cross section
A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)
1810.8 keV gamma production cross section
846.8 keV level cross section
A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)
A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)
2085.1 keV level cross section
A. Negret - Neutron inelastic scattering measurements at GELINA Results: 56Fe(n,n’)
Total inelastic level cross section
A. Negret - Neutron inelastic scattering measurements at GELINA
Summary
• Introduction
• Experimental setup
• Experimental results: 56Fe(n,n’)
• Data analysis
• Conclusions
A. Negret - Neutron inelastic scattering measurements at GELINA Data analysis
Sensible points of the analysis: background of the 846.8 keV transition The strongest gamma transition (846.8 keV) may overlap with:
• 72Ge(n,n’): 834 keV + Ge recoil energy
• 27Al(n,n’): 844 keV
A. Negret - Neutron inelastic scattering measurements at GELINA Data analysis
206Pb(n,n’) check
A. Negret - Neutron inelastic scattering measurements at GELINA Data analysis
56Fe(n,n’) with various sample thicknesses
A. Negret - Neutron inelastic scattering measurements at GELINA
Summary
• Introduction
• Experimental setup
• Experimental results: 56Fe(n,n’)
• Data analysis
• Conclusions
A. Negret - Neutron inelastic scattering measurements at GELINA Conclusions
Conclusions
• We measured 56Fe(n,n’) cross sections using the GELINA neutron source and the GAINS gamma spectrometer of EC-JRC-IRMM:
• gamma production cross sections• level cross sections• total inelastic cross section
• Very detailed consistency checks were performed to make sure that the data are reliable.
• Significant differences from the previous measurements persist and remain unexplained.