Neutron inelastic scattering measurements at the GELINA facility of EC-JRC-IRMM A. Negret 1, C....

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 Introduction

HH-NIPNE, Romania & EC-JRC-IRMM, Belgium


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 ()


Neutron inelastic scattering

Gamma production cross section

Level cross section

Total cross section


Why do we measure inelastic cross sections


Sensitivity studies

How do we measure


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



• Data analysis

• Conclusions


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)


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


DC440 Acqiris digitizers:• 420 MS/s (2.38 ns/sample)

• 12 bits (4096 amplitude channels)

Summary

• Introduction



• Data analysis

• Conclusions


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


56Fe(n,n’): gamma spectrum


846.8 keV gamma production cross section

846.8 keV level cross section



2085.1 keV level cross section


Total inelastic level cross section


Summary

• Introduction



• 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


206Pb(n,n’) check


56Fe(n,n’) with various sample thicknesses


Summary

• Introduction



• 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.

Neutron inelastic scattering measurements at the GELINA facility of EC-JRC-IRMM A. Negret 1, C....

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